JPS61202585A - Magnetic recording device for camera signal - Google Patents

Abstract

PURPOSE:To obtain a clear reproduced picture without doubling even if the period of the lock signal of a camera switching device is made short by so forming the title device that the synchronous signal is converted to a frame synchronizing signal, and the synchronized video signals from respective video cameras are sequentially switched based on the said converted signal, and the recorded in a magnetic recording means. CONSTITUTION:When the intermittent recording mode is selected by a mode selecting switch, the video signal is intermittently transferred to the magnetic tape of a VTR 3 at every frame with a prescribed time interval in advance. The clock signal for the above operation is supplied to a switch controller 23 via a switch 51, and a video switch 22 is sequentially switched in synchromization with the said clock signal, accordingly, the signal is recorded to the VTR 3 to which the respective video signals from the video cameras C1, C2, C3, ...CN are sequentially inputted by every frame. When the continuous recording mode is being selected by the mode selecting switch, the field synchronizing signal from a synchronous signal generator 21 is supplied in parallel to the respective video cameras C1, C2, C3, ...CN of plural cameras 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a camera signal magnetic recording device, and more particularly to a device for switching video signals from a plurality of black and white or color video cameras and magnetically recording them on a magnetic tape. It is.

[Prior Art] A series of system equipment consisting of a single black-and-white or color video camera or a plurality of video cameras, a camera switcher that controls switching of these video cameras, and a monitor television has conventionally been used for crime prevention, It has been widely used in banks and supermarkets for monitoring purposes. Furthermore, since magnetic recording devices (hereinafter abbreviated as VTR) have become popular for consumer use at low cost over the past few years, the above-mentioned system equipment can be
In combination with R, it became possible to record video camera signals on magnetic tape and later inspect and analyze the recorded contents.

On the other hand, VTR recording time can now be up to eight hours using the VH8 system as an example, making it possible to cover normal business hours. However, it is troublesome to change video cassette tapes every day, and 8W
# If you want to record for more than 2 hours, if the video cassette tape ends in the middle, you will not be able to fit it onto one tape.
Furthermore, so-called intermittent recording, in which the magnetic tape is moved intermittently, is used for reasons such as the fact that even if it is not recorded continuously 24/7 but is recorded in pieces over time, so-called frame-drop recording, there is no problem in practical engineering. A VTR based on this method was developed.

When this is used, intermittent recording can be performed for any length of time on one video cassette tape, such as 24 hours, 48 hours, or even longer if the period of intermittent recording is longer, and the above-mentioned disadvantages can be solved.

In addition, we have adopted the current normal recording, so-called continuous recording method, to this intermittent recording method VTR, and
If the recording format can be automatically converted for I-fold signals,
The intermittent recording method is used during normal, safe conditions, but in the event of an emergency, when a control signal is sent to the VTR, the system instantly converts to continuous recording, making it possible to record the situation at the scene in great detail.

Next, a conventional camera signal magnetic recording device will be explained. First, the configuration of this device will be explained. This camera signal magnetic recording device is mainly composed of an intermittent recording type VTR and a continuous recording type VTR, a plurality of video cameras, and a camera switch. In more detail, V.T.
R includes a magnetic tape for recording the video signal of the video camera and a mode selection switch for selecting intermittent recording or continuous recording of the video signal, and during intermittent recording, a clock signal synchronized with the cycle of intermittent recording is sent to the VTR. is output from. The plurality of video cameras may be black and white or color video cameras. The camera switcher has a synchronization signal generator that generates a field synchronization signal to match the timing of the vertical synchronization signal of each video camera's video signal, and a synchronization signal generator that sequentially switches the video signals of each video camera to output one video signal. It consists of a video switch that controls switching, and a switching controller that controls switching of this video switch.

Next, the intermittent recording operation of this device will be explained. During intermittent recording, a clock signal from the VTR is given to the switching controller, and the switching controller t11j controls switching of the video switch using this clock signal, and the video switch sequentially switches the video signals from each video camera. derived. The video signal for one frame from each video camera corresponding to the switching position of this video switch is VT.
The clock signal is input to R and recorded on the magnetic tape, and the entire apparatus is in a standby state until the next clock signal is applied to the switching controller. By repeating these operations, the video signals from each video camera are sequentially recorded one frame at a time on the magnetic tape.

Next, the continuous recording operation of this device will be explained. During continuous recording, the clock signal is not output from the VTR,
A clock signal fixed to a predetermined video camera or a clock signal generated within the camera switch is applied to the switch controller. The switching controller controls switching of the video switch using this clock signal, and the video signal of a designated video camera is derived from the video switch, or the video signals from each video camera are sequentially switched and derived. The video signals of the designated video camera corresponding to the switching position of the video switch or of each video camera that is sequentially switched are continuously recorded on the magnetic tape in the usual manner.

[Problems to be solved by the invention] In the case of continuous recording, there are times when it is necessary to use all the video cameras to capture the constantly changing situation at the scene, which is usually an emergency situation. The video cameras are switched one after another by an internally generated clock signal, so that apparently all the video cameras are recorded.

However, this internal output signal is normally suppressed to a minimum of about 0.5 seconds. For example, if there are 8 video cameras, the time it takes for one cycle of switching is 0.5 seconds x 8-4 seconds. For a single video camera, video signals are only recorded on magnetic tape every 4 seconds, and
Even though R is making continuous recording, it is extremely difficult to record the contents of all the video cameras in detail.

Therefore, it would seem better to shorten the period of the internal clock signal, but this is not possible for the following reasons. V
In TR, in order to control the magnetic tape and rotating drum during playback, a so-called control signal is recorded on the magnetic tape in synchronization with the frame period of the video signal during recording, and this control signal and the internal clock of the video switch If the signal cycles are not synchronized, the signal for one frame, that is, one frame at the moment the video camera is switched, will contain one frame of the video camera before switching and one frame of the video camera after switching. One field is apparently recorded on the magnetic tape as one frame signal. If you play this back, the screens of both video cameras will appear as duplicates. If the period of the internal clock signal is 0.5 seconds and the frame period is 1/30 seconds, the rate at which the above double screen appears is (1/30) , /' 0 , 5
= 17715, which is at a level that poses no problem in practical use, but there is a problem in that if the period of the internal clock signal is shortened, double screens occur frequently, making it impractical.

One way to solve these problems would be to connect all video cameras to a single VTR, but this is far from practical in terms of cost, stack space, and the complexity of inspecting and analyzing recorded magnetic tape. It cannot be said that it is a method that can be used for

The present invention was made to solve this problem, and an object of the present invention is to provide a camera signal magnetic recording device that can obtain clear reproduced images without duplication even if the cycle of the clock signal of the camera switch is shortened. shall be.

Means for Solving Problem E] The camera signal magnetic recording device according to the present invention synchronizes the video signals of a plurality of video cameras using a synchronization signal from a synchronization signal generating means, and converts the synchronization signal into a frame by a conversion means. The switching means sequentially switches the video signals of the synchronized video cameras based on the frame synchronization signal, and the video signals from the switching means are magnetically recorded in synchronization with the frame synchronization signal. It was designed to be recorded on the means.

[Operation] In the present invention, by sequentially switching the video signals of each video camera synchronized by the switching means based on the frame synchronization signal, each video signal for each frame is input to the VTR, and the video signals for each frame are input to the VTR. Each video signal is recorded on the magnetic recording means in synchronization with the frame synchronization signal, so one field of the video signal before switching and one field of the video signal after switching appear. It is not recorded as an upper frame signal.

[Example] As described above, the shorter the period of the clock signal, the more clearly the situation at the site can be recorded. In the shortest possible case, the video camera should be switched for each frame of the video signal, and this invention was developed based on this idea.

FIG. 1 is a block diagram of a camera signal magnetic recording device according to an embodiment of the present invention, and FIG. 2 is a time chart showing the operation timing of each part of this device. First, the configuration of this device will be explained. In the figure, the camera signal magnetic recording device is mainly composed of a plurality of video cameras 1, a camera switch 2, a magnetic recording device (VTR) 3, a bistable multivibrator 4, and a changeover switch 5. . To explain in more detail, the plurality of video cameras 1 include N color or black and white video cameras C.
It is composed of I, C2, C3, C4, . . . CN. The camera switch 2 includes a synchronization signal generator 21 that generates a field synchronization signal, a video switch 22 that sequentially switches each video signal from N video cameras, and a switching controller 23 that controls switching of the video switch 22. It is composed of.

The VTR3 includes a mode selection switch for selecting intermittent recording or continuous recording of video signals, and the VTR3 records each video signal of the video cameras C1, C2, C3, C4°...CN intermittently or continuously on a magnetic tape. to be recorded. Further, during intermittent recording, the VTR3 outputs a clock signal synchronized with the cycle of the intermittent recording. The bistable multivibrator 4 reduces the period of the field synchronization signal from the synchronization signal generator 21 to half to generate a frame synchronization signal. The changeover switch 5 is composed of a switch 51 and a switch 52.
3 and, in the case of continuous recording, a frame synchronization signal from the bistable multivibrator 4. The switch 52 is switched to apply a frame synchronization signal to the VTR 3 only in the case of continuous recording.

Next, the intermittent recording operation of this device will be explained. When the intermittent recording mode is selected by the mode selection switch, the magnetic tape of the VTR 3 is intermittently sent one frame at a time of the video signal at preset time intervals, and at this time the above clock signal is output. . This clock signal is applied to the switching W unit 23 via the switch 51, and the video switches 22 are sequentially switched in synchronization with the clock signal. Thus, VTR3 has video camera C.
Each video signal from CN 1, C2, C3, . . . is input one frame at a time and recorded on the magnetic tape.

Next, the continuous recording operation of this apparatus will be explained with reference to the time chart of FIG. Here, a case will be described in which there are four video cameras, but cases in which the number of video cameras is different can also be explained using the same concept as in the following explanation. When the continuous recording mode is selected by the mode selection switch, the field synchronization signal from the synchronization signal generator 21 is transmitted to each video camera CI, C2 of the plurality of video cameras 1.
°C3, . . . Video camera C1 signal and video camera C2 signal given in parallel to CN and shown in FIG.

Create the timing of the vertical synchronization signal of the video camera C3 signal and video camera 04 signal. This field synchronization signal is also given to the bistable multivibrator 4 at the same time, and the second
As shown in the figure, a frame synchronization signal 4g is created in which the t'' state is inverted when the field synchronization signal is applied.

The frame synchronization signal is applied to the switching controller 23 via a switch 51 and to the VTR 3 via a switch 52.

The switching controller 23 generates a control signal that sequentially switches the video switches 22 every time a switching signal, which is a frame synchronization signal, is applied from the changeover switch 5. Thus, the video switch 22 outputs the video camera C1 signal and the video camera C2 signal every frame period, as shown in FIG.

Video camera C3 signal, video camera C4 signal.

Video camera C1 signal, video camera C2 signal.

. . . are obtained, and these video signals are continuously and sequentially recorded on the magnetic tape of the VTR 3. On the other hand, since the VTR 3 is given a frame synchronization signal, the frame period of the video signal of each video camera and the period of the control signal of the VTR 3 are synchronized, and this frame synchronization signal is sent to the magnetic field via the control head of the VTR 3. It is recorded directly on the tape as a control signal. The purpose of this control signal is to identify one frame of the video signal during playback.

As described above, the magnetic tape of the VTR 3 records a video signal in which the video camera signal is sequentially switched every frame period, and a control signal synchronized with the frame period of this video signal.

Naturally, in a VTR without intermittent recording, no clock signal is output, so the switch 51 is omitted and the frame synchronization signal, which is the output of the bistable multivibrator 4, is switched.
Just connect it directly to the tlJm device 23. At the same time, the switch 52 is turned on to use the frame synchronization signal as a control signal for the VTR 3. In addition, if there is only one video camera, turn off the switch 52 and use a normal VTR.
used as.

With the above camera transmission @ magnetic recording device, it is safe!
By setting the VTR to intermittent recording mode and synchronizing the switching of multiple video cameras to the intermittent cycle, each frame of the magnetic tape records the corresponding camera signal, significantly reducing the amount of magnetic tape used. can do.

Furthermore, in the event of an emergency, by continuously operating the VTR and switching between multiple video cameras frame by frame, the situation at the scene can be precisely recorded on the magnetic tape.

[Effects of the Invention] As described above, according to the present invention, the video signals of a plurality of video cameras are synchronized by the synchronization signal from the synchronization signal generating means, and the same signal is converted into a frame synchronization signal by the conversion means. , based on the frame synchronization signal, the switching means t sequentially switches the video signals of the synchronized video cameras, and the video signal F from the switching means is synchronized with the frame synchronization signal t, and the magnetic recording means Since the video signals of multiple video cameras are switched sequentially and recorded continuously on the VTR, the IgJa of the video camera is different from the 17 r of the video signal before switching the video cameras. One field of the subsequent video signal appears to be one frame L, and is not recorded as a signal. Therefore, it is possible to obtain a camera signal magnetic recording device that can provide clear reproduced images without any blemishes.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a camera signal magnetic recording device which is an embodiment of the present invention. FIG. 2 is a time chart showing the operation timing of each part of the camera signal magnetic recording device according to the embodiment of the present invention. In the figure, 1 is a plurality of video cameras, C1°C2,
C3, C4,...CN is a video camera, 2 is a camera switch, 3 is a magnetic recording device (VTR), 4 is a bistable multivibrator, 5 is a changeover switch, 51.52 is a switch, 21 is a synchronization signal generator 22 is a video switch, 2
3 is a switching controller. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (3)

[Claims] (1) a plurality of video cameras; a synchronization signal generation means for generating a synchronization signal for synchronizing the video signals of each of the video cameras; a conversion means for converting the synchronization signal into a frame synchronization signal; and the conversion means A camera signal magnet comprising: a switching means for sequentially switching the video signals of each of the video cameras in response to an output; and a magnetic recording means for magnetically recording the video signal from the switching means periodically on the output of the converting means. Recording device. (2) The camera signal magnetic recording device according to claim 1, wherein the frame synchronization signal is recorded as a synchronization control signal in the magnetic recording means. (3) The magnetic recording means includes: a mode selection means for selecting continuous recording or intermittent recording of the video signal; and an intermittent synchronization signal generation means for generating an intermittent periodic signal synchronized with the intermittent recording; In response to the mode selection means selection output, in the case of the continuous recording, the frame synchronization signal is output to the switching means and the magnetic recording means, and in the case of the intermittent recording, the intermittent periodic signal is outputted to the switching means. 3. The camera signal magnetic recording apparatus according to claim 1, wherein the video signal of each video camera is sequentially switched in response to the intermittent synchronization signal.