JPH10243384A - Time lapse vtr - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extremely extend the life of a rotating head and to record continuous video before the generation of an alarm signal on a tape by successively writing intermittently recorded input signals in a first memory device, continuously recording the contents on a tape and endlessly recording continuous television signals in a second memory device. SOLUTION: Intermittently recorded input signals are successively written in a first memory device 4, and intermittence/continuity conversion is operated. Thus, they are recorded in a VTR 11 as continuous signals, and as a result, a recording magnetic pattern on a tape becomes normal regardless of the intermittent recording. Also, the input signals are continuously recorded in a second memory device 5, and also endless recording is set. Thus, the previous videos are always left only for a time corresponding to the memory capacity, and the endless recording in the second memory device 5 is stopped according to the input of an alarm signal so that the continuous videos before the point of time of the generation of the alarm signal are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called time-lapse VT for long-time recording used in a surveillance camera or the like.
R, and more particularly to a recording method of the video signal.

[0002]

2. Description of the Related Art A VTR used for a general purpose has a recording time of several hours, and is not suitable for recording for more than 24 hours for recording an unexpected situation. Therefore, for such a purpose, a long-time recording VTR called a time-lapse VTR has been developed and used. This VTR
In this example, the normal VTR is intermittently fed to increase the recording time. For example, if recording is performed one field per second, the recording time is extended 60 times.

[0003] At present, 960 tapes for two hours are used.
A VTR capable of recording time has also been developed. In this case 4
That is, the time is extended by 80 times, and one field is recorded every 16 seconds. Originally, recording is performed for 960 hours on a two-hour recording tape, so that there are various problems, and a solution is awaited.

[0004]

As is apparent from the purpose, a time-lapse VTR samples continuous events at regular intervals and records them for a long period of time, and reproduces them when an unexpected event occurs. . On the other hand, the VTR is unsuitable for use such as recording only one field and stopping it while waiting for the next recording.

Therefore, during the recording mode, the VTR is in an operating state.
It can be said that it is almost the same as the recording state of the TR. For example, in the 960 hour mode, it is difficult to record one field, that is, 1/60 second, and stop for about 16 seconds as described above. As a result, during this time, only the tape transfer is stopped and other operations are performed. Become.

On the other hand, the rotating head of a VTR wears little by little due to sliding with a tape.
It is said that the usage limit is from 00 hours to 2000 hours.
This life is greatly affected by the usage environment, but 20
It is difficult to greatly exceed 00 hours. Therefore 960
If the tape is used in the time mode, the life of the tape will be reached when two tapes are recorded. This is a period of 80 days.

Next, the magnetic pattern recorded on the tape of the VTR is determined on the assumption that the tape is running at a constant speed, and is determined by the tape speed and the rotating head speed. In a normal consumer VTR, the inclination angle of the pattern drawn by the rotary head when the tape is stopped is more sluggish than during running. Therefore, it is difficult to match the pattern while intermittently feeding the tape, since the tape is started from a stop at a constant speed in a very short time.

As a result, recording by intermittent feeding causes a recording pattern to be inconsistent with a regular pattern, causing a problem of compatibility. In addition, since tracking cannot be performed correctly during reproduction, the S / N deteriorates at the top and bottom of the screen. Become. As described above, it is no exaggeration to say that the problems caused by intermittent feed and the wear of the rotary head are two major problems in the quality of the current time-lapse VTR.

As a functional problem, in order for the time-lapse VTR to be useful for investigating the cause of an unexpected situation, it is important to know the situation immediately before the event occurs. On the other hand, since the alarm signal is normally issued upon detecting that "thing has happened", the image before that is skipped and skipped, and the decisive moment may not be recorded as the image.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to match the recorded tape pattern with a regular pattern which is the same as that during normal running, and extend the life of the rotary head. It is an object of the present invention to provide a time-lapse VTR capable of recording a continuous image before tape generation of an alarm signal on a tape.

[0011]

In order to achieve the above object, a time-lapse VT in which continuous input television signals are intermittently recorded by thinning them out in units of an integral multiple of a field.
In R, a plurality of writable and readable memory devices are provided, and input signals to be intermittently recorded are sequentially written to the first memory device, and when the memory device is written by a predetermined amount, the contents are written. A continuous signal is read out and continuously recorded on a tape, and a continuous television signal is recorded endlessly in a second memory device.

It is also useful to provide an alarm signal input terminal, stop the endless recording to the second memory device by inputting a signal to the terminal, and continuously record the input television signal on the tape. is there.

Furthermore, the continuous recording of the input television signal on the tape is terminated under predetermined conditions, the recording is returned to the first memory device intermittently, and the contents of the second memory device are continuously recorded on the tape. It is also useful to return the second memory device to endless recording thereafter.

[0014]

The time-lapse VTR having the above-described structure includes a plurality of memory devices, and sequentially writes input signals to be intermittently recorded in the first memory device to perform intermittent-continuous conversion. Is recorded as a continuous signal. As a result, the recording magnetic pattern on the tape can be made regular even though the recording is intermittent.

In the second memory device, the input signal is continuously recorded, and since the endless recording is performed, the immediately preceding image always remains for a time corresponding to the memory capacity. By stopping the endless recording in the second memory device, it is possible to obtain a continuous image before the alarm signal is generated.

Since the recording on the tape changes from an intermittent video to a continuous video due to the input of the alarm signal, the video after the alarm signal is generated is not thinned out. Stop the continuous recording of the television signal, return to the intermittent recording to the first memory device, and transfer the contents of the second memory device to the tape, so that the continuous video from before the alarm signal is generated until after it is recorded on the tape I can do things.

Further, as described above, since the intermittent video is stored in the memory device and then continuously recorded on the tape, the VTR can be stopped except during the continuous recording period, so that the life of the rotary head is significantly extended. I can do things. For example, if it is possible to store one minute of video in the memory device, the 960-hour mode will record continuously for one minute every eight hours and the remaining seven
The VTR can be stopped for 59 minutes.

[0018]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a main part of an embodiment of the present invention.

A television signal such as a television camera output is applied to the input terminal 1 of FIG. This signal is applied to the AD converter 2, the synchronization separation circuit 6, and the switch II circuit 8. The synchronization signal is extracted from the input signal by the synchronization separation circuit 6 and applied to the timing controller circuit 7 to generate control pulses required for each circuit and send them to each of them.

The input signal applied to the AD converter 2 is converted into a digital signal using a clock pulse or the like created by the timing controller circuit 7. Normally, 8 bits are used for AD conversion of a video signal. The digitized signal is applied to the field sampling circuit 3 and the memory II device 5.

The field sampling circuit 3 is a circuit for thinning out an input signal at a preset ratio in a unit of an integral multiple of a field. For example, when recording is performed for 96 hours using a 2-hour tape, the input signal is set to 1/48. become. That is, 48
Only one field is sampled between the fields, and only the sampled field is sent to the memory I device 4. The sampling pulse is created by the timing controller circuit 7.

Digital data enters the memory I unit 4 intermittently and is stored at an address designated by the timing controller circuit 7 each time. On the other hand, data is continuously input to the memory II device 5,
The data is sequentially stored at the address specified by the timing controller circuit 7.

When the memory capacity of the memory II device 5 becomes full, old data is rewritten in order of new data. Therefore, it is constantly updated with new data,
It is an endless record. The top address at which the latest data is written is always known by the timing controller circuit 7, and when the writing is stopped, the immediately preceding data can be read in chronological order.

When the capacity of the memory I device 4 becomes full, the mode of the device becomes the read mode, and the contents thereof are sequentially read out, enter the DA converter 9 via the switch I circuit 10, and return to the analog signal. Here, the switch I circuit 10
The DA converter 9 is controlled by the timing controller circuit 7. The signal that has been DA converted and returned to analog passes through the switch II circuit 8, enters the VTR 11, and is continuously recorded. When the reading of the contents of the memory I device 4 ends, the VTR 11 stops again, the rotating head (not shown) also stops, and the memory I device 4 returns to the write mode.

When the memory I device 4 is in the read mode, a signal may be sent from the field sampling circuit 3. The timing is known by the timing controller circuit 7, and each time the signal is sent from the memory I device 4. Is set to the write mode, and reading is performed continuously. When the memory I device 4 is a semiconductor memory, the same address cannot be simultaneously written and read, but the control is performed by the timing controller circuit 7.

The memory I device 4 and the memory II device 5 are written as separate blocks in FIG.
One device may be divided into two regions and used.
The device may be a semiconductor memory or a hard disk drive. In short, it is divided into multiple areas,
It suffices if they can be used individually equivalently, regardless of how they are physically configured.

Next, the operation when an alarm signal is applied to the input terminal 12 will be described. The alarm signal is generated in an emergency or the like, and is, for example, a signal for detecting a trespass in security of a building. When this signal is added, the timing controller circuit 7 switches the switch II circuit 8 to the input terminal 1 side and sets the VTR 11 to continuous recording. At that time, even in the continuous recording mode by a signal from the memory I device 4, the operation is immediately stopped and the above operation is started.

When the switch II circuit 8 is on the input terminal 1 side, the field sampling circuit 3 stops sampling and the memory I device 4 stops writing. Similarly, writing to the memory II device is stopped. Here, if we add a little explanation about the alarm signal,
In this practical example, the presence / absence of the same signal, that is, a 1-bit signal, is handled. However, the signal need not always be 1 bit, and may be a signal of several bits representing temperature, for example.

An example using an alarm signal of several bits will be briefly described (not shown). For example, before switching the switch II circuit 8 to set the VTR 11 in the continuous recording mode according to the value, the sampling of the field sampling circuit 3 is performed. It is possible to capture a video signal corresponding to the alarm signal by changing the ratio.

After the VTR 11 enters the continuous recording mode in response to the input of the alarm signal, it returns to the original state when a predetermined condition is satisfied. Usually, this condition is set by a combination of the case where the alarm signal disappears or the case where a certain period of time has passed. However, when a few bits of the alarm signal are used, it is possible to adaptively return according to the value. I can do it. For example, when the temperature is used as an alarm signal, it is possible to end the continuous recording mode of the VTR 11 when the temperature reaches a predetermined temperature.

At the time when the VTR 11 ends the above-described continuous recording, a mode for transferring the contents of the memory II unit 5 to the VTR 11 is entered. At this time, the switch I circuit 10 switches to the memory II device 5 side, and the switch II circuit 8
Side. The contents of the memory II device 5 are sequentially read, returned to the analog signal by the DA converter 9 via the switch I circuit, and passed through the switch II circuit 8 to the V signal.
Continuously recorded in TR11 and switch I circuit 10
Is switched to the memory device 4 side.

When the reading of the contents of the memory II device 5 is completed, the device again enters the endless recording mode. When the VTR 11 ends the continuous recording by the alarm signal, the field sampling circuit 3 enters the original sampling mode again and is sequentially written into the memory I device 4.

In this embodiment, the description is made by treating the digitally converted television signal as it is. It is well known that the capacity of the memory device can be significantly reduced by performing data compression. In this case, a data compression circuit may be inserted into the output of the AD converter 2, and a data decompression circuit may be inserted immediately before the DA converter 9. Motion JPEG method, wavelet transform,
An MPEG system or the like is possible.

Although field sampling is performed after digitization, it goes without saying that field sampling can be performed in an analog state. In this case, the input signal from the input terminal 1 enters the field sampling circuit first and then enters the AD converter. Therefore Memory II
Another AD converter is required for the device. VTR11
It goes without saying that even if the and other blocks are separated as separate devices, they can be used.

[0035]

Since the present invention is configured as described above, it has the following excellent effects.

(1) The wear per hour of the rotary head can be significantly reduced, and the life can be extended. As a result, the time for replacing the rotary head can be significantly extended. (2) The magnetic pattern recorded on the tape can be changed to the state when the tape runs, and a good S / N image can be obtained during reproduction. (3) An image before the occurrence of the alarm signal can always be obtained and can be recorded on the tape, which makes it extremely easy to determine the cause afterward. (4) The degree of thinning can be changed by an alarm signal, and time-lapse recording can be performed according to an expected event when an alarm signal is generated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a time lapse VTR embodying the present invention.

[Explanation of symbols]

 1.12 Input terminal AD converter 3. Field sampling circuit 4. 4. Memory I device 5. Memory II device 6. Synchronization separation circuit 7. Timing controller circuit 8. Switch II circuit DA converter 10. Switch I circuit 11. VTR

Claims (3)

[Claims] 1. A time-lapse VTR for intermittently recording a continuous input television signal by thinning it out in units of an integral multiple of a field, comprising a plurality of writable and readable memory devices, and intermittently recording an input signal. Are sequentially written to the first memory device, and when the memory device is written by a predetermined amount, the contents of the memory device are read out as a continuous signal and are continuously recorded on the tape,
A time-lapse VTR characterized in that continuous television signals are recorded endlessly in a second memory device. 2. An alarm signal input terminal, wherein endless recording to a second memory device is stopped by a signal input to the terminal, and an input television signal is continuously recorded on a tape. The time lapse VTR according to claim 1, wherein 3. The continuous recording of the input television signal on the tape is terminated under predetermined conditions, the recording is returned to the intermittent recording on the first memory device, and the contents of the second memory device are continuously recorded on the tape. 3. The time-lapse VTR according to claim 2, wherein the second memory device is returned to endless recording thereafter.