JPS62248154A - Video tape recorder - Google Patents

Abstract

PURPOSE:To surely record/reproduce a desired pattern by comparing a video signal of a reference pattern stored in a memory with a present video signal so as to switch the operating mode based on the comparison output. CONSTITUTION:When a pattern desired to be observed once more is displayed on a receiver during the reproduction of a magnetic tape T, the user closes a switch 14 to write a desired pattern digital video signal in a field memory 15. The VTR is switched into the search mode after the reproduction of said program and a search mode control signal from a system control circuit 17 is supplied and the tape T is searched in the opposite direction. Thus, the comparison circuit 16 compares the digitized reproducing video signal with the digital video signal of the desired pattern read from the memory 15. As a result, a coincidence output is fed from the circuit 16. when both the comparison and reference video signals are coincident. Thus, a still mode signal is fed to a running control circuit 9 from the circuit 17 and a desired pattern is subjected to still reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to operating mode switching of a video tape recorder.

[Summary of the invention]

The present invention compares the video signal of the standard It & 11 screen stored in the memory with the current video signal, and switches the operation mode of the video tape recorder based on this comparison, thereby ensuring that the desired screen is recorded. I set it to 5 for playback.

[Conventional technology]

Conventionally, in order to reproduce the desired screen of a particular set of examiners recorded on videotape, a videotape recorder (
VTR) y As a high-speed playback (search) mode, a tape counter that mechanically measures the amount of tape travel based on the rotation of the reel, or a control signal (C
Using the reading of the CTL counter that electrically counts the VT as a clue, the tape is run at high speed until it reaches the predicted recording position, and after finding the desired screen on the receiver's playback screen, the VT
The user would switch the FL to low-speed playback mode, check the desired screen, and switch to static playback mode if necessary.

Furthermore, when a phenomenon whose occurrence is difficult to predict, such as volcanic activity, is to be monitored over a long period of time, a long-term recording device that utilizes a TV right camera and VTR is used.

The mainstream of such recording devices is to reduce the consumption of magnetic tape by keeping the rotary head constantly rotating and recording every few frames of one field instead of feeding the recording tape at a very slow speed. However, the applicant has
As disclosed in No. 1-32,674, only the camera is kept in constant operation, and when the sensor detects, for example, an explosion sound, the shutter of the camera is opened, and
Some VTRs, which were in a standby state, are activated to record video signals for one field using a low-speed rotating head.

[Problem that the invention seeks to solve]

However, with conventional VTRs, when in search mode, it is difficult to reliably search for the correct recording position of a desired screen depending on the tape counter or CTL counter, and there is a problem that it is tedious to keep an eye on the playback screen. there were.

In addition, when used for long-term recording, if the rotating head is constantly operated, the rotating head and tape may be damaged, and if the VT)L is kept on standby, a sensor is required and monitoring is required. There is a problem in that the sensor may detect sounds or the like associated with a phenomenon that is not targeted, leading to a malfunction.

In view of the above, an object of the present invention is to provide a video tape recorder that can reliably record and reproduce a desired screen.

[Means for solving problems]

The present invention comprises an analog-to-digital converter for converting an analog video signal into a digital video signal, a storage means for storing the digital video signal, and a reference digital video signal read from the means and an analog-to-digital converter. The video tape recorder is provided with a comparison means for comparing the output of the video tape and the output of the video tape, and the operation mode is switched based on the comparison output of the comparison means.

[Effect]

According to this configuration, a desired screen is reliably recorded and reproduced.

〔Example〕

An embodiment of a video tape recorder according to the present invention will be described below with reference to FIG.

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, the magnetic tape T is fed out from a supply reel (υ) and wound onto a take-up reel (2), while a pair of magnetic heads HA and HB are mounted at an angle of 1800. The drum (3) K is wound at a predetermined angle and passed between the pinch roller P and the capstan (4).A motor ( 53 and (6) are each connected,
The rotating drum (3) and capstan (4) K are motors (
and (8) are respectively combined. Reference numeral (9) is a travel control circuit, which outputs an appropriate drive output according to each operation mode of the VTR to both reel motors t51. (61, drum motor (power and supplied to capstan motor (8).

The reproduced RF signals from the magnetic heads HA and HB are sent to the signal processing circuit U via a head changeover switch (not shown).
supplied to υ. The analog video signal output from the signal processing circuit is led to an output terminal +12, and is supplied to a receiver (not shown), as well as an A-D converter (13). The digital video signal from 13 is supplied to the field memory α9 via the switch α, and is also supplied as a comparison input to the comparison circuit tIQ.This comparison circuit contains a field memo') Q51
The digital video signal read from the comparator circuit is supplied as a reference input, the output of the comparison circuit is supplied to the system control circuit αη, and the mode control signal from the system control circuit α is supplied to the travel control circuit (9). .

The operation of this embodiment is as follows.

During playback of the magnetic tape T on which a specific program is recorded, if a screen that the user wants to see again later is displayed on the receiver, the user closes switch I and the digital video signal of the desired screen is displayed on the field. Written to memory us. After the program is played, the VTR is switched to search mode, and a search mode control signal is supplied from the system control circuit aη, and the reel motor (5) and (
6) is supplied with a drive output for high-speed reproduction in the reverse direction, and a drive output is supplied to the drum motor (force), and the tape T running at high speed in the reverse direction is scanned by the magnetic heads HA and H9 to perform a reverse search. will be carried out.

Then, the comparison circuit 4 compares the digitized high-speed reproduction video signal and the digital video signal of the desired screen read from the field memory (151) on a field-by-field basis.

The comparison circuit (le) includes a counting circuit, and when both the comparison and reference video signals match at a predetermined number or more sample points for each line of the screen, the counting circuit advances; It is configured so that a matching output is obtained when the step is performed.

When a coincidence output is supplied from the comparator circuit, a stationary mode control signal is sent from the system control circuit (Iη) to the travel control circuit (9).
), tape running is stopped and the desired screen is reliably played back statically.

Note that in the search mode, a predetermined portion on the screen where the noise par appears is excluded from comparison. Furthermore, since the reproduced signal from the tape includes no-signal portions due to dropouts and the like, corrections such as smoothing are performed.

Next, another embodiment of the present invention will be described with reference to FIG.

Another embodiment of the invention is shown in FIG. In FIG. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals and redundant explanation will be omitted.

In Figure 2, the video signal from the TV camera ■ is VT
It is commonly supplied to the A-D converter (13) and the signal processing circuit through the input terminal υ of R, and the output of the signal processing circuit is connected to the magnetic head HA via a head changeover switch (not shown). and HB.

The rest of the structure is the same as the embodiment shown in FIG.

The operation of the embodiment of FIG. 2 is as follows.

First, a TV camera (to) is installed at a predetermined monitoring position to capture an image of a normal scene in which the phenomenon to be monitored does not occur, and a digital video signal of this scene is transmitted by closing switch I.
It is stored in field memory a9.

The TV camera 2■ continues to be in operation to monitor the target phenomenon, and the VTR is switched to recording pause mode. Then, the comparator compares the surveillance video signal from the TV camera (a) with the normal video signal read from the field memory.

Since both video signals generally match until a phenomenon to be monitored occurs, in this embodiment, the recording pause mode of the VTR is maintained while a matching output is obtained from the comparator circuit 4. Ru.

Note that, in order to confirm the normal operation of the monitoring device at a later date, regular recording may be performed, for example, recording one screen every hour.

When a phenomenon to be monitored occurs and the monitoring video signal from the TV camera (7) becomes different from the normal video signal from the memo IJ (15), a discrepancy output is supplied from the comparison circuit 4 to the system control circuit η. and the system control circuit (l
A recording mode control signal is supplied from η to the travel control circuit (9). This allows the pinch roller P to move from the capstan (
4), drive output is supplied to each motor (5j to (8)), and a video signal of the monitoring phenomenon is transmitted to the tape T running at a specified speed in the forward direction via the magnetic head H and HB. is recorded.

In both of the above-described embodiments, the storage means is a field memory, but it may of course be a frame memory, or in some cases, a sheet-like recording medium such as a video floppy.

Further, in the embodiment shown in FIG. 1, the desired screen to be stored in the memory may be the screen viewed during recording.

Furthermore, when reproducing a magnetic tape on which periodic recording has been performed using the embodiment shown in FIG.
It is also possible to switch to the low-speed playback mode at the position where the video signal of the monitoring phenomenon is recorded.

〔Effect of the invention〕

As described in detail above, according to the present invention, the image 1# of the reference screen stored in the memory! Since the signal is compared with the current video signal and the operation mode is switched based on the comparison output, a video tape recorder that can reliably record and reproduce a desired screen can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of one embodiment of a video tape recorder according to the invention, and FIG. 2 is a block diagram showing the structure of another embodiment of the invention. (9) is a travel control circuit, aυ and - are signal processing circuits,
Q3) is an analog-to-digital converter, (151 is a field memory, uQ is a comparison circuit, αη is a system control circuit, and (to) is a TV left camera.

Claims (1)

[Scope of Claims] An analog-to-digital converter for converting an analog video signal into a digital video signal, storage means for storing the digital video signal, a reference digital video signal read from the storage means, and the analog-to-digital converter for converting an analog video signal into a digital video signal; A video tape recorder comprising: comparison means for comparing the output of the digital converter, and an operation mode is switched based on the comparison output of the comparison means.