JPS62200990A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform satisfactory variable speed reproduction without using an A/D converter, a D/A converter and a frame memory in a recording part by changing the ratio of the interlace of an image pickup tube when using a method for dividing one field of a video signal into plural tracks and recording. CONSTITUTION:There are provided an image pickup means 20 for dividing the video signal of the one frame of the number N of scanning lines, and a frame cycle Tf into 2n sets of the video signals in the interlace of 2n:1 (n=2, 3, 4, ..., N/2), an FM modulating means 21, recording and reproducing means 22-25 for sequentially assigning one set of the FM modulated video signals to one of 2n tracks on a magnetic tape by a rotating head 2 rotating at the cycle of Tf/n, an FM demodulating means 26 and the A/D converting means 27 and the memory means 28. The stored reproducing video signals are rearranged for the scanning line unit and the memory means 28 is controlled to have the video signal of the interlace of 2:1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a helical scan video tape recorder (hereinafter abbreviated as VTR), and particularly when one field is divided into multiple tracks for recording, it is possible to perform good variable speed playback. The present invention relates to a video signal recording and reproducing device suitable for a camera-integrated or portable VTR.

Conventional technology A rotating two-head helical scan VTR is employed as a basic system in many VTRs, typified by the VF6 and β systems. The basic recording format of this VTR is shown in FIG. 3a. In the figure, 1 is the magnetic tape, 2 is the recording track, is the tape running direction, H is the head moving direction, and P is 1
This is the distance that the magnetic tape travels during the frame (2) yield). (In the case of 2:1 interlace) A, B, C, and D correspond to the positions shown in Figure 3 on the screen. The number of rotations of a rotary head cylinder on which a magnetic head of a VTR having a mechanical system capable of forming such a recording format is mounted is equal to the frame frequency.

In order to record a wider band video signal using this VTR, it is necessary to increase the relative speed between the head and the tape. For example, if you want to record a signal with twice the band of the original video signal, you will need to rotate the rotating cylinder at twice the number of rotations, and the tape running speed will also have to be twice that of the original video signal.
It needs to be doubled.

In this case, the number of recording tracks in Figure 3 B.

Points B, C, and D appear on the screen as shown in Figure 3, C.

Furthermore, in this case, P is the distance that the magnetic tape travels during one field.

The method of dividing one field of images into a plurality of parts (segments) on the time axis and recording each part on a separate track is called a segment recording method.

The disadvantages of this method are (1) the presence of head switching points within the screen; (2) Since the head crosses the track during variable speed reproduction, the segment positions within the screen are not reproduced correctly and a normal screen cannot be obtained. etc.

Among them, (1) can be solved by forming a blanking part in the vicinity of the head switching point in the screen by time axis shift processing and recording and reproducing. (Television Society Technical Report TlCB5 a3-1) The disadvantage of (2) will be specifically explained below. FIG. 4 is a recording pattern diagram for the segment method shown in FIG. Here, 3 and 3'
are the trajectories drawn on the tape by the two heads, each located at the 1000 position, when the tape feed speed is 4 times faster. Fourth
21 to F8 in the figure are the first ones when the tape speed is normal.
- Shows how the fourth field is played back. Furthermore, the hatched portions 81 to S8 in this figure indicate the portions where the trajectory 3.3' of O is reproduced at 4x speed. FIG. 4C shows one screen that is played back at 4x speed.

This screen consists of images in the upper half and lower half alternately in units of band-shaped images with a width of % of the entire screen, and it is difficult to distinguish the image contents.

The above is an example of 4x high-speed playback, but any n
The same is true in the case of variable speed reproduction of double speed or 1/n times speed, and a screen is reproduced in which the locations on the screen are mixed in segment units.

In order to solve the above-mentioned problems, one field of video signal is divided into n consecutive scanning lines, and all scanning lines in the divided group belong to a different group from each other. Another possible method is to divide each of the n sets into continuous video signals and sequentially record each set as one track of video signals. The above recording method will be described below.

FIG. 5 shows a specific example of the above recording method. Below is scan line 1
125 high-definition signals with a field frequency of 5 of 1z (2:1 interlace) are sent to a rotating 2-head helical scan VTR with a cylinder rotation speed of 60 Hz.
This is an example of recording as .

Figure 5a shows the recording pattern on the magnetic tape;
, C, and D correspond to the position indicated by b on the screen. In this example, one field is composed of two tracks, similar to the VH5 and β systems.

"1*"2... indicates each track. C indicates the horizontal scanning line number constituting each track. In order to record with such a phonimat, it is necessary to rearrange the order of the video signals in units of horizontal scanning lines.

FIG. 6a shows an example of a hardware configuration for performing such signal processing. Vi is a video signal input terminal, 4 is a MU/D converter, 5 is a frame memory, 6 is a D/MU converter, 7 is an FM modulator, 8 is a recording amplifier, and 9 is a recording head. 10 is a reproducing head, 11 is a reproducing amplifier, 12 is F
13 is a MU/D converter, 14 is a frame memory, 16 is a D/A converter, and vo is a video signal output terminal.

This operation will be explained below. Input video signal is terminal v1
and is digitized by the MU/D converter 4. This signal is input to frame memory 5. Details of the frame memory 5 are shown in FIG. frame memory 6
are field memories 16, 17, switches 5w1. Consists of switch SW4. Field memory 16 is % field memory 1s, 19. SW2. Consists of SW3. Field memory 17 has a similar configuration to field memory 16.

An input to the frame memory 5 is given to an input terminal Fi. SWl is a switch that is inverted for each field.

The first field signal is input to field memory 16. Sw2 is a switch that is inverted for each horizontal scanning line, and the % field memory 18. % field memory 19 alternately. After completing writing for one field period, Sw1 is inverted, and the second field is written to the field memory 17. During the second field period, the field memory 16 is in a read state. First, the % field memory 18 is read out for a % field period, and the field memory 19 is read out for the next % field period. SW3 is inverted for each % field according to the above operation. Above, field memory 16
A timing chart regarding the operation is shown in FIG.

Data is written into the field memory 17 during the second field period, and read out during the next first field period in the same manner as described above.

The timing chart will be omitted. 5vr4 is always SWl;! :Flip in the opposite direction. Through the above signal processing, a time-series signal to be recorded as an output of the frame memory 5 in the format shown in FIG. 5 is obtained. The output of the frame memory 5 is input to a D/A converter 6 and becomes an analog video signal. This signal is transmitted to the 7M modulator 7. Recording amplifier8. It is recorded on the tape 1 via the recording head 9.

During playback, the signal recorded on tape 1 is transferred to playback head 1.
0. After being converted into an analog video signal via a regenerative amplifier 11 and a 7M demodulator 12, it is digitized by an A/D converter 13 and input to a frame memory 14. The configuration of the frame memory 14 is similar to that of the frame memory 5, but
The operation is different because the original signal must be obtained by reverse processing. That is, Swl is inverted every field, and 3
w2 is per % field, Sws is per line, S
wa is reversed in the opposite direction to Swl.

As a result, the same video signal as the input video signal is obtained as a digital signal at the output of the frame memory 14. This signal is converted into an analog video signal by the D/A converter 15 and output.

Next, the case where a tape recorded in such a format is played back at variable speed will be explained in comparison with the case at normal speed.

Figures 7a and 7b show the case of normal speed playback. G of a, +
``2'' is a rough image reproduced by each head (image skipped by one line as shown in Figure 6C), and by processing this with the Figure 6 reproduction circuit, a normal reproduction signal can be obtained. Figure b shows a reproduced image when output without performing reproduction processing.

In this case, information for one complete field can be obtained by two head scans, but the G1.2 obtained in the first scan is
G2 obtained in the second scan also includes information on the entire screen. CR the video signal reproduced by two scans as is
If it is displayed on T, a screen like b will be displayed.

On the other hand, in the case of 4x speed playback, the heads 3, 3 in Figure 5a,
31, it runs on the tape. In this case, Figure 7C
01 to G4 in the first scan, 0 in the second scan like
Each part of the signals 5 to G6 is reproduced.

If this reproduced signal is displayed on a CRT in the same manner as above, it will be displayed as shown in d. This is a signal similar to b in the case of normal speed. Therefore, even in the case of quadruple speed playback, a normal screen can be reproduced by the same signal processing as in the case of normal speed playback. It is clear that the above idea holds true in the case of other variable speeds as well. In addition, although we have explained the case where the cylinder rotation frequency is twice the frame frequency, generally when it is increased to n times, by distributing n consecutive scanning lines to different tracks,
Exactly the same effect can be obtained.

Problems to be Solved by the Invention However, in the above configuration, as shown in FIG. Therefore, it is inevitable that the device will become larger.

Means for Solving the Problems The present invention processes a video signal of one frame with the number of scanning lines N and the frame period Tf by 2n:1 interlacing (n:2,
3, 4, --------, N/2); an FM modulating means for FM modulating the one frame video signal; and an FM modulating means for FM modulating the FM modulated video signal. a recording/reproducing means for sequentially recording and reproducing one set of the video signals on 2n tracks on a magnetic tape with two rotating heads rotating with a period T f /n; FM demodulation means for FM demodulating the FM-modulated reproduced video signal; human/D conversion means for converting the FM-demodulated reproduced video signal into digital quantities; a storage means for temporarily storing a reproduced video signal; and a control film for controlling the storage means so that the reproduced video signal stored in the storage means is rearranged in units of scanning lines to become a 2:1 interlaced video signal. and a D/A conversion means for converting the output of the storage means into an analog quantity.

Effect of the Invention The present invention has the above-described configuration, and when recording one field of a video signal by dividing it into a plurality of tracks, the recording section is equipped with a MU/D converter, a D/A converter, a frame memory, and their peripheral devices. This makes it possible to obtain a normal screen by performing relatively simple processing during variable speed playback without using a variable speed playback.

Embodiment FIG. 1 shows a block diagram of a video signal recording and reproducing apparatus in an embodiment of the present invention. In Figure 1, 2
o is an image pickup tube, 21 is an FM modulator, 22 is a recording amplifier, 2
3 is a recording head, 24 is a playback head, 25 is a playback amplifier, 26 is an FM demodulator, 27 is a MU/D converter, 28 is a frame memory, and 29 is a D/A converter. The operation of the video signal recording and reproducing apparatus of this embodiment configured as described above will be described below. In this embodiment, the number of scanning lines is 11.
Let us consider the case where a high-definition signal with 25 lines and a field frequency of 601 (2:1 interlace) is recorded on a rotating two-head helical scan VTR with a cylinder rotation frequency of 601-ray.

The video signal obtained by the image pickup tube 2o is modulated by an FM modulator 21, and then sent to a recording amplifier 22. It is recorded on the magnetic tape 1 via the recording head 23.

FIG. 2 shows the target of the image pickup tube 20 in FIG. 1. In the conventional method, as shown in a, the target 7) of the image pickup tube 2o is 1.2, 3. After scanning once, 563.
564,565. 2=1 interlacing is performed in which scanning is performed as follows, but in this embodiment, 4:1 interlacing is performed with the field frequency of the image pickup tube 2Q set to 1201 (z). The field will be scanned over the target like b.

When the above 41-interlaced video signal is recorded on the magnetic tape 1 by the recording/reproducing apparatus shown in FIG. 1, the cylinder rotation frequency is set to e as described above.

Because of the ratio, one field of FIG. 2 will be recorded in one recording track 2 on the magnetic tape 1 of FIG. The format will be the same.

Since the recording formats are the same, the reproducing section of the video signal recording/reproducing apparatus shown in FIG. 1 may be the same as the reproducing section of the conventional video signal recording/reproducing apparatus shown in FIG. 6.

In other words, according to this embodiment, if the device has an image pickup unit, such as a camera-integrated or portable VTR, the scanning of the image pickup tube is set to 4:1 in a method of recording video signals with the cylinder rotation frequency set to a 60 ratio. By using interlacing, it is possible to create a recording format that allows good variable speed playback without using a M/D, D/A converter, or frame memory in the recording section, making the device more compact,
It can be expected to be lighter and cheaper. Image tube scanning 4:1
Interlacing can be achieved relatively easily by simply changing the circuit.

In this example, the case where the cylinder rotation speed is twice the frame frequency has been explained, but in general, when the cylinder rotation speed is set to n times, exactly the same effect can be expected by setting the scanning of the image pickup tube to 2n91 interlace. .

Further, in this embodiment, a No. 1 evil vision signal was considered, but the same applies to video signals of other systems. Further, as for the method of multiplexing the luminance signal and the color signal, TCI signal system, composite signal system, component signal system, etc. can be considered, but the same applies in all cases.

According to the present invention, as described in detail, a camera-integrated VTR is provided.
Alternatively, when using a portable VTR that records one field of the video signal by dividing it into multiple tracks, you can simply change the inotarase ratio of the image pickup tube.
It is possible to create a recording former that allows good variable speed playback without using a D converter, D/MU converter, or frame memory, making the device smaller, lighter, and cheaper. Its practical effect is great.

This is particularly effective for ENG VTRs, etc., which require high image quality and small size.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video signal recording and reproducing device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the target of the image pickup tube of the video signal recording and reproducing device of the same embodiment, and FIG. 3 is a VT
4 is an explanatory diagram of the basic VTR system for variable speed playback, FIG. 5 is an explanatory diagram of the conventional example, FIGS. 6 a and b are circuit block diagrams of the conventional example, and FIG. 6 C is a timing diagram, and FIG. 7 is an explanatory diagram of a monitor output of a reproduced video signal in a conventional example. 1...Magnetic tape, 2...Recording track, 3゜31...During variable speed playback, 4,13,
2 completed...k/D converter, 5, 14.28...
...Frame memory, 6°15.29...D
/FM converter, 7.21...FM modulator, 8,2
2... Recording amplifier, 9, 23... Recording head, IQ, 24... Playback head, 11°2
5...Reproduction amplifier, 12.26...F
M demodulator, 16.17... field memory,
18.19...% field memory, 2o...
・Image tube. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
The figures are Fig. 3 (b) (,ni) (no) (C) Fig. 5 A (, -e (a-) (b) Fig. 6 (■ /A Fig. 7 (ku) (0 n

Claims (1)

[Claims] The video signal of one frame with the number of scanning lines N and the frame period Tf is interlaced with 2n:1 (n=2, 3, 4, ......
, N/2) into 2n sets of video signals;
FM modulation means for FM modulating the video signal;
The modulated video signals are sequentially distributed onto the magnetic tape by two magnetic heads mounted at 180° intervals on a rotating cylinder that rotates at a period Tf/n, and one set of the video signals is assigned to one track. a recording/reproducing means for recording and reproducing a frame signal as 2n tracks; and an FM demodulating means for FM demodulating the reproduced FM modulated reproduced video signal.
demodulating means; A/D converting means for converting the FM demodulated reproduced video signal into a digital quantity; storage means for temporarily storing the reproduced video signal of 2n tracks converted into the digital quantity; and the memory. A control means for controlling the storage means to rearrange the reproduced video signal stored in the means in units of scanning lines to become a 2:1 interlaced video signal; and D for converting the output of the storage means into an analog quantity.
/A conversion means.