JPH03214874A - Digital video signal recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital VTR capable of recording television signals of different formats on a tape of the same format.

[Conventional technology]

As a method for recording television signals without degrading the image quality, a digital VTR that records using digital codes is known. Here, we will show an example of Dl-VTR, which has been internationally standardized as a digital VTR (References: SMPTE Journal, Vol. 95,
No. 3, pp. 359-400). In the D1-VTR, the speed is 15 per second as shown in Figure 2.
Four heads 12-1~ are mounted on the drum 11 rotating at 0 rotations.
12-4 is installed. Therefore, i50x per second
4=600 tracks will be recorded. If this is used to record a television signal with 525 scanning lines and 60 Hz fields, one field of signal will be recorded on 10 tracks 14 on the tape 13, as shown in FIG. 3(a). Note that of the 525 scanning lines, 500 effective scanning lines are actually recorded.

By the way, as a television signal, in addition to this, the scanning line 625
There is a book with a field count of 50Hz.

If this signal is recorded on the same VTR, one field of the signal will be recorded on 12 tracks 16 on the tape 15, as shown in FIG. 3(b). Note that the scanning line 62
Of the 5 lines, 600 effective scanning lines were actually recorded. As a result, there is an advantage that television signals of different field frequencies can be recorded using a VTR with the same mechanical parameters such as the number of heads, drum rotation speed, and tape feed speed.

[Problem to be solved by the invention]

According to the above recording system, the number of tracks per field differs between television systems, so tapes are not compatible between television systems. For example, a tape on which a 525/60 television signal is recorded cannot be played back as a 625/50 television signal, and vice versa. Therefore, even if the program is the same, there is a problem in that separate tapes are required for each television system.

An object of the present invention is to solve this problem and provide a VTR that can record and reproduce television signals of different systems on the same tape.

[Means to solve the problem]

In the present invention, the effective image area from which retrace signals, synchronization signals, etc. are removed from television signals of different systems is digitally recorded on tape in a common code format.
Recording and reproduction are performed using a VTR having a drum rotation speed and a tape feed speed determined by each field frequency. Furthermore, a retrace signal, synchronization signal, etc. are added to the reproduced signal to create a television signal for each system. [Operation] As a result of the above, the head always draws the same track locus on the tape, and the tape format becomes common among television signals. Therefore, television signals of each system can be recorded and reproduced on a common tape.

〔Example〕

In the D1-VTR, the effective scanning lines actually recorded are 50 in the 525/60 system, as mentioned above.
0 lines, 600 lines in the 6 2 5/5 0 method,
Each one was different. In the present invention, this is set to a common value, for example, 510 lines.7 Also, the effective pixels of one scanning line are set to 720 pixels. That is, as shown in FIG. 4, it is assumed that an invalid image area 17 consisting of blanking periods, synchronizing signal periods, etc. is removed, and an effective image area 18 defined by 510 x 720 pixels in both systems is recorded on the tape. Since the effective image areas are the same in both television systems, the number of tracks per field for recording them can be made equal.

As a result, in the 625/50 system,
Although the number of recorded scanning lines per field is 90 fewer than that of the D1-VTR, this is unavoidable in light of the effects of the present invention, which will be described later.

Here, if the number of tracks per field is N, the number of VTR heads that record and reproduce these is M sets, the number of rotations per second of the drum on which the heads are mounted is F rotations, and the field frequency is fHz, then FxM=fxN・= (1) holds true. Therefore, for example, if F=120, M=8, and N=16, f=120x8/16 =60 (2) and can be reproduced as a television signal with a field frequency of 60 Hz. Also, leave M and N as they are, and only set F to 100.
When changed to rotation, f = 100 x 8/16 = 50, and can be reproduced as a television signal with a field frequency of 50 Hz. That is, the same tape can be reproduced as a television signal with a predetermined number of fields by changing the rotational speed F of the drum to a predetermined value. Similarly, by changing the rotational speed F of the drum to a predetermined value, a television signal with a predetermined number of fields can be recorded on a tape with the same number of tracks. In order to keep the tape recording pattern the same even when the drum rotation speed is changed, it is necessary to keep the tape moving distance per drum rotation constant. Change it in proportion to. for example,
The tape feed speed of 5 2 5/6 0 method is 30cm/
If it is seconds, then the tape feed speed of the 625/50 system is 25 cm/second.

Although M = 8, these eight heads may be arranged evenly (at 45 degree intervals) on the circumference of the drum as shown in Figure 2, or for example, they may be arranged in groups of four at 180 degree intervals. It may be placed in Also. N = 16 tracks are evenly arranged as shown in Figure 3. FIG. 1 shows the signal flow of the VTR of the present invention.

An analog television signal is converted into a digital code by an A/D converter 1, and an effective image area extracting circuit 2 extracts only an effective image area from which blanking periods and synchronizing signal periods are removed. A parity generation circuit 3 adds a parity code for error correction and detection to this signal.

The modulation circuit 4 converts this into a code suitable for recording.
Recording is performed on a tape using a magnetic head rotating in a tape running system 5. The reproduced signal is converted into the original digital code by the demodulation circuit 6, and the code errors caused by the recording and reproduction process are corrected by the error correction circuit 7. A blanking period and a synchronizing signal period are added to this by a circuit 8 for adding a blanking period and a synchronizing signal period.
The D/A converter 9 converts the signal back to an analog TV signal. The control circuit 10 sets the number of revolutions of the rotating drum and the feed speed of the head to predetermined values in accordance with the number of fields of the reproduced television signal.

Note that Figure 1 shows only the basic part for digital recording, so for example, shuffling, which changes the time order of recording codes to reduce the influence of code errors, and replacing erroneous image areas with surrounding correct signals can be used. Descriptions of parts that are used in the actual device but are not directly related to the present invention, such as concealment, have been omitted.

〔Effect of the invention〕

In the present invention, a common effective image area is recorded among television system signals having different field frequencies and numbers of scanning lines, and the number of rotations of the head drum and the feeding speed of the tape are set to values proportional to the number of fields. As a result, the tape format can be made common among television systems, and the same tape can be used for different television systems, which is a great advantage.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the basic configuration of the VTR of the present invention, Fig. 2 is a diagram showing the head peripheral area of a conventional VTR, Fig. 3(a),
(b) is a diagram showing the tape format of a conventional VTR;
FIG. 4 is a diagram showing an effective image area recorded on the VTR of the present invention. In the figure, 1 is an A/D converter, 2 is an effective image area extraction circuit, 3 is a parity generation circuit, 4 is a modulation circuit, 5 is a tape running system, 6 is a demodulation circuit, 7 is an error correction circuit, and 8 is a retrace line. period, a synchronization signal period addition circuit, 9 a D/A converter, 10 a control circuit, 11 a rotating drum, 12 a magnetic head, 13
．． 15 is a magnetic tape, 14.16 is a recording track, 17
18 indicates an invalid image area, and 18 indicates an effective image area. 1st eye 2nd eye Figure 3 (L) 3rd eye (MU) Figure 4

Claims (1)

[Claims] An effective image area common to multiple television systems with different numbers of fields and scanning lines is recorded on a tape fed at a speed proportional to F by a drum equipped with M sets of heads and rotating at a frequency of F. A digital video signal recording device that records and reproduces data in the form of digital codes on a book track, adds a retrace signal and a synchronization signal to the reproduced signal, and outputs the resultant signal as a video signal with a field frequency of FM/N.