JPH0737209A - Digital signal recording / reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] Recording is performed on a magnetic tape even in the long-time recording mode without increasing the number of magnetic heads and at the same recording track pitch as in the standard recording mode. [Structure] A magnetic tape 1 is obliquely wound around a rotary cylinder 2 over 180 degrees, and is run by a pinch roller 4 and a capstan 5. The tape speed control means 7 is operated by the compression command signal input from the compression mode input terminal 8.
Controls the rotation speed of the capstan motor 6 so that the running speed of the magnetic tape 1 becomes a predetermined speed. The compression encoding means 10 compresses the digital information input from the digital information input terminal 9 by the compression command signal. The magnetic head selecting means 11 uses one of the magnetic heads 3 of the magnetic tapes to compress the information compressed by the compression encoding means 10 according to the compression command signal so that the azimuth angles of the adjacent recording tracks are different. The recording head of the magnetic head 3 is selected by judging whether or not the recording is to be performed on the recording head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording / reproducing apparatus such as a digital VTR or a PCM tape recorder for compressing digital information such as a video signal or an audio signal and recording it on a magnetic tape.

[0002]

2. Description of the Related Art In recent years, digital signal recording / reproducing apparatuses have been
Due to advances in compression / expansion technology and error correction technology, digital signals have been compressed and recorded without being recorded on a magnetic tape. For example, "The future of image information recording technology" (Journal of the Television Society of Japan, Vol.46, No.10, pp1
222 to 1229) "Table 1, Table 2 Digital VTR prototypes of each company" were announced, and the video signals were digitized using a compression method such as DCT, DPCM or ADRC. It is compressed and recorded on magnetic tape. As an example, if the encoded information amount is a video signal of 115 Mb / s, 2
Can be compressed to a recording data rate of 5 Mb / s,
As a result, 2 channels x 8mm VTR
It is possible to record by the two head configuration.

In the digital signal recording / reproducing apparatus, the long-time recording mode is realized by making the recording track pitch narrower than the recording track pitch in the standard recording mode, as in the conventional analog signal recording / reproducing apparatus. Therefore, a narrow magnetic head dedicated to the long-time recording mode is required, which increases the number of magnetic heads.

When the recording data rates are different, the rotational speed of the rotary cylinder and the running speed of the magnetic tape are changed according to the recording data rate in order to keep the recording density constant. For example, the recording data rate is 1 /
When it becomes 2, the rotation speed of the rotary cylinder and the running speed of the magnetic tape are halved.

[0005]

In the above structure, the recording track pitch must be narrowed for long-time recording, and high-precision tracking is required. There is also a problem that the number of magnetic heads mounted on the rotary cylinder increases by adding a dedicated magnetic head. Further, in order to record digital signals of different recording rates, the number of revolutions of the rotary cylinder and the running speed of the magnetic tape are changed, so that there is a problem that the contact state (head touch) between the magnetic head and the magnetic tape is deteriorated. Was there.

In view of the above problems, the present invention can perform recording in the long-time recording mode without increasing the number of magnetic heads and at the same recording track pitch as in the standard recording mode. It is an object of the present invention to provide a digital signal recording / reproducing apparatus capable of coping with a plurality of recording data rates without changing, and capable of high density recording by azimuth recording.

[0007]

In order to solve the above problems, in a digital signal recording / reproducing apparatus of the present invention, when a magnetic tape is run and digital information is recorded on the magnetic tape, the magnetic head reads the digital information. Recording is performed once during scanning (an integer of n ≧ 2).

Further, there is provided a magnetic head selecting means for selecting a magnetic head at the time of recording so that the recording azimuth angles of the adjacent recording tracks are different.

Further, there is provided compression encoding means for compressing and encoding the digital information to be recorded according to the running speed of the magnetic tape.

[0010]

According to the present invention, a plurality of digital information can be recorded with substantially the same recording track width without adding a magnetic head by the above-mentioned structure, so that the number of rotations of the rotary cylinder is independent of tracking accuracy. Since it can support multiple recording data rates without changing
The head touch can be stabilized.

Further, the azimuth recording enables high density recording, and the compression encoding means can compress the digital information amount in accordance with the tape traveling speed and record it.

[0012]

Embodiments of the digital signal recording / reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a digital signal recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a magnetic tape and 2 is a rotating cylinder. 3 is a magnetic head, and here, magnetic head pairs having different azimuth angles (R, L) are (R1, L1),
A total of four magnetic heads of two sets (R2, L2) are mounted on the rotary cylinder 2 so as to face each other by 180 degrees.

FIG. 2A shows a setting diagram of the azimuth angle of the magnetic head pair (R1, L1) provided on the rotary cylinder, and FIG. 2B shows the azimuth angle of the magnetic head pair (R2, L2). An example of the setting diagram of FIG. As is clear from this figure, the azimuth angles of R1 and R2 are the same, and the azimuth angles of L1 and L2 are the same. As shown in FIGS. 9A and 9B, the head R1 and the head L1 and the head R2 and the head L2 are provided on the rotary cylinder with a step by a width x. The track width formed when recorded on the tape may be set to a desired one track pitch width.

4 is a pinch roller, 5 is a capstan, 6
Is a capstan motor, 7 is a tape speed control means, 8 is a compression mode input terminal, 9 is a digital information input terminal, 1
Reference numeral 0 is a compression encoding means, and 11 is a magnetic head selection means.

The operation of the digital signal recording / reproducing apparatus configured as described above will be described below with reference to FIG.

In FIG. 1, a magnetic tape 1 is obliquely wound around a rotary cylinder 2 over 180 degrees, and is run by a pinch roller 4 and a capstan 5. By the compression command signal input from the compression mode input terminal 8, the tape speed control means 7 controls the capstan motor 6 so that the traveling speed of the magnetic tape 1 becomes a predetermined speed.
Control the rotation speed of. In addition, the compression encoding means 10 compresses the digital information input from the digital information input terminal 9 by the compression command signal. The magnetic head selection means 11 follows the compression command signal and the compression encoding means 1
It is determined which of the magnetic heads 3 is used to record the information compressed by 0 on the magnetic tape 1 so that the azimuth angles of the adjacent recording tracks are different, and the recording head of the magnetic head 3 is selected. Do.

FIG. 3 shows an example of the configuration of the compression encoding means 10. At the time of recording, the digital signal input from the terminal 20 is first a DCT converter (discrete cosine converter).
At 21, the time domain is converted into a value in the frequency domain, this value is input to the quantizer 22 and quantized, and further, the entropy encoder 23 performs coding processing. The compression / encoding means 10 compresses the digital information at a compression ratio according to the compression command signal. This compression requires at least one of the DCT converter 21, the quantizer 22, and the entropy encoder 23. It is realized using. Then, the compressed digital signal is output from the terminal 24. It should be noted that during reproduction, an operation reverse to the compression operation during recording is performed. In the above description, the example in which the DCT transform is used as the quantizing means has been shown, but a quantizing means such as vector quantizing can also be used. The compressed digital information may be standardized image compression data such as MPEG (Moving Pic).
(ture Expert Group) can handle compressed video data standardized.

FIGS. 4 and 5 show recording timings when a digital signal is recorded.
Is a head switching signal, (b) is a recording track, (c)
Indicates the head to be used and the recording section.
FIG. 4 is a timing chart in the recording mode. In the section where the head switching signal is'H 'by the magnetic head selecting means 11, recording is performed using R1 and L1 of the magnetic head 3, and the section where the head switching signal is'L'. Will not record. Therefore, since the digital information input from the digital information input terminal 9 is recorded on the magnetic tape 1 only by using the magnetic head pair (R1, L1) on one side of the magnetic head 3, while the rotary cylinder 2 makes one revolution. 2 tracks are continuously recorded with a track width Tp. That is, two tracks are recorded while each of (R1, L1) (R2, L2) of the magnetic head 3 scans once. The traveling speed of the magnetic tape 1 is set by the tape speed control means 7 so that the magnetic tape 1 travels two tracks while the rotating cylinder 2 makes one rotation. Since the azimuth angle of the track to be recorded is different from the azimuth angle of the adjacent track, it is possible to record without providing a gap between the tracks, and high density recording can be realized.

FIG. 5 is a timing chart in another recording mode (long-time recording mode), where the amount of digital information to be recorded is 1 / 2.5 of that in the embodiment of FIG. The information amount of the signal input from the digital information input terminal 9 is 1 /
2.5, or the compression encoding means 10 compresses the digital information of the signal input from the digital information input terminal 9 to 1 / 2.5, so that the digital information to be recorded is 1/2. It can be set to 5.

In this embodiment, (R1,
2 with a magnetic head pair of (L1) or (R2, L2)
Since the tracks are recorded simultaneously, the rotary cylinder 2 is 2.
Scanning recording is performed once during five rotations. Therefore, as shown in FIG. 4C, the magnetic head selecting means 11 first selects (R1, L1) of the magnetic head 3 to record the digital information on the tape, and the rotary cylinder 2 has 2.5 times.
After the rotation, recording is performed using (R2, L2) of the magnetic head 3, and after 2.5 rotations of the rotary cylinder 2, recording is performed using (R1, L1) of the magnetic head 3 is repeated. As a result, continuous recording tracks can be formed. That is, (R1, L1) and (R2, L2) of the magnetic head 3 perform recording alternately every 2.5 rotations of the rotary cylinder 2.

The running speed of the magnetic tape 1 is 1 / 2.5 of the tape speed shown in FIG. 4 because the amount of information to be recorded is 1 / 2.5.
Since the rotation speed of the rotary cylinder 2 does not change, two tracks are recorded every 2.5 rotations of the rotary cylinder 2, so that the recording track width of FIG. Data can be recorded on the magnetic tape 1 with the same track width as Tp. Thus, the rotary cylinder 2 rotates 2.5 times, that is, the magnetic head 3 (R
1, L1) and (R2, L2) perform recording once during a total of 5 scans. The azimuth angle of the recording track is (R1, L1), (R2, L2) of the magnetic head 3.
Since recording is alternately performed, the azimuth angles of adjacent tracks are not the same, as is clear from FIG.

Next, the operation during reproduction will be described. Figure 4
Since the magnetic head 3 can reproduce the same recording track twice at the time of reproducing the signal recorded in the recording mode of No. 3, by collecting the digital information having good S / N of the reproduced signal and performing the reordering. , A recorded digital signal can be obtained. Therefore, highly accurate tracking is not required during reproduction.

In the recording mode of FIG. 5, since the recording track is scanned 5 times, the recorded signal can be reproduced without loss of information up to 2.5 times speed reproduction in which the same track is reproduced twice or more. . That is, when recording is performed once every n scans, reproduction is performed at least twice at the time of reproduction, that is, reproduction is performed without loss of information without strict tracking until n / 2 times speed reproduction. Therefore, high-speed reproduction without information loss is possible. Therefore, since the data can be reproduced at a transfer speed n / 2 times the data transfer speed at the time of recording, it is possible to transfer the data to another recording medium, for example, a disk recording medium at a high speed. In addition, the reproduced digital data can be temporarily stored in the memory and only the necessary data can be output, so that the image data can be reproduced like a strobe.

Furthermore, since the rotational speed of the rotary cylinder 2 does not change depending on the amount of digital information to be recorded, the relative speeds of the magnetic tape 1 and the magnetic head 3 can be made almost the same, and the magnetic head 3 and the magnetic tape 1 can be made to have the same relative speed. The contact state (head touch) can be made uniform regardless of the recording mode. Therefore, recording / reproducing of a signal on / from the magnetic tape 1 can be favorably performed.

In this embodiment, the magnetic head 3
Two heads are mounted on the rotary cylinder 2 facing each other by 180 degrees, but one head may be mounted. Further, although they are opposed to each other by 180 degrees and attached at two places, they may be attached to the rotary cylinder 2 at one place.

[0027]

As described above, according to the present invention, digital information is recorded at a rate of once every n scans of the magnetic head, so that the recording is performed with substantially the same recording track width without adding a magnetic head. Since it is possible to deal with a plurality of recording data rates regardless of tracking accuracy and without changing the number of rotations of the rotary cylinder, it is possible to stabilize the head touch and record a plurality of digital information.

Further, since the magnetic head selecting means for selecting the magnetic head is provided so that the azimuth angles of the adjacent recording tracks are different from each other, the high density recording can be performed by the azimuth recording.

Further, since the compression / encoding means for varying the recorded digital information according to the running speed of the magnetic tape is provided, the digital information amount can be compressed and recorded according to the running speed of the tape. It is possible to record for a long time.

At the time of reproduction, the magnetic head scans the recording track a plurality of times, so that it is not necessary to perform highly accurate tracking, and the track can be narrowed. Further, if information is recorded at a rate of once every n scans of the magnetic head at the time of recording, all information recorded up to n / 2 times speed can be reproduced at the time of high-speed reproduction, so that no information is lost. High-speed reproduction is possible, and data can be transferred to another recording medium at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital signal recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an azimuth angle of a magnetic head mounted on a rotary cylinder of a digital signal recording / reproducing apparatus according to the present invention.

FIG. 3 is a block diagram showing a configuration example of a compression encoding unit according to the present invention.

FIG. 4 is a timing chart for explaining a recording / reproducing operation in one embodiment of the present invention.

FIG. 5 is a timing chart for explaining a recording / reproducing operation in another embodiment of the present invention.

[Explanation of symbols]

 1 magnetic tape 2 rotating cylinder 3 magnetic head 4 pinch roller 5 capstan 6 capstan motor 7 tape speed control means 8 compression mode input terminal 9 digital information input terminal 10 compression encoding means 11 magnetic head selection means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshio Sakakibara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Toshio Inaji 1006, Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd (72) Inventor Eiji Ueda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A digital signal recording / reproducing apparatus in which a magnetic tape is wound around a rotary cylinder, and digital information is recorded / reproduced in a helical track by a magnetic head mounted on the rotary cylinder. The magnetic head n times (n ≧ 2 integer)
A digital signal recording / reproducing apparatus which records on a magnetic tape once every scan. 2. A digital signal recording / reproducing device according to claim 1, wherein a magnetic head is arranged on the rotating cylinder so that the recording azimuth angles of the helical tracks formed on the magnetic tape are different from each other on adjacent tracks. apparatus. 3. The digital signal recording / reproducing apparatus according to claim 1, wherein at least one pair of magnetic heads having different azimuth angles are mounted on the rotary cylinder. 4. A magnetic head selecting means for selecting a magnetic head used for recording on a magnetic tape so that recording azimuth angles of helical tracks formed on the magnetic tape are different from each other on adjacent tracks. The digital signal recording / reproducing apparatus according to claim 3. 5. A compression encoding means is provided, wherein the compression encoding means varies the compression ratio of the input digital information in accordance with the running speed of the magnetic tape and encodes it. 5. The digital signal recording / reproducing apparatus according to claim 4.