JPH09161463A - Data recording/reproducing method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect searching code surely by recording the same searching code continuously for the porpoise of a high speed searching and also recording the code being scattered for the purpose of a low speed searching. SOLUTION: Searching codes are recorded collectively for the purpose of a high speed searching while the searching codes are recorded being scattered for the purpose of a low speed searching. In other words, a first half L1 of one track is made as area of the searching code for the purpose of a high speed searching and the second half L2 of the track as area of the searching code for the purpose of a low speed searching. The same search IDs are recorded collectively in the area L1 and searching codes are recorded in the area L2 being scattered. Thus, as the first half of one track is used for the collective recording of the searching codes for the purpose of a high speed searching and the second half thereof for the scattered recording of the searching codes for the purpose of a low speed searching, the searching codes can be detected accurately either in the case of the high speed searching or the low speed searching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording / reproducing method and device for recording / reproducing digital data on a magnetic tape, and more particularly to searching.

[0002]

2. Description of the Related Art Digital data is recorded on a magnetic tape /
Since a tape streamer drive for reproduction has a huge recording capacity, it is widely used for backing up data stored in a storage device such as a hard disk. The tape streamer drive is suitable not only for backup but also for recording large file data such as moving image data.

As such a tape streamer drive, for example, a tape cassette similar to an 8 mm VTR tape cassette is used, and a rotary head is used to record / reproduce digital data on a magnetic tape by a helical scan system. Something has been proposed.

In such a tape streamer drive, as an input / output interface, for example, SCSI is used.
(Small Computer System Interface) interface is used. At the time of recording, data is input from the host computer via the SCSI interface. This input data is sent in fixed-length block units. In the tape streamer drive, this input data is compressed with a variable length code using, for example, the LZ code, and is temporarily stored in the buffer memory. The data stored in the buffer memory is sent to the recording / reproducing system for each predetermined group and recorded on the magnetic tape by the rotary head. At the time of reproduction, the data on the magnetic tape is reproduced by the rotary head and temporarily stored in the buffer memory. The data from this buffer memory is expanded to the original data and SC
It is sent to the host computer via the SI interface.

In such a tape streamer drive, a search operation is performed to search for a desired tape position. Conventionally, there are known ones in which the search code is recorded on the entire track, and ones in which the search code is recorded at one or two positions determined on the track. However, in this case, the search code is recorded on the entire track or in a predetermined area, so that the recording efficiency is not good. Further, it is necessary to distinguish the search track or area from the data track or data area, which causes a problem that the configuration becomes complicated.

Therefore, there has been proposed a method in which data is recorded in small block units to which a sync and an ID are added, and the search code is recorded in the ID of each block. This has the advantages of simplifying the track format and eliminating the need to determine whether a data track or data area is being played back, thus simplifying the configuration.

[0007]

When data is recorded for each of a plurality of blocks on one track and the search code is included in the ID of each block, the blocks of the blocks are divided between the high speed search and the low speed search. The way they are picked up is different. From this, it can be considered that the method of recording the search code suitable for the high speed search and the method of recording the search code suitable for the low speed search are different from each other. If the search code is not properly arranged so as to be suitable for high-speed search and low-speed search, respectively, the search code can be reliably detected during high-speed search, but the search code cannot be picked up during low-speed search, or The search code can be reliably detected during the low speed search, but the search code may not be picked up during the high speed search.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a data recording / reproducing method and apparatus capable of reducing the search code detection error in both high speed search and low speed search.

[0009]

SUMMARY OF THE INVENTION The present invention is a data recording / reproducing method for recording / reproducing digital data on a magnetic tape by a rotary head, in which the same search code is continuously recorded for high-speed search and at a low speed. A data recording / reproducing method is characterized in that search codes are dispersedly recorded for a search.

According to the present invention, one track is divided into a high speed search area and a low speed search area, the same search code is continuously recorded in the high speed search area, and the search code is dispersed in the low speed search area. I try to record it.

According to the present invention, the first azimuth track is used for high-speed search, the same search code is continuously recorded on the first azimuth track, and the second azimuth track is used for low-speed search. The search code is distributed and recorded on the 2 azimuth tracks.

According to the present invention, in a data recording / reproducing apparatus for recording / reproducing digital data on a magnetic tape by a rotary head, the same search code is continuously recorded for high speed search, and the search code is recorded for low speed search. A data recording / reproducing apparatus characterized in that means for recording in a distributed manner is provided.

The same search code is continuously recorded for high speed search, and the search codes are dispersed and recorded for low speed search. Therefore, the search code can be reliably detected in both the high speed search and the low speed search.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a tape streamer drive to which the present invention can be applied. This tape streamer drive has a tape width of 8 m
Using a tape cassette of m, by the helical scan system,
Data is recorded / reproduced on the magnetic tape.

As shown in FIG. 2, reels 2A and 2B are arranged in the tape cassette 1, and a magnetic tape 3 having a tape width of 8 mm is wound between the reels 2A and 2B. Digital data is recorded / recorded on this magnetic tape 3.
Will be played. A non-volatile memory 4 is arranged in the tape cassette 1. From the module of the nonvolatile memory 4, a plus 5V power supply terminal 5A, a data input / output terminal 5B, a clock input terminal 5C, and a ground terminal 5D are derived. The nonvolatile memory 4 stores the manufacturing date and manufacturing location of each tape cassette, the thickness and length of the tape, the material, management information of each partition, user information, and the like.

As shown in FIG. 3, the external appearance of the tape cassette 1 is basically composed of an upper case 6, a lower case 7 and a guard panel 8 and is basically a tape cassette used for an ordinary 8 mm VTR. It is similarly configured. On the label surface 9 of this tape cassette 1, terminal pins 10A, 10A,
B, 10C and 10D are provided. These terminal pins 1
0A, 10B, 10C, and 10D are plus 5 derived from the nonvolatile memory 4 provided in the tape cassette 1.
The V power supply terminal 5A, the data input / output terminal 5B, the clock input terminal 5C, and the ground terminal 5D are respectively connected.

In FIG. 1, reference numeral 11 is a rotary drum.
Recording heads 12A and 12B and reproducing heads 13A and 13B are arranged on the rotary drum 11. Recording head 1
2A and 12B have a structure in which two gaps having different azimuth angles are arranged very close to each other. Similarly, the reproducing heads 13A and 13B have a structure in which two gaps having different azimuth angles are arranged extremely close to each other.

The magnetic tape 3 drawn from the tape cassette 1 is wound around the rotary drum 11. The rotary drum 11 is rotated by the drum motor 14. Also,
The magnetic tape 3 is sent by a capstan motor and a pinch roller (not shown). The drum motor 14 is rotated under the control of the mechanical controller 17. The mechanical controller 17 performs processing such as drum servo and tracking servo. Mechanical controller 17
And a system controller 15 that performs overall control are bidirectionally connected.

The recording data on the magnetic tape 3 is modulated by the modulation / demodulation circuit 18 and supplied to the recording heads 12A and 12B via the RF amplifier 19. Recording head 12
Data is recorded on the magnetic tape 3 by A and 12B along the inclined track. The recording heads 12A and 12B have different azimuth angles, and the inclined tracks are tracks having different azimuth angles.

The data on the magnetic tape 3 is reproduced by the reproducing head 13.
Reproduced by A and 13B. The outputs of the reproducing heads 13A and 13B are supplied to the modulation / demodulation circuit 18 via the RF amplifier 19. Reproduction data is demodulated by the modulation / demodulation circuit 18.

In this tape streamer drive, a SCSI interface is used for data input / output. That is, when recording data, the data is sent from the host computer 25. This data is input via the SCSI interface 20. This input data is supplied to the data compression / expansion circuit 21.

The data compression / expansion circuit 21 performs data compression / expansion processing by the LZ code. LZ
The code compresses the data by detecting the repetition of the input character string.

The output of the data compression / expansion circuit 21 is output from the buffer memory 2 under control of the buffer controller 22.
It is temporarily stored in 3. Data recording is performed for each group. One group is data of a predetermined number of tracks. One group of data output from the buffer memory 26 is supplied to the modulation / demodulation circuit 18. The recording data is modulated by the modulation / demodulation circuit 18. The output of the modulation / demodulation circuit 18 is output via the RF amplifier 19 to the recording head 1
2A and 12B. Recording heads 12A and 1
The data is recorded on the magnetic tape 3 by the 2B in the inclined track.

When reproducing the data, the recording data of the magnetic tape 3 is reproduced by the reproducing heads 13A and 13B. The outputs of the reproducing heads 13A and 13B are supplied to the modulation / demodulation circuit 18 via the RF amplifier 19. Reproduction data is demodulated by the modulation / demodulation circuit 18. The output of the modulation / demodulation circuit 18 is the buffer controller 22.
It is temporarily stored in the buffer memory 23 under the control of.

The output of the buffer memory 23 is supplied to the data compression / expansion circuit 21. Data compression / expansion circuit 2
By 1, the data is decompressed and restored to the original data.
The output of the data compression / expansion circuit 21 is output to the host computer 25 via the SCSI interface 20.

The tape cassette 1 has a MIC (Memory I
A non-volatile memory 4 called an n cassette) is provided. Data is input / output to / from the nonvolatile memory 4 by the system controller 15. Information is exchanged between the non-volatile memory 4 and the host computer 25 using SCSI commands.

FIG. 4 shows the structure of data recorded on the magnetic tape 3. Data is arranged on one track as shown in FIG. That is, ATF areas for tracking control are provided at both ends of one track,
Data is recorded in the meantime. Data is recorded / reproduced in one track in units of blocks. One block consists of a sync, an ID, and data.

This ID is generated by the ID circuit 26.
A search code is included in the ID. As will be described later in detail, the search code is recorded by concatenating the same search code in a continuous block for high-speed search, and is distributed and recorded for low-speed search. For example,
In the first half of one track, the same search code is recorded in a continuous block for high speed search, and in the second half of one track, search codes are dispersed and recorded for low speed search.

At the time of search, the ID circuit 26 detects the ID. The detected ID is the system controller 1
Sent to 5. A search is performed using this ID.
The same search code is recorded for consecutive blocks for high-speed search, and the search codes are recorded for low-speed search in a dispersed manner.Therefore, the search code can be used for both high-speed search and low-speed search. Can be reliably detected.

Then, as shown in FIG. 5, data is recorded on the magnetic tape 3 with a predetermined number of tracks as one group. Since the record data is compressed in a variable length by the LZ code, it is uncertain how many records of data will be included in one group.

As described above, in the tape streamer drive to which the present invention is applied, the same search code is recorded by contiguous blocks for high speed search, and the search codes are distributed and recorded for low speed search. Therefore, the search code can be reliably detected in both the high speed search and the low speed search. This will be described below.

First, the conditions for ensuring that the search code can be detected during the search will be considered. When searching, the tape is sent at high speed. Since recording is performed with heads having different azimuth angles, when the tape is fed at high speed, the reproduced waveform becomes a gem-like waveform as shown in FIG.

That is, when the tape is fed at a high speed, as shown in FIG. 7, the head makes a plurality of tracks Ta1, Tb1, T
a2, Tb2, ... Adjacent tracks Ta1, Tb
Signals of 1, Ta2, Tb2, ... Are recorded by heads having different azimuth angles. Therefore, when the head traces a track with the same azimuth angle, a large reproduction output is obtained, but when a track with a different azimuth angle is traced, the reproduction output becomes smaller. For example, when tracing is performed with the head of A azimuth, the portion where the reproduction output is large corresponds to the case where the tracks Ta1, Ta2, ...
The part where the reproduction output is small is the track Tb1 of B azimuth,
This corresponds to tracing Tb2, ... Therefore, as shown in FIG. 6, the reproduced waveform becomes a gem-like waveform, and if N times the search is performed, N times are obtained by one scan.
Individual gem waveforms (portions with high reproduction output) can be obtained.

As shown in FIG. 8, a reproducing head width Th is wider than the track pitch Tp. For example, a reproducing head having an azimuth angle A has a track Ta having the same azimuth angle A.
Is traced, since the head is completely tracing on the track Ta from the position shown in FIG. 8A to the position shown in FIG. 8B, the reproduction output becomes flat. The amount of movement during this period is (Th-Tp). The period during which the reproduction output is sufficiently flat is a period during which the reproduction output is sufficiently obtained. Therefore, when performing a search by detecting the search code of the block ID, it is necessary to be able to pick up at least one block of data while the reproduction output is flat.

Here, as shown in FIG. 8, the track pitch is Tp, the reproducing head width is Th, and as shown in FIG. 6, the flat portion of the reproduction output is L and the reproduction waveform pitch is P. The pitch P of the reproduced waveform corresponds to the reproduced waveform of two tracks, and (Th-Tp) corresponds to the flat portion L. Therefore, the relationship of P: L = (2 * Tp) :( Th-Tp) is established. Therefore, the flat portion L of the reproduced waveform can be expressed as L = (Th−Tp) × P / (2 × Tp).

From this fact, if the flat portion L obtained by the above equation is at least one block, at least one block ID is always detected and the search code can be detected.

By the way, when a search is performed at N times,
Data of one block or more may be reproduced from each track. When one block or more of data is reproduced from each track, the same ID is recorded in a reliable manner so that the ID can be reliably detected during high-speed search.

Here, how many blocks of data are reproduced from each track will be obtained. As shown in FIG. 9, the number of blocks in one track is B, and the double speed number is N. If the number of blocks in one track is B, data for B blocks can be obtained in one scan. If the double speed number is N, it means that data for B blocks has been obtained in N tracks.
Therefore, the number of blocks per track is (B / N)
Is required. Therefore, (B
It is considered preferable to continuously record the same search ID collectively in an integer block larger than / N).

However, if the same search ID is continuously recorded together in this way, it is good for high-speed search.
During the low speed search, the pitch P becomes large, so that the number of detection errors increases. In the case of a low-speed search, when the same search ID is recorded collectively, it is more likely that the search code can be picked up and the search code detection error is reduced when distributedly recorded.

Therefore, in the present invention, the search code is recorded for the high speed search, and the search code is distributed and recorded for the low speed search.

That is, in FIG. 10, for example, the first half L1 in one track is a search code area for high speed search, and the second half L2 is a search code area for low speed search. In the area L1 of the search code for high speed search, the same search ID is continuously recorded collectively. Search codes are dispersedly recorded in the search code area L2 for low speed search. In this way, for example, in the case of high-speed search, the first half of one track is recorded with a search code for high-speed search and the second half of one track is dispersedly recorded for low-speed search. Also, the search code can be reliably detected even in the case of low speed search.

In the above example, the first half L of one track
1 for the search code area for high-speed search and the second half L2
Is divided into a search code area for low speed search, and as shown in FIG. 11, both ends L11 and L13 of one track are used as a search code area for high speed search.
The center L12 may be used as a search code area for low speed search.

Further, as shown in FIG. 12, for example, a track of azimuth A is recorded with a search code for high speed search, and a track of azimuth B is recorded with dispersed search codes for low speed search. You may leave it.

[0044]

According to the present invention, the same search code is continuously recorded for high speed search, and the search codes are dispersed and recorded for low speed search. For this reason,
The search code can be reliably detected in both the high speed search and the low speed search.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a tape streamer drive to which the present invention can be applied.

FIG. 2 is a plain view used for explaining an example of a tape cassette to which the present invention is applied.

FIG. 3 is a perspective view used for explaining an example of a tape cassette to which the present invention is applied.

FIG. 4 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 5 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 6 is a waveform diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 7 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 8 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 9 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 10 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 11 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

FIG. 12 is a schematic diagram used to describe a tape streamer drive to which the present invention can be applied.

[Explanation of symbols]

 15 system controller 26 ID circuit

Claims (4)

[Claims] 1. A data recording / reproducing method for recording / reproducing digital data on a magnetic tape by a rotary head, wherein the same search code is continuously recorded for high speed search and the search code is dispersed for low speed search. A data recording / reproducing method characterized in that the recording is performed by recording. 2. One track is divided into a high speed search area and a low speed search area, the same search code is continuously recorded in the high speed search area, and the search code is dispersed in the low speed search area. The data recording / reproducing method according to claim 1, wherein the data recording / reproducing is performed. 3. A first azimuth track is used for high-speed search, the same search code is recorded continuously on the first azimuth track, and a second azimuth track is used for low-speed search. 2. The data recording / reproducing method according to claim 1, wherein the search code is dispersedly recorded on the azimuth tracks of 2. 4. A data recording / reproducing apparatus for recording / reproducing digital data on a magnetic tape by a rotary head, wherein the same search code is continuously recorded for high speed search and the search code is dispersed for low speed search. A data recording / reproducing apparatus characterized in that a means for recording is provided.