JPH1021503A - Method and device for reproducing tape recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain an effective recovery when an error of re-produced data is generated, by repeating the reproduction trial of the data at a different reproducing speed from the normal reproducing speed and finding out a suitable operating point. SOLUTION: Error in the data is checked by an ECC means 4, and a data error information 4a is outputted. The reread is decided by a system controller 7 in accordance with the error information 4a, then an instruction 7a to change the reproducing speed is given to a servo mechanism 8. By the servo mechanism 8, the reproducing speed is changed from the one at the normal time based on the reproducing speed changing instruction 7a from the system controller 7, thus the data reproduction at the changed reproducing speed 8a is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for reproducing a tape recording medium, and more particularly to a method for re-reading (read retry) when an error occurs in a tape recording medium and a reproducing apparatus capable of re-reading (read retry). Things.

[0002]

2. Description of the Related Art A tape streamer used for backing up computer data and the like requires high reliability of reproduced data. Therefore, management and elimination of errors that occur during reproduction are extremely important requirements. For this reason, the streamer usually protects data by adding an ECC (error correction code),
Using a combination of techniques such as rewriting (write retry) when an error is detected during r Write (hereinafter referred to as RAW) and rereading (read retry) when an error is detected during playback, Improves reliability.

FIG. 5 is an explanatory diagram of a conventional error detection. FIG. 6 is an explanatory diagram of a conventional rewrite operation. Hereinafter, referring to both figures, rewriting (write retry)
And rereading (read retry) will be described.

[0004] As shown in FIG. 5, when an ECC error is detected in the data block A in the RAW, as shown in FIG. Rewriting is to be additionally written as the next data block AA.

At this time, when rewriting is performed, the data block A in which an error has been detected is assigned an address I on the tape.
D (the start point address and the end point address of the block) is registered in the defect location table. Therefore, at the time of reproduction, this defective portion table is referred to, and the data block A which is confirmed to be normal by RAW without using the defective data block A is used.
A data is used. On the other hand, when an error is detected during the reproduction of data, rereading data from the same portion again is rereading.

Conventionally, in both rewriting and rereading, recording / reproducing conditions (for example, reproducing speed, etc.) on a tape have been executed normally, that is, the same as standard recording / reproducing conditions. Also,
Normally, data that is confirmed to be normal by RAW at the time of recording is not transcribed or appended to the same tape, so that in rereading, rewriting is performed on another part of the tape, while Will be re-read using the same part of.

[0007]

In the prior art, as described above, conditions for rereading (for example, reproduction speed) are performed under the same conditions as the first reading, so that a fatal case such as a large scratch on the tape is caused. Naturally, even if a data error occurs due to deterioration of the tape due to aging, wear of the head, deterioration of the characteristics of the RF circuit, etc., it is necessary to re-read the data under the same conditions as the first reading. Become.

Therefore, there is a problem that it is unlikely that data that could not be normally reproduced in the first reading can be normally reproduced in the second and subsequent readings by re-reading. As described above, the conventional technique has a drawback that data recovery success in the case of a reproduced data error due to a change with time is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and disadvantages of the prior art, and an object of the present invention is to provide a tape recording apparatus for operating a reproducing apparatus whose operating point fluctuates due to aging or the like at a suitable operating point. An object of the present invention is to provide a medium reproducing method and a reproducing apparatus.

That is, the present invention relates to a method and apparatus for reproducing a tape recording medium which changes the characteristics of a reproduction signal by changing the reproduction speed at the time of re-reading and recovers errors in reproduced data to the maximum.

[0011]

In general, when a data error occurs due to deterioration of a tape medium due to aging, abrasion of a head, or deterioration of characteristics of an RF circuit, a tape / head / RF circuit or the like is generally used. In many cases, the optimum point of the characteristics of the reproduction system is shifted from the normal state.

Therefore, in order to achieve the above object, a method and apparatus for reproducing a tape recording medium according to the present invention is a magnetic recording apparatus for recording digital data on a tape recording medium.
In a device provided with a data error detecting means such as C, a data error is detected during reproduction and read retry (reread) is performed.
Is performed when data is reproduced at a reproduction speed different from a normal reproduction speed.

With the above-described configuration, data can be reproduced at a reproduction speed that avoids a characteristic deterioration point due to a temporal change of the tape head system or the RF circuit, and thus effective recovery in the event of a reproduced data error becomes possible.

When the method and apparatus for reproducing a tape recording medium according to the present invention have a reproduction speed higher (or lower) than the standard reproduction speed, the preferable read operation point of the apparatus is high ( Alternatively, when shifting to the (lower) speed side, the preferred read operation point can be easily reached.

Further, when the method and apparatus for reproducing a tape recording medium according to the present invention records and saves at least the reproduction speed and the position information of the block on the tape recording medium upon successful re-reading. Can use the information of the optimum condition recorded on the tape medium at the time of reading the same block thereafter, and realize more efficient reading processing.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A reproducing apparatus for a tape recording medium according to the present invention is a magnetic recording apparatus for recording digital data on a tape recording medium. Re-reading is performed to minimize the reproduction error caused by the deterioration of the characteristics of the tape head system, the RF system, and the like.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a functional block diagram of an embodiment of a tape recording medium reproducing apparatus according to the present invention. FIG.
As shown in FIG. 1, a tape recording medium reproducing apparatus 1 according to the present invention is a helical tape streamer, and includes a recording / playback head 2, an RF amplifier 3,
ECC means 4, buffer memory 5, interface 6,
The system includes a system controller 7 and a servo mechanism 8.

In the figure, the flow of data is indicated by thick arrows,
For example, the read data flows through the recording / playback head 2, the RF amplifier 3, the ECC means 4, the buffer memory 5, and the interface 6 in this order, and is output to the host computer. Also, the write data follows the reverse process.

The ECC unit 4 checks data for errors and outputs data error information 4a. Thus E
The error information 4a obtained from the CC unit 4 is used as a determination material for the system controller 7 to retry.

The system controller 7 sends the error information 4
Based on "a", rereading is determined, and a reproduction speed change instruction 7a is given to the servo mechanism 8.

The servo mechanism 8 changes the reproduction speed from the normal reproduction speed based on the reproduction speed change instruction 7a from the system controller 7, and enables data reproduction at the changed reproduction speed 8a.

FIG. 2 shows an operation flow at the time of rereading according to the present invention. First, with the counter N reset (step S1), data is reproduced at a normal reproduction speed (step S2). At this time, if a data error is not detected (step S3), it is checked whether or not the data block is completed (step S9). If the data block is completed, the process is terminated. The reproduction of the data block is started (step S10).

However, if a data error is detected in step S3, the counter N is incremented (step S4), the tape is returned to the beginning of the data block (step S6), and the reproduction speed is changed to change the tape again. Reproduction is attempted (step S7). The change in the reproduction speed is, for example, a decrease in the tape running speed by k%, but is not limited to this.

The counter N limits the number of re-reads, and the value of the counter N does not exceed the limit M (step S).
At 5), the trial is repeated. In other words, if a data error is detected even when the reproduction is attempted again, the reproduction is attempted again with the speed further reduced by k%.

When the counter N exceeds the limit value M,
Even if the trial is repeated, it is determined that normal reproduction of data is no longer possible, and an error is made (step S8). The value of M can be determined from the speed range in which data can be reproduced determined by the characteristics of the device mechanism (mechanism), the servo, and the RF circuit, and the value of the change rate k of the reproduction speed at the time of retry.

In this configuration, the rate of change k is fixed. However, the rate of change k may be changed each time rereading is performed in accordance with the circuit characteristics of the tape streamer and the characteristics of the device mechanism. Further, as shown in FIG. 3, in the retry in the present invention, a plurality of trials are repeated while gradually increasing or decreasing the tape running speed each time, and a suitable operation point is determined by trial and error.

As shown in FIG. 3, if the tape running speed is the standard v, the area swept by the head per unit time is S, but if this is reduced by k%, the tape running speed becomes the standard. (1-k) times v, and the sweep area is S
(1-k) times of Further, in the next trial, the tape running speed becomes the square root of (1-k) times the standard v, and the sweep area becomes (1-k) square root of S. In this way, the tape running speed gradually decreases each time the trial is repeated, and a suitable operating point is searched for. The same applies to the gradually increasing k%.

In short, the allowable operating point is deviated from the standard reproduction speed due to deterioration of the tape medium due to aging, wear of the head, deterioration of the characteristics of the RF circuit, and the like.
Since the error occurs, the main point of the present invention is to repeat the reproduction trial by increasing or decreasing the tape running speed and to determine the optimum operation point by trial and error.

FIG. 4 shows a main part of another embodiment of the tape recording medium reproducing apparatus according to the present invention. In the present embodiment, re-reading is repeated a plurality of times by changing the reproduction speed,
When the re-reading is successful, the relevant information (for example, the start and end addresses of the block) is set as a successful read condition (for example, the reproduction speed V = k1 m / sec) as an optimal condition for reading the block. Record it in the appropriate position on the tape medium. As a result, when an opportunity to read this block occurs later, it becomes possible to use the recorded information on the optimal conditions.

As described above, according to the method and apparatus for reproducing a tape recording medium according to the present invention, by changing the reproduction speed and trying re-reading, the contact state of the tape head and the frequency of the reproduction signal are improved. The band changes, and as a result, S
The reproduction signal characteristics such as the / N ratio change. Therefore, by reading a signal whose characteristic has changed through a reproducing system having a characteristic shifted from the normal state, reading with less error becomes possible.

[0031]

As described above, according to the method of reproducing a tape recording medium according to the first aspect of the present invention, when performing a read retry (rereading), data is reproduced at a reproduction speed different from a normal reproduction speed. Since the reproducing operation is repeated to find a suitable operating point, this configuration makes it possible to reproduce the data at a reproducing speed that avoids the characteristic deterioration point due to the aging of the tape head system or the RF circuit. Effective recovery when an error occurs becomes possible.

Further, by gradually changing the reproduction speed in a plurality of rereading trials, it is possible to improve the degree of success of the retrying.

In the method of reproducing a tape recording medium according to the second aspect of the present invention, since the reproduction speed is set to a speed higher than the standard reproduction speed, the preferred read operation point of the apparatus is shifted to a higher speed side. If so, a suitable read operation point can be easily found.

Similarly, in the tape recording medium reproducing method according to the third aspect of the present invention, the reproducing speed is set to a speed lower than the standard reproducing speed. , It is possible to easily find a suitable read operation point.

According to a fourth aspect of the present invention, there is provided a method for reproducing a tape recording medium, in which re-reading is repeated a plurality of times while changing a reproducing speed. Since the relevant information is recorded at an appropriate position on the tape medium as the optimal condition for reading, this makes it possible to obtain the optimal information recorded on the tape medium at the subsequent reading opportunity at the same place. The use of the condition information enables more efficient read processing with a minimum number of trials.

In the tape recording medium reproducing apparatus according to the fifth aspect of the present invention, when performing a read retry (rereading), a data reproduction trial is repeated at a reproduction speed different from a normal reproduction speed, and a suitable reproduction is performed. Since reading is performed after finding an operation point, this configuration makes it possible to reproduce data at a reproduction speed that avoids a characteristic deterioration point due to aging of the tape head system or the RF circuit. Errors can be effectively recovered, and reliable data reproduction becomes possible.

In the tape recording medium reproducing apparatus according to the sixth aspect of the present invention, since the reproducing speed is higher than the standard reproducing speed, the preferable read operation point of the apparatus shifts to the higher speed side. If so, it can be easily adjusted to a suitable read operation point.

Further, in the tape recording medium reproducing apparatus according to the seventh aspect of the present invention, since the reproducing speed is lower than the standard reproducing speed, the preferable reading operation point of the apparatus shifts to the lower speed side. If so, it can be easily adjusted to a suitable read operation point.

The tape recording medium reproducing apparatus according to claim 8 of the present invention performs re-reading a plurality of times by changing the reproducing speed, and when the re-reading is successful, the successful read condition is set to the block. Since the relevant information is recorded at an appropriate position on the tape medium as the optimal condition for reading, this makes it possible to obtain the optimal information recorded on the tape medium at the subsequent reading opportunity at the same place. The use of the condition information enables more efficient read processing with a minimum number of trials.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an embodiment of a tape recording medium reproducing apparatus according to the present invention.

FIG. 2 is an operation flowchart at the time of re-reading of the tape recording medium reproducing apparatus according to the present invention.

FIG. 3 is an explanatory diagram of the principle of a method for reproducing a tape recording medium according to the present invention.

FIG. 4 is an explanatory view of a main part of another embodiment of the tape recording medium reproducing apparatus according to the present invention.

FIG. 5 is an explanatory diagram of conventional error detection.

FIG. 6 is an explanatory diagram of a conventional rewrite operation.

[Explanation of symbols]

1. Reproduction device for tape recording medium according to the present invention, 2.
Recording / playback head, 3 ... RF amplifier, 4 ... ECC means, 4a ... Data error information, 5
... Buffer memory, 6 interface, 7 system controller, 7a playback speed change instruction, 8
... Servo mechanism, 8a... Changed playback speed.

Claims (8)

[Claims] 1. A magnetic recording apparatus for recording digital data on a tape recording medium, comprising a data error detecting means such as an ECC. When a data error is detected during reproduction and a read retry (reread) is performed, a standard A method for reproducing data from a tape recording medium, wherein data is reproduced at a reproduction speed different from the reproduction speed. 2. The method according to claim 1, wherein the reproduction speed is higher than a standard reproduction speed. 3. The method according to claim 1, wherein the reproduction speed is lower than a standard reproduction speed. 4. The tape recording medium according to claim 1, wherein at least the reproduction speed and the position information of the block are recorded and stored on the tape recording medium when the re-read succeeds. How to play. 5. A magnetic recording apparatus for recording digital data on a tape recording medium, comprising a data error detecting means such as an ECC, wherein when a data error is detected at the time of reproduction and a read retry (reread) is performed, a normal operation is performed. A tape playback device for playing back data at a playback speed different from the playback speed of the tape recording medium. 6. The apparatus according to claim 5, wherein the reproduction speed is higher than a standard reproduction speed. 7. The tape recording medium reproducing apparatus according to claim 5, wherein the reproducing speed is lower than a standard reproducing speed. 8. The tape recording medium according to claim 5, wherein at least the reproduction speed and the position information of the block are recorded and stored on the tape recording medium when the re-read succeeds. Playback device.