JPH03102680A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the acquiring performance of reproduced data by providing a means demanding data which should be reproduced based on address information, a means judging whether the demanded reproduced data exists within a block where an error flag is generated or not or the like. CONSTITUTION:The means demanding the data which is reproduced based on the address information, a means outputting the error flag, a means showing that correction is impossible by a correction flag, the means judging whether the demanded reproduced data exists within the block where the error flag is generated or not and a means reading out only the demanded data are provided. Then, the data of large capacity is reproduced and the errors of frame unit among them are checked and corrected. As the result of that, even when the frame which cannot be corrected exists, all the data is not dealed with as invalid but only the demanded data is transferred as far as the error flag is not generated in the block of the data. Thus, the acquiring efficiency of the data is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording and reproducing device that improves the performance of acquiring reproduced data in a digital audio table recorder or the like.

(Prior Art) There is a digital audio tape recorder (abbreviated as DAT) that records digital signals on a magnetic tape and reproduces the recorded signals by forming a helical scanning track.

FIG. 3 is a block diagram showing a conventional DAT system.

When data is to be recorded, the data is outputted from, for example, the host i/computer 200 or the portable disc playback device via the bus 11 and introduced into the interface 12 of the data processing section 100. The data introduced into the interface 12 is read by the system microcomputer 13 and its data content is determined.

For example, there is control data (command) at the top of the recording data, and the system microcomputer 13 can start recording processing or reproduction processing in accordance with this control data. The system microcomputer 13 includes a read-only memory (ROM) 14 that stores programs for controlling the microcomputer 13 and a random access memory (R) that secures a work area.
AM) 15 is connected.

The following description assumes that a data write command is given from the host computer 200.

In this case, the control data includes a write command, an associated address, and the like. If this address is included, the system microcomputer 13 controls the tape feeding mechanism and address search circuit through the servo processing device 16 to search for the tape position where data should be written.

On the other hand, the system microcomputer 13 can control the interface 12, random access memory (hereinafter referred to as RAM) 21, parity processing section 22, etc. through the internal control circuit 20.

First, the microcomputer 13 takes in data to be recorded from the interface 12 into the buffer RAM 21. Next, parity bits are added to the data in the buffer RAM 21 by the parity processing unit 22, for example, in units of 45 frames (for example, a large capacity of 2 Mbits). In addition, this part can also perform error correction on data that has undergone parity processing (hereinafter referred to as C3).
processing). The data subjected to the C3 processing is input to the next parity processing section 23. Here, a parity bit using a Reed-Solomon code is added.

The data handled here is in small capacity units of about 128K bits at most, and is subjected to cross-interleave processing using, for example, a C1 series and a C2 series. In DAT, two tracks of data are treated as one frame. The CI series data is interleaved in blocks in the track direction of the tape and subjected to parity processing, and the C2 series data is deinterleaved in blocks in the direction across the tracks.

The data processed above is stored in the recording and modulation circuit 24.
is input. The recording and modulation circuit 24 converts, for example, 8-bit data into 10-bit data.

Since digital data is a set of "1" and "0", if it remains 8 bits, the lowest frequency signal will be obtained when the data is "00...O", and "010...O".
10101'', the highest frequency signal will be obtained.

If this continues, the frequency range will become wider and the recording characteristics of the device will not be able to cover it sufficiently, and the presence of signals in the low frequency range may have an adverse effect on servo circuits and the like. Therefore, bit conversion is performed to eliminate low frequency signals.

The signal modulated in this way is sent to A via the recording amplifier 25.
It is supplied to the head and B head.

Next, a case where a read command is supplied from the host computer 200 will be described. In this case as well, the system computer 13 reads the address included in the command,
The designated tape position will be searched through the servo processing device 16.

Once the desired location is detected, the system transitions to playback operation. The signals reproduced by A' head and B' head are
The signal is input to a data slice and phase equalization circuit 32 via an equalizer amplifier 31. In the data slice and phase synchronization circuit 32-1, an internal clock phase-synchronized with the data is generated and data is extracted by the data slice. The internal clock is generated based on clock data recorded as PLL data. The data obtained here is input to the demodulation circuit 33 and converted from 10 bits to 8 bits. The 8-bit data is temporarily stored in the sofa RAM 21. This captured data is, for example, a large amount of data for several frames. Next, under the control of the internal control circuit 20, error checking and correction of the C1 series and the C2 series using the error correction processing unit 34 is performed for each frame.

In DAT, two tracks of data are treated as one frame. Therefore, error checking and correction of the C1 series and 02 series can be performed by reading data from the head A' and B'.

When C1 series error checking and correction processing is performed, an error flag (hereinafter referred to as C1 flag) indicating the presence of an error is set. If so, the C1 flag is sent to the system microcomputer 13.

There is a limit to the error correction ability, and if there are too many C1 flags, errors in the C2 series cannot be corrected, so the system microcomputer 13 determines that the data is unusable and moves on to the next process.

For example, data may be read again or data may be interpolated. Furthermore, if correction by the C2 series is not possible, a correction flag (IPF) indicates that correction is impossible and is manually input to the internal control circuit 20. Processing of the next frame then begins.

In the error correction processing unit 34, if the number of error flags in the 01 series is small and is within the correction capability of the C2 series, error correction is performed, and the buffer R is sent again through the internal control circuit 20.
The data array is arranged in AM and written as normal data. At this time, the capture flag (I) indicates the reliability of the data.
PF) is also input to the internal control circuit 20. The internal control circuit 20 notifies the system microcomputer 13 of the contents of the correction flag (IPF). Accordingly, the system microcomputer 13 determines whether or not the 03 process is necessary in the parity processing unit 22. If the contents of the correction flag (IPF) indicate that everything is normal, there is no need for correction by C3 processing, and the system microcomputer 13
Execute the transfer routine to . However, if correction by C3 processing is necessary and possible (if the content of the correction flag indicates that it is within the correction capability by 03 processing), the parity processing unit 22 is used to perform the correction processing.

The magnetic recording and reproducing apparatus described above has a function of determining whether data to be recorded is normally recorded during a recording operation.

The arrangement of the A, B heads, A', and B' heads on the rotating drum is as shown in Figure 4. The following A' head reproduces the signal of the recording track of the A head, and the B head also reproduces the signal from the recording track of the A head. The following B' head is configured to reproduce the signal of the recording track. The recording and reproduction timing chart in this case is as shown in FIG.

The reproduced signal is inputted to the error correction processing unit 34 via the equalizer amplifier 31, the data slice and phase synchronization circuit 32, and the demodulation circuit 33, and is subjected to error correction, as in the above-described reproduction mode.

If the error correction processing unit 34 obtains a C1 flag that exceeds the correction capability, the system microcomputer 13 determines that there is an abnormality in the recording pattern and executes the next process. For example, a flag indicating that the data recorded immediately before is defective is recorded on the next track, and the data stored in the buffer RAM 21 is again subjected to parity processing and recorded along with address information and the like. If A'
Head [3/If the error correction result of the data read by the head is good, the host computer 20
The next command from 0 is read, and if there is a write command, the next data recording process is performed.

If there is no command from the host computer 200,
The tape is stopped through the servo processing device 16 to complete the operation.

(Problems to be Solved by the Invention) As described above, DAT has an error check and correction function when reproducing data, and is designed to ensure data reliability. However, the existence of this error checking and correction function can be rather inconvenient. That is, error correction is performed as shown in Fig. 6 (A
). First, one frame of reproduced data (one track or two tracks) is checked for errors in the C1 series, and if the number of errors is less than a predetermined number, error correction is performed in the C2 series. T shown in the figure
0 is the data of track 10 (see FIG. 6(B)) formed into blocks.

The error flags of the C1 series blocks all indicate that there is no error (0 mark). In this case, C2 series error correction processing is performed, the data is arranged, and then written to the RAM again. Further, Tl in the figure indicates that errors were present in four blocks (X marks) as a result of an error tick in the C1 series. In this case, C2
Error correction by series is not possible. Furthermore, T5 in the figure
indicates that there was an error in one block as a result of error checking of the C1 series. At this time, C2
Error correction based on series is possible.

In this way, a correction flag (IPF) indicating whether or not correction by the C2 series has been performed for each frame ν-frame is transmitted to the system microcomputer through the internal processing circuit. Here, the system microcomputer needs to determine whether it is possible to perform error correction by C3 processing on the large amount of data. Therefore, the contents of the correction flag (IPF) are determined. The illustrated example shows that there were three frames in the C2 sequence for which error correction was not possible. Therefore, assuming that the error correction ability by C3 processing is 2 or less error locations, in this example, there are 311 error locations, so it is determined that correction is impossible.

When this determination is made, the system is set to treat the entire data stored in the buffer RAM as invalid. In this case, settings are made to perform data interpolation or data re-reading.

However, as described above, it is not efficient to reproduce a large amount of data (for example, six tracks of a tape), perform error checking and correction processing, and then invalidate all the data at the end.

In particular, the data to be reproduced requested by the host computer is not limited to large-capacity units as described above.

Therefore, in the present invention, even if it is determined that error correction is impossible for a large unit of data, it is determined whether the requested reproduction data part is normal or not. It is an object of the present invention to provide a magnetic recording and reproducing device that can obtain reproduction data of a requested area and improve efficiency.

[Structure of the Invention] (Means for Solving the Problems) This invention blocks digital data, performs parity processing on at least two series, records it on a recording medium, and detects errors in the signal reproduced from the recording medium. In a magnetic recording and reproducing apparatus that can obtain original reproduced digital data through checking and correction processing, there is provided a means for requesting data to be reproduced using address information, and a means for searching a reproduction position on a recording medium according to the address information. A predetermined unit of data reproduced from a reproduction position is temporarily stored in a buffer memory, and an error check is performed on each of multiple blocks of data using a first series, and if an error is found, the data is If error correction is possible in the second series using means for outputting error flags and the number of error flags obtained by this means, error correction is performed in the second series, and correction of the second series is performed. means for indicating that correction is not possible by means of a correction flag if the result is beyond the capacity; and a means for indicating that correction is not possible using a correction flag; and a means for indicating that correction is not possible by means of this means; and means for reading only the requested data from the buffer memory if the requested reproduction data exists in a block that does not generate the error flag. be.

(Function) By the above means, even if a large amount of data is reproduced and there are uncorrectable frames as a result of error checking and correction for each frame, the requested data block will be flagged as an error flag. Data acquisition efficiency can be improved because only the requested data can be transferred, rather than treating all data as invalid unless a problem has occurred.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The overall block configuration is similar to the block shown in Figure 3, but
System microcomputer 13 and internal #J control circuit 2
The configuration of the 0 determination processing circuit is different. Therefore, with reference to the block in FIG. 3, the characteristic parts of the present invention will be shown and explained in FIG. 1.

A request for reproduction data is made from the host computer 200 via the data bus 11. To request playback data,
It is a command in a predetermined format, and is decoded by the system microcomputer 13 through the interface 12.

The system microcomputer 13 determines the tape address where the requested data is recorded and controls the servo processing device 16. When a desired address is searched under this control, the process moves to data reproduction processing (steps SL, S2, 83, S4, and S5 in FIG. 1).

In the next step S6, C1 as described above is used.
Error checking of the series and error correction of the C2 series are performed. At this time, an error flag and a correction flag (IPF) are generated. Correction flag (Ir'
F) is introduced into the system microcomputer 13 (step S7). Here, the correction flag (IPF)
A content determination is performed (step S8), and if it is within the error correction capability of the C3 process, the C3 process is performed in step S14. In addition, the contents of the correction flag (IPF) are
If the correction ability is greater than or equal to the correction ability of the C3 process, the process moves to step S9 and the data retrieval process is performed again. Then, as before, check the error of the 01 series and C2
Series error correction processing is performed (step S10).

At this stage, the content of the correction flag (rPF) is determined again (step Sll). If it is within the correction capability of the C3 process, the process moves to step Sl4. The reason for re-capturing data in this manner is that the error in the previously captured data may be due to, for example, temporary head clogging or dust adhesion to the tape.

Also in step Sll, if the content of the correction flag (IPF) exceeds the correction ability of C3 processing, step Sll
Move to l2. In such a case, data may be lost due to a scratch on the tape, for example.

In step SI2, what kind of correction flag (IP
Check whether F) is obtained. That is, as shown in FIG. 2, a correction flag (IPF) attached to data for which processing of the C1 series and C2 series has been completed is determined.

Here, for example, if the data requested by the host computer is data in an area shown by diagonal lines in the figure, the correction flag (IPF) for the block including this area should be normal data ( Q mark) is shown. Therefore, in such a case, in step Sl3, the system microcomputer 13 specifies only a partial area of the buffer RAM 21 in which the requested data is stored, reads the data, and sends the data to the host computer 200 through the interface 12. Perform the processing to transfer.

In the above explanation, if error correction by 03 processing is not possible in step S8, the data is read again. However, if it is necessary to save time, jump from step S8 to step S12. The routine may be structured to do so. In this case, the process returns from step SL2 to step S2 and data is read again.

In the above explanation, the processing results in the C1 series and the C2 series are looked at, and it is determined whether or not the requested data block has a correction flag before proceeding to the C3 process.

However, the present invention is not limited to this, and the determination may be made by looking at an error flag at the stage of proceeding to C2 series processing.

[Effects of the Invention] As described above, according to the present invention, even if it is determined that error correction is impossible for a large unit of data, it is determined whether the requested portion of the reproduced data is normal or not. In this way, if it is normal, the reproduction data of the requested area can be acquired, and efficiency can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a data explanatory diagram shown to explain an example of the operation of the device of the present invention, and Fig. 3 shows a conventional digital magnetic recording/reproducing device. 4 is an explanatory diagram showing the arrangement of the magnetic head, FIG. 5 is an explanatory diagram of the tape trace timing of the magnetic head in FIG. 4, and FIG. 6 is an explanatory diagram to explain the conventional error tick and correction processing. FIG. 12...Interface, 13...System microcomputer, 14...RAM, 15...RO
M, 21... Buffer RAM, 22, 23... Parity processing unit, 24... Recording and modulation circuit, 25...
・Recording amplifier, 31...Equalizer amplifier, 32・
. . . Data slice and phase synchronization circuit, 34 . . . Error correction processing section.

Claims (1)

[Claims] Digital data is divided into blocks, parity-processed in at least two series, and recorded on a recording medium, and the signal reproduced from the recording medium is subjected to error checking and correction processing to reproduce the original reproduced digital data. A magnetic recording and reproducing apparatus that can be obtained includes: means for requesting data to be reproduced using address information; means for searching a reproduction position on a recording medium according to the address information and reproducing the data; and a means for reproducing data from the reproduction position. means for temporarily storing a predetermined unit of data in a buffer memory, performing error checking on each of a plurality of blocks of data using a first series, and outputting an error flag for the block if an error is found; According to the number of error flags set, if the error correction of the second series is possible, the error is corrected in the second series, and if the error correction capacity of the second series is exceeded, a correction flag is used to indicate that the error cannot be corrected. means for determining whether or not the requested playback data exists within the block that generated the error flag if the means yields an uncorrectable result; A magnetic recording/reproducing apparatus characterized by comprising means for reading only the requested data from the buffer memory when the reproduced data exists in a block in which the error flag does not occur.