Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data verification
Reexamination Certificate
1999-08-05
2001-10-23
Neal, Regina Y. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data verification
C360S046000
Reexamination Certificate
active
06307698
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic tape read apparatus and in particular to a magnetic tape read apparatus having a plurality of read heads as well as an error identification method.
2. Description of the Related Art
Conventionally, in a magnetic tape read apparatus, a data which has been read is amplified for processing, and according to a processed result, a read error is detected.
However, in the aforementioned conventional magnetic tape read apparatus, it is difficult to determine whether a read error has been caused by a medium quality deterioration or scratch or by a read head performance lowering or dust adhesion.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a magnetic tape read apparatus capable of identifying a read error cause and an error identification method.
The magnetic tape read apparatus according to the present invention is for reading magnetic data items recorded on magnetic tapes and comprises:
a plurality of read means for reading magnetic data items from the magnetic tapes;
a plurality of amplifying means for amplifying each of the data items which have been read by the plurality of read means;
automatic gain control circuits for controlling amplitudes of the respective data items which have been amplified by the plurality of amplifying means;
comparison means for comparing the data items which have been amplified by the plurality of amplifying means;
an error identification circuit for detecting a read level lowering in the read means according to the comparison result; and
a signal processor for processing the data items whose amplitudes have been controlled by the automatic gain control circuits, detecting a read error according to the processed data items, wherein if a read error is detected, the signal processor identifies a read error cause according to the detection result in the error detection circuit.
According to another aspect of the present invention, the comparison means compares to one another amplitudes of the data items which have been amplified by the plurality of amplifying means.
According to still another aspect of the present invention, when a read error is detected, the signal processor references the detection result of the error identification circuit. If any of the read means has a read level lowered, it is determined that the read error has been caused by that read means, and if no read means has a read level lowered, it is determined that the read error has been caused by other than the read means.
According to yet another aspect of the present invention, the error identification circuit outputs a detection flag signal to the signal processor if any of the read heads has a lowered read level. Upon reception of the detection flag signal, the signal processor determines that the read error has been caused by that read means having the lowered read level. Otherwise, the signal processor determines that the read error has been caused by other than the read means.
According to yet still another aspect of the present invention, there is provided an error identification method in a magnetic tape read apparatus having a plurality of read means for reading magnetic data items recorded on magnetic tapes. That is, a lowered read level of the read means is detected by comparing amplitudes of the magnetic data items which have been read by the plurality of read means. When a read error is detected, the cause of the read error is identified according to whether any of the read means has a lowered read level.
If any of the read means has a lowered read level, it is determined that the read error cause is that read means. If none of the read means has a lowered read level, it is determined that the read error has been caused by other than the plurality of the read means.
In the present invention having the aforementioned configuration, the comparison means compares to one another amplitudes of data items read from the plurality of read means and amplified by the plurality of amplifiers; the error identification circuit detects a lowered read level according to the comparison result in the comparison means; and the signal processor, upon detection of a read error, references the detection result in the error identification circuit. If any of the read means has a lowered read level, it is determined that the read error has been caused by the read means, and if no read means has a lowered read level, it is determined that the read error has been caused by other than the read means.
Thus, a read error cause is determined according to the comparison of the read levels of the read heads. Accordingly, when a read error is caused, it can be known whether the error has been caused by the medium quality deterioration including scratches or the read means performance lowering or dust adhesion.
REFERENCES:
patent: 5398140 (1995-03-01), Rhodes et al.
patent: 5455720 (1995-10-01), Norton
patent: 4-310606 (1992-11-01), None
Hayes Soloway Hennessey Grossman & Hage PC
Neal Regina Y.
NEC Corporation
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