Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data verification
Reexamination Certificate
2000-12-08
2004-02-03
Holder, Regina N. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data verification
C360S069000, C360S031000, C324S210000
Reexamination Certificate
active
06687071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique of effectively removing deposit such as stain which adhere to a magnetic head disposed on a head drum so as to move along a circular locus in a magnetic tape drive apparatus.
2. Description of the Related Art
In a magnetic tape drive apparatus such as a video tape recorder (hereinafter referred to as “VTR”) for performing a recording/reproducing operation on a magnetic tape with a recording/reproducing magnetic head which is disposed on a head drum and moves along a circular locus, plural recording/reproducing magnetic heads (hereinafter referred to as “recording/reproducing heads”) are secured to the head drum, and they scan the surface of a magnetic tape fed from a supply reel side to a take-up reel side at a predetermined speed while being moved due to the rotation of the head drum.
Since the recording/reproducing heads are brought into contact with the surface of the magnetic tape in the recording/reproducing operation, there is such a problem that they are deposited with magnetic powder falling off the magnetic tape, dust, etc. and also with depositions which have been formed as a result of thermal denaturing of the above things and then deposition onto the recording/reproducing heads (hereinafter referred to as “stain”), resulting in deterioration of electromagnetic conversion characteristic.
In general, the deposit of the recording/reproducing heads is removed by using head cleaning means such as a so-called head cleaning roller to thereby prevent the electromagnetic conversion characteristic from being deteriorated.
Recently, following increase of an information amount to be handled, the recording density has been required to be enhanced, and thus it has been indispensable for recording/reproducing heads to use a so-called MR head having higher detection sensitivity than a so-called inductive head.
However, the MR head generally has a lower allowable range to abrasion, and this abrasion problem is getting more critical than ever in such a device as VTR in which a magnetic tape and a recording/reproducing head are brought into contact with each other at all times. Accordingly, it promotes abrasion itself to frequently clean a recording/reproducing head using an MR head with cleaning means.
Therefore, there has been proposed a magnetic tape drive apparatus in which an error rate of a magnetic tape is detected and recording/reproducing heads are cleaned with cleaning means when the error rate thus detected is worse (larger) than a predetermined value. In this magnetic tape drive apparatus, the error rate as a reference value is fixed and unvaried. Therefore, for example when a magnetic tape or the like which has originally a worse (larger) error rate is used, the recording/reproducing heads are frequently cleaned although they are not deposited, so that the abrasion of the recording/reproducing heads is promoted.
SUMMARY OF THE INVENTION
The present invention has been implemented in view of the foregoing problem, and has an object to provide a magnetic tape drive apparatus and a magnetic head cleaning method which can prevent abrasion of a recording/reproducing head having a small allowable range to abrasion such as an MR head and also effectively remove deposit of the head due to deposition of stain or the like.
In order to attain the above object, a magnetic tape drive apparatus according to the present invention is characterized by comprising cleaning means for removing deposit such as stain adhering to a magnetic head to clean the magnetic head, error rate detection means for detecting the error rate of the magnetic tape when data are recorded/reproduced onto/from the magnetic tape, and error rate storage means for storing the error rate detected by the error rate detection means, wherein when the error rate detected by the error rate detection means is increased at a predetermined rate with respect to an error rate which is detected at any time point and stored, the magnetic head is cleaned by the cleaning means.
A magnetic head cleaning method according to the present invention is characterized in that a magnetic head is cleaned by cleaning means when the error rate of a magnetic tape being used is increased at a predetermined rate with respect to an error rate which is detected at any time point and stored.
Accordingly, deposit such as stain can be effectively removed, and excessive cleaning which induces abrasion of the magnetic head can be prevented.
REFERENCES:
patent: 5253126 (1993-10-01), Richmond
patent: 5973892 (1999-10-01), Hasegawa et al.
patent: 6215618 (2001-04-01), Anderson et al.
patent: 6411083 (2002-06-01), Inaba
Nagai Nobuyuki
Ozue Tadashi
Holder Regina N.
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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