Dynamic magnetic information storage or retrieval – General recording or reproducing
Reexamination Certificate
1999-01-05
2001-05-08
Huber, Paul W. (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
C360S313000, C360S134000
Reexamination Certificate
active
06229662
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a helical scan magnetic recording/reproducing apparatus and a magnetic tape used in the helical scan magnetic recording/reproducing apparatus.
2. Description of the Related Art
In a magnetic recording/reproducing apparatus employing a magnetic tape as a recording medium, such as a video tape recorder, an audio tape recorder or a data storage system for a computer, a helical scan system is used to raise the recording density to increase the recording capacity.
For this type of the magnetic recording/reproducing apparatus, a demand is raised for further increasing the recording density and the recording capacity. To this end, there is proposed in the helical scan magnetic recording/reproducing apparatus a technique of using a magneto-resistive effect magnetic head (MR head) as a playback magnetic head.
The MR head is a magnetic head employing a magneto-resistive effect element (MR element) in its magnetically sensitive portion. It has a sensitivity higher than with an inductive magnetic head and can develop a large playback output. Thus, by using the MR head as a playback magnetic head, a higher recording density and a higher recording capacity can be realized.
However, if, in the helical scan magnetic recording/reproducing apparatus, the MR head is substituted for the inductive magnetic head for use as a playback magnetic head, a number of problems, that have not been experienced with the inductive magnetic head, are raised.
Specifically, the magnetic recording/reproducing apparatus is lowered significantly in durability such that a practically tolerable durability cannot be obtained. Moreover, there may be raised such problems as failure to output reproduced signals (dropout) notwithstanding the high playback output from the MR head.
Thus, the helical scan magnetic recording/reproducing apparatus, employing a MR head as a playback magnetic head, has much to be desired, such that a practically usable apparatus has not been realized.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a magnetic recording/reproducing apparatus usable as a helical scan magnetic recording/reproducing apparatus employing a MR head as a playback magnetic head.
It is another object of the present invention to provide a magnetic tape which renders it possible to realize a helical scan magnetic recording/reproducing apparatus employing a MR head as a playback magnetic head.
In one aspect, the present invention provides a magnetic recording/reproducing apparatus for reproducing signals by a helical scan system from a magnetic tape having a magnetic layer formed on a non-magnetic substrate thereof, including a magneto-resistive effect magnetic head for reproducing signals from the magnetic tape, and a rotary drum carrying the magneto-resistive effect magnetic head, the magnetic tape being such a magnetic tape having a large number of projections on the tape surface and containing an electrically conductive material in the magnetic layer.
Since the present magnetic recording/reproducing apparatus uses a magnetic tape containing an electrically conductive material as a magnetic layer, static charges are not likely to be accumulated on the magnetic tape, so that the magnetic head is less likely to be produced due to static destruction. Also, since the present magnetic recording/reproducing apparatus uses a magnetic tape having a number of projections formed on its tape surface, the true contact area between the magnetic tape and the MR head is extremely small, so that it is unlikely that the sense current which should flow through the MR head
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flows through the magnetic tape to produce electrical shorting.
Also, in the magnetic recording/reproducing apparatus, the magneto-resistive effect magnetic head includes a MR device as a magnetically sensitive device for detecting signals from the magnetic tape. One of the terminals derived from the MR device is preferably connected to the rotary drum. If the static electricity accumulated in the magnetic tape is discharged, any excess current produced by the discharge is allowed to exit efficiently towards the rotary drum to render destruction of the MR device less prone to destruction otherwise caused by static charges.
In another aspect, the present invention provides a magnetic tape used in a magnetic recording/reproducing apparatus adapted for reproducing signals in accordance with a helical scan system using a magneto-resistive effect magnetic head, including a tape-shaped non-magnetic substrate, and a magnetic layer formed on the non-magnetic substrate and containing an electrically conductive material, there being formed a large number of projections on a surface of the tape facing the magneto-resistive effect magnetic head.
With the present magnetic tape, in which the electrically conductive material is contained in its magnetic layer, static charges are less likely to be accumulated, so that it is unlikely that the MR head be destructed by discharge of the static charges. Also, since a number of projections are formed on the tape surface, the true contact area between the magnetic tape and the MR head is extremely small. The result is that there is only little risk of the sense current flowing in the magnetic tape instead of through the MR device to produce electrical shorting.
With the magnetic recording/reproducing apparatus according to the present invention, static destruction of the MR head can be prohibited, using the MR head of the helical scan system, to improve durability, while reducing occurrences of dropout.
With the magnetic tape of the present invention, it is possible to prevent static destruction of the MR head
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of the magnetic recording/reproducing apparatus of the helical scan system employing a MR head as the reproducing magnetic head, to improve its durability, while reducing occurrences of dropout.
Thus, in accordance with the present invention, a MR head that is able to develop a high sensitivity and a high output can be used as a reproducing magnetic head loaded on the magnetic recording/reproducing apparatus of the helical scan system, thus assuring a higher recording density and a larger recording capacity.
REFERENCES:
patent: 5995306 (1999-11-01), Contreras et al.
patent: 6151191 (2000-11-01), Muftu et al.
Ikegami Tomohiro
Kamatani Yoshiteru
Ozue Tadashi
Saito Takehiko
Shirai Toshio
Huber Paul W.
Sonnenschein Nath & Rosenthal
Sony Corporation
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