Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse...
Reexamination Certificate
2000-02-08
2001-12-04
Dinh, Tan (Department: 2651)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Reexamination Certificate
active
06327227
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a magnetic recording-reproduction apparatus and a magnetic recording-reproduction method that are preferably used in a perpendicular magnetic recording system of an optical assist type, etc. and that are capable of performing high-density recording in a magnetic disk device and a magnetic tape device.
BACKGROUND OF THE INVENTION
Tremendous research efforts have been directed to a perpendicular magnetic recording system for a long time as a system which can carry out recording with higher density as compared with a system that carries out magnetic recording in the longitudinal direction (in the in-plane direction) (longitudinal magnetic recording system). In order to achieve a next-generation magnetic recording technique that enables a recording density exceeding 10 Gb/in
2
, various studies and developing efforts have been directed to designs and machining processes for heads and media having constructions that unitize features of the perpendicular magnetic recording system. In particular, with respect to magnetic heads used for perpendicular magnetic recording/reproducing processes, studies have been directed to a single magnetic pole head which has an optimal construction.
Along with the recent developments in the technique for achieving higher density in the longitudinal magnetic recording system, a method in which the thickness of the main magnetic pole of the single magnetic pole head is made equal to the track width has been proposed and this method has attracted public attention as a recording system which well utilizes the high-density recording characteristic of the perpendicular magnetic recording (for example, see IEEE Transactions On Magnetics, vol. 30, No. 6, November, 1994, pp3900-3902).
In this method, information is written by using a plurality of recording single magnetic pole heads that are aligned in a direction parallel to the track direction of a magnetic medium, and information is read out by using a plurality of reproducing single magnetic pole heads that are aligned in a direction perpendicular to the track direction. This method makes it possible to carry out a deep sub-micron track recording with a track width of not more than 0.5 &mgr;m.
Moreover, also in a tracking servo system and a high-speed accessing system for such high-density tracks, a track following technique with higher precision which exceeds the conventional servo performances is required. For this reason, in a separate manner from the above-mentioned recording single magnetic pole head, a reproducing single magnetic pole head is installed and its main magnetic pole is aligned so as to make the length direction perpendicular to the tracks; thus, the head is designed so as to have a wider width in the track traversing direction so that a multi-track reproducing is carried out. Here, the tracking is performed based upon the above-mentioned reproducing single magnetic pole head so as to meet the high-speed reproducing process and track following process.
However, in the above-mentioned conventional apparatus, the reproducing process is carried out by using one single magnetic pole head in a manner so as to extend over a plurality of tracks; consequently, pieces of information on a plurality of tracks are simultaneously reproduced, with the result that crosstalk tends to occur. For this reason, an advanced multivalued signal processing circuit, etc., which is completely different from that of the conventional magnetic recording signal process, is required in a separate manner. The resulting problem is that an extremely complex magnetic recording-reproduction apparatus is required.
Moreover, in the conventional apparatus having a reproducing single magnetic pole head in a separate manner from the recording single magnetic pole head, a magnetic head, which has two heads, that is, a recording single magnetic pole head and a recording single magnetic pole head, in a hybrid manner, has to be installed. The resulting problem is that a complicated head manufacturing process is required.
DISCLOSURE OF THE INVENTION
In order to solve the above-mentioned problems, a magnetic recording-reproduction apparatus in accordance with the present invention, which carries out recording and reproducing processes on and from a magnetic recording-reproducing medium on which a perpendicular magnetic recording layer made of a ferrimagnetic material whose magnetic compensation temperature is set to approximately room temperature is formed, is provided with: a recording-reproducing magnetic head constituted by a plurality of single magnetic pole magnetic heads having respective main magnetic poles whose length directions are aligned in the same direction as the information track direction of the magnetic recording-reproducing medium, the recording-reproducing magnetic head being used for both recording and reproducing; and a temperature-raising means for allowing an area facing the main magnetic poles of the respective single magnetic pole heads in the perpendicular magnetization layer to have a temperature rise.
In the above-mentioned arrangement, the recording-reproducing magnetic head is constituted by not less than two of the single magnetic pole magnetic heads which have respective main magnetic poles whose length directions are aligned in the same direction as the information track direction of the magnetic recording-reproducing medium, and which are used for both recording and reproducing. This makes it possible to increase the tracking density. The magnetic recording-reproducing medium used in the above-mentioned magnetic recording-reproduction apparatus is provided with the perpendicular magnetic recording layer made from a ferrimagnetic material having a magnetic compensation temperature set to approximately room temperature; therefore, an area (portion) of the recording layer that is virtually at room temperature exhibits a smaller saturated magnetization, thereby minimizing the leakage magnetic flux therefrom.
The following description will discuss a process in which information is recorded and reproduced on and from the above-mentioned magnetic recording-reproduction medium by using the recording-reproducing magnetic head. In this case, one portion of an area in the perpendicular magnetic recording layer facing the main magnetic poles of the single magnetic pole heads is subjected to a temperature rise (for example, by irradiation with a light beam or heating by using a minute thermal source), and the recording and reproducing processes are carried out as follows:
When, upon recording, the temperature of a recording area is raised to the vicinity of the Curie temperature so that the coercive force of the perpendicular magnetic recording layer becomes nearly zero, the leakage magnetic field from the single magnetic pole heads is applied to the recording area so that the information is readily recorded thereon. In other words, a high track density is achieved by a recording process using the narrow track that nearly corresponds to the width of each main magnetic pole of the single magnetic pole heads.
In contrast, when, upon reproducing, the temperature of a reproducing area is raised so as to allow the saturated magnetization of the ferrimagnetic material to reach the vicinity of the maximum value, a non-temperature-rise area, that is, an area that faces the main magnetic poles of the single magnetic pole heads and is maintained in the vicinity of the magnetic compensation temperature (virtually, room temperature); therefore, a magnetic flux released from the saturated magnetization only from the temperature-rise area (reproducing area) is detected by the single magnetic pole heads facing the area with high precision. This makes it possible to positively solve the conventional problem that information separation is not properly made due to the operation carried out in a manner extending over a plurality of recording bits in the track direction, and consequently to reproduce information recorded with high linear density that is an original feature of
Conlin David G.
Dike Bronstein, Roberts & IP Group
Dinh Tan
Sharp Kabushiki Kaisha
Tucker David A.
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