Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-11-29
2003-05-06
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06560069
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This application relates to perpendicular recording heads for use with magnetic recording media. More specifically, the invention relates to a perpendicular recording head wherein the layers of material comprising the recording head's components are deposited perpendicular to the recording medium's direction of travel.
2. Description of the Related Art
Perpendicular recording heads for use with magnetic recording media have been proposed to overcome the storage density limitations of longitudinal recording heads. Perpendicular recording heads typically include a pair of magnetically coupled poles, with the main pole having a significantly smaller surface area than the opposing pole. A coil is located adjacent to the main pole for inducing a magnetic field in the main pole. Magnetic recording media used with perpendicular recording heads typically includes an upper layer having alternating magnetically hard tracks and nonmagnetized transitions. A magnetically soft lower layer will typically be located adjacent to the recording layer, opposite the recording head. Due to the difference in surface area between the main pole and opposing pole, and the magnetic flux passing through the soft underlayer between the two poles, the orientation of magnetic flux within the recording tracks will be oriented perpendicular to the recording medium, and parallel to the magnetic flux within the main pole.
The recording density is inversely proportional to the width of the magnetically hard recording tracks. The width of these tracks is a function of the width of the recording heads main pole. Presently available main poles are currently produced through lithographic processes. The width of the main pole is therefore limited by the resolution of these lithographic processes.
Therefore, there is a need for an improved perpendicular recording head having a main pole with a narrow width. Further, there is a need for a perpendicular recording head having a main pole capable of being produced by processes having better resolution than lithography. Additionally, there is a need for a method of manufacturing a perpendicular recording head capable of producing main poles for use with narrow trackwidths.
SUMMARY OF THE INVENTION
The present invention is a perpendicular recording head for use with magnetic recording media. Although not limited to such use, such a recording head is particularly useful for fixed or hard drives for computers.
A perpendicular recording head of the present invention includes a main pole magnetically coupled to an opposing pole. The bottom surface of the opposing pole has a significantly greater surface area than the bottom surface of the main pole. An electrically conductive coil passes adjacent to the main pole for inducing magnetic flux within the main pole. The direction of magnetic flux within the main pole may be reversed by reversing the direction of current flow through the coil.
A preferred and suggested method of making a perpendicular recording head of the present invention involves depositing the material to form the main pole and opposing pole on the side of a slider. The material is thereby deposited perpendicular to the recording medium's direction of travel, and parallel to the recording medium's trackwidth. Therefore, the trackwidth is a function of the amount of material deposited on the side of the slider to form the main pole. The increased area of the opposing pole relative to the main pole may be achieved by depositing the opposing pole over a longer portion of the slider, or by depositing a thicker layer of material to form the opposing pole.
Alternatively, the perpendicular recording head may be manufactured by first depositing the opposing pole on the side of the slider, followed by depositing a magnetically permeable joint between the main and opposing poles, a coil, and lastly, a main pole. As before, the trackwidth is defined by the thickness of material deposited to form the main pole. The opposing pole may be given a greater bottom surface area than the main pole by either increasing the length of the slider on which the opposing pole is deposited, or by increasing the thickness of material deposited to form the opposing pole.
A typical magnetic recording medium for use in conjunction with a perpendicular recording head includes an upper layer having a plurality of magnetically permeable tracks separated by nonmagnetized transitions, and a magnetically permeable lower level. The lower level is magnetically soft relative to the tracks.
The recording head is separated from the magnetic recording medium by a distance known as the flying height. The magnetic recording medium is moved past the recording head so that the recording head follows the tracks of the magnetic recording medium, with the main pole oriented parallel to the tracks and perpendicular to the trackwidth. Current is passed through the coil to create magnetic flux within the main pole. The magnetic flux will pass from the main pole through the track, into the lower layer, and across to the opposite pole. The flux will thereby cause the magnetic fields in the tracks to align with the magnetic flux of the main pole. Changing the direction of electric current changes the direction of the flux created by the recording head and therefore the magnetic fields within the magnetic recording medium. Because the surface area of the opposing pole is significantly greater than the surface area of the main pole, the magnetic flux density passing through the opposing pole will be significantly lower than the magnetic flux density passing through the main pole. Therefore, only the magnetic flux immediately adjacent to the bottom surface of the main pole will affect the orientation of the magnetic fields within the tracks. A binary “zero” is recorded by maintaining a constant direction of magnetic flux through the main pole, and a binary “one” is recorded by changing the direction of magnetic flux through the main pole.
When writing to a magnetic recording medium, the rate of decrease of magnetic field strength with increasing distance from the trailing edge of the main pole determines the recording density possible within a given track. This decrease in magnetic field strength determines the ability of the main pole to effect the orientation of magnetic flux within that portion of the track directly below the main pole, without effecting the orientation of magnetic flux in the track sector immediately behind the sector for which a write operation is being performed. Therefore, the dimension of the main pole parallel to the track does not effect recording density, and is only critical for ensuring that the surface area of the main pole's bottom is significantly less than the area of the opposing pole's bottom surface. Because the only critical dimension of the main pole is controlled by the thickness of material deposited to form the main pole, the method of producing such a perpendicular recording head is particularly simple and efficient. Additionally, because magnetic flux immediately adjacent to the opposing pole's bottom surface is not sufficiently strong to effect the orientation of magnetic flux within the magnetic recording medium, the position of the opposing pole relative to the main pole is limited only by the need to maintain a flow of magnetic flux between the main and opposing poles of the perpendicular recording head, and the soft underlayer of the magnetic recording medium. The opposing pole may therefore be located in front of, to the side of, or behind the main pole.
It is therefore an aspect of the present invention to provide a perpendicular recording head for use with magnetic recording media having a narrower main pole than can be produced by presently used lithography methods.
It is another aspect of the present invention to provide a perpendicular recording head wherein the width of the main pole is determined by the process of depositing the material forming the main pole to the appropriate
Khizroev Sakhrat
Litvinov Dmitri
Heinz A. J.
Pietragallo Bosick & Gordon
Seagate Technology LLC
Towner, Esq. Alan G.
Watko Julie Anne
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