Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2001-01-16
2003-10-07
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S125330
Reexamination Certificate
active
06631054
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates to a thin film magnetic head, a magnetic head device a magnetic disk device, and a method for manufacturing a thin film magnetic head.
2) Related Art Statement
Combination type thin film magnetic heads, each having an inductive type writing element and a MR reading element, have been employed as thin film magnetic heads to constitute magnetic disk drive devices of memory devices in a computer.
Two types of longitudinal magnetic recording element and perpendicular magnetic recording element are well known as the inductive type writing element. In this specification, a thin film magnetic head having the longitudinal magnetic recording element will be called as a “longitudinal recording thin film magnetic head”, and a thin film magnetic head having the perpendicular magnetic recording element will be called as a “perpendicular” recording thin film magnetic head.
The above thin film magnetic head is mounted at the forefront of a head supporting device called as a gimbal. The head supporting device is driven by a position determining device. A rotary-actuator system is generally employed as the drive system of the position determining device. The thin film magnetic head is positioned on a given track position of a magnetic disk through the rotation drive of the position determining device for the head supporting device. The position of the thin film magnetic head on the magnetic disk is defined by a rotation angle called as a “skew angle”.
Generally, the position of the center line of the writing element of the thin film magnetic head tangent to the circumference of the magnetic disk is defined as skew angle zero. If the thin film magnetic head is moved toward the inside or the outside of the magnetic disk, the skew angle is increased from the zero value of the skew angle. The skew angle is normally set within 25 degrees.
The edge portion of the thin film magnetic head, which corresponds to the outflow edge of airflow when the magnetic disk is rotated, is called as a trailing edge, and the opposite edge portion to the trailing edge is called as a leading edge.
For realizing a high recording density in the magnetic disk using the thin film magnetic head, it is required that data amount (data density) to be restored in the unit area of the magnetic disk is enhanced. The surface recording density depends on the performance of the recording element of the magnetic head.
In the longitudinal recording thin film magnetic head, the surface recording density can be enhanced by reducing the gap length between the pole portions of the writing element. However, the reduction of the gap length is restricted because the magnetic flux generated in between the pole portions is decreased as the gap length is decreased.
In the longitudinal recording thin film magnetic head, if the data track number recordable in the magnetic disk is increased, the surface recording density can be enhanced. The recordable data track number is usually called as a “TPI (track per inch)”. The TPI performance of the writing element can be developed by reducing the size of the thin film magnetic head to define the data track width. The head size is usually defined as a “track width”. In this specification, the track width direction will be called as a “track direction”.
An attempt is made to narrow the track width of the longitudinal recording thin film magnetic head in prior art documents. For example, Kokai Publications Kokai Hei 7-262519 and 7-225917 disclose that a first pole portion is processed by ion beam milling with a second pole portion as a mask, obtained by photolithography, so that the track width of the first pole portion can correspond to that of the second pole portion.
Kokai Publication Kokai Hei 6-28636 discloses a method for narrowing a track width as follows: After a first magnetic yoke layer (first yoke portion) is formed, a photoresist layer is formed, in which an opening is formed in order to form a magnetic pole edge assembly composed of a first pole portion, a gap film, and a second pole portion. Then, the magnetic pole edge assembly is formed in the opening, and thereafter, the part of the photoresist layer positioned at the forefront of the assembly is removed. Subsequently, a coil structure and an insulating film are formed by a conventional manner, and a second magnetic yoke layer (second yoke portion) is formed.
However, the aspect ratio (a ratio “t/w” of a thickness “t” to a width “w”) of the magnetic film constituting the writing pole portion is increased as the track width of the writing pole portion is narrowed. The narrowing the track width for high recording density enables the TPI to have a higher value, and thus, the distance between the adjacent tracks is set to an extremely small value of for example about 0.9 &mgr;m.
If the magnetic film constituting the writing pole portion, particularly the magnetic film positioned at the trailing edge side (usually called as a “top magnetic film”) has a higher aspect ratio, the edge of the top magnetic film may be overlapped on the neighboring track in a large skew angle region. As a result, data recorded in the neighboring track may be rewritten or erased.
It is known that a perpendicular recording thin film magnetic head can have remarkably high recording density compared with the above longitudinal recording thin film magnetic head. However, if the perpendicular recording thin film magnetic head also have a higher TPI, the magnetic field generated from the side edge of the writing magnetic pole is overlapped on the neighboring track in a large skew angle region. As a result, data recorded in the neighboring track may be rewritten and erased. Herein, the wording “side edge” means edge portion of the writing magnetic pole in the track direction.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thin film magnetic head, a magnetic head device and a magnetic disk drive device which can avoid magnetic harmful effects such as the above data-rewriting and data-erasing in the neighboring track.
It is another object of the present invention to provide a thin film magnetic head, a magnetic head device and a magnetic disk drive device which, in developing their TPI performances and realizing their high density recording, can avoid magnetic harmful effects such as the above data-rewriting ad data-erasing in the neighboring track.
It is still another object of the present invention to provide a method for preferably manufacturing the above thin film magnetic head.
For achieving the above objects, a thin film magnetic head according to the present invention includes a slider and at least one inductive type electromagnetic conversion element, and is driven in a radial direction of a magnetic disk at a given skew angle, as combined with the magnetic disk.
The inductive type electromagnetic conversion element includes a first magnetic film and a second magnetic film and a coil film, and is supported by the slider. One edge portion of the first magnetic film is positioned at an air bearing surface (hereinafter, called as an “ABS”) side, and the first magnetic film is extended backward from the ABS. The second magnetic film is positioned at a trailing edge side, and one edge portion of the second magnetic film is opposed to the first magnetic film by a given distance in the ABS side. Then, the second magnetic film is extended backward from the ABS, and joined with the first magnetic film. The coil film is whirled around the magnetic circuit composed of the first and second magnetic films.
The one edge portion of the second magnetic film has at least one side surface inclined at a given inclination angle not less than the maximum skew angle in a track direction.
As mentioned above, the one edge portion of the first magnetic film is positioned at the ABS side, and the one edge portion of the second magnetic film is opposed to that of the first magnetic film via the given distance. Then, the first magnetic film is extended backward from the ABS, and the secon
Miyazaki Tetsuo
Yamanaka Noboru
Oliff & Berridg,e PLC
Ometz David L.
TDK Corporation
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