Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2000-06-02
2002-11-26
Nguyen, Hoa T. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06487045
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic disc apparatus, a magnetic head, and a production method thereof and in particular, to a magnetic head in which a recording/reproduction element is mounted on a magnetic head slider via a piezoelectric element so that the position of the recording/reproduction element can be adjusted in job mode by displacement of the piezoelectric element, and its production method, and to a magnetic disc apparatus using the magnetic head, and its production method.
2. Description of the Related Art
In a magnetic disc apparatus, recording density can be increased by increasing the recording density (linear recording density) of the magnetic disc rotation direction and the recording density (track density) of the magnetic disc radial direction.
In order to increase linear recording density, it is necessary to reduce the spacing between the magnetic head recording/reproduction element and the magnetic disc. In a conventional magnetic disc apparatus using a float type slider, spacing is reduced by weakening the floating power of the float type slider.
FIG. 10
is a perspective view of a conventional magnetic head (conventional float type magnetic head) using a float type slider.
FIG. 10
shows the magnetic head with its float surface (to face a magnetic disc) upward. The reference symbol
20
denotes a slider,
13
denotes a float plane, and
21
denotes a recording/reproduction element.
When floating power of a float type slider is weakened, spacing can follow a greater waviness of the magnetic disc. However, when floating power is weakened, spacing cannot follow a surface configuration (wavelength from micrometers to millimeters, and frequency from several tens of kHz to several hundreds of kHz) of a dimension similar to that of the magnetic head slider. Accordingly, the spacing fluctuates. Moreover, the magnetic head may be brought into contact with the magnetic disc, causing friction.
Moreover, in a conventional magnetic disc apparatus, in order to increase track density, for example, a rotary actuator is used to perform track positioning by driving a head gimbal assembly consisting of a support spring and a magnetic head slider, in a magnetic disc radial direction.
However, in the case of a head gimbal assembly, the magnetic head position is to be controlled via a structure of a low rigidity and low resonance frequency such as a gimbal spring from a position far away from the magnetic head. Accordingly, it is difficult to perform track positioning with high speed and high accuracy.
Moreover, in the case of a recording/reproduction element in contact with a magnetic disc, the magnetic head is moved against friction between the recording/reproduction element and the magnetic disc. Accordingly, it becomes more difficult to perform track positioning with high accuracy.
Thus, in the conventional magnetic disc apparatus, it has been difficult to simultaneously improve linear recording density and track density. For improving recording density, various suggestions have been made. Firstly, conventional techniques for improving linear recording density will be shown.
Tribology and Mechanics of Magnetic Storage System, Volume 7, 1990, pp 158-164 [1] discloses a technique for reducing spacing by burying a piezoelectric element expanding and contracting in parallel to the drive electric field, into the back of a float type magnetic head slider and applying an electric field to this piezoelectric element.
FIG. 11
is a perspective view of a conventional magnetic head (magnetic head slider) in which a piezoelectric element is buried into the back of a float type magnetic head slider.
FIG. 12
explains the operation of a conventional magnetic head (magnetic head slider) in which a piezoelectric element is buried into the back of a float type magnetic head slider. In
FIG. 11
, the reference symbol
20
denotes a slider,
21
denotes a recording/reproduction element,
22
denotes a layered piezoelectric element, and
23
denotes electrodes. In
FIG. 12
, the reference symbol
30
denotes a magnetic disc. The reference symbol
24
a indicates a displacement direction of the piezoelectric element,
24
b indicates a displacement direction of the recording/reproduction element caused by the displacement of the piezoelectric element, and
17
indicates the spacing direction.
Japanese Patent Publication 1-107385 [2] discloses a magnetic recording apparatus in which a displacement sensor measures the distance between a magnetic recording medium and a magnetic head and an actuator is driven so as to maintain the distance constant, so that the interval between the medium and the head is reduced. This magnetic recording apparatus is constituted as follows. The interval between the magnetic recording medium and the magnetic head is measured by an intensity change of the return light emitted from a light reflection intensity type displacement meter through an optical fiber and reflected from the medium surface. The magnetic head uses a piezoelectric actuator driven by a servo circuit and an amplifier according to a displacement fluctuation signal from the light reflection intensity type displacement meter, and maintains a constant distance from the surface of the magnetic recording medium. Thus, by measuring the distance between the magnetic recording medium and the magnetic head using a displacement sensor so that the distance is maintained constant by driving the actuator attached to the magnetic head, it is possible to maintain a very small interval between the magnetic recording medium and the magnetic head as a non-contact state or contact state with a very small weight.
Japanese Patent Publication 7-235157 [3] discloses a magnetic disc apparatus in which the distance between the magnetic head and the magnetic disc is measured from time to time and maintained constant while performing a signal recording/reproduction so that a floating margin is reduced and recording is enabled with a smaller floating amount. This magnetic disc apparatus is constituted as follows. When the magnetic disc apparatus is started and the magnetic disc is rotated at a comparatively low speed, the magnetic head floats over the magnetic disc surface and reads a signal recorded, with the reproduction element mounted, while traveling in a floating state. From strength of this signal, a detailed floating amount fluctuation is read and a control signal is transmitted to the piezoelectric element. The piezoelectric element, upon reception of the control signal, expands and contracts in the longitudinal direction so as to raise and lower the recording element and the reproduction element according to the unevenness of the surface so as to maintain a predetermined distance from the surface and maintain a float amount constant. Accordingly, it is possible to obtain a magnetic disc apparatus having a smaller float amount and a higher recording density. Moreover, it is possible to prevent contact between the magnetic head and the magnetic disc.
Next, conventional techniques for improving mainly the track density will be shown.
Although the document name [4] is unknown, there has been suggested a technique to drive a support spring supporting a magnetic head slider by an electromagnetic actuator in order to increase track density.
The Japan Society of Mechanical Engineers, proceedings (4), No. 98-1, 1998, pp 208-209 [5] describes a technique to drive an entire magnetic head slider by a piezoelectric element beam.
The Japan Society of Mechanical Engineers, proceedings (4), No. 98-1, 1998, pp 210-211 [6] describes a technique to drive a recording/reproduction element by an electrostatic actuator provided at the back end of a slider.
Japanese Patent Publication 3-245315 [7] discloses a head slider on which a drive member is provided for changing the position of a transducer in the positioning direction (track width direction), so as to perform positioning with high speed and high accura
Hayes & Soloway PC
NEC Corporation
Nguyen Hoa T.
Watko Julie Anne
LandOfFree
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