Bearings – Rotary bearing – Fluid bearing
Reexamination Certificate
1999-10-14
2001-04-17
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Fluid bearing
C384S100000, C384S144000
Reexamination Certificate
active
06217218
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydrodynamic bearing spindle motor suitable for use in a hard disk or the like used for a personal computer and various audio-visual appliances.
2. Description of the Prior Art
FIG. 2
shows a hydrodynamic bearing spindle motor for use in a known hard disk. In the known hydrodynamic bearing spindle motor of
FIG. 2
, a base
1
has radial bearing portions
1
a
and acts as a fixed member. A rotary shaft
2
is secured to a flange
4
so as to be rotated together with the flange
4
and is rotatably supported by the radial bearing portions
1
a
of the base
1
and a thrust bearing
9
so as to be smoothly rotated at high speed. Lubricant
3
is provided in a clearance between the radial bearing portions
1
a
and the rotary shaft
2
and oil having a predetermined viscosity is usually employed as the lubricant
3
. A plurality of, for example, four disks
5
are mounted on an outer periphery of the flange
4
in parallel with each other and the flange
4
is coaxially fixed to the rotary shaft
2
so as to act as a rotational member. Each of the disks
5
is constituted by a magnetic disk used generally for a hard disk of a personal computer. A coil
6
is fixed to the base
1
, while a magnet
7
is attached to the flange
4
so as to confront the coil
6
. By effecting flow of electric current through the coil
6
, rotational force is generated between the coil
6
and the magnet
7
and thus, the flange
4
can be rotated at high speed. A clearance
8
is formed between the base
1
and the flange
4
. The thrust bearing
9
is secured to the base
1
so as to bear thrust load of the rotary shaft
2
.
Operation of the known hydrodynamic bearing spindle motor of the above described arrangement is described below. By effecting flow of electric current through the coil
6
, rotational force is generated between the coil
6
and the magnet
7
and thus, the flange
4
having the disks
5
mounted thereon is rotated together with the magnet
7
at high speed. Therefore, information signals such as image and sound signals and text data are recorded on the disks
5
by a magnetic head (not shown). Meanwhile, if the information signals have been recorded on the disks
5
, the information signals can be reproduced on the disks
5
by the magnetic head.
Since the lubricant
3
is provided between the rotary shaft
2
and the radial bearing portions la as described above, the flange
4
secured to the rotary shaft
2
can be rotated at high speed smoothly. Meanwhile, lubricant (not shown) is provided also between the rotary shaft
2
and the thrust bearing
9
so as to serve to bear thrust load of the rotary shaft
2
smoothly.
However, in the known hydrodynamic bearing spindle motor, the lubricant
3
provided in the clearance between the radial bearing portions
1
a
and the rotary shaft
2
leaks out of the radial bearing portions
1
a
due to impact caused by fall of the known hydrodynamic bearing spindle motor, etc. and is carried through the clearance
8
between the flange
4
and the base
1
by centrifugal force due to high-speed rotation of the flange
4
so as to finally adhere to the disks
5
. If the lubricant
3
has adhered to the disks
5
as described above, such an inconvenience is incurred that the recording head cannot properly record and reproduce the image and sound signals, etc. on the disks
5
.
SUMMARY OF THE INVENTION
Accordingly, an essential object of the present invention is to provide, with a view to eliminating the above mentioned drawback of prior art hydrodynamic bearing spindle motor, a hydrodynamic bearing spindle motor in which even if lubricant leaks out of a bearing portion due to impact caused by fall of the hydrodynamic bearing spindle motor, etc., the lubricant does not adhere to disks such that recording and reproduction can be performed properly.
In order to accomplish this object of the present invention, a hydrodynamic bearing spindle motor according to the present invention comprises: a fixed member which has a radial bearing portion; a rotational member; a rotary shaft which is rotatably supported by the radial bearing portion of the fixed member and is secured to a substantially central location of the rotational member so as to extend in a vertical direction of the hydrodynamic bearing spindle motor such that the rotational member is disposed above the fixed member; lubricant which is provided between the radial bearing portion of the fixed member and the rotary shaft; a projection which is provided on a lower face of the rotational member so as to be disposed radially outwardly of the rotary shaft and has an oblique inner periphery expanding gradually radially outwardly towards a distal end of the projection; a lubricant receiving means which is secured to an upper face of the fixed member so as to be disposed radially outwardly of the projection; and oil repellent for repelling the lubricant, which is applied to the projection and its vicinity; wherein the lubricant receiving means is provided at a location to which the lubricant repelled by the oil repellent and scattered from the projection through rotation of the rotational member adheres.
In accordance with the present invention, even if the lubricant leaks out of the bearing portion due to impact caused by fall of the hydrodynamic bearing spindle motor, etc., the lubricant does not adhere to the disks and thus, recording and reproduction can be performed properly.
REFERENCES:
patent: 5112141 (1992-05-01), Asada et al.
patent: 5647672 (1997-07-01), Fukutani
patent: 5708539 (1998-01-01), Schuh
patent: 5789836 (1998-08-01), Hayakawa
patent: 5810480 (1998-09-01), Asada et al.
patent: 5859745 (1999-01-01), Elsing et al.
Inomata Hiromichi
Inoue Hiroshi
Matsuoka Kaoru
Obata Shigeo
Omura Masashi
Hannon Thomas R.
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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