Bearings – Rotary bearing – Fluid bearing
Reexamination Certificate
1999-12-23
2001-08-21
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Fluid bearing
C384S107000, C384S112000, C384S115000, C384S123000
Reexamination Certificate
active
06276831
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rotary apparatus which is rotated at high speed, such as a light deflection apparatus using a polygon mirror, or motors.
In the light deflection apparatus rotating at high speed using the polygon mirror as a rotor, or motors rotating at high speed around a rotation axis, a dynamic pressure bearing is provided between a rotational body and an irrotational body, and the high speed rotation is carried out.
FIG. 21
is a sectional view showing an example of the rotary apparatus provided with the dynamic pressure bearing. A rotary unit
102
which rotates facing a radial fixed member
111
which is fixed on a support base
103
, is radial dynamic pressure rotated in between both members at the radial dynamic pressure bearing portion
112
. Further, on both shaft end portions of the radial fixed member
111
, a thrust fixed member
113
which forms a perpendicular surface to the shaft of the radial fixed member
111
, is provided, and a rotary unit
102
which is rotated being sandwiched between a thrust fixed member
113
A and a thrust fixed member
113
B, which are positioned at an upper and a lower portions, is thrust dynamic pressure rotated at a thrust dynamic pressure bearing portion
121
.
On the radial dynamic pressure bearing portion
112
and/or the thrust dynamic pressure bearing portion
121
, a dynamic pressure generating groove formed symmetrically with the bearing surface is provided, and a wind generated by the high speed rotation of the rotary unit
102
is introduced into the dynamic pressure generating groove, and the strong wind pressure is generated from the symmetrically formed dynamic pressure generating groove, and a gap in several &mgr;m unit is formed between the radial fixed member
111
and the rotary unit
102
, and the resistance between them is decreased, thereby, the high speed rotation is attained at the radial dynamic pressure bearing portion
112
. Further, a fine gap is formed also between the thrust fixed members
113
A,
113
B and the rotary unit
102
, and while the rotary unit
102
is floated a very little, the high speed rotation is performed at the thrust dynamic pressure bearing portion
121
.
In the conventional rotary apparatus provided with the dynamic pressure generating groove which is symmetrical to the dynamic pressure bearing portion, generally, in order to prevent the contact generated during high speed rotation and to decrease the vibration, the dynamic balance is decreased, however, when the dynamic balance is too small, the unstable phenomenon of the rotation is generated on the contrary. In the conventional rotary apparatus, in the adjustment, the upper limit of the dynamic balance is regulated by the tolerance limit of the vibration, and the lower limit is regulated by the tolerance limit of the stability, and the dynamic balance is corrected so that it is within the range between the regulated upper limit and the lower limit, or the gap between the fixed portion of the radial dynamic pressure bearing portion (radial fixed member) and the rotational body (rotary unit) is appropriately adjusted, thereby, the stability in the high speed rotation is obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rotary apparatus in which the unstableness of rotation does not occur even in an area in which the dynamic balance is small, and the large adjustment range can be obtained, and which has excellent productivity, and can obtain the stable rotation performance in the high speed rotation.
The above object can be attained by any one of the following structures.
(1) A rotary apparatus which has a radial fixed member and a rotary unit which can be rotated to the radial fixed member, and in which dynamic pressure generating grooves are formed in a radial dynamic pressure bearing portion at which the radial fixed member faces the rotary unit, the rotary apparatus is characterized in that the dynamic pressure generating grooves are formed asymmetrically.
(2) A rotary apparatus which has: a radial fixed member; a thrust fixed member arranged in an almost vertical direction to the radial fixed member; and a rotary unit which is in an almost parallel direction to the thrust fixed member and which can be rotated to the radial fixed member, and in which dynamic pressure generating grooves are formed in a thrust dynamic pressure bearing portion at which the thrust fixed member faces the rotary unit, the rotary apparatus is characterized in that the dynamic pressure generating grooves are formed asymmetrically.
(3) A rotary apparatus which has a rotary unit rotatable to the radial fixed member, the rotary apparatus is characterized in that the shape of the radial dynamic pressure bearing portion at which the radial fixed member faces the rotary unit is formed asymmetrically.
(4) A rotary apparatus which has: a radial fixed member; a thrust fixed member arranged in an almost vertical direction to the radial fixed member; and a rotary unit which is in an almost parallel direction to the thrust fixed member and which can be rotated to the radial fixed member, the rotary apparatus is characterized in that the shape of the thrust dynamic pressure bearing portion at which the thrust fixed member faces the rotary unit is formed asymmetrically.
REFERENCES:
patent: 4678348 (1987-07-01), Tielemans et al.
patent: 4798480 (1989-01-01), Van Beek
patent: 5181783 (1993-01-01), Sherman et al.
patent: 5385408 (1995-01-01), Tevaarwerk
patent: 5932946 (1999-08-01), Miyasaka et al.
patent: 6024493 (2000-02-01), Tempest et al.
Kamimura Naoji
Ono Naohiro
Takahashi Yuko
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Hannon Thomas R.
Konica Corporation
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