Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
2000-08-10
2003-04-15
Cao, Allen (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
Reexamination Certificate
active
06549508
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a turntable and a disk driving device which are used to load and rotate a disk or the like, which serves as a recording and reproducing medium of a signal.
2. Description of the Related Art
In general, a compact disk player (CD player) carries out an a operation in which a CD is loaded on a turntable which is anchored to a rotational shaft of a spindle motor, in which the spindle motor is driven, and in which a signal which was recorded by an optical pickup is reproduced while the CD is rotated together with the turntable.
In order that the turntable used in this way can reliably transmit rotational torque from the rotational shaft of the spindle motor to the CD, extracting force of the rotational shaft after the rotational shaft was pressed into and mounted to an insertion hole of the turntable is strictly set to a value within a predetermined range.
Further, in order that a recording surface of the CD which is loaded and rotated on the turntable does not vibrate, a CD loading surface of the turntable is strictly set so as to be perpendicular to the rotational shaft of the spindle motor (preventing a so-called surface vibration).
Conventionally, as illustrated in
FIGS. 14 through 16
, a turntable
10
formed from a polycarbonate resin is used as the turntable to meet the above-described requirements.
The illustrated turn table
10
is structured by taking advantage of small shrinkage of the polycarbonate resin at the time of molding, and thereby, a good mold transferring ability thereof.
Namely, in the turntable
10
, a shaft head portion
20
, which fits into an unillustrated circular opening of a CD, is formed at a top portion of a boss portion
16
provided with an insertion hole
12
, and a discoid table portion
18
, which is provided with a loading portion
14
, is provided integrally at the periphery of the shaft head portion
20
.
The boss portion
16
is formed in the shape of a thick cylinder. The shaft head portion
20
of the boss portion
16
is formed thick and a cross-sectional configuration thereof is inverted V-shaped. A conical surface portion of the upper side of the shaft head portion
20
is formed as a guide portion
22
for guiding the circular opening of the CD to the shaft head portion
20
. A plurality of auxiliary ribs
24
are provided at a portion of the lower side of the boss portion
16
and at an inner portion of a groove of the shaft head portion
20
whose cross-sectional configuration is inverted V-shaped.
An unillustrated iron pan, which is used to suck and hold the CD by magnetic force, is provided on the upper surface of the table portion
18
at the periphery of the shaft head portion
20
. The ring-shaped loading portion
14
, which stands upright by one step at the upper side of the table portion
18
, is formed at the periphery thereof.
Further, gates
26
for injecting the polycarbonate resin, which has been melted within a mold for the turntable
10
, are provided at portions of the table portion
18
which are hidden by the unillustrated iron plate.
When the turntable
10
of this configuration is molded and manufactured from the polycarbonate resin, since coefficient of friction of the polycarbonate resin to a metal is large, the coefficient of friction changes by a large amount in accordance with a state of surface roughness or a size of press-contacting force of the polycarbonate resin which presses and contacts the metal. Also, due to large modulus of elasticity, an error in the surface configuration of the polycarbonate resin which presses and contacts the metal cannot be absorbed. In consideration of the above-described facts, it is necessary to manufacture the turntable
10
so that extracting force of a rotational shaft when the turntable
10
is mounted to the rotational shaft of a spindle motor falls within a predetermined range. Moreover, as a material of the turntable
10
, a polycarbonate resin containing glass fibers may be also used. In this case, mold shrinkage is even smaller and modulus of elasticity is even larger.
As a result, the turntable
30
is molded at high precision so that, at the time of injection molding, the surface roughness of the inner circumferential surface of the insertion hole
12
, through which the rotational shaft of the spindle motor is inserted, is constant, that the inner diameter of the entire insertion hole
12
is constant, that roundness of the entire insertion hole
12
is constant, and that sink at the time of injection molding is not generated at the inner circumferential portion of the insertion hole
12
.
Further, when the turntable
10
is mounted to the rotational shaft of the spindle motor, in order that the CD loading portion
14
of the turntable
10
is perpendicular to the rotational shaft of the spindle motor and surface vibrations do not occur, the turntable
10
is molded at high precision so that deformation such as warpage or the like does not occur to the CD loading portion
14
of the turntable
10
and is molded at high precision so as to maintain high perpendicularity of the insertion hole
12
to the loading portion
14
.
Regarding the above-described turntable
10
formed from polycarbonate resin which is an expensive material, extremely high injection molding technique and mold management are required when the turntable
10
is manufactured. Thus, the price of the product increases.
Therefore, it is desired that the resin which is a material of the turntable
10
is a polyacetal resin or the like which is comparatively inexpensive and is widely used in general as an engineering plastic.
However, when the polyacetal resin is used as a material and the turntable
10
having the configuration shown in
FIGS. 14 through 16
is subjected to injection molding, the following drawbacks may arise. First, due to the characteristic in which mold shrinkage of the polyacetal resin is large, sink at the time of injection molding is generated at the inner circumferential portion of the insertion hole
12
, such that extracting force of the rotational shaft when the turntable
10
is mounted to the rotational shaft of the spindle motor may be smaller than a predetermined necessary value. Second, manufacturing error in the rotational shaft of the spindle motor is added to the generation of sink at the inner circumferential portion of the insertion hole
12
at the time of injection molding, such that the extracting force of the rotational shaft when the turntable
10
is mounted to the rotational shaft may be smaller than the predetermined necessary value.
Moreover, since the CD loading portion
14
of the turntable
10
is thick, sink becomes larger and deformation such as warpage or the like occurs easily. Further, because the boss portion
16
which is provided with the insertion hole
12
is thick, deformation due to the sink occurs and a large error is made to positional precision between the boss portion
16
and the loading portion
14
. Thus, when the turntable
10
is mounted to the rotational shaft of the spindle motor, the CD loading portion
14
of the turntable
10
is not perpendicular to the rotational shaft of the spindle motor, and surface vibrations may take place.
SUMMARY OF THE INVENTION
With the aforementioned in view, an object of the present invention is to newly provide a turntable and a disk driving device using the same, wherein the turntable can be formed from a comparatively inexpensive material and is also structured so that the predetermined quality of a product can be manufactured easily and inexpensively in accordance with ordinary injection molding technique and ordinary mold management.
A first aspect of the present invention is a turntable on which a disk is loaded, the turntable comprising: a fixing portion into which a rotational shaft which rotates the turntable is pressed, the fixing portion being elastically deformable in a radial direction of the fixing portion; and a reinforcer which is provided at an outer circumference of the fixing portion, the r
Matsumoto Yukio
Nakamura Toshio
Otomo Satoshi
Aiwa Co. Ltd.
Cao Allen
Fulbright & Jaworski L.L.P.
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