Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
1999-07-12
2001-05-01
Miller, Brian E. (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
Reexamination Certificate
active
06226254
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates to a disk drive mechanism in which a disk such as a CD (compact disk) and a DVD (digital video disk) is mounted on a turn table, and turned; and more particularly to a mechanism for suppressing the eccentric vibration of a disk which is turned at high speed by a disk drive mechanism.
2. Related Art
There has been a strong demand for improvement of an access speed to a disk as a disk memory such as a CD-ROM, a CD-R/W and a DVD-ROM has been popularly employed in the art. For instance, research has been conducted on an increase in the rotating speed of a disk memory twenty-four times or thirty-two times as high as the ordinary speed of rotation of the CD. In those cases, the speed (rpm) of the disk is 5000 to 6000 rpm. In the future, it may be necessary to increase the speed of the disk to about 10000 rpm.
However, in the case where, when the disk is turned at high speed as described above, a mass eccentricity causes the following problems. First the placement of the disk on the turn table may be shifted. Also the disk will experience an eccentric vibration. Especially the disk such as a DVD and a CD-ROM which is formed by bonding two disks (front and rear disk pieces) together is liable to suffer from mass eccentricity. On the other hand, according to the present industrial standard, the mass eccentricity up to 1 g.cm is permitted. Hence, when turned at high speed, the disk may suffer from eccentric vibration. If the disk suffers from eccentric vibration as described above, then the optical pickup may be lowered in signal writing and reading accuracy, or the vibration may be transmitted to another mechanism adjacent to the disk drive mechanism, which adversely affects the disk drive operation, or makes a noise. This difficulty may be eliminated by the provision of a disk vibration preventing device in addition to the disk drive mechanism. However, in this case, the device is unavoidably bulky as a whole. Therefore, the provision of a conventional disk vibration preventing device is not practical.
On the other hand, in order to prevent the eccentric vibration of the disk which turns at high speed, a vibration preventing device has been provided. In
FIG. 11
, reference numeral
104
designates the vibration preventing device. In the device
104
, an annular magnet
101
is fixedly mounted on the rotary shaft
100
of an electric motor, and a cylindrical outer wall
102
is provided around the magnet
101
, and a plurality of steel balls are provided between the magnet
101
and the outer wall
102
. With the vibration preventing device, as the speed of the motor increases, the steel balls
103
are shifted to the outer wall
102
by centrifugal force, and as the speed of the motor becomes higher than the resonance frequency of the device, the steel balls
103
remain stable being shifted in the direction opposite to the direction of mass eccentricity F as indicated by the two-dot chain lines. As a result, the mass eccentricity F and the centrifugal force are canceled out by each other, so that the vibration of the disk is prevented. However, the above-described vibration preventing device
104
suffers from the following problems: In the case where the speed of rotation is high, 5000 rpm or higher, the signal writing and reading operation is lowered in accuracy. Furthermore, in the use of the disk which has no mass eccentricity, the friction and shift of the steel balls
103
in the device
104
increases the eccentricity, which may result in the eccentric vibration.
The disk drive mechanism is known in the art which, in order to concentrically mount the disk on the turn table, has a disk position determining mechanism. However, this method makes the disk drive mechanism bulky and high in manufacturing cost.
SUMMARY OF INVENTION
In view of the foregoing, an object of the invention is to provide a disk drive mechanism with which even if a disk suffering from mass eccentricity is turned at high speed, the eccentric vibration is minimized.
According to an aspect of the present invention, there is provided a disk drive mechanism comprising:
a rotary shaft;
a turn table including:
a shaft engaging section secured to said rotary shaft;
a placing section on which a disk is placed;
an elastic coupling section coupling said shaft engaging section and said placing section to each other so that said placing section be radially movable with respect to said shaft engaging section;
an electric motor turning said disk with aid of said rotary shaft and said turn table; and
a regulating member secured to said rotary shaft to regulate a radial displacement of said placing section of said turn table, which is a predetermined value or more.
According to the disk drive mechanism of the present invention, the disk is free from eccentric vibration when turned at high speed. Therefore, while the disk is turned at high speed, the accuracy with which data are written in or read out of the disk is prevented from being lowered by the eccentric vibration, and other devices are prevented from being adversely affected by the vibration, and making the acoustic noise is also prevented. Furthermore, the occurrence of eccentric vibration can be prevented. This feature prevents the vibration fatigue, which increases the service lives of the members such as for instance the electric motor. Moreover, the disk drive mechanism of the invention, unlike the conventional one, needs no disk position determining mechanism, which minimizes the mechanism and reduced the manufacturing cost of the same.
In addition, in the disk drive mechanism of the invention, the eccentric vibration is prevented merely by providing the coupling section at a part of the turn table. Hence, the mechanism of the invention needs no intricate means such as the conventional eccentric vibration suppressing mechanism, which contributes to a reduction in the manufacturing cost of the mechanism.
Only when the disk suffers from mass eccentricity, or only when the disk is eccentrically placed on the placing section, the center of rotation of the disk is shifted, and therefore in the case, too, where the disk suffers from no such eccentricity, the motor can be rotated at high speed. Hence, all the disks which are normally employed can be turned at high speed stably (without being swingably turned).
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patent: 5761186 (1998-06-01), Mushika et al.
patent: 5889757 (1999-03-01), Mori et al.
patent: 6038206 (2000-03-01), Mukawa
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Komatsu Fumito
Takasawa Kiyotsugu
Kabushiki Kaisha Sanyo Seiki Seisakusho
Miller Brian E.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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