Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
1999-08-20
2002-09-10
Edun, Muhammad (Department: 2651)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S044320, C369S053190
Reexamination Certificate
active
06449224
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a micro-adjustment mechanism for adjusting installation angle of the spindle motor in an optical disk player, i.e. CD-ROM, CD-player, CD-R, CD-RW, DVD-ROM and DVD-player.
BACKGROUND OF INVENTION
The following technical information may be further referred to in order to have an in-depth understanding of the background and prior art technology regarding the invention.
1. International Standard ISO/IEC 10149, first edition, 1989-09-01, Global Engineering Documents, Irvine, Calif. 92714, USA.
2. Small Form Factor Committee, Specification of ATA Packet Interface for CD-ROM's, SFF-8020, Revision 1.2, Feb. 24, 1994.
3. SCSI-2 draft proposed American National Standard, Revision 10
c.
4. Red book, Compact Disc-Digital Audio(CD-DA), by Sony Corp. and Philips N. V., April 1987.
5. Yellow book, Compact Disc-Read Only Memory (CD-ROM), by Sony Corp. and Philips N. V., Nov. 1988.
It is well known that there are multiple distinctive servo loops employed in a disk player to reproduce data by guiding the laser beam over the data track through track-search, in-track-following, and focus operations. The prior art servo control system for the optical disk player includes U.S. Pat. Nos. 4,485,337, 4,783,774, 5,289,097, 5,246,479, 5,257,252, 5,345,347, 5,808,978, 5,751,680, 5,796,707 and 5,001,690.
The Red Book mentioned above requires the pitch of disk data tracks to be 1.6 &mgr;m and 0.74 &mgr;m respectively for CD-ROM and DVD. The in-track-following error of the optical pickup must be within 0.1 &mgr;m for CD-ROM and within 0.022 &mgr;m for DVD to assure a normal data read/write operation. As an example, for a disk with a diameter of 120 mm, the allowable traverse distance for the pickup during data access operation is 3.5 cm. In order to achieve the long distance movement and precision positioning requirements for the pickup, typical pickup is controlled by a dual-actuator system. That is, one in-track-following actuator is responsible for in-track-following operation, which is in nature of high frequency and short distance movement, and another actuator is responsible for search track operation which is in nature of low frequency and long distance movement. Furthermore, the allowable eccentricity is +200 &mgr;m and −200 &mgr;m for CD-ROM, and +100 &mgr;m and −100 &mgr;m for DVD. Despite the operation speed, the servo control for the in-track-following operation must always overcome the existing eccentricity of the disk and/or the physical damage over the surface and, at the same time, keep the in-track-following error within the allowable range (0.1 &mgr;m). Theoretically, to accurately reproduce the data on the track, the laser beam radiating from the source must be incident upon the surface of the disk vertically. If there is a minor incident angle error, one denotes it as the optical axis tilt angle. As the track data density and spin speed of the player, e.g. DVD, increase substantially, the existence of the tilt angle would affect the quality and reliability of data reproduction.
As shown in
FIG. 1
, the optical disk player includes a pickup traverse
10
connected to the loading module (not shown) through four positioning screws (not shown), and is tiltable with respect to the loading module. On the traverse
10
, there is provided a spindle
16
, which spins in high speed when operated, a turntable
18
and a pickup
12
, which is capable of making rectilinear reciprocal movement.
During rectilinear reciprocal movement of the pickup
12
, the first guide rail
14
supports and guides the pickup
12
. The second guide rail
15
is responsible for the supporting in the horizontal direction to prevent the falling of pickup
12
with respect to axis of the first guide rail
14
. During the data reproduction operation of pickup
12
, the supporting function of the first guide rail
14
and the second guide rail
15
defines an optical pickup surface along which the pickup
12
moves. The disk
13
sits on the turntable
18
and spins accordingly. During rotation of the disk
13
, it defines a spin surface. In theory, to achieve a best data reproduction result, the spin surface should parallel the optical pickup surface. As such, the light beam from the pickup
12
may then be vertically incident to the disk surface and makes the incline angle to be ideally zero regardless of which data track is selected.
Referring to
FIG. 2
, the optical pickup
12
is movably supported on a feeder
21
. The feeder
21
is driven by the actuator
11
in a well-known manner so that optical pickup
12
moves radially in reference to the surface of the optical disk
13
. The optical pickup
12
includes a carriage
121
, a source of a light beam, e.g., a semiconductor laser device
122
, a collimator lens
123
, a semi-transparent mirror
124
, a device for placing a laser beam on the optical disk
13
, e.g., an objective lens
125
, a split photosensor
126
, an in-track-following actuator
127
and a focusing actuator
128
. The laser device
122
radiates the laser beam. The collimator lens
123
, the semi-transparent mirror
124
and the objective lens
125
guide the laser beam to the optical disk
13
so that the laser beam is placed on the optical disk
13
in a form of light spot. The optical pickup
12
then scans concentric tracks of the optical disk
13
one after another or a spiral track of the optical disk
13
with the light spot of the laser beam moving in radial direction during the disk information reproduction operation. The laser beam is reflected by the optical disk
13
and then applied to the split photosensor
126
through the objective lens
125
and the semi-transparent mirror
124
. The split photosensor
126
detects from the reflected laser beam information data responding to a state, e.g., a strength of the reflected laser beam, and produces an electrical signal responding to the information. The objective lens
125
is movably mounted on the carriage
121
of the optical pickup
12
. The in-track-following actuator
127
controls position of objective lens
125
in the radial direction of the disk
13
so that the light spot of the laser beam follows a center of a prescribed track. The tracking control of the objective lens
125
may be made by a conventional tracking control system. The focusing actuator
128
controls the position of objective lens
125
in the perpendicular direction to the surface of the optical disk
13
so that the light spot of the laser beam is accurately focused on a prescribed track. The focusing control of the objective lens
125
may be made by a conventional focusing control system.
SUMMARY OF INVENTION
Based on the requirement mentioned above, the main objective of the invention is to reduce the incline or elevation angle of the optical axis of the pickup to substantial zero and therefore obtain a reliable high speed data reproduction.
A micro-adjustment apparatus for the spindle motor installation angle in an optical disk player is provided. The optical disk player includes a traverse, and the traverse includes a pickup, a first guide rail, and a framework. The pickup includes a light source for supplying a light beam, and the first guide rail guiding the pickup during data reproduction. A spin surface is defined while the spindle is spinning.
The micro-adjustment apparatus includes a supporting plate, a pivotal device, a first adjustable pivotal device, and a second adjustable pivotal device.
The supporting plate supports the spindle motor and is adjustably coupled to the framework.
The pivotal device is disposed at a first predetermined location on the supporting plate and contacts with the first guide rail.
The first adjustable pivotal device is disposed at a second predetermined location on the supporting plate for adjusting an elevation angle of the supporting plate such that the light beam is substantially vertical to the spin surface.
The second adjustable pivotal device is disposed at a third predetermined location on the supporting plate for adjusting an incli
Lee Wei-Pang
Liu Shi-Wei
Asustek Computer Inc.
Edun Muhammad
Rabin & Berdo P.C.
LandOfFree
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