Optical disk drive with adaptive compensator

Details Optical disk drive with adaptive compensator Optical disk drive with adaptive compensator

2002-04-10

2004-04-06

Edun, Muhammad (Department: 2655)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S044250, C369S112010

Reexamination Certificate

active

06717892

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to an optical disk drive (for example, compact disk drive or DVD drive) capable of reading data stored on an optical disk (for example, CD or DVD). More specifically, the present invention discloses an optical disk drive comprising an adaptive compensator for preventing an actuator from entering a non-linear region.
2. Description of the Prior Art
In current technology, an optical disk is lightweight, small physical volume, and low cost. In addition, optical disks have a high capacity for information storage, making optical disks an indispensable information-storing medium.
Of course, high-density information stored on an optical disk is read out by an optical disk drive for further processing. The high-speed requirements of modern society demand not only a continuous increase of data storage density on the optical disk, but also demand a high speed optical disk drive for reading the data on the optical disk. In order to allow the optical disk drive to read high-density data quickly, the optical disk drive must have a precise control system. Therefore, developing a precise control system for the optical disk drive is an important topic of the information industry.
Please refer to FIG.
1
.
FIG. 1
is a perspective view of an optical disk drive
10
according to the prior art. The optical disk drive
10
reads data stored on an optical disk
14
. The optical disk drive
10
includes a housing
12
and a rotatable base
16
installed on the housing
12
. The housing
12
further comprises a hole
17
that shows a sled
18
inside the housing
12
. The sled
18
inside the housing
12
is capable of sliding left and right so as to scan data stored on the optical disk
14
. When the optical disk
14
is put on the base
16
and rotated by the base
16
, the sled
18
slides left and right along the hole
17
so that the optical disk drive
10
reads data stored on the optical disk
14
.
For further illustration of the inner construction of the optical disk drive
10
, please refer to FIG.
2
.
FIG. 2
is a perspective view of the inner structure of the optical disk drive
10
according to the prior art. In order to clearly show the inner structure of the optical disk drive
10
, a portion of the housing
12
of the optical disk drive
10
is omitted in FIG.
2
. Inside the optical disk drive
10
, a spindle motor
15
on the housing
12
is capable of rotating the base
16
and further driving the optical disk
14
on the base
16
. For clarity,
FIG. 2
only shows a portion of the optical disk
14
. The sled
18
slides left and right on a path
30
along a direction
34
shown in FIG.
2
. The sliding of the sled
18
is driven by a driving device
20
. The driving device
20
comprises a driving motor
20
a
installed inside the housing
12
, a gear
20
b
rotated by the driving motor
20
a
and a sawtooth plate
20
c
on the sled
18
. When the driving motor
20
a
rotates the gear
20
b
, the sawtooth plate
20
c
, engaging with the gear
20
b
, pushes the sled
18
to slide left and right along the slide
30
. For reading high-density data stored on the optical disk
14
, the sled
18
controls an actuator
22
, which is capable of moving left and right in a direction
36
within a predetermined range on the sled
18
, as shown in
FIG. 2. A
lens
32
is installed on the actuator
22
, and connects with a light source
26
installed on the sled
18
. Light (for example, a laser) is emitted from the light source
26
and passes through the lens
32
on the actuator
22
optically, and then shines on the bottom surface of the optical disk
14
. The light reflected from the optical disk
14
passes through the lens
32
on the actuator
22
. The light is then sent back to the sled
18
, so that the optical disk drive
10
is capable of reading the data stored on the optical disk
14
. Meanwhile, the actuator
22
slides left and right on the sled
18
, and is driven by a servo device
24
on the sled
18
. The servo device
24
provides a push force to drive the actuator
22
left and right.
In order to read the high-density data stored on the optical disk
14
well, the optical disk drive
10
comprises a control system for controlling the operation of the actuator
22
and the sled
18
. Please refer to FIG.
3
.
FIG. 3
is a diagram of the control system of the optical disk drive
10
according to the prior art. In the current optical disk standard, data is written onto the optical disk
14
along tracks. The optical disk shown in
FIG. 3
shows one of the tracks
46
with data stored therein. For reading data on the track
46
, the sled
18
and the actuator
22
on the optical disk drive
10
must make the lens
32
lock the position of the track
46
. Therefore, the optical disk drive
10
is capable of reading data stored on the track
46
with the rotation of the optical disk
14
. For this purpose, the control system of the optical disk drive
10
comprises a control circuitry
38
for controlling the operation of the optical disk drive
10
. The control circuitry
38
has a compensation device
48
for controlling both the driving device
20
and the servo device
24
. Furthermore, a sensor
28
is installed on the sled
18
and is connected with the actuator
22
. This means that the light emitted from the light source
26
passes through the lens
32
and shines incident onto the optical disk
14
. The light may be reflected from the optical disk
14
into the sensor
28
by passing through the lens
32
on the actuator
22
again. By analyzing the light incident on the sensor
28
, the sensor
28
is capable of sensing whether the lens
32
locks on the track
46
. The result is then transmitted into the control circuitry
38
. According to this result, the control circuitry
38
makes the compensation device
48
to control the driving device
20
and the servo device
24
for adjusting the operation of the sled
18
and the actuator
22
respectively. Therefore, the lens
32
is able to lock the track
46
, and the optical disk drive
10
reads data stored on the track
46
of the optical disk
14
correctly.
The control system of the prior optical disk drive
10
is used for locking the track
46
. The control circuitry
38
controls the operation of the sled
18
and the actuator
22
through the driving device
20
and the servo device
24
respectively. Compared with the actuator
22
, the move range of the sled
18
is larger, but the response of the control circuitry
38
is slower. In addition, the movement of the sled
18
is not very accurate, so it can only make a rough locking motion. On the other hand, the move range of the actuator
22
is smaller, but the response is quicker. So the actuator
22
is able to make an accurate locking. The control circuitry
38
controls both the sled
18
and the actuator
22
, so the control circuitry
38
needs to give consideration to both kinds of track locking. The control of the sled
18
and the actuator
22
is not only related with the control circuitry
38
, but also related with the mechanical characteristics of the driving device
20
and the servo device
24
. Please refer to
FIG. 3
again. The servo device
24
provides a pushing force to push the actuator
22
left and right within a predetermined range
40
on the sled
18
, but the relationship between the push force received by the actuator
22
and the displacement of the actuator
22
within the predetermined range may change due to different positions of the actuator
22
in the predetermined range. The predetermined range
40
is divided into a linear region
44
and a non-linear region
42
. In the linear region
44
, the push force, provided by the servo device
24
for pushing the actuator
22
, has a linear relationship with the displacement of the actuator
22
. Relatively, within the non-linear region
42
of the predetermined range
40
, the push force received by the actuator
22
has a non-linear relationship with the displacement of the actuator
22
.

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