Optical disk apparatus

Details Optical disk apparatus Optical disk apparatus

2001-12-26

2004-01-13

Edun, Muhammad (Department: 2655)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S044340, C369S044360, C369S124010

Reexamination Certificate

active

06678221

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an optical disk apparatus which performs recording or reproduction of information into/from an optical disk and, more particularly, to one which can perform adjustment of a track error signal reliably and effectively thereby to shorten a start-up time at starting this apparatus into which an optical disk medium is installed.
BACKGROUND ART
Hereinafter, a conventional optical disk apparatus will be described.
FIG. 14
is a block diagram illustrating a constitution of the conventional optical disk apparatus.
In
FIG. 14
, numeral
2
denotes an optical disk medium such as a CD, a CD-ROM, a DVD, and an MO, which has a track for information recording, and numeral
1
denotes an optical pickup which collects a semiconductor laser to irradiate the light to a target position on the optical disk medium
2
, thereby to perform recording and reproduction of information, and this comprises an optical system and a driving system. The optical system collects a laser beam on the surface of the optical disk medium
2
or detects a deviation between a irradiated position of a laser beam and a target position on the optical disk medium
2
, and it comprises a semiconductor laser, lenses, a beam splitter, a photodiode or the like (all not shown). On the other hand, the driving system is driven to perform a focus control which makes an objective lens follow plane wobbles on the optical disk medium
2
or a tracking control which makes the objective lens follow track wobbles, and keeps the positional relationship between the target position on the optical disk medium
2
and a laser beam spot constant, and it mainly comprises a magnet, a coil, and a support member (all not shown). The driving system serves as an actuator which drives the lenses of the optical system.
Numeral
3
denotes an operational amplifier which performs various arithmetic processings to a returned light quantity signal from the optical disk medium
2
which returned light is detected by photodiodes which are divided into plural parts, which photodiodes construct the optical pickup
1
, and it outputs a focus error signal (hereinafter, referred to as FE signal) presenting a focus deviation quantity of the laser beam spot on the optical disk medium
2
, a track error signal (hereinafter, referred to as TE signal) presenting a positional deviation amount of the laser beam spot with relative to a track on the optical disk medium
2
, and a reproduction signal (hereinafter, referred to as RF signal) presenting information recorded as a change in light reflectance on the optical disk medium
2
. Numeral
4
denotes a focus control circuit which performs a focus control of collecting the laser beam irradiated from the optical pickup
1
to focus the same on the optical disk medium
2
, numeral
5
denotes a focus driving circuit which is controlled by the focus control circuit
4
and drives an actuator of an objective lens of the optical pickup
1
, and numeral
6
denotes a micro processing unit (hereinafter, referred to as MPU) presenting an arithmetic processing unit, and by a command of this MPU
6
, ON/OFF of the above-mentioned focus control operation is operated. Numeral
7
denotes an adjusting circuit which comprises an offset control circuit
71
and a variable gain amplifier
72
, and receives the TE signal outputted from the operational amplifier
3
, adjusts a gain and an offset by settings from the MPU
6
, and outputs a track error signal after adjustment (hereinafter, referred to as a TEA signal), numeral
8
denotes a tracking control circuit which receives the TEA signal and performs a control so that the irradiated position of the laser beam follows the track of the optical disk medium
2
, and numeral
9
denotes a tracking driving circuit which drives the objective lens of the optical pickup
1
with controlled by the tracking control circuit
8
, and ON/OFF of this tracking control operation is operated by a command of the MPU
6
.
Numeral
10
denotes a traverse control circuit which receives a control output signal (hereinafter, referred to as TRO signal) outputted from the tracking control circuit
8
, and generates a TVO signal presenting a control signal for moving the optical pickup
1
itself to follow in a radial direction of the optical disk
2
when the irradiated position of the laser beam of the optical pickup
1
follows the spiral track on the optical disk medium
2
, numeral
11
denotes a traverse driving circuit which receives the TVO signal and drives an after-mentioned traverse motor
12
, and numeral
12
denotes a traverse motor which moves the optical pickup
1
in a radial direction of the optical disk medium
2
. Further, numeral
13
denotes a signal processing circuit which receives the RF signal outputted from the operational amplifier
3
, and reproduces information from the optical disk medium
2
, and it extracts a SYNC signal presenting a synchronization signal from the RF signal. Numeral
14
denotes a spindle motor control circuit which receives the SYNC signal extracted from the signal processing circuit
13
and outputs a DMO signal for controlling the rotation number of the optical disk medium
2
, numeral
15
denotes a spindle motor driving circuit which receives the DMO signal from the spindle motor control circuit
14
and drives an after-mentioned spindle motor, and numeral
16
denotes a spindle motor for rotating the optical disk medium
2
, and the rotation of the spindle motor
16
can be also controlled at a prescribed rotation number by inputting an FG signal indicating a rotation number to the spindle motor control circuit
14
, not by the SYNC signal.
Next, an adjusting operation of the track error signal, which is performed when the conventional optical disk apparatus on which the optical disk medium
2
is mounted is started will be described with reference to the flow chart in FIG.
15
.
When the optical disk medium
2
is mounted on the optical disk apparatus or the power is turned ON (Step S
901
), the MPU
6
initializes the position of the optical pickup
1
(Step S
902
). More specifically, the traverse motor
12
is driven so as to move the optical pickup
1
forcibly to the inner periphery side of the optical disk medium
2
until an innermost periphery switch (not shown) is pressed (Step S
903
). When there is no innermost periphery switch, the traverse motor
12
is kept driven while the optical pickup
1
is surely moved to a limit of the movable range in which the optical pickup
1
can move to the inner periphery side. After the optical pickup
1
is moved to the innermost periphery position of the optical disk medium
2
in this way, the optical pickup
1
is moved to the outer periphery side for a prescribed time so as to be located at a position where the track on the optical disk medium
2
exists (Step S
904
).
FIG. 16
illustrates an area structure of the optical disk medium, such as a general compact disk (hereinafter, referred to as a CD), a recordable CD-R, or a rewritable CD-RW, in a radial direction. As shown in
FIG. 16
, the innermost periphery part is a clamp area A
1
for mounting the disk, and an information area A
2
where a track exists exists outside the clamp area. In the inner periphery and outer periphery of the information area A
2
, there exist mirror surface areas A
30
and A
31
in which a reflecting layer is formed but no tracks exist and substrate areas A
40
and A
41
made only of transparent substrates. Therefore, the optical pickup
1
is located in the information area A
2
of the optical disk medium
2
by the above-described operation of initializing the position of the optical pickup
1
.
Next, a returned light quantity from the optical disk medium
2
when an objective lens of the optical pickup
1
is operated up and down in a focus direction is detected from the level of the RF signal, and the presence or absence of the disk is judged (Step S
905
). At that time, it is utilized that a prescribed RF signal level can be obtained when the optical disk medium
2

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