Laser power controller and optical disk device

Details Laser power controller and optical disk device Laser power controller and optical disk device

2001-05-11

2003-09-16

Tran, Thang V. (Department: 2653)

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Mechanism control by the control signal

C369S044260, C369S116000

Reexamination Certificate

active

06621779

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a laser power control device which is used for recording/reproduction of digital disks and to an optical disk apparatus which uses the laser power control device, and relates to a laser power control device for controlling a laser power and an optical disk apparatus which uses the laser power control device.
BACKGROUND ART
In a recordable/reproducible DVD-RAM disk, the inside of the disk is divided into a plurality of zones. The number of rotations is constant within each zone, but is different between different zones. In general, such a system is called a zone CLV. Each zone is divided into a plurality of sectors, and each sector is formed by a data recording region in which information can be recorded and an address region in which the address of the sector has been previously recorded. Another feature of this system is that the data recording region can extend over both a guiding groove region of the disk (hereinafter, referred to as “groove”) and a region between the guiding groove regions (hereinafter, referred to as “land”). Address information is recorded in address portions so that a pair of address portions are offset from each other and each address portion extends over the groove and the land.
In order to smoothly perform reproduction in the data recording region based on the above special format, a single wave corresponding to a divisional component of a clock component (hereinafter, referred to as a “wobble”) is formed in an address region and a data recording region while cutting a disk. When reproducing from the disk, the wave component is detected as a tracking error signal.
Hereinafter, a conventional optical disk recording/reproduction device will be described.
FIG. 11
is a block diagram of a conventional optical disk recording/reproducing device
700
. In
FIG. 11
, reference numeral
1
denotes a motor; reference numeral
2
denotes an optical disk; reference numeral
3
denotes an optical head; reference numeral
4
denotes a reproduction signal/servo signal detection circuit for generating a reproduction signal, a focus error signal, and a tracking error signal from an output signal obtained from the optical head
3
; reference numeral
5
denotes focus/tracking control means for controlling the optical head
3
by using a servo signal from the reproduction signal/servo signal detection circuit
4
and for controlling the motor
2
; reference numeral
6
denotes a reproduction signal binarizing circuit for binarizing the reproduction signal; reference numeral
7
denotes a demodulator for demodulating the binarized reproduction signal to generate reproduction data; reference numeral
8
denotes a laser driving circuit for driving a laser which is a light source of the optical head
3
; reference numeral
9
denotes a recording signal generation circuit for generating a signal for modulating laser light by the laser driving circuit based on the data obtained after modulation; reference numeral
10
denotes a modulator for modulating data to be recorded so as to generate a signal which is supplied to the recording signal generation circuit
9
; reference numeral
11
denotes power control means for controlling the laser power during recording/reproduction of data; reference numeral
12
denotes a gate signal generator for generating various gate signals based on a clock of a reference clock generator
14
; reference numeral
13
denotes an error correction/address detection device for detecting and correcting the error amount of the reproduction data demodulated by the demodulator
7
and for detecting an address in the same data sequence; reference numeral
14
denotes the reference clock generator for generating a reference clock for recording/reproduction of data; reference numeral
15
denotes a CPU which gives the error correction/address detection circuit a command to measure a BER (Bit Error Rate), which can set the power in the recording power setting means, and which manages a user interface.
Hereinafter, an operation of the optical disk recording/reproduction device
700
having the above structure will be described.
An output signal read out from the optical disk
2
by the optical head
3
is supplied to subsequent process circuits as a reproduction signal, a focus error signal, and a tracking error signal by the reproduction signal/servo signal detection circuit
4
. The focus error signal and the tracking error signal are supplied to the focus/tracking control means
5
. The optical head
3
is controlled by the focus/tracking control means
5
so as to follow the wavering of the disk surface and decentration of the disk. The reproduction signal is supplied to the reproduction signal binarizing circuit
6
, and the binarized data sequence and a read clock which is in synchronization with the data are output to the demodulator
7
. The reference clock generator
14
generates a reference clock which is necessary for modulating/demodulating data to be recorded/reproduced by this apparatus.
The demodulator
7
performs modulation using the supplied binarized data sequence and the read clock according to a demodulation rule, and outputs the demodulated data to the error correction/address detection device
13
using the reference clock. The output reproduction data is supplied to the subsequent error correction/address detection device
13
, and an address position on a track is detected by the detection device
13
. An address detection signal is supplied to the gate signal generator
12
, and the gate signal generator
12
uses this signal as a position reference on the track to generate, using the gate signal, a signal which is necessary during recording/reproduction.
Data to be recorded is converted by the modulator
10
into a data sequence to be recorded according to a modulation rule. The data sequence obtained by the conversion is further converted by the recording signal generation circuit
9
into a signal for modulating laser light, and this signal is supplied to the laser driving circuit
8
. The laser driving circuit
8
modulates the laser light which is a light source of the optical head
3
for recording data on the disk. The recording is performed at a recording power predetermined by the CPU
15
.
An operation of the optical disk recording/reproducing device having the above structure when recording is performed in a sector of a DVD-RAM disk is described with reference to FIG.
12
. Each zone of the DVD-RAM disk is divided into a plurality of sectors, and each sector includes a data recording region in which information can be recorded and an address region in which an address of the sector has been recorded. In
FIG. 12
, a reproduction signal from the disk is shown in FIG.
12
(
a
); a corresponding tracking error signal is shown in FIG.
12
(
b
); a read gate signal, which is a representative gate signal necessary for reproduction of data/address, is shown in FIG.
12
(
c
); a detection signal of the address is shown in FIG.
12
(
d
); a recording gate signal, which is another representative gate signal necessary for recording is shown in FIG.
12
(
e
); and an operation gate signal of the modulator is shown in FIG.
12
(
g
).
A signal read out through the optical head
3
is output by the reproduction signal/servo signal detection circuit
4
as a reproduction signal shown in FIG.
12
(
a
) and a tracking error signal shown in FIG.
12
(
b
).
Assuming that the number of rotations of a disk in a zone N is equal to a target number of rotations, a read gate signal for reading an address of a target sector L is activated at timing (c)-
2
in FIG.
12
(
c
) using an address detection signal for a sector previous to the target sector L in which data is to be recorded as a reference.
The demodulator
7
performs demodulation based on data from the reproduction signal binarizing circuit
6
and the read clock, and reading of an address is performed in the error correction/address detection device
13
. When the address has been normally read out, the detection device
13
generates a

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