Optical disk device with abnormal jump detection

Details Optical disk device with abnormal jump detection Optical disk device with abnormal jump detection

1998-06-10

2001-01-09

Huber, Paul W. (Department: 2753)

Dynamic information storage or retrieval

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

Mechanism control by the control signal

C369S044320

Reexamination Certificate

active

06172952

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical disk device for recording/reproducing data to/from an optical disk.
2. Description of the Related Art
As is known in the art, an optical disk which can be recorded/reproduced includes a plurality of tracks. Each track is further divided into a plurality of sectors, and data is recorded/reproduced to/from the disk by sectors. The data recording/reproduction operation is often performed while the disk is rotated at a constant number of rotations, or a constant rotational velocity (CAV: Constant Angular Velocity). For example, wobbling of the tracks on the optical disk is detected so as to produce a wobble signal which has a cycle corresponding to the number of rotations of the optical disk. Based on the wobble signal, a constant number of rotations of the optical disk is reached, after which data is recorded/reproduced to/from the disk in synchronization with a reference clock signal.
Hereinafter, conventional disk recording/reproduction devices will be described.
FIG. 6
is a block diagram illustrating a conventional disk recording/reproduction device. Referring to
FIG. 6
, the disk recording/reproduction device includes: a motor
101
; an optical disk
102
; an optical head
103
; a reproduced signal/servo signal detection circuit
104
for producing a reproduced signal, a focusing error signal and a tracking error signal from an output signal of the optical head
103
; a reproduced signal digitization circuit
105
for digitizing the reproduced signal; a demodulator
106
for generating reproduced data by demodulating the digitized reproduced signal; a laser drive circuit
107
for driving a laser as a light source for the optical head
103
; a recording signal generation circuit
108
for generating, from the modulated data, a signal for optically modulating laser light by the laser drive circuit
107
; a modulator
109
for generating a signal for the recording signal generation circuit
108
by modulating data to be recorded; a focusing/tracking control section
110
for controlling the motor
101
and the optical head
103
using the servo signal from the reproduced signal/servo signal detection circuit
104
; a reference clock generator
111
for generating a reference clock signal which is used to generate various gate signals needed for recording/reproducing data; a gate signal generator
112
for generating the various gate signals based on the reference clock signal from the reference clock generator
111
; an error corrector/address detector
123
for correcting errors in the reproduced data which has been demodulated by the demodulator
106
and for detecting an address from this data; a bias circuit
124
for generating bias voltages; a comparator
125
for comparing the tracking error signal output from the reproduced signal/servo signal detection circuit
104
with the bias voltages generated by the bias circuit
124
so as to detect an abnormal jump; and a number-of-rotation error detection circuit
126
for detecting the number of rotations of the motor
101
by using the reference clock signal.
In the disk recording/reproduction device having such a structure, data is read out from the optical disk
102
using the optical head
103
while the optical disk
102
is rotated at a predetermined number of rotations. The reproduced signal/servo signal detection circuit
104
receives an output signal of the optical head
103
. Based on the output signal, the reproduced signal/servo signal detection circuit
104
generates a reproduced signal, a focusing error signal and a tracking error signal, and provides these signals to the subsequent processing circuits. The focusing/tracking control section
110
is provided with the focusing error signal and the tracking error signal, and controls the optical head
103
to always follow the skew and/or the eccentricity of the disk. The reproduced signal digitization circuit
105
is provided with a reproduced signal, and the demodulator
106
is provided with the digitized reproduced signal and a read clock signal which is synchronized with the reproduced signal.
The reference clock generator
111
generates a reference clock signal needed for modulating/demodulating data to be recorded/reproduced by this device. The demodulator
106
converts the reproduced signal to reproduced data using the digitized reproduced signal and the read clock signal in accordance with a predetermined demodulation rule. The reproduced data is then output to the error corrector/address detector
123
in synchronization with the reference clock signal. The error corrector/address detector
123
detects the addresses of the track on the optical disk
102
from the reproduced data, and outputs address detection signals. Based on the address detection signal, the gate signal generator
112
generates a gate signal in synchronization with the reference clock. The gate signal indicates the timing of address detection, which is periodically performed by the optical head
103
. The gate signal is used when detecting an address or when recording/reproducing data.
When recording data is input to the modulator
109
, the modulator
109
modulates the recording data in accordance with a modulation rule. Based on the modulated output, the recording signal generation circuit
108
generates and outputs a signal for optically modulating laser light. Based on the signal from the recording signal generation circuit
108
, the laser drive circuit
107
drives a laser light source of the optical head
103
so that laser light is irradiated from the laser light source. Thus, the recording data is written immediately after the address region on the optical disk
102
.
The comparator
125
compares the tracking error signal generated by the reproduced signal/servo signal detection circuit
104
with predetermined voltages from the bias circuit
124
so as to detect an abnormal jump.
The number-of-rotation error detection circuit
126
compares the number of rotations (or the rotation cycle) of the motor
101
(indicated by the number-of-rotation detection signal from the motor
101
) with the frequency (or the cycle) of the reference clock signal from the reference clock generator
111
so as to determine how close the current number of rotations of the motor
101
is to the intended number of rotations. When the error falls within a predetermined range, the number-of-rotation error detection circuit
126
outputs a recording enable signal which allows the device to perform a recording operation. In response to the recording enable signal, the modulator
109
, the recording signal generation circuit
108
and the laser drive circuit
107
can start a recording operation.
The operation of the device having such a structure for reproducing/recording data from/to sectors on the optical disk
102
will be described with reference to the timing diagrams of
FIGS. 7A
to
7
G. Each sector on the optical disk
102
includes an address region, where the address of the sector is recorded, and a data recording region for data recording/reproduction.
The reproduced signal/servo signal detection circuit
104
receives an output signal from the optical head
103
. Based on the output signal, the reproduced signal/servo signal detection circuit
104
generates a reproduced signal, as illustrated in
FIG. 7A
, and a tracking error signal, as illustrated in FIG.
7
B.
When the number of rotations of the optical disk
102
is matched with the intended number of rotations, in order to read the address of the target sector K, the read gate signal of
FIG. 7C
is activated at a timing (c)-
1
based on the address detection signal which has been output for the sector previous to the target sector K. The read gate signal is used as, for example, a start signal for a synchronization operation of the PLL (Phase Locked Loop) circuit, which is provided in the reproduced signal digitization circuit
105
. In response to the read gate signal, the PLL circuit in the reproduced signal digitization c

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