Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Reexamination Certificate
1999-12-30
2003-03-25
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
C369S047430, C369S053300, C369S047470
Reexamination Certificate
active
06538967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to method and apparatus for controlling a reproducing/recording speed of an optical disk in an optical disk device.
2. Description of the Related Art
FIG. 1
is a schematic block diagram of a general optical disk player, which comprises an optical pickup unit
11
for detecting recorded signals from an optical disk
10
inserted; a driver
21
for driving a sled motor
12
a
to move the optical pickup
11
and a spindle motor
12
b
to rotate the optical disk
10
; an R/F unit
20
for equalizing and shaping the RF signal reproduced by the pickup
11
into binary signals; a servo unit
30
for controlling the optical pickup
11
and the driver
21
; a digital signal processor (DSP)
30
for processing the binary signals from the R/F unit
20
into 14-bit EFM data; an EFM demodulator
50
for demodulating each 14-bit EFM data into a corresponding 8-bit data; a CIRC decoder
70
for detecting and correcting errors of the demodulated data in an ECC data block; and a controller
60
for controlling the servo unit
30
and the disk reproduction speed depending upon whether the data error is corrected or not.
The detailed reproduction operation of the optical disk player structured as above is as follows. First, the optical disk
10
is inserted and then starts to rotate. The recorded signals are reproduced as high frequency (referred as “RF” hereinafter) signals by the optical pickup
11
. The reproduced RF signals are equalized and then converted into binary signals by the R/F unit
11
.
Meanwhile, the controller
60
distinguishes the type of the inserted optical disk
10
based on the reproduced RF signals. For this type distinction, the controller
60
compares the reproduced signal level with the pre-determined standard level, and discriminates the type of the optical disk
10
according to the comparison result.
With regard to the comparison result, if the RF signal level is below the standard level, the controller
60
considers the optical disk
10
to be a writable one, for example CD-R or CD-RW, and if it is above the standard level, the controller
60
considers the disk
10
to be a read-only disk such as CD-ROM.
After the type of disk decision has been made, the controller
60
rotates the optical disk
10
at a reproduction speed according to the determined disk type. That is, the controller
60
applies a driving voltage corresponding to its maximum speed to the spindle motor
12
b
through the servo unit
30
and the driver
21
if the determined type is a read-only, and applies a driving voltage corresponding to the maximum speed divided by a predetermined value to the spindle motor
12
b
to rotate the optical disk
10
at a lower speed.
Under the condition that the disk
10
is being rotated at the chosen speed, the RF signals reproduced from the rotating optical disk
10
by the pickup
11
are converted into binary signals in the R/F unit
20
as explained above. The binary signals are restored into EFM modulated digital data by the DSP
30
.
When the DSP
30
detects one or more data errors which may be caused from signal drop out etc. during the data restoring process, it generates an error-notifying signal and sends it to the controller
60
. The EFM demodulator demodulates series of the restored 14-bit digital data into series of corresponding 8-bit data on the basis of the pre-stored EFM conversion table.
Meanwhile, when the specific signal indicating that the reproduction error is received from the DSP
30
, the controller
60
controls the CIRC decoder
70
to try to correct the error of the demodulated digital data received from the EFM demodulator, so that the CIRC decoder
70
tries to recover the error data into normal data a preset number of times.
However, if the error data is not recovered to a normal data (even though the error correction process has been performed several times), the controller
60
controls the driving voltage applied to the spindle motor
12
b
through the servo unit
30
and the driver
21
to adjust the rotation speed of the optical disk
10
to a lower speed, re-detects the recorded signals of disk location where the error data is reproduced through the optical pickup
11
, and then performs the above-explained error correction process again.
In the conventional reproduction method for an optical disk described hereinbefore, the reproduction speed of an optical disk is changed to a lower speed and then the corresponding data area is re-read if an error data, which may be caused from an abnormal disk condition, reproduced from an optical disk cannot be recovered to normal data even after error correction trials of the preset number. However, such retrials to correct error and data re-reading at a reduced speed causes delay time in reproduction, which results in discontinuity in video or audio being reproduced.
In addition, in the conventional optical disk player, the gain values of a servo unit for tracking and focussing servo control are selected from among only two values (appropriate for high and low speed), so that the tracking and focussing control of an optical pickup during the gradual speed adjustment cannot be performed accurately.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide method and apparatus for controlling a disk speed in advance according to a distinguished disk condition to reduce delay time in reproduction while maintaining precise servo control.
In order to achieve the objective, another method according to the present invention comprises the steps of detecting a disk type or a disk condition based on the characteristics of a reproduced signal from an optical disk; displaying possible reproduction speeds on a screen according to the detected disk type or disk condition; and executing a servo control program appropriate for the reproduction speed selected from among the displayed reproduction speeds.
REFERENCES:
patent: 5289451 (1994-02-01), Ashinuma et al.
patent: 5761699 (1998-06-01), Hatanaka
patent: 5764610 (1998-06-01), Yoshida et al.
patent: 5903531 (1999-05-01), Satoh et al.
patent: 5903536 (1999-05-01), Lee et al.
patent: 5963517 (1999-10-01), Nakagaki et al.
patent: 6154428 (2000-11-01), Lee
patent: 6195321 (2001-02-01), Takamine et al.
patent: 6195322 (2001-02-01), Ohtani et al.
patent: 0123320 (1992-04-01), None
LG Electronics Inc.
Tran Thang V.
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