Dynamic information storage or retrieval – Information location or remote operator actuated control – Selective addressing of storage medium
Reexamination Certificate
1999-03-25
2002-06-04
Hudspeth, David (Department: 2651)
Dynamic information storage or retrieval
Information location or remote operator actuated control
Selective addressing of storage medium
C369S047220, C369S047270, C369S047470, C369S053210, C369S059250, C369S053350
Reexamination Certificate
active
06400658
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a recordable and reproducible DVD-RAM (digital versatile disk-random access memory) disk reproduction apparatus, and more particularly, to a DVD-RAM disk apparatus for reducing errors during detection of identification (ID) data from a signal read from the DVD-RAM disk.
A recent form of a DVD is a DVD-RAM capable of recording and deleting data freely. Such a DVD-RAM disk has a recording capacity capable of recording massive amounts of data. The DVD-RAM disk comprises data sectors for use in recording data. Each data sector largely includes a header region and a recording region. The header region is divided into two sub-regions which are disposed adjacent to each other. Here, a region which is located in a relatively higher position is defined as an upper header region, and a region which is located in a relatively lower position is defined as a lower header region. The header region includes ID data containing a sector number and sector information. The recording region is called a user region which includes main data being information to be recorded.
FIG. 1
shows the structure of a general DVD-RAM disk reproduction apparatus. Referring to
FIG. 1
, the DVD-RAM disk reproduction apparatus includes an optical pickup
12
for reading signals from a DVD-RAM disk
11
, and a playback signal amplifier
13
for amplifying signals read via the optical pickup
12
. The DVD-RAM disk reproduction apparatus also includes an equalizer
14
for receiving a playback signal amplified in the playback signal amplifier
13
and equalizing the received signal for frequency characteristic compensation, a data detector
15
for producing a digital signal from the signal equalized in the equalizer
14
, and a phase locked loop (PLL)
16
for synchronizing the output of the data detector
15
with a sync clock and outputting the synchronized result to a digital signal processor.
FIG. 2
is a detailed circuit diagram showing the playback signal amplifier
13
shown in FIG.
1
. As shown in
FIG. 2
, the playback signal amplifier
13
includes a pair of operational amplifiers
21
and
22
for respectively obtaining a sum and a difference of four signals A, B, C and D picked up by divided-by-four photodiodes in the optical pickup
12
, and a header region detector
23
for receiving the difference signal obtained by the operational amplifier
22
and detecting a header region of the DVD-RAM disk
11
. The header region detector
23
includes an upper header region detector
231
and a lower header region detector
232
for respectively detecting an upper header region and a lower header region based on the input difference signal, and a logical sum unit (OR)
233
for logically summing signals of the detected upper and lower header regions. The playback signal amplifier
13
also includes a multiplexer RF MUX
24
for selecting the sum signal and difference signal obtained in the pair of the operational amplifiers
21
and
22
according to a result of the operation of the logical sum unit
233
, and outputting the select result to the equalizer
14
. The operation of the conventional DVD-RAM disk reproduction apparatus of
FIGS. 1 and 2
having the above structure will be described in more detail with reference to
FIGS. 3A through 3G
.
As shown in
FIG. 3A
, the DVD-RAM disk
11
includes a header region and a recording region in each sector of a track, in which the header region comprises two portions of an upper header region and a lower header region. A signal read via the optical pickup
12
from the DVD-RAM disk
11
having such a track structure is processed via two paths in the playback signal amplifier
13
.
Referring to
FIG. 2
, the first operational amplifier
21
of the playback signal amplifier
13
adds all four signals A, B, C and D picked up by the divided-by-four photodiodes in the optical pickup
12
and outputs a sum signal A+B+C+D as shown in
FIG. 3B
to the multiplexer
24
. The second operational amplifier
22
obtains a push-pull signal and outputs a difference signal (A+B)−(C+D) as shown in
FIG. 3C
to the multiplexer
24
, in which the latter added result is subtracted from the former added result. Here, the sum signal A+B+C+D is used in order to reproduce user data recorded in a recording region on a disk track, and the difference signal (A+B)−(C+D) is used in order to reproduce ID data in a header region thereof. Although the signal in the header region also appears in the sum signal A+B+C+D as shown in
FIG. 3B
, the characteristics of the signal appearing in the difference signal (A+B)−(C+D) as shown in
FIG. 3C
is better. Thus, the difference signal (A+B)−(C+D) of
FIG. 3C
is used for detection of the ID data in the header region. The upper header region detector
231
and the lower header region detector
232
in the header region detector
23
commonly receive the difference signal (A+B)−(C+D) shown in
FIG. 3C
obtained from the second operational amplifier
22
and detect the upper header region and the lower header region, respectively. Accordingly, the upper header region detector
231
and the lower header region detector
232
output the upper header region signal HD
1
and the lower header region signal HD
2
as shown in
FIGS. 3D and 3E
, respectively. That is, although not shown in the drawing, the upper header region detector
231
and the lower header region detector
232
include an envelope detector and a comparator, respectively. The upper header region detector
231
and the lower header region detector
232
each detect an envelope value from the difference signal (A+B)−(C+D) and compares the detected envelope value with a corresponding predetermined reference value, to thereby determine a portion corresponding to the upper header region and the lower header region. If the portion is determined as the upper header region or the lower header region, the corresponding upper header region detector
231
or the lower header region detector
232
outputs a high-level signal represented as a binary signal “
1
” and otherwise outputs a low-level signal represented as a binary signal “O”, as the upper header region signal and the lower header region signal as shown in
FIGS. 3D and 3E
, respectively. The logical sum unit
233
receives the upper and lower header region signals of HD
1
and HD
2
of
FIGS. 3D and 3E
detected in the upper header region detector
231
and the lower header region detector
232
and logically sums the received signals, to obtain a header region signal HD
3
shown in FIG.
3
F and outputs the same as a signal for controlling the multiplexer
24
. The multiplexer
24
selectively outputs one of the sum signal A+B+C+D of FIG.
3
B and the difference signal (A+B)−(C+D) of
FIG. 3C
to the equalizer
14
according to the header region signal HD shown in
FIG. 3F
applied from the logical sum unit
233
in the header region detector
23
. That is, the multiplexer
24
selects the difference signal (A+B)−(C+D) of
FIG. 3C
during a high-level interval represented as a binary signal “1” of
FIG. 3F
, and selects the sum signal A+B+C+D of
FIG. 3B
during a low-level interval represented as a binary signal “0”, and outputs the selected signal as an RF signal. The equalizer
14
equalizes the RF signal selectively output from the multiplexer
24
in the playback signal amplifier
13
and then compensates for frequency characteristics, to thereby output the compensated result to the data detector
15
. The data detector
15
detects data from the equalized signal and the PLL
16
restores the clock to be output to a digital signal processor.
As described above, the conventional DVD-RAM disk reproduction apparatus uses a difference signal (A+B)−(C+D) of the four signals picked up in the photodiodes in the optical pickup, in order to detect ID data of the header
Joo Seong-Sin
Jung Soo-Yul
Kim Tae-Kyung
Lee Yong-Jae
Seo Jung-Eon
Chu Kim-Kwok
Hudspeth David
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
LandOfFree
DVD-RAM disk reproduction apparatus for reducing errors... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with DVD-RAM disk reproduction apparatus for reducing errors..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and DVD-RAM disk reproduction apparatus for reducing errors... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2931246