Dynamic information storage or retrieval – Information location or remote operator actuated control – Selective addressing of storage medium
Reexamination Certificate
1999-02-24
2001-06-05
Dinh, Tan (Department: 2651)
Dynamic information storage or retrieval
Information location or remote operator actuated control
Selective addressing of storage medium
C369S047180, C369S053120
Reexamination Certificate
active
06243331
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to method and apparatus for performing address interpolation on a storage medium, such as an optical disk, in which data items and addresses, associated with the data items, are stored.
A prior art address interpolation apparatus is disclosed in Japanese Laid-Open Publication No. 8-111075, for example.
FIG. 10
illustrates the configuration of this address interpolation apparatus.
In
FIG. 10
, an optical disk
201
is a storage medium, in which video, music or information is stored and which is rotationally driven by a spindle motor (not shown). An optical pickup
202
irradiates laser light onto the optical disk
201
and receives its reflected radiation using a photodetector, thereby reading out the information stored in the optical disk
201
.
An RF signal processor
203
extracts RF reproduced signal, tracking error signal, focus error signal and so on from the information read out by the optical pickup
202
from the optical disk
201
. A demodulator
204
demodulates the RF reproduced signal extracted by the RF signal processor
203
. The reproduced signal, demodulated by the demodulator
204
, is input to an address decoder
207
and a sync signal detector
205
. The sync signal detector
205
separates a sync signal from the reproduced signal. If the sync signal is absent because of the dirt attached onto the optical disk
201
, for example, then a sync signal interpolator
206
performs interpolation to obtain a substitute sync signal. Accordingly, sync signals can be obtained at regular intervals without any interruption.
The address decoder
207
performs a cyclic redundancy check (CRC) on addresses contained in the reproduced signal. If any address error has been spotted as a result of the CRC, then the address decoder
207
produces and outputs an address error detection flag. Conversely, if there are no address errors found, then the address decoder
207
outputs the correct addresses as they are. The address error detection flag is produced and output in synchronism with the substitute sync signal, which has been obtained through interpolation by the sync signal interpolator
206
. An address interpolator
208
receives addresses or address error detection flags from the address decoder
207
. If an address has been supplied from the address decoder
207
, then the address interpolator
208
outputs the address as it is. Alternatively, if an address error detection flag has been supplied from the address decoder
207
, then the address interpolator
208
produces and outputs an interpolated address. Once the number of times of address interpolation carried out in the address interpolator
208
reaches a predetermined maximum number, address reading is aborted and various types of processing like retry is performed. The maximum number of times address interpolation may be repeatedly performed back to back is defined within a range from 7 to 10, for example. It should be noted that this number of times (in this specification, referred to as a “maximum number of times of address interpolation” or simply “maximum number”) is variable with the capacity of an associated memory into which data is stored.
A controller
209
receives the address or interpolated address from the address interpolator
208
and specifies an address in a storage medium (not shown), at which data, associated with the address or interpolated address, should be written.
Although not illustrated in
FIG. 10
, if any erroneous data items exist among a great number of data items obtained from the reproduced signal, then these erroneous data items are corrected. If such error correction is impossible, then various types of processing like retry is performed.
A conventional address interpolation apparatus like this, however, has the following problems. An address error might happen because of the dirt attached onto the surface of the disk. But another address error might happen because a servo system has lost its control due to some reason to miss the address of the target (in this specification, such a condition will be called a “servo failure”). Although an address error could happen because of any of these two different reasons, the conventional address interpolation apparatus always performs the address interpolation the same number of times, because the maximum number of times of address interpolation is fixed in the apparatus. That is to say, the address interpolation is performed regardless of whether the error results from the dirty surface of the disk or the servo failure.
Accordingly, if the address interpolation is performed the maximum number of times to correct the address error resulting from the dirty surface of the disk, then retry processing is carried out, even though no servo failure has happened. If the optical disk is partitioned into a plurality of sectors, then the same group of sectors as that read out during a series of operations is read out again. However, these sectors are located under the same dirty surface and are less likely to be read out correctly. Thus, it is highly probable that the retry processing is repeated many times. In such a situation where this processing is repeated numerous times in vain, data cannot be reproduced smoothly enough from an optical disk that often causes read errors. Accordingly, the resultant performance in reproducing data from such a disk is far from satisfactory.
On the other hand, if an address error has happened because the target address was missed due to a servo failure, then retry processing won't be started until the address interpolation has been repeatedly performed the maximum number of times. Accordingly, the retry processing cannot be performed in time and the reproducing speed adversely decreases.
SUMMARY OF THE INVENTION
An object of the present invention is providing method and apparatus for performing address interpolation on an optical disk to improve the performance and increase the speed in reproducing data from the optical disk.
To achieve this object, according to the present invention, the maximum number of times of address interpolation is not fixed at a constant value, but changed in accordance with a reproduced signal, e.g., how many times errors have happened in reading data items or associated addresses from the reproduced signal.
Specifically, the method of the present invention is designed for performing address interpolation on an optical disk, in which predetermined data items and addresses, associated with the data items, are stored. The method includes the steps of: a) reproducing a signal, containing the data items and addresses, from the optical disk; b) producing an interpolated address for at least one of the addresses that has not been decoded successfully from the reproduced signal; and c) changing, in accordance with the reproduced signal, a maximum number of times the interpolated address is produced. In the step b), the number of times the interpolated address is repeatedly produced is equal to or smaller than the changed maximum number of times.
In one embodiment of the present invention, the optical disk is partitioned into a plurality of sectors. Associated ones of the addresses are stored in each said sector. And in the step c), the maximum number of times is changed in accordance with the number of addresses that exist within each said sector and have not been decoded successfully from the reproduced signal.
In another embodiment of the present invention, in the step c), the maximum number of times is changed in accordance with the number of data items that are contained in the reproduced signal and require error correction.
In still another embodiment, the optical disk is partitioned into a plurality of sectors. And in the step c), if at least one of the data items, contained in the reproduced signal for each said sector, requires error correction, then the maximum number of times is changed into a larger number.
The apparatus of the present invention is designed for performing address interpolation on an optical disk, in wh
Manabe Noriyuki
Sakamoto Hiroshi
Dinh Tan
Harness & Dickey & Pierce P.L.C.
Matsushita Electric - Industrial Co., Ltd.
LandOfFree
Method and apparatus for performing address interpolation on... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for performing address interpolation on..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for performing address interpolation on... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2517990