Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Control of information signal processing channel
Reexamination Certificate
2000-07-11
2003-08-12
Tran, Thang V. (Department: 2653)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Control of information signal processing channel
C369S053310
Reexamination Certificate
active
06606288
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an optical disk reproduction apparatus and a method for controlling an optical disk reproduction apparatus and, more particularly, to an optical disk reproduction apparatus which can successively reproduce data recorded on an optical disk and a method for controlling the optical disk reproduction apparatus.
BACKGROUND ART
An optical disk reproduction apparatus has a servo for controlling rotation of an optical disk and a position of an optical pickup so as to correctly read out data recorded on the disk at a constant rate. The servo is easily affected by vibrations, or flaws or dusts on the disk and thus, reading of data is sometimes interrupted. Therefore, a shockproof function is required to resume reading of data from an appropriate position so as to prevent data from being output discontinuously, even when the reading of data is interrupted. At this time, since a position where the reading of data is to be resumed cannot be decided only by the control of a position of the optical pickup, the above-described position for resumption is Usually decided after the data is confirmed by using the shockproof function.
FIG. 5
is a block diagram illustrating a structure of a prior art musical CD reproduction apparatus. A disk
21
is a CD having musical data recorded thereon. An optical pickup
22
irradiates a laser light to the disk
21
to read the musical data recorded on the disk
21
. An analog signal processing unit
23
obtains conditions of tracking and focusing from the data read by the optical pickup
22
as well as binarizes the data read by the optical pickup
22
. A servo
24
controls the tracking and the focusing of the optical pickup
22
. A digital signal processing unit
25
comprises a CIRC (Cross-Interleave-Reed-Solomon Code) processing unit
251
, a formatting circuit
252
, a memory arbitration circuit
253
, an output data FIFO memory
254
, a comparator
255
, and a buffering resumption request generating circuit
256
, and processes data binarized by the analog signal processing unit
23
to output processed data as reproduced data. A memory
26
temporarily stores the data processed by the digital signal processing unit
25
. A microcomputer
27
obtains information from the respective elements and controls operations of the respective elements.
An operation of the prior art musical CD reproduction apparatus will be described. The optical pickup
22
irradiates a laser light to the disk
21
and converts a light reflected from the disk
21
into a signal to output the signal to the analog signal processing unit
23
. The analog signal processing unit
23
outputs conditions of tracking and focusing to the servo
24
on the basis of the signal from the optical pickup
22
as well as binarizes the signal from the optical pickup
22
to output a binarized signal to the digital signal processing unit
25
. The servo
24
outputs a control signal to the optical pickup
22
on the basis of the information from the analog signal processing unit
23
to control the tracking and the focusing. The CIRC processing unit
251
performs, for the binarized data, EFM (Eight to Fourteen Modulation) demodulation, separation of CD (Compact Disk)-DA (Digital Audio) data from subcode data, and error correction processing for the CD-DA data, and outputs processed data to the formatting circuit
252
. The formatting circuit
252
converts the CD-DA data output from the CIRC processing unit
251
into a prescribed format and then outputs converted data to the memory
26
via the memory arbitration circuit
253
. Data buffered in the memory
26
is read out at a prescribed rate to be sent to the output data FIFO memory
254
via the memory arbitration circuit
253
, and output the same as reproduced data. An amount of the data stored in the memory
26
, being controlled by the. microcomputer
27
, does not exceed a capacity of the memory
26
.
During reproduction from the disk
21
, when the microcomputer
27
detects, on the basis of the information from the servo
24
, that an error occurs in the reading of data, the microcomputer
7
instructs the digital signal processing unit
25
to interrupt the buffering as well as instructs the servo
24
to move the optical pickup
22
to a position before the position of data where the reading error occurs on the disk
21
. In addition, the latest block of data buffered in the memory
26
is kept in the comparator
255
as expectation data.
The comparator
255
captures the CD-DA data read out from the disk
21
after the optical pickup
22
moves, and compares the CD-DA data with the expectation data. The comparator
255
outputs “H” when all the data are in coincidence, and outputs “L” when at least one of the data is in uncoincidence, to the buffering resumption request generating circuit
256
.
When the buffering resumption request generating circuit
256
receives “H” from the comparator
255
, the buffering resumption request generating circuit
256
requests the formatting circuit
252
to resume the buffering, and then the formatting circuit
252
resumes the buffering from data following to the CD-DA data which is judged in coincidence by the comparator
255
. On the other hand, when the buffering resumption request generating circuit
256
receives “L” from the comparator
255
, the microcomputer
27
instructs the servo
24
to move the optical pickup
22
to a further forward position, and continues to compare the CD-DA data with the expectation data until the comparator
255
outputs “H”.
Usually, when the CD-DA data is reproduced by an optical disk reproduction apparatus having the above-described structure, the data read out from the disk
21
is controlled to be read out at a higher rate than that of data output as reproduced data from the output data FIFO memory
254
. That is, a rate of buffering data in the memory
26
is higher than a rate of reading out data from the memory
26
. Therefore, even when the buffering to the memory
26
is interrupted, the output data FIFO memory
254
reads out the data stored in the memory
26
at a prescribed rate and outputs reproduced data. That is, while data is stored in the memory
26
, the optical disk reproduction apparatus can output reproduced data continuously.
In addition, Japanese Published Patent Application No.Hei.9-17124 discloses another shockproof function utilizing subcode data. When the buffering is interrupted, the shockproof function disclosed herein reads out and holds time information contained in subcode data which is written last, returns a CD pickup unit to an interruption point, then compares time information of subcode data included in data read out thereat with the time information held at the interruption, and instructs a timing of the buffering resumption.
On the other hand, when data is read out by the optical disk reproduction apparatus, errors may creep in the data. Further, there is a possibility that errors still remain in data after error correction is performed and that the data containing the errors are output as reproduced data. Here, in many cases, the errors contained in the reproduced data are of a negligible level. Particularly, in case of a musical CD where adjacent data have high correlations, even if a few errors are contained in the reproduced data, the errors cannot be recognized by the human ear in many cases.
In the prior art optical disk reproduction apparatus as described above, errors occurring also during a usual reproduction, independent of the buffering interruption, may be contained in the expectation data held in the comparator
255
and the CD-DA data. Therefore, in some cases, the comparator
255
cannot confirm coincidence of all data sequences and thus, the buffering cannot be resumed.
The present invention is made to solve the above problems, and it is an object of the present invention to provide an optical disk reproduction apparatus which can appropriately instruct buffering resumption, even when errors occurring in data independent of the buffering interruption are c
Okazaki Makoto
Ueda Yasushi
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel L.L.P.
Tran Thang V.
Vuong Bach
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