Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
1993-09-08
2001-07-03
Tran, Thang V. (Department: 2651)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S044250
Reexamination Certificate
active
06256274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an optical disc apparatus, and more particularly to an improvement of an optical disc apparatus for recording desired information to a disc recording medium through a memory circuit with a large capacity.
2. Description of the Related Art
Conventionally, there is proposed an optical disc apparatus by which desired information is thermo magnetically recorded to an optical magnetic disc through a memory circuit with a large capacity.
More specifically, in this type of the optical disc apparatus, recording information is sequentially stored in a memory circuit and the stored recording information is sequentially read out and recorded to the optical magnetic disc.
In the optical disc apparatus, the recording information is recorded by using pregrooves on the optical magnetic disc as a reference so that a recording track is formed along the pregroove and the recording information is recorded in predetermined cluster units using to the pregroove as a reference.
Further, in the optical disc apparatus, when the discontinuity of the address data is detected while information is recorded, it is determined that atracking jump is caused by a vibration or the like. Then, a quantity of light of an optical beam is changed to the quantity of light for reproduction and thereafter the leading head of the sector, the tracking of which has been jumped, is detected.
With this arrangement, in the optical disc apparatus, the recording information is recorded again with respect to the portion of the recording information which cannot be correctly recorded due to the tracking jump.
For example, U.S. Pat. No. 5,012,461 is known in which, as described above, discontinuity of the address data is detected so as to change a laser power to a power for reproduction.
Further, in such kind of optical disc apparatus, even if the tracking jump occurs, predetermined information can be recorded successively by effectively using a capacity of the memory circuit.
For example, U.S. Pat. No. 5,224,087, filed Aug. 19, 1991 is known, wherein desired data is recorded successively by using the memory circuit.
Above address data is recorded to the optical magnetic disc at a cycle of 13.3 [msec]. So reading address data adjacent to current address data takes 13.3 [msec] at least.
On the contrary, in the event of a tracking jump, the positions of several tens of tracks to which an optical beam is irradiated are changed in 1 to 2 [msec]. Consequently, when tracking jumping is detected based on comparing current address data and previous address data, if controlling it after obtaining a detecting result, the tracking jump has already completed, and thus a problem arises in that recorded data may be erased by mistake before the intensity of the light beam is changed to the quantity of light used in reproduction.
As a method of solving this problem, it is considered a method of detecting a tracking jump based on a tracking error signal could be considered.
More specifically, the track zero-crossing signal is generated by detecting a point changed the signal level of the tracking error signal to a positive side or negative side about a zero level. Further, an off-track signal is generated for detecting the off track by comparing a light reflected from the optical magnetic disc with a predetermined value, and then a tracking jump is detected by using the above two signals.
A different structure from the above detecting method, for example, Japanese Patent Laid-Open No. 11546/1984 is known, in which a track crossing signal is generated by comparing the tracking error signal with predetermined level to detect a tracking jump.
When, however, a tracking jump is detected based on the track zero-crossing signal or the off-track signal, it is determined that a tracking jump has occurred even if a scratch, dust or the like is present on the optical magnetic disc, and thus the recording operation is unnecessarily interrupted and there is a problem that useless control is repeated in recording.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of this invention is to provide an optical disc apparatus, capable of securely and quickly detecting a tracking jump and preventing recorded data from being erased.
The foregoing object and other objects of this invention have been achieved by the provision of an optical disc apparatus
1
for recording desired information D
1
to a disc recording medium
2
by irradiating a light beam L
1
to the disc recording medium
2
, which comprises a tracking error signal generation means
24
for receiving the reflected light of the light beam L
1
and generating a tracking error signal based on the reflected light, a comparison means
24
for outputting the comparison result TZC between the tracking error signal and a predetermined reference level, an off-track signal generation means
24
for generating an off-track signal OFTRK the signal level of which is changed when the light beam jumps off a track, based on the reflected light, latch means
36
,
38
for latching the off-track signal OFTRK using the comparison result TZC as a reference and outputting a latch signal S
3
, count means
40
,
42
for counting the latch signal S
3
and outputting a counting result S
5
, reset means
50
,
52
for initializing the count means
40
,
42
in a predetermined period after the latch signal S
5
rises up, decoders
44
,
46
,
48
for outputting a tracking jump detection signal SHOCK by determining that the light beam L
1
has jumped off a target track when the counting result S
5
reaches a predetermined value, and a light quantity change means
30
for changing a quantity of light of the light beam L
1
to the quantity of light for reproduction based on the tracking jump detection signal SHOCK when the light beam L
1
jumps off the target track.
Further, there is provided an optical disc apparatus for recording desired information D
1
on a disc recording medium
2
by irradiating an optical beam L
1
to the disc recording medium
2
, which comprises a tracking error signal correction means
24
for receiving the reflected light of the light beam L
1
and creating a tracking error signal based on the reflected light, a comparison means
24
for outputting the comparison result TZC of the tracking error signal and a predetermined reference level, an off-track signal generation means
24
for generating an off-track signal OFTRK the signal level of which is changed when the light beam L
1
jumps off a track, based on the reflected light latch means
36
,
38
for latching the off-track signal OFTRK using the comparison result TZC as a reference and outputting a latch signal S
3
, count means
40
,
42
for counting the latch signal S
3
and outputting a counting result S
5
, a scratch detection means
24
for detecting a scratch on the disc recording medium based on the reflected light and outputting a scratch detection signal DFECT when the light beam L
1
scans the scratch, reset means
50
,
52
for initializing the count means
40
,
42
in a predetermined period after the latch signal S
3
rises up as well as initializing the count means
40
,
42
based on the scratch detection signal DFECT, decoders
44
,
46
,
48
for outputting a tracking jump detection signal SHOCK by determining that the light beam L
1
has jumped off a target track when the counting result S
5
reaches a predetermined value, and a light quantity change means
30
for changing a quantity of light of the light beam L
1
to the quantity of light for reproduction based on the tracking jump detection signal SHOCK when the light beam L
1
jumps off the target track.
Further, in this invention, the reset means
50
,
52
initializes the count means
40
,
42
when a quantity of light of the light beam L
1
is changed to the quantity of light for reproduction.
Further, in this invention, the light quantity change means
30
includes a light beam modulation means
84
for modulating the light beam L
1
by a predetermined f
Arataki Yuji
Nakazawa Tetsuji
Chu Kim-Kwok
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Sony Corporation
Tran Thang V.
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