Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
2001-03-14
2003-12-30
Huber, Paul W. (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S047140
Reexamination Certificate
active
06671240
ABSTRACT:
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to a defective region processing apparatus and a defective region processing method for processing a defective region on an information storage medium including a plurality of regions, and an information storage device for recording information on the information storage medium.
(ii) Description of the Related Art
As a high-density information storage medium for recording/producing sound data or image data, an optical storage medium or magnetic storage medium are known. Spiral or concentric tracks are typically provided on such an information storage medium, and these tracks are divided into a plurality of regions which are generally called sectors. Information is stored by writing marks in these sectors by using a magnetic field or heat, and information is reproduced by reading the marks generated by the magnetic field or light.
A plurality of such sectors are provided on the information storage medium, and a defective sector may be generated during production or use of the information storage medium. An information storage device for recording information on an information storage medium or a formatting device for formatting an information storage medium is, therefore, provided with a function as a defective region processing device which executes a process for prohibiting use of such a defective sector or a process for registering a normal preliminary sector instead of such a defective sector.
With recent improvement in the computer technology, a data size or a quantity of sound data or image data to be used is increasing and enhancement of recording density of the information storage medium is eagerly desired. Miniaturization of the track pitch is demanded in order to greatly improve the recording density of the information storage medium.
As a technique for miniaturizing the track pitch, land and groove recording is proposed by which information is recorded on both flute-like grooves and protruding lands alternately provided on the storage medium.
FIG. 1
is a view showing sectors on an information storage medium adopting the land and groove recording.
FIG. 1
illustrates one groove
1
and two lands
2
and
3
sandwiching that groove. Both the groove
1
and the lands
2
and
3
are used as tracks, and a plurality of sectors are provided to each track. Numbers for differentiating the sectors are given to these multiple sectors. For example, the 10th sector Sct
10
, the 11th sector Sct
11
, the 12th sector Sct
12
, . . . are provided on the groove
1
depicted in this drawing, and the 0th sector Sct
0
, the first sector Sct
1
, the second sector Sct
2
, . . . , the 20th sector Sct
20
, the 21st sector Sct
21
, the 22nd sector Sct
22
, . . . are provided to the respective two lands
2
and
3
sandwiching the groove
1
. That is, serial numbers are given to respective sectors provided in one track, and numbers given to a sector are different by 10 from those given to another sector adjacent to the former in a transverse direction of the tracks.
In this manner, both the grooves and the lands are used as tracks in the land and groove recording. The track pitch can be, therefore, simply reduced to approximately ½ as compared with a technique using only one of the grooves and the lands as tracks, and the recording density can be doubled if the linear recording density remains unchanged. Accordingly, the above-described technique is extremely important for realizing the high-density recording.
However, if the land and groove recording and the like is adopted to greatly miniaturize the track pitch, when reading a mark on a given track, cross talk caused due to a mark on a track adjacent to that track prevents the mark from being read. For example, when reading the mark recorded in the 11
th
sector Sct
11
in
FIG. 1
, cross talk occurs due to the mark in the first sector Sct
1
or the mark in the 21
st
sector Sct
21
.
FIG. 2
is a graph showing an example of cross talk.
The upper part in
FIG. 2
shows a signal waveform
4
of a read signal obtained when performing reading with respect to an erased sector having no mark therein. A mark is written on a sector adjacent to the erased sector in a transverse direction of the tracks.
Further, the lower part of the
FIG. 2
graph shows a waveform
5
of a gate signal indicative of a significant part in the read signal. In the signal waveform
4
of the read signal shown in the upper part of the graph, only a portion corresponding to a time interval during which the waveform
5
of the gate signal shown in the lower part rises is a significant signal waveform.
A flat waveform
4
_
1
and a spike-like waveform
4
_
2
exist in the signal waveform
4
of the read signal, and the flat waveform
4
_
1
is indicative of a signal caused due to an erased sector and the spike-like waveform
4
_
2
is indicative of cross talk owing to a sector on an adjacent track. The signal intensity of such cross talk may be strong such that the signal is hardly differentiated from an original read signal. In such a case, a mark is prevented from being read.
In the prior art defective region processing apparatus or defective region processing method, the above-described cross talk caused due to a defective sector keeps preventing a mark in a sector adjacent to the defective sector in the transverse direction of the tracks from being read even after a process for prohibiting use of the defective sector or a process for registering a normal preliminary sector instead of the defective sector is executed.
Although the above problem becomes prominent in an optical disk device adopting the land and groove recording, this problem occurs not only in such a device but it can be generally observed in an information storage device having the narrow track pitch.
SUMMARY OF THE INVENTION
In view of the above-described drawback, an object of the present invention is to provide a defective sector processing apparatus and a defective sector processing method capable of processing a defective sector so that a mark in a sector adjacent to the defective sector can be normally read, and an information storage device provided with a function as such a defective sector processing apparatus.
Since a mark can be normally read even though miniaturization of the track pitch is attained when the present invention is used, realization of high density of the information storage medium can greatly proceed.
To this end, a defective region processing apparatus according to the present invention comprises:
a mark writing section writing a mark onto an information storage medium which has a recording area divided into a plurality of regions, on which information is recorded by writing a mark in a region, and from which information is reproduced by reading the recorded mark;
a judging section making judgment upon whether a region having a mark written therein by the mark writing section is a normal region or a defective region; and
a recording state changing section changing a recording state of a mark in a region determined as a defective region by the judging section so that cross talk caused due to that region can be reduced.
The term “region” used herein may be a generally called sector, a block consisting of a plurality of sectors, or multiple divided sectors.
In addition, the recording state changing section may change the recording state by using the mark writing section or may change the recording state by using means independent from the mark writing section.
Moreover, the defective region processing apparatus according to the present invention may be incorporated in an information storage device for recording information on an information storage medium or may be incorporated in a formatting device for formatting an information storage medium.
According to the defective region processing apparatus of the present invention, since the recording state of a defective region is changed so that cross talk due to that region can be reduced, a mark in a region adjacent to the defective region can
Karakawa Yuji
Yanagi Shigenori
Greer Burns & Crain Ltd.
Huber Paul W.
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