Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1998-09-29
2001-01-09
Edun, Muhammad (Department: 2753)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S047360, C369S044130
Reexamination Certificate
active
06172956
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical recording medium having a track in which one of the sidewalls of a groove wobbles according to, for example, either rotation synchronization information or address information or both, and further relates to an optical recording/reproducing device for recording information into the optical recording medium, and further relates to a manufacturing method for manufacturing such an optical recording medium.
BACKGROUND OF THE INVENTION
Conventional technology has been developed for recording information both in the land and in the groove to improve the track density of an optical disk as a recording medium. For example, Japanese Laid-Open Patent Application No. 5-314538/1993 (Tokukaihei 5-314538) discloses a method of forming a track for storing information both in the land and in the groove thereof.
Referring to
FIG. 27
, a magnified view of an optical disk, the following is an explanation about the method of forming a track disclosed in the above laid-open patent application. An optical disk
101
has a groove
102
,
104
,
106
, etc. and a land
103
,
105
, etc. provided alternately to form respective information recording tracks. For example, a sidewall
108
, one of the sidewalls of the groove
104
, wobbles according to, for example, rotation synchronization information and address information. In other words, the sidewall
108
stores therein a wobble signal that is FM-modulated from the rotation synchronization information and/or address information.
The optical disk
101
is configured so that the distance between the adjacent wobbling sidewalls (e.g., the distance between the sidewall
108
and an adjacent wobbling sidewall
107
of the groove
102
, or the distance between the sidewall
108
and another adjacent wobbling sidewall
109
of the groove
106
) is longer than the diameter of a light beam
110
. Therefore, the light beam
110
is prevented from reading out the wobble signal stored in the sidewall
107
and
109
.
With the optical disk
101
configured as above, as the optical beam
110
tracks, for example, the groove
104
, a wobble signal is reproduced from the sidewall
108
of the groove
104
. Rotation synchronization information and address information are read out of the wobble signal to control rotation of the optical disk and reproduce address information. In this case, the distance between the wobbling sidewall
108
of the groove
104
and the wobbling sidewall
109
of the adjacent groove
106
is set to be longer than the diameter of the optical beam
110
. Therefore, the periphery of the light beam
110
is configured not to reach the sidewall
109
when the groove
104
is tracked. Therefore, the wobble signal of the sidewall
108
of the groove
104
is not interfered by the wobble signal of the sidewall
109
.
When the land
103
is tracked, a wobble signal is reproduced out of the sidewall
108
in the same manner as above. In this case, since only the sidewall
107
of the adjacent groove
102
wobbles and is located opposite from the land
103
, the periphery of the light beam
110
does not reach the sidewall
107
when the land
103
is tracked. Therefore, the wobble signal of the sidewall
108
of the land
103
is not interfered by the wobble signal of the sidewall
107
.
Consequently, if the optical disk
101
configured in the above manner is used, the cross-talk of the wobble signal is reduced, the rotation of the optical disk
101
is surely controlled, and the address information is precisely read out. Hereinafter, the track in which a wobble signal is stored only in one of the sidewalls of the land and of the groove will be referred to as a one-side wobbling track. Therefore, the groove
104
and the land
103
oppositely sandwiching the wobbling sidewall
108
have the same rotation synchronization information and address information.
A well-known method of improving the recording density of an optical disk is a constant liner velocity (CLV) method. Referring to
FIG. 28
, the following is an explanation about information recording/reproducing device that carries out the CLV recording with respect to an optical disk of a one-side wobbling track.
First, to record information with the CLV method, a wobble signal including rotation synchronization information is stored with the CLV method into one of the sides of the track of the optical disk
101
in advance. An optical pickup
111
radiates a light beam to the optical disk
101
provided with a wobbling track, and extracts a wobble signal aa out of a track error signal or a total signal that are reproduced from the reflected light. The wobble signal aa is inputted to an address information reproducing section
112
and to a CLV rotation control section
113
. Then a clock cc of a constant frequency is inputted from a crystal oscillator
114
to the address information reproducing section
112
and to the CLV rotation control section
113
.
Next, in the address information reproducing section
112
, address information is FM-modulated from the wobble signal aa according to the clock cc. The CLV control section
113
compares the phase of the rotation synchronization signal included in the wobble signal aa and the phase of the clock cc, and outputs a drive signal bb to a spindle motor
115
so that the phases synchronize. The rotation of the optical disk
101
is controlled in this manner. Since the wobble signal aa is stored with the CLV method, the rotation of the optical disk
101
can be controlled with the CLV method.
Incidentally, in order to access recording information at high speeds, the position where the recording of the information starts needs to synchronize with the rotation of the disk and thus always the same. In this manner, the address in search can be found by predicting the rotation of the disk during the search for information, thereby enabling high speed search. Japanese Laid-Open Patent Application No. 4-184718/1992 (Tokukaihei 4-184718), “OPTICAL DISK AND OPTICAL DISK DEVICE”, discloses a method of storing a reference position in the optical disk in advance in the above manner, and determining the position where the recording of the information starts according to that reference position. Referring to
FIGS. 29 and 30
, the following explains the above method.
In the optical disk
120
, the groove
121
sandwiched between the land
123
and
124
functions as a track for recording/reproducing the information. The track
121
has an index mark
122
, a wobbling once for every round, that is stored when the track
121
is formed in the optical disk
120
.
A comparator in a device (not shown) for reproducing the optical disk
120
compares a track error signal dd read out of the index mark
122
and a slice level ee to obtain an index mark detection signal ff (reference signal). The index mark detection signal ff functions as a reference for the absolute position once for a round of the optical disk
120
. The index mark detection signal ff can format the address information in synchronization with the rotation of the optical disk
120
.
The length of the index mark
122
is set to be approximately equal to an information recording bit, and has a position detection precision of less than the length of the information bit (not more than 1 micron). In other words, the position where the recording of the information starts is lined up once for every round highly precisely by storing the index mark
122
in advance.
However, even if the position where the recording of the information starts is determined, the positions of the recording bits thereafter vary depending on a variation of the rotation of the optical disk. When the recording is completed, the variation have been accumulated and greatly changes the position where the recording ends. Therefore, the position where the recording ends and a position where the next recording starts may overlap.
Therefore, a conventionally typical method of avoiding the overlapping with the position where the next recording starts is to shift forward in advan
Conlin David G.
Dike, Bronstein, Roberts and Cushman
Edun Muhammad
Neuner George W.
Sharp Kabushiki Kaisha
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