U.S. patent number RE38,503 [Application Number 09/945,635] was granted by the patent office on 2004-04-20 for information recording disk.
This patent grant is currently assigned to Hitachi, Ltd., Hitachi Maxell, Ltd.. Invention is credited to Shinichi Arai, Tamotsu Iida, Takeshi Maeda.
United States Patent |
RE38,503 |
Iida , et al. |
April 20, 2004 |
Information recording disk
Abstract
An information recording disk having a structure that a
ring-shaped recording region is divided into a plurality of
concentric, annular blocks, each of the blocks is divided in a
circumferential direction into a plurality of equal sectors, and a
recording track and a pit train for generating a header signal are
previously formed in the recording region so that the recording
density of a block increases as the block is nearer to the outer
circumference of the recording region, .Iadd.in comparison with
constant angular velocity type, .Iaddend.is disclosed in which disk
the recording region has a portion where blocks are pre-formatted
so that the pit pitch of the header-signal generating pit train
formed on the innermost recording track of the outer one of two
adjacent blocks is greater than the pit pitch of the header-signal
generating pit train formed on the innermost recording track of the
inner block.
Inventors: |
Iida; Tamotsu (Tsuchiura,
JP), Arai; Shinichi (Odawara, JP), Maeda;
Takeshi (Kokubunji, JP) |
Assignee: |
Hitachi Maxell, Ltd. (Ibaraki,
JP)
Hitachi, Ltd. (Tokyo, JP)
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Family
ID: |
32073989 |
Appl.
No.: |
09/945,635 |
Filed: |
September 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
541742 |
Jun 21, 1990 |
05255261 |
Oct 19, 1993 |
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Foreign Application Priority Data
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Jun 27, 1989 [JP] |
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1-162671 |
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Current U.S.
Class: |
369/275.3;
369/44.26 |
Current CPC
Class: |
G11B
20/1258 (20130101); G11B 7/00745 (20130101); G11B
7/24085 (20130101); G11B 2020/1274 (20130101); G11B
2220/2537 (20130101) |
Current International
Class: |
G11B
20/12 (20060101); G11B 007/24 () |
Field of
Search: |
;369/275.3,275.2,275.4,44.26,44.34,53.2,53.41 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3604916 |
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Aug 1986 |
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DE |
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2578346 |
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Sep 1986 |
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FR |
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62-80865 |
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Apr 1987 |
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JP |
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Primary Examiner: Dinh; Tan
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
We claim:
1. An information recording disk comprising an annular structure,
having an inner circumferential periphery and an outer
circumferential periphery, and a concentric ring-shaped recording
region provided thereon between the inner circumferential periphery
and the outer circumferential periphery and the recording region
including a plurality of concentric, annular blocks extending from
an innermost annular block adjacent to the inner circumferential
periphery to an outermost annular block adjacent to the outer
circumferential periphery, each of the plurality of annular blocks
being divided in a circumferential direction into a plurality of
sectors, each of the plurality of sectors in any one of the
plurality of annular blocks being of equal sector length, the
number of sectors in an outer one of two adjacent annual blocks
being larger than the number of sectors in an inner one of two
adjacent annular blocks, and having a plurality of recording tracks
and a plurality of pit trains for generating a header signal
preformed in each of said annular blocks, at least one of said
plurality of pit trains being associated with each of said
plurality of sectors such that the recording density of an annular
block increases from said innermost annular block to said outermost
block, .Iadd.in comparison with constant angular velocity type,
.Iaddend.the sector length of each of the sectors in the outer one
of two adjacent annular blocks is greater than the sector length of
each of the sectors in the inner annular block, and the
header-signal generating pit train is preformed therein in each of
the plurality of sectors so that all the sectors in adjacent
annular blocks have the same recording capacity, wherein the
recording region has a recording portion in which at least two of
the plurality of annular blocks are pre-formatted so that a pit
pitch of the header-signal generating pit train formed on an
innermost recording track of the outer one of two adjacent annular
blocks is larger than the pit pitch of the header-signal generating
pit train formed on the innermost recording track of the inner
annular block and sector length is defined as the length of the
innermost recording track in any one of the plurality of annular
blocks divided by the number of sectors in such annular block.
2. The information recording disk according to claim 1 wherein each
of the plurality of annular blocks has the same number of recording
tracks.
3. An information recording disk comprising an annular structure,
having an inner circumferential periphery and an outer
circumferential periphery, and a concentric ring-shaped recording
region provided thereon between the inner circumferential periphery
and the outer circumferential periphery, and the recording region
including a plurality of concentric, annular blocks extending from
an innermost annular block adjacent to the inner circumferential
periphery to an outermost annular block adjacent to the outer
circumferential periphery, each of the plurality of annular blocks
being divided in a circumferential direction into a plurality of
sectors, each of the plurality of sectors in any one of the
plurality of annular blocks being of equal sector length, sector
length being defined as the length of the innermost recording track
in any one of the plurality of annular blocks divided by the number
of sectors in such annular block, the number of the sectors in an
outer one of two adjacent annular blocks being larger than the
number of sectors in an inner one of two adjacent annular blocks,
and having a plurality of recording tracks and a plurality of pit
trains for generating a header-signal preformed therein, and
further having the plurality of add-on pit trains, an add-on pit
train being defined as a pit train recorded by a user, one of said
plurality of header-signal generating pit trains and one of said
plurality of add-on pit trains being associated with each of said
plurality of sectors, wherein the header-signal generating pit
train and the add-on pit train formed from an innermost recording
tract radially outwardly to an outermost recording tract of the
outer one of said two adjacent annular blocks increase in pit pitch
greater than the header-signal generating pit train and the add-on
pit train formed from an innermost recording track of the inner one
of said two adjacent annular blocks, to obtain a larger jitter
margin in the header signal generating pit train and the add-on pit
train of the outer one of said two adjacent annular blocks than in
the header-signal generating pit train and the add-on pit train of
said the inner one of said two adjacent annular blocks.
4. An information recording disk comprising an annular structure,
having an inner circumferential periphery and an outer
circumferential periphery, and a concentric ring-shaped recording
region provided thereon between the inner circumferential periphery
and the outer circumferential periphery, and the recording region
including a plurality of concentric, annular blocks extending from
an innermost annular block adjacent to the inner circumferential
periphery to an outer most annular block adjacent to the outer
circumferential periphery, each of the plurality of annular blocks
being divided in a circumferential direction into a plurality of
sectors, each of the plurality of sectors in any one of the
plurality of annular blocks being of equal sector length, sector
length being defined as the length of the innermost recording track
in any one of the plurality of annular blocks divided by the number
of sectors in such annular block, the number of sectors in an outer
one of two adjacent annular blocks being larger than the number of
sectors in an inner one of two adjacent annular blocks, and having
a plurality of recording tracks and a plurality of trains for
generating a header-signal preformed therein, and further having a
plurality of add-on pit trains, an add-on pit train being defined
as a pit train recorded by a user, one of said plurality of
header-signal generating pit trains, and one of said plurality of
add-on pit trains being associated with each of said plurality of
sectors, wherein: said header-signal generating pit train and said
add-on pit trains are formed on or alongside said tracks disposed
in the direction from an innermost track to an outermost track of
each of said annular blocks and extending circumferentially having
pit pitch gradually increased from said innermost track to said
outermost track in each of said annular blocks, and each of said
pit pitch of said header-signal generating pit trains and add-on
pit trains of each of the tracks disposed in an outer one of two
adjacent annular blocks is wider than the corresponding pit pitch
of the header-signal generating pit trains and add-on pit trains
formed on or alongside the tracks disposed in the direction from an
innermost track to an outermost track and extending
circumferentially formed in an inner annular block than that in
said outer annular block, in a degree to increase jitter margin in
the header-signal generating pit trains and add-on pit trains in
outer annular blocks compared to the header-signal generating pit
trains and add-on pit trains in inner annular blocks.
Description
BACKGROUND OF THE INVENTION
The present invention relates to information recording disks such
as an optical disk, and more particularly to an optical disk
according to a novel method of dividing a recording region into
parts and of forming a header-signal generating pre-pit train.
An optical disk of the modified constant angular velocity (MCAV)
type has been proposed which is higher in recording density than an
optical disk of the constant angular velocity (CAV) type.
In the optical disk of the MCAV type, a ring-shaped recording
region is divided in radial directions into a plurality of
concentric, annular blocks, each of the blocks being divided in a
circumferential direction into a plurality of equal sectors so that
the number of sectors included in the outermost block is about
twice as large as the number of sectors included in the innermost
block and sectors included in all the blocks have substantially the
same length, and a pit train for generating a header signal is
previously formed in each sector at a fixed pit pitch.
When this optical disk is rotated at a constant angular velocity,
and an appropriate clock frequency is used for each block, a linear
recording density can be made constant in the whole of the
recording region extending from the inner circumference thereof to
the outer circumference (refer to Japanese Patent Application
JP-A-62-80,865).
SUMMARY OF THE INVENTION
A reproduced signal read out from an optical disk is separated into
a data pulse and a clock pulse by a window-signal which is produced
by a data separator, and then data is reconstructed.
The reproduced signal obtained from the optical disk includes
jitter due to variations in rotational speed of a disk driving
motor, variations in laser output power, variations in output of a
variable frequency generator, variations in recording sensitivity
on the optical disk, the deformation of the disk in a rotating
state, and other reasons. In other words, a peak position in the
reproduced signal is shifted before and behind a reference position
in a writing operation. Accordingly, when the window width is not
made large, the time margin of the peak shift for the window width,
that is, a jitter margin is reduced, and thus a reproducing error
is readily generated.
When the optical disk is rotated at a constant angular velocity,
the jitter due to the above-mentioned factors is kept substantially
constant at the inner and outer parts of the optical disk. In an
optical disk of the MCAV type, however, a pit train for generating
a header signal is previously formed at a constant pit pitch at the
inner and outer parts of the disk, and thus the width of the window
signal produced by the data separator is small at an outer block
having a large linear velocity for the light spot. Hence, as the
light spot is nearer to the outermost block, the jitter margin is
reduced, and the reproducing error is easy to generate.
It is an object of the present invention to provide an information
recording disk which can solve the above-mentioned problem of the
prior, and is high in recording density and low in error rate.
In order to attain the above object, according to the present
invention, there is provided an information recording disk having a
structure that a ring-shaped recording region is divided into a
plurality of concentric, annular blocks, each of the blocks is
divided .[.is.]. .Iadd.in .Iaddend.a circumferential
.[.directions.]. .Iadd.direction .Iaddend.into a plurality of equal
sectors, and a recording track and pit train for generating a
header signal are previously formed in the recording region so that
the recording density of a block increases as the block is nearer
to the outer circumference of the recording region, .Iadd.in
comparison with constant angular velocity type, .Iaddend.in which
disk the recording region has a portion where blocks are
pre-formatted so that the pit pitch of the header-signal generating
pit train formed on the innermost recording track of the outer one
of two adjacent blocks is larger than the pit pitch of the
header-signal generating pit train formed on the innermost
recording track of the inner block.
In a case where the characteristics of the variable frequency
generator included in the data separator are kept constant, the
width of the window signal produced by the data separator is
increased as the pit pitch of the header-signal generating pit
train is larger, and the time duration of the window signal is
decreased as the linear velocity of recording track is larger.
According, when the pit pitch of the header-signal generating pit
train is made large at outer blocks where a recording track has a
large linear velocity, reduction in window width due to the large
linear velocity of recording track is substantially cancelled by an
increase in pit pitch of the header-signal generating pit
train.
Although the window width is decreased by employing the large
linear velocity, the decrease is minimized by intentionally
increasing the pit pitch.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view showing an embodiment of an information
recording disk according to the present invention.
FIG. 2 is a schematic diagram for explaining the structure of each
of blocks included in the embodiment of FIG. 1.
FIG. 3 is a schematic diagram for explaining the sector
configuration in the embodiment of FIG. 1.
FIG. 4 is a table showing an example of the format of a 12-in.
optical disk.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of an optical disk according to the present invention
will be explained below, by way of example.
FIG. 1 is a plan view showing the embodiment of the invention.
Referring to FIG. 1, a center hole 1 is provided in a substrate 2,
and a ring-shaped recording region 3 is formed on a central portion
sandwiched between the innermost and outermost portions of the
substrate so that the recording region 3 is concentric with the
center hole 1.
The recording region 3 is divided in radial directions into a
plurality of concentric, annular blocks 4a, 4b, 4c, . . . and 4x,
and each of the blocks 4a to 4x is divided in a circumferential
direction into a plurality of sectors 5a, 5b, 5c and so on.
Further, as shown in FIG. 2, recording tracks 6 for guiding a light
spot are concentrically or spirally formed at a constant track
pitch in the whole of the recording region 3 extending from the
innermost portion thereof to the outermost portion.
The track pitch is usually as small as about 1.6 .mu.m. It is to be
noted that the format shown in FIG. 1 can include the desired
recording tracks (that is, spiral tracks or concentric tracks).
Further, the recording region 3 is divided into the blocks 4a to 4x
so that each block includes the same number of recording
tracks.
As shown in FIG. 3, each of the blocks 4a to 4x is divided into a
plurality of equal sectors 5a, 5b, 5c, and so on so that the number
of sectors included in the outer one of adjacent blocks is one or
two greater than the number of sectors included in the inner block,
and the sector length in the outer block is greater than the sector
length in the inner block. Now, let us consider an inventive
optical disk shown in FIG. 4. For example, the sector length in a
block which is indicated by a block number of 25 and has a radius
of 212.4 mm, is 8.78 mm, and the sector length in a block which is
indicated by a block number of 26 and has a radius of 215.5 mm, is
8.792 mm. In other adjacent blocks, also, the sector length in the
outer block is greater than the sector length in the inner block.
It is to be noted that the sector length indicates the length of
the innermost one of recording tracks included in a fan-shaped
sector.
Further, as shown in FIG. 2, in a head portion of that part of a
recording track 6 which is induced in one of the sectors 5a, 5b,
5c, and so on, there is formed a pre-pit train 7 for indicating the
address of the sector and others and for generating, for example, a
header signal. When the present embodiment is viewed in a direction
parallel to the main surface thereof, the pre-pit train 7 is
observed, as shown in FIG. 1, in the form of a straight line
produced along the boundary between adjacent ones of the sectors
5a, 5b, 5c, . . . and
The pit pitch p of the pre-pit train 7, as shown in FIG. 2, is made
proportional to the sector length. Accordingly, in the whole
recording region of the present embodiment extending from the
innermost block 4a to the outermost block 4x, the pit pitch of the
prepit train 7 formed in the outer one of adjacent blocks is larger
than the pit pitch of the pre-pit train 7 formed in the inner
block.
As mentioned above, in the present embodiment, the pit pitch p used
in a block increases, as the block is nearer to the outer
circumference of the recording region. Accordingly, a reduction in
window width due to the large linear velocity of a recording track
can be substantially cancelled by an increase in pit pitch of the
pre-pit train. Thus, a sufficiently large jitter margin can be
obtained all over the recording region extending from the inner
circumference thereof to the outer circumference, and an error rate
can be reduced.
Further, in the present embodiment, the number of sectors included
in a block increases, as the block is nearer to the outer
circumference of the recording region. Accordingly, the recording
density of outer blocks is high .Iadd.in comparison with constant
angular velocity type.Iaddend.. Thus, a high-density optical disk
can be obtained which is equal in recording capacity to a
conventional optical disk of the MCAV type.
FIG. 4 shows an example of the format of an optical disk according
to the present invention. This optical disk has a diameter of 12
inches, and the recording region of the optical disk is divided
into 47 blocks which have the same width in radial directions and
are indicated by block numbers of 0 to 46. Recording tracks are
formed at a track pitch of 1.5 .mu.m in the whole of the recording
region extending from the inner circumference thereof to the outer
circumference. Thus, 1024 recording tracks are arranged in each
block.
The innermost block having a block number of 0 is divided into 51
equal sectors, and the number of sectors included in a block is
incremented by one each time a block number is increased by one.
Thus, as shown in FIG. 4, the sector length in the outer one of
two-adjacent blocks selected from 47 blocks is always greater than
the sector length in the inner block. Incidentally, the term
"diameter" in FIG. 4 indicates the diameter of the innermost
recording track of each block, and the term "sector length" in FIG.
4 indicates a value which is obtained by dividing the length of the
innermost recording track of each block by the number of sectors
included in the block.
A pre-pit train for generating a header signal is formed in a head
portion of each sector, and the pit pitch of the pre-pit train is
set so that each of sectors included in the recording region has a
recording capacity of 1.146 bytes. Accordingly, the pit pitch is
proportional to the sector length, and is increased from a minimum
value in the innermost block to a maximum value in the outermost
block. In more detail, the pit pitch in the innermost block is
1.366 .mu.m, and the pit pitch in the outermost block is 1.466
.mu.m. It is known from a ratio of the pit pitch in the outermost
block to the pit pitch in the innermost block that the window width
in the outermost block becomes greater than the window width in the
innermost block by a factor of about 1.073.
The gist of the present invention resides in that the recording
region of an information recording disk includes a portion where
each block is divided into sectors and a header-signal generating
pit train is formed in each sector so that the pit pitch of the pit
train formed in the outer one of adjacent blocks is larger than the
pit pitch of the pit train formed in the inner block. Accordingly,
the recording region of an information recording disk according to
the present invention may be divided into sectors in a manner
different from the above embodiment, or may have a format different
from the above-mentioned.
In the above embodiment, a pre-pit train is formed in all the
blocks existing between the inner circumference and outer
circumference of the recording region so that the pit pitch of the
pre-pit train formed in the outer one of adjacent blocks is larger
than the pit pitch of the pre-pit train formed in the inner block.
Alternatively, the above format may be applied only to blocks which
exist on the outside of a central portion of the recording region
in radial directions and readily generate a reproducing error.
Generally speaking, in a case where a reproducing operation is
performed for an optical disk of the MCAV type, it is necessary to
use different data clocks for individual blocks. In a case where
blocks included in that special portion of the recording region
where the reproducing error is easy to generate, are made different
in the number of sectors included in one block from each other in
accordance with the present invention, it is necessary to change
the data clock in the special portion of the recording region, as
in a case where a reproducing operation is performed for a
conventional optical disk of the MCAV type. Through the data clock
is needed to be differentiated, it is substantially as same as in
MCAV since employing of different data clocks is utilized in
MCAV.
In the above embodiment, the recording region is divided into
sectors so that the number of sectors included in the outer one of
adjacent blocks is greater than the number of sectors included in
the inner block by one. Alternatively, the recording region may be
divided into sectors so that the number of sectors included in the
outer one of adjacent blocks is greater than the number of sectors
included in the inner block by two or more.
Further, in the above embodiment, each block is divided into
sectors and a pre-pit for generating a header signal is formed in
each sector so that all the sectors included in the recording
region have the same recording capacity. In this case, the number
of sectors included in an outer block is greater than the number of
sectors included in an inner block, and thus the recording capacity
of the outer block is greater than that of the inner block. In a
case where the optical disk is formatted so that all the blocks
included in the recording region have the same recording capacity,
the number of recording tracks included in an outer block is made
smaller than the number or recording tracks included in an inner
block.
In the above embodiment, the recording region is divided into
blocks so that all the blocks include the same number of recording
tracks. Alternatively, the number of recording tracks included in a
block may be different from the number of recording tracks included
in another block.
Although the format of a 12-in. optical disk has been explained, by
way of example, the present invention is applicable to an optical
disk having a desired diameter.
Although an inventive optical disk having a pre-pit train has been
explained in the foregoing, the present invention is also
applicable to an optical disk having an add-on pit train.
As has been explained in the foregoing, according to the present
invention, a reduction in window width due to a large linear
velocity of recording track is substantially cancelled by an
increase in pit pitch of a pit train for generating a header
signal, and thus a sufficiently larger jitter margin is obtained
all over the recording region extending from the inner
circumference thereof to the outer circumference.
Further, according to the present invention, the recording density
of a block increases as the block is nearer to the outer
circumference of the recording region, .Iadd.in comparison with
constant angular velocity type, .Iaddend.and hence a high-density
optical disk can be obtained which is substantially equal in
recording capacity to a conventional optical disk of the MCAV
type.
Thus, according to the present invention, there is provided an
information recording disk which is low in error rate and large in
recording capacity.
The invention being thus described, it will be obvious that the
same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of invention, and
all such modifications as would be obvious to one skilled in the
art are intended to be included within the scope of the following
claims.
* * * * *