U.S. patent application number 14/602976 was filed with the patent office on 2015-07-30 for disk-shaped information recording medium, disk cartridge and information recording and reproducing apparatus.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to Kazuya HISADA, Hidemi ISOMURA, Yoshihiro KAWASAKI, Mamoru SHOJI, Shuji TABUCHI.
Application Number | 20150213829 14/602976 |
Document ID | / |
Family ID | 53679603 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150213829 |
Kind Code |
A1 |
SHOJI; Mamoru ; et
al. |
July 30, 2015 |
DISK-SHAPED INFORMATION RECORDING MEDIUM, DISK CARTRIDGE AND
INFORMATION RECORDING AND REPRODUCING APPARATUS
Abstract
An information recording medium of the present exemplified
embodiment is configured by laminating a substrate having a
predetermined thickness and a substrate having a predetermined
thickness to each other. A film forming region including a
recording region, a clamp region and a rib are formed on one
surface of the information recording medium. A film forming region
including a recording region, a clamp region and a rib are formed
on the other surface of the information recording medium. On both
surfaces, the components are formed in the order of the rib, the
clamp region and the film forming region toward an outer peripheral
side from an inner peripheral side.
Inventors: |
SHOJI; Mamoru; (Osaka,
JP) ; KAWASAKI; Yoshihiro; (Okayama, JP) ;
TABUCHI; Shuji; (Okayama, JP) ; ISOMURA; Hidemi;
(Okayama, JP) ; HISADA; Kazuya; (Okayama,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
53679603 |
Appl. No.: |
14/602976 |
Filed: |
January 22, 2015 |
Current U.S.
Class: |
720/725 ;
369/280 |
Current CPC
Class: |
G11B 23/0021 20130101;
G11B 7/24 20130101; G11B 7/24047 20130101; G11B 7/24044 20130101;
G11B 33/0438 20130101; G11B 7/26 20130101; G11B 7/24097 20130101;
G11B 2007/240012 20130101; G11B 23/0035 20130101 |
International
Class: |
G11B 7/24097 20060101
G11B007/24097; G11B 7/24094 20060101 G11B007/24094 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2014 |
JP |
2014-010895 |
Oct 30, 2014 |
JP |
2014-221882 |
Claims
1. A information recording medium having a disk shape comprising: a
substrate having a predetermined thickness; a first surface forming
one surface of the substrate; a second surface forming the other
surface of the substrate; a cylindrical portion in which a through
hole penetrating a center of the substrate is formed; a first
recording region formed on a first surface side; a second recording
region formed on a second surface side; a first clamp region with
which a clamper is brought into contact when the first recording
region is reproduced, the first clamp region being formed on the
first surface side; a second clamp region with which a clamper is
brought into contact when the second recording region is
reproduced, the second clamp region being formed on the second
surface side; a first rib formed in a circular annular shape on the
first surface side and on an inner peripheral side of the first
clamp region; a second rib formed in a circular annular shape on a
second surface side and on an inner peripheral side of the second
clamp region; and a first printing region formed between the first
rib and the first recording region.
2. The information recording medium according to claim 1, further
comprising a thin wall portion configured to surround an outer
diameter of the cylindrical portion, the thin wall portion having a
thickness smaller than the predetermined thickness, wherein the
thin wall portion includes: a non-inclined surface formed on the
thin wall portion; and an inclined surface formed on an outer
diameter side of the non-inclined surface at the thin wall portion
and inclined at a predetermined angle with respect to the
non-inclined surface.
3. The information recording medium according to claim 1, wherein
the first printing region is formed on the first surface.
4. The information recording medium according to claim 1, wherein
the first printing region is formed between the first surface and
the second surface.
5. The information recording medium according to claim 1, wherein a
second printing region is formed between the second rib and the
second recording region.
6. The information recording medium according to claim 5, wherein
the second printing region is formed on the second surface.
7. The information recording medium according to claim 5, wherein
the second printing region is formed between the first surface and
the second surface.
8. The information recording medium according to claim 1, further
comprising a thin wall portion configured to surround an outer
diameter of the cylindrical portion, the thin wall portion having a
thickness smaller than the predetermined thickness, wherein the
first surface side and the second surface side of the substrate are
symmetrical to each other.
9. A disk cartridge comprising a case in which the information
recording medium described in claim 1 is stored in an overlapping
manner.
10. An information recording and reproducing apparatus comprising:
the disk cartridge described in claim 9; a mechanism for taking out
the information recording medium from the disk cartridge; a
mechanism for recording information in the information recording
medium taken out from the disk cartridge or for reproducing
information from the information recording medium taken out from
the disk cartridge; and an electric circuit for controlling
recording of information in the information recording medium or
reproduction of information from the information recording medium
from the disk cartridge
Description
BACKGROUND
[0001] 1. Field
[0002] This disclosure relates to a recording medium in which
information is recorded, and more particularly to a disk-shaped
recording medium, and a disk cartridge which stores a plurality of
disk-shaped recording media in a stacked manner.
[0003] 2. Description of the Related Art
[0004] An optical disk includes a substrate and a cylindrical
portion mounted on a center portion of the substrate and having a
through hole. As one example of the optical disk, for example,
there has been disclosed an optical disk where a notched portion is
formed on an outer diameter side of a cylindrical portion (refer to
Unexamined Japanese Utility Model Publication No. 1-103022, for
example). As another example of the optical disk, there has been
disclosed an optical disk where a label printing region is formed
on one surface of the optical disk (refer to Unexamined Japanese
Patent Publication 5-198015).
SUMMARY
[0005] An information recording medium according to an exemplary
embodiment of the present disclosure is a disk-shaped information
recording medium, and includes: a substrate; a first surface; a
second surface; a cylindrical portion; a first recording region; a
second recording region; a first clamp region; a second clamp
region; a first rib; a second rib; and a first printing region. The
substrate has a predetermined thickness. The first surface is one
surface of the substrate. The second surface is the other surface
of the substrate. A through hole which penetrates the center of the
substrate is formed in the cylindrical portion. The first recording
region is formed on a first surface side. The second recording
region is formed on a second surface side. The first clamp region
is formed on a first surface side, and a clamper is brought into
contact with the first clamp region when the first recording region
is reproduced. The second clamp region is formed on a second
surface side, and a clamper is brought into contact with the second
clamp region when the second recording region is reproduced. The
first rib is formed in a circular annular shape on the first
surface side and on an inner peripheral side of the first clamp
region. The second rib is formed in a circular annular shape on a
second surface side and on an inner peripheral side of the second
clamp region. The first printing region is formed between the first
rib and the first recording region.
BRIEF DESCRIPTION OF DRAWINGS
[0006] FIG. 1A is a perspective view of an optical disk according
to a first exemplary embodiment as viewed from a front surface of
the optical disk;
[0007] FIG. 1B is a perspective view of the optical disk according
to the first exemplary embodiment as viewed from a back surface of
the optical disk;
[0008] FIG. 2 is a cross-sectional view showing the structure of a
center portion of the optical disk according to the first exemplary
embodiment;
[0009] FIG. 3 is a perspective view of the optical disks according
to the first exemplary embodiment in a state where the optical
disks are stored in a disk cartridge in a stacked manner;
[0010] FIG. 4 is a cross-sectional view showing a state where the
optical disks according to the first exemplary embodiment overlap
with each other;
[0011] FIG. 5 is a schematic view of an information recording and
reproducing apparatus for the optical disk;
[0012] FIG. 6A is a side view showing a state where a separation
arm is inserted into through holes formed at the center of the
stacked optical disks according to the first exemplified
embodiment;
[0013] FIG. 6B is a plan view of the separation arm according to
the first exemplary embodiment in a state shown in FIG. 6A as
viewed from above;
[0014] FIG. 6C is a side view showing a state immediately before
the stacked optical disks according to the first exemplary
embodiment are separated from each other;
[0015] FIG. 6D is a plan view of the separation arm in the state
shown in FIG. 6C as viewed from above;
[0016] FIG. 6E is a side view showing a state immediately after the
stacked optical disks according to the first exemplary embodiment
are separated from each other;
[0017] FIG. 6F is a plan view of the separation arm in a state show
in FIG. 6E as viewed from above;
[0018] FIG. 7 is an explanatory view showing a state where a
foreign substance is mixed into a thin wall portion of a center
cylindrical portion according to the first exemplary
embodiment;
[0019] FIG. 8 is an explanatory view for explaining a case where
non-symmetrical disks according to the first exemplary embodiment
are stacked;
[0020] FIG. 9 is a cross-sectional view showing the structure of a
center portion of an optical disk according to a second exemplary
embodiment;
[0021] FIG. 10 is a cross-sectional view showing the structure of a
center portion of an optical disk according to a third exemplary
embodiment;
[0022] FIG. 11A is a plan view of a clamper in an information
recording and reproducing apparatus for an optical disk;
[0023] FIG. 11B is a cross-sectional view of the damper in the
information recording and reproducing apparatus for the optical
disk;
[0024] FIG. 12A is a perspective view of a turntable in the
information recording and reproducing apparatus for an optical
disk;
[0025] FIG. 12B is a cross-sectional view of the turntable in the
information recording and reproducing apparatus for the optical
disk;
[0026] FIG. 13A is a plan view of an optical disk formed such that
a clamp region and film forming region do not overlap with each
other;
[0027] FIG. 13B is a cross-sectional view of the optical disk
according to a third exemplary embodiment in a state where the
optical disk is set on the information recording and reproducing
apparatus;
[0028] FIG. 14 is a cross-sectional view showing the structure of a
center portion of an optical disk according to a modification of
the third exemplary embodiment;
[0029] FIG. 15A is a cross-sectional view of an optical disk
according to a modification of the third exemplary embodiment where
a printing region is formed on an inner side of a substrate;
[0030] FIG. 15B is a cross-sectional view of an optical disk where
a printing region is formed on a side where a substrate is
laminated and a radial position of the printing region overlaps
with a clamp region;
[0031] FIG. 16 is a cross-sectional view showing the structure of a
center portion of an optical disk according to another exemplary
embodiment;
[0032] FIG. 17A is a perspective view of the optical disk according
to another exemplary embodiment as viewed from a front surface of
the optical disk; and
[0033] FIG. 17B is a perspective view of the optical disk according
to another exemplary embodiment as viewed from a back surface of
the optical disk.
DETAILED DESCRIPTION
[0034] Hereinafter, exemplary embodiments are described in detail
by reference to drawings when appropriate. However, there may be
cases where detailed descriptions more than necessary are omitted.
For example, there may be cases where the detailed description of
matters which are already well-known and the repeated description
of the substantially same configuration are omitted. This enables
the description made hereinafter from being unnecessarily redundant
thus facilitating the understanding of the present disclosure by
those who are skilled in the art.
[0035] The inventors of the present disclosure give the
accompanying drawings and the following descriptions to allow those
who are skilled in the art to sufficiently understand the present
disclosure, and the subject defined in the claims is not intended
to be restricted thereby.
First Exemplary Embodiment
[0036] First exemplary embodiment is described hereinafter with
reference to FIG. 1 to FIG. 7.
[1-1. Constitution]
[1-1-1. Optical Disk]
[0037] FIG. 1A is a perspective view of optical disk 10 (one
example of a disk-shaped information recording medium) of the first
exemplary embodiment as viewed from a front surface side. FIG. 1B
is a perspective view of optical disk 10 (one example of the
disk-shaped information recording medium) of the first exemplary
embodiment as viewed from a back surface side. Here, the optical
disk is, for example, a Blu-ray (registered trademark) Disc (BD), a
DVD, a CVD or the like. Optical disk 10 is formed by laminating
substrate 11 (one example of a substrate) having a predetermined
thickness and substrate 14 (one example of a substrate) having a
predetermined thickness to each other. Optical disk 10 also
includes: center cylindrical portion 13 on a front surface side
where through hole 12 (a portion of the cylindrical portion) is
formed; and center cylindrical portion 15 on a back surface side
where through hole 12 (a portion of the cylindrical portion) is
formed. Substrate 11 (one example of the substrate, one example of
the first surface) and substrate 14 (one example of the substrate,
one example of the second surface) are formed by injection molding
using a transparent resin such as polycarbonate. As shown in FIG.
2, on substrate 11 and substrate 14, a recording film for recording
information, film forming region 107 (one example of first
recording region) which includes a cover layer, and film forming
region 108 (one example of second recording region) which includes
a cover layer are formed respectively. Substrate 11 and substrate
14 are laminated to each other such that a surface of substrate 11
on which film forming region 107 is formed and a surface of film
forming region 108 on which film forming region 108 is formed form
outer sides respectively.
[0038] Optical disk 10 according to the present exemplary
embodiment is formed by laminating substrate 11 and substrate 14 to
each other and hence, warping of optical disk 10 can be reduced.
When it is unnecessary to take into account warping of optical disk
10, optical disk 10 may be formed of a single plate. In forming
optical disk 10 by laminating substrate 11 and substrate 14 to each
other, for decreasing eccentricity, it is necessary to laminate
substrate 11 and substrate 14 to each other with high accuracy such
that the center through hole formed in substrate 11 and the center
through hole formed in substrate 14 agree with each other. On the
other hand, when optical disk 10 is formed of a single plate, the
above-mentioned drawback does not arise and hence, optical disk 10
can be formed easily.
[0039] Through hole 12 is formed in the vicinity of the center of
substrate 11 and the center of substrate 14 for enabling mounting
of optical disk 10 on turntable 56 described later (FIG. 5).
[0040] FIG. 2 is a cross-sectional view of substrate 11 and
substrate 14 of optical disk 10 according to first exemplary
embodiment. Thin wall portion 21 (one example of thin wall portion)
having a smaller thickness than substrate 11 is formed on an
outer-diameter side portion of center cylindrical portion 13 formed
on a recording surface side of substrate 11. In the same manner,
thin wall portion 27 (one example of thin wall portion) having a
smaller thickness than substrate 14 is formed on an outer-diameter
side portion of center cylindrical portion 15 formed on a recording
surface side of substrate 14. Thin wall portion 21 has: a
horizontal surface 23 (one example of non-inclined surface);
inclined surface 22 (one example of inclined surface) formed
continuously with horizontal surface 23; and vertical surface 24
formed continuously on an inner diameter side of horizontal surface
23. In the same manner, thin wall portion 27 has: a horizontal
surface 25 (one example of non-inclined surface); inclined surface
26 (one example of inclined surface) formed continuously with
horizontal surface 25; and vertical surface 28 formed continuously
on an inner diameter side of horizontal surface 25.
[0041] Inclined surface 22 makes inclination angle E with respect
to horizontal surface 23. In the same manner, inclined surface 26
makes inclination angle F with respect to horizontal surface 25. In
the first exemplary embodiment, inclination angle E and inclination
angle F are substantially equal to each other.
[0042] Horizontal surface 23 and horizontal surface 25 are parallel
to each other, and substrate 11 is formed such that an outer
diameter side of center cylindrical portion 13 is notched. In the
same manner, substrate 14 is formed such that an outer diameter
side of center cylindrical portion 15 is notched.
[0043] In the first exemplary embodiment, inclination angle E which
inclined surface 22 makes with respect to horizontal surface 23 and
inclination angle F which inclined surface 26 makes with respect to
horizontal surface 25 may be set to an angle of approximately 30
degrees (25 degrees to 35 degrees), for example.
[0044] An occupying ratio of inclined surface 22 with respect to
horizontal surface 23 in thin wall portion 21 may be small or
large. Further, inclined surface 22 may have the substantially
equal occupying ratio as horizontal surface 23. An occupying ratio
of inclined surface 26 with respect to horizontal surface 23 in
thin wall portion 27 may be small or large. Further, inclined
surface 26 may have the substantially equal occupying ratio as
horizontal surface 23.
[1-1-2. Disk Cartridge]
[0045] FIG. 3 is a view showing a state of disk cartridge 31 (one
example of disk cartridge) where a plurality of optical disks 10
are stored in the inside of case 31a in a stacked state. Disk
cartridge 31 is mounted in information recording and reproducing
apparatus 50 (FIG. 5) described later in a state where the
plurality of optical disks 10 are stacked.
[0046] FIG. 4 shows a state where two optical disks 10 are stacked
to each other. Optical disk 10a on an upper side includes substrate
11a and substrate 14a, and optical disk 10b on a lower side
includes substrate 11b and substrate 14b. By storing a plurality of
optical disks 10 of the first exemplary embodiment in disk
cartridge 31 in a directly overlapping manner, optical disks 10 can
be used as a cartridge-type recording medium of large capacity. In
FIG. 4, for facilitating the description of the exemplary
embodiment, the example where two optical disks 10a, 10b are
stacked is shown. However, the number of optical disks may be three
or more.
[1-1-3. Information Recording and Reproducing Apparatus]
[0047] FIG. 5 schematically shows the configuration of information
recording and reproducing apparatus 50 (one example of information
recording and reproducing apparatus) according to the present
exemplary embodiment. Information recording and reproducing
apparatus 50 performs recording or reproduction of information with
respect to optical disks 10 stored in disk cartridge 31.
Information recording and reproducing apparatus 50 includes:
optical pickup drive device 51; optical pickup 52; motor 54;
turntable 56; and clamper 55. Information recording and reproducing
apparatus 50 also includes electric circuit 53 (one example of
electric circuit) which controls recording or reproduction of
information with respect to optical disk 10. Information recording
and reproducing apparatus 50 further includes: separation arm 58
which takes out optical disk 10 from disk cartridge 31; and arm
drive circuit 59 for driving separation arm 58.
[0048] Optical pickup 52 is driven by optical pickup drive device
51, and transmits a focus signal, a tracking signal, a gap signal
and an RF signal to electric circuit 53 in accordance with a
position of optical pickup 52 from optical disk 10. In response to
these signals, electric circuit 53 transmits a signal for driving
an object lens actuator to optical pickup 52. Upon receiving this
signal, optical pickup 52 performs a focus control, a tracking
control, a gap control and a tilt control with respect to optical
disk 10, thus performing reading, writing or erasing of
information.
[0049] Dick cartridge 31 stores a plurality of optical disks 10 in
the inside thereof in a stacked state as described above, and is
set in the inside of information recording and reproducing
apparatus 50 by an operation of a user. Separation arm 58 takes out
optical disk 10 in the inside of disk cartridge 31 in accordance
with a control performed by arm drive circuit 59, and moves optical
disk 10 to a tray for setting optical disk 10 on turntable 56.
Optical disk 10 which is taken out is mounted on turntable 56 so
that optical disk 10 is brought into a state where recording or
reproduction of information can be performed by optical pickup 52
as described above.
[0050] Optical disk 10 according to the present exemplary
embodiment can record information on both surfaces thereof and
hence, before optical disk 10 is moved to the tray for setting
optical disk 10 on turntable 56, optical disk 10 may be inversed by
a disk inversing mechanism when necessary. Alternatively, after
information is recorded on one surface of all optical disks 10 in
the inside of the disk cartridge, the direction of disk cartridge
31 may be inversed manually, and information may be recorded on the
other surface of all optical disks. Further, optical pickup 52 may
be disposed on both sides of optical disk 10.
[1-2. Operation]
[0051] FIG. 6A to FIG. 6F are explanatory views for describing a
method of separating a plurality of stacked optical disks 10a, 10b.
The plurality of stacked optical disks can be separated from each
other by controlling the above-mentioned separation arm 58. FIG. 6A
is a side view showing a state where separation arm 58 is inserted
into through holes 12a, 12b formed at the center of stacked optical
disks 10a, 10b. FIG. 6B is a plan view of separation arm 58 in a
state shown in FIG. 6A as viewed from above. FIG. 6C is a side view
of stacked optical disks 10a, 10b in a state immediately before
stacked optical disks 10a, 10b are separated from each other. FIG.
6D is a plan view of separation arm 58 in a state shown in FIG. 6C
as viewed from above. FIG. 6E is a side view showing a state
immediately after stacked optical disks 10a, 10b are separated from
each other. FIG. 6F is a plan view of separation arm 58 in a state
shown in FIG. 6E as viewed from above.
[0052] As shown in FIG. 6A and FIG. 6B, firstly, separation arm 58
is lowered so that separation arm 58 passes through through hole
12a formed in optical disk 10a on an upper side, and lowering of
separation arm 58 is stopped immediately before separation arm 58
passes through through hole 12b formed in optical disk 10b on a
lower side.
[0053] Then, as shown in FIG. 6C and FIG. 6D, four pawls 61 project
from separation arm 58 at intervals of approximately 90 degrees,
and extend toward spaces each of which is formed by a notch on a
lower side at the center of optical disk 10a (corresponding to thin
wall portion 27 in FIG. 2) and a notch on an upper side at the
center of optical disk 10b (corresponding to thin wall portions 21
in FIG. 2).
[0054] Subsequently, as shown in FIG. 6E and FIG. 6F, separation
arm 58 is elevated while maintaining pawls 61 in an extending state
so that pawls 61 are brought into contact with a surface of a lower
side of the thin wall portion of optical disk 10a on an upper side.
Then, in a state where pawls 61 support optical disk 10a,
separation arm 58 and optical disk 10a are elevated integrally.
Accordingly, optical disk 10a and optical disk 10b are separated
from each other.
[0055] As described above, by making use of the thin wall portion
formed at the center of the substrate of optical disk 10, optical
disks 10 which are directly stacked to each other can be separated
from each other. In the above-mentioned configuration, it is
important that the thin wall portion has a wide space for normally
separating optical disks 10 from each other. However, any foreign
substance such as a dust is liable to stagnate in the thin wall
portion. In this case, pawls 61 cannot maintain optical disk 10a on
an upper side at the accurate position and hence, there arises a
possibility that the operation of separation arm 58 will become
unstable or pawl 61 will be broken.
[0056] Hereinafter, the relationship between the thin wall portion
of optical disk 10 and a foreign substance is described with
reference to FIG. 7. FIG. 7 is a view showing one example of the
behavior of foreign substances in a substrate separated state and a
substrate immediately-before-separation state with respect to
optical disk 10 according to the present exemplary embodiment and
optical disk 71 according to a comparison example. Optical disk 10
is the optical disk according to the first exemplary embodiment
where an inclination angle made between a horizontal surface and an
inclined surface of a thin wall portion at a substrate center
portion is set to approximately 30 degrees. On the other hand, in
optical disk 71, an inclination angle between a horizontal surface
and an inclined surface of a thin wall portion at the center of a
substrate is set to approximately 90 degrees.
[0057] Firstly, the substrate separated state is described. The
substrate separated state is a state where the substrate exists in
a single form. For example, the substrate separated state is a
state taken on during the movement of an optical disk by separation
arm 58, a state taken on immediately after the optical disk is
moved to a tray for guiding the optical disk to turntable 56 and an
optical disk is placed on turntable 56 or a state where an optical
disk is taken out from disk cartridge 31. Also with respect to
stacked substrates, the uppermost substrate is treated as being in
a substrate separated state.
[0058] Firstly, in optical disk 10, any foreign substance which
falls from above as indicated by numeral 72 will leap back onto an
inclined surface and move away from optical disk 10. Alternatively,
a foreign substance will go downward while rolling on an inclined
surface as indicated by numeral 73, and will roll on a horizontal
surface as it is, and move away from optical disk 10. That is,
optical disk 10 has an advantageous effect that a foreign substance
will minimally adhere to optical disk 10 due to the formation of
the inclined surface.
[0059] On the other hand, optical disk 71 has no inclined surface
as indicated by 74 and hence, any foreign substance which falls
from above will likely to stay or stagnate on the horizontal
surface as it is.
[0060] Next, the substrate immediately-before separation state is
described. The substrate immediately-before separation state is a
state where pawls 61 project from separation arm 58 and extend
toward the inside of thin wall portion at the center of the
substrate for separating a plurality of stacked substrates (state
shown in FIG. 6C and FIG. 6D).
[0061] Firstly, in optical disk 10, a force in the lateral
direction is applied to any foreign substance on the horizontal
surface due to pawls 61 as indicated by numeral 75 and hence, this
foreign substance will slide obliquely in the upward direction
along the inclined surface.
[0062] On the other hand, in optical disk 71, although any foreign
substance on the horizontal surface will move toward a deep side
due to pawls 61 as indicated by numeral 76, when this foreign
substance stagnates at a deep side, the foreign substance cannot
move any further and, eventually, there is a possibility that this
foreign substance will stop the movement of pawls 61 or the
direction that pawls 61 move will be deviated.
[0063] As described previously, optical disk 10 according to the
present exemplified embodiment has the inclined surface on the thin
wall portion at the center of the substrate and hence, any foreign
substance can easily move. As a result, this foreign substance
minimally stagnates and hence, the present exemplified embodiment
can acquire an advantageous effect that the foreign substance will
not obstruct the substrate separating operation.
[0064] As has been described above, the present exemplified
embodiment can prevent the adhesion or the stagnation of a foreign
substance in the thin wall portion by forming the inclined surface
on the thin wall portion at the center of the substrate of optical
disk 10.
[0065] Optical disk 10 according to the present exemplified
embodiment is an optical disk capable of recording information on
both surfaces, the optical disk being formed by laminating two
substrates to each other symmetrically in a front-and-back
direction. Here, with reference to FIG. 8, the description is made
with respect to an optical disk capable of recording information on
both surfaces which is formed by laminating two substrates to each
other asymmetrically in a front-and-back direction.
[0066] In FIG. 8, numeral 81 indicates the case where optical disks
10 each of which is formed by stacking the substrates symmetrically
in a front-and-back direction, and numeral 82 indicates the case
where optical disks 10 each of which is formed by laminating the
substrates symmetrically in a front-and-back direction to each
other are stacked and, at the same time, the second disk from the
top has a front surface and a back surface thereof inversed
up-side-down. In both cases, a space which allows the extension of
pawls 61 of separation arm 58 is secured. On the other hand, in the
case indicated by numeral 84 where optical disks 81 each of which
is formed by laminating the substrates asymmetrically in a
front-and-back direction are stacked, a space which allows the
extension of pawls 61 of separation arm 58 cannot be secured. That
is, when optical disks are wrongly disposed at the time of
initially storing the optical disks in disk cartridge 31, there
arises a drawback that the optical disks cannot be separated from
each other.
[0067] Optical disk 10 according to the present exemplified
embodiment is formed by laminating the substrates such that the
substrates are symmetrical in a front-and-back direction and hence,
the optical disks can be separated from each other regardless of
the disposition of the optical disks at the time of storing the
optical disks in disk cartridge 31.
[1-3. Advantageous Effects and the Like]
[0068] As described above, optical disk 10 according to the present
exemplified embodiment includes thin wall portion 21 formed on an
outer diameter side of through hole 12 at the center of substrate
11 on the front surface thereof, and thin wall portion 21 has
horizontal surface 23 and inclined surface 22. Accordingly, the
present exemplified embodiment can prevent the adhesion or the
stagnation of a foreign substance on the inner diameter portion of
substrate 11, that is, on the periphery of through hole 12 and
hence, it is possible to prevent the deterioration of quality of
optical disk 10.
[0069] Further, optical disk 10 according to the present
exemplified embodiment includes thin wall portion 27 formed on an
outer diameter side of through hole 12 at the center of substrate
14 also on the back surface thereof, and thin wall portion 27 has
horizontal surface 25 and inclined surface 26. Accordingly, the
present exemplified embodiment can prevent the adhesion or the
stagnation of any foreign substance on the inner diameter portion
of substrate 14, that is, on the periphery of through hole 12 and
hence, it is possible to prevent the deterioration of quality of
optical disk 10.
[0070] Further, disk cartridge 31 according to the present
exemplified embodiment stores a plurality of stacked optical disks
10 therein, each of optical disks 10 includes the thin wall portion
formed on the outer diameter side of the through hole at the center
of the substrate, and the thin wall portion has the horizontal
surface and the inclined surface. Accordingly, even when optical
disks 10 are used in a stacked state in disk cartridge 31, stacked
optical disks 10 can be accurately separated from each other and,
at the same time, it is possible to prevent the deterioration of
quality of optical disks 10.
[0071] Further, optical disk 10 has the symmetrical structure in
the front-and-back direction by laminating the substrates to each
other and hence, optical disks 10 can be separated from each other
with certainty regardless of the disposition of optical disks 10 at
the time of storing optical disk 10 in disk cartridge 31.
Second Exemplified Embodiment
[2-1. Constitution]
[0072] FIG. 9 is a cross-sectional view of optical disk 900 (one
example of disk-shaped information recoding medium) according to a
second exemplified embodiment. Optical disk 900 is formed by
laminating substrate 91 and substrate 95 to each other, and thin
wall portions 921, 927 are respectively formed at the center of
substrate 91 and substrate 95. Optical disk 900 according to the
present exemplified embodiment differs from optical disk 10
according to the first exemplified embodiment with respect to a
point that optical disk 900 according to the present exemplified
embodiment has three curvature portions 92, 93, 94 on substrate 91
and three curvature portions 992, 993, 994 on substrate 95. Other
configurations of optical disk 900 are substantially equal to the
corresponding configurations of optical disk 10.
[0073] Curvature portion 92 is formed on an outer edge of through
hole 914, that is, between outer diameter 90 of a center
cylindrical portion and horizontal surface 97. Curvature portion 93
is formed between horizontal surface 97 and inclined surface 98.
Curvature portion 94 is formed between inclined surface 98 and
horizontal surface 99 corresponding to a recording surface of
substrate 91.
[0074] In the same manner, curvature portion 992 is formed on an
outer edge of through hole 914, that is, between outer diameter 990
of a center cylindrical portion and horizontal surface 997.
Curvature portion 993 is formed between horizontal surface 997 and
inclined surface 998. Curvature portion 994 is formed between
inclined surface 998 and horizontal surface 913 corresponding to a
recording surface of substrate 95.
[2-2. Advantageous Effects and the Like]
[0075] As described above, according to optical disk 900 of the
present exemplified embodiment, in addition to the advantageous
effects acquired by the first exemplified embodiment, since the
thin wall portion formed at the center of substrate 91 has
curvature potions 92, 93, 94, it is possible to further easily and
effectively remove any foreign substance in a substrate separated
state and a substrate immediately before separation state shown in
FIG. 7, for example. To be more specific, due to the formation of
curvature portion 92, any foreign substance which adheres to an
inner diameter side of horizontal surface 97 will easily slip down
into through hole 914 from horizontal surface 97. Due to the
formation of curvature portion 93, a foreign substance will go
downward while rolling on inclined surface 98, move on horizontal
surface 97 smoothly without substantially decreasing a speed and,
thereafter, roll on horizontal surface 97 and fall in through hole
914, and can be removed from substrate 91. Further, due to the
formation of curvature portion 94, when pawls 61 of separation arm
58 (FIG. 6A) are inserted, any foreign substance will slide upward
on inclined surface 98 in an oblique upward direction and hence, it
is possible to prevent a stagnating foreign substance from
obstructing a separating operation by pawls 61 (FIG. 6E).
[0076] Further, when the direction of the optical disk is inversed
upside down, due to the formation of curvature portion 992, any
foreign substance which adheres to an inner diameter side of
horizontal surface 997 will easily slip down into through hole 914
from horizontal surface 997. Due to the formation of curvature
portion 993, a foreign substance will go downward while rolling on
inclined surface 998, move on horizontal surface 997 smoothly
without substantially decreasing a speed and, thereafter, roll on
horizontal surface 997 and fall in through hole 914, and can be
removed from substrate 95. Further, due to the formation of
curvature portion 994, when pawls 61 of separation arm 58 (FIG. 6A)
are inserted, any foreign substance will slide upward on inclined
surface 998 in an oblique upward direction and hence, it is
possible to prevent a stagnating foreign substance from obstructing
a separating operation by pawls 61 (FIG. 6E).
[2-3. Modification]
[0077] It is not always necessary that the above-mentioned all
curvature portions 92, 93, 94, 992, 993, 994 be formed. It is
sufficient that only one or two curvature portions are formed.
Third Exemplified Embodiment
[3-1. Constitution]
[3-1-1. Optical Disk]
[0078] FIG. 10 is a cross-sectional view of optical disk 100 (one
example of disk-shaped information recording medium) according to a
third exemplified embodiment. Optical disk 100 according to the
third exemplary embodiment differs from optical disk 10 according
to the first exemplified embodiment and optical disk 900 according
to the second exemplified embodiment with respect to a point that
optical disk 100 according to the third exemplified embodiment
includes first rib 103 and second rib 104 having a circular annular
shape on both surfaces thereof. Further, in optical disk 100, first
clamp region 105 and film forming region 107 which includes a
recording film and a cover layer are formed on a front surface
side, and second clamp region 106 and film forming region 108 which
includes a recording film and a cover layer are formed on a back
surface side.
[0079] In optical disk 100, due to the formation of first rib 103
and second rib 104, when a plurality of optical disks 100 are
stacked as shown in FIG. 3, it is possible to prevent the
occurrence of a case where a region which stores and reproduces
data is damaged due to the collision of two film forming regions.
Further, in the case of the stacked optical disks described with
reference to FIG. 6, it is possible to prevent the occurrence of
the case where two film forming regions are adhered to each other
due to a contact therebetween resulting in the optical disks being
unable to be separated from each other. Still further, a gap formed
between the stacked optical disks can be increased by first rib 103
and second rib 104 and hence, pawls 61 of separation arm 58 can be
easily inserted between the optical disks thus facilitating the
optical disk separating operation.
[0080] When optical disk 100 is placed on a tray or the like in a
separation state, first rib 103 or second rib 104 is brought into
contact with a surface of the tray. Accordingly, it is possible to
prevent the occurrence of the case where film forming region 107 or
film forming region 108 in which data is recorded is damaged by
being brought into contact with the surface of the tray or the
occurrence of the case where a dust on the surface of the tray
adheres to the region where data is recorded or reproduced.
[3-1-2. Position of Clamp Region]
[0081] Next, with respect to optical disk 100 according to the
present exemplified embodiment, the positional relationship between
first clamp region 105 and film forming region 107 and the
positional relationship between second clamp region 106 and film
forming region 108 are described. As shown in FIG. 10, first clamp
region 105 is formed such that first clamp region 105 does not
overlap with film forming region 107. In the same manner, second
clamp region 106 is formed such that second clamp region 106 does
not overlap with film forming region 108.
[0082] FIG. 11A is a plan view of clamper 55 (FIG. 5) of
information recording and reproducing apparatus 50. FIG. 11B is a
cross-sectional view of clamper 55 of information recording and
reproducing apparatus 50. Clamper 55 includes projecting portions
111 and metal portion 112.
[0083] FIG. 12A is a perspective view of turntable 56 (FIG. 5) of
information recording and reproducing apparatus 50. FIG. 12B is a
cross-sectional view of turntable 56 of information recording and
reproducing apparatus 50. Turntable 56 includes: center projection
portion 121 for holding the center cylindrical portion of the
optical disk; and a magnet portion 122 mounted on an upper portion
of center projecting portion 121.
[0084] At the time of performing an information recording or
reproducing operation, optical disk 100 is moved to a position
above turntable 56 and, thereafter, optical disk 100 is placed on
turntable 56 by inserting center projecting portion 121 of
turntable 56 into through hole 12 formed at the center of optical
disk 100. Then, optical disk 100 is clamped between clamper 55 from
above and turntable 56. At this stage of operation, metal portion
112 of clamper 55 and magnet portion 122 of turntable 56 attract
each other and hence, the position of optical disk 100 is fixed.
Recording or reproducing of information with respect to optical
disk 100 is performed while turntable 56 is rotated by motor 54
(see FIG. 5). Further, at this stage of operation, projecting
portions 111 of clamper 55 are brought into contact with the clam
region of optical disk 100.
[0085] FIG. 13A is a plan view of optical disk 100 formed such that
first clamp region 105 and film forming region 107 do not overlap
with each other. FIG. 13B is a cross-sectional view showing a state
where optical disk 100 is gripped by clamper 55 on turntable
56.
[0086] As shown in FIG. 13B, at the time of performing a recording
or reproducing operation with respect to optical disk 100, a load
is applied to projecting portions 111 of clamper 55 and second ribs
104. Accordingly, as heights of projecting portions 111 and second
ribs 104 are set to be higher, a space formed between an inner
peripheral portion of optical disk 100 and clamper 55 and a space
formed between an inner peripheral portion of optical disk 100 and
turntable 56 become wider. Accordingly, the recording or
reproducing operation is influenced by air resistance and hence,
power consumption is increased.
[0087] Accordingly, it is desirable to set the heights of first
ribs 103 and second ribs 104 as low as possible within a range
where an advantageous effects described above, that is, the
protection of the recording and reproducing regions and the ease of
separation of stacked optical disks can be realized. It is more
preferable that the heights of first ribs 103 and second ribs 104
be set to 150 micrometer or less.
[0088] When projecting portion 111 is brought into contact with
film forming region 107, there is a possibility that a defect such
as a crack will occur in film forming region 107 due to a pressure
applied to projecting portion 111. Further, when optical disk is
repeatedly loaded, the above-mentioned defect spreads so that there
may be a case where recording or reproduction of information by the
optical disk cannot be performed eventually. By forming first clamp
region 105 and film forming region 107 such that these regions do
not overlap with each other as in the case of optical disk 100
according to the present exemplified embodiment, the rupture of
film forming region 107 by projecting portion 111 can be
prevented.
[0089] Film forming region 107 includes at least a recording region
and a cover region which is formed on a front surface side of the
recording region. Provided that the cover region is not
deteriorated due to a contact with a clamper 55 and the recording
region is formed on a more outer diameter side and a outer
peripheral side of the cover region, the clamp region and the film
forming region may abut each other so long as the clamp region and
the recording region do not abut each other.
[0090] In optical disk 100 according to the present exemplified
embodiment, first rib 103 and second rib 104 are formed on an inner
diameter side of first clamp region 105 and second clamp region
106. Due to such a configuration, the recording region can be
increased compared to the case where the ribs are formed on an
outer diameter side of the clamp region while realizing the
advantageous effects described above, that is, the protection of
recording and reproducing regions and the ease of separation of
stacked optical disks.
[3-2. Modifications]
[3-2-1. Modification 1]
[0091] FIG. 14 shows a modification of optical disk 100 according
to the present exemplified embodiment. Differing from optical disk
100, optical disk 150 further includes first printing region 151
and second printing region 152. First printing region 151 and first
clamp region 102 are separated from each other. In the same manner,
second printing region 151 and second clamp region 102 are
separated from each other. The printing region and the clamp region
are disposed such that these regions do not overlap with each other
and hence, it is possible to prevent the rupture of first printing
region 151 or second printing region 152 by projection portion 111
of clamper 55, and the generation of dust caused by clamping first
printing region 151 and second printing region 152. Further,
projection portions 111 of clamper 55 are brought into contact with
uneven portions of printing portions on first printing region 151
and second printing region 152 so that it is possible to prevent
the generation of a play in optical disk 150 at the time of
clamping.
[0092] Printing is performed by using an acrylic resin paste
containing pigment, for example, wherein a printed portion is cured
by UV irradiation. With respect to an undercoat for the printing
portion, the undercoat is formed by a generally known method which
uses a paste, for example. In the present exemplified embodiment,
as such a paste, a paste which contains 25 to 30 weight % of
urethane resin and 70 to 75 weight % of an acrylic resin is used.
This paste is applied by coating by a printing method which uses a
screen plate made of polyester and, thereafter, a coated paste is
cured by UV irradiation. With respect to a urethane resin, when an
average value of particle size distribution is approximately 3.5
.mu.m to 5.0 .mu.m, an undercoat portion is slightly formed into an
uneven shape. Accordingly, when the rib wears in a state where
optical disks overlap with each other, for example, or even when
the rib is not formed, it is possible to prevent the occurrence of
the case where the optical disks are adhered to each other so that
the optical disks cannot be separated from each other.
[0093] The undercoat and the print may be formed by methods which
differ from the above-mentioned method.
[0094] The same content may be printed on first printing region 151
and second printing region 152 for the purpose of identifying a
kind and a recording capacity of an optical disk, or information
which distinguishes the surfaces of the optical disk may be printed
on first printing region 151 and second printing region 152.
Further, a kind or a recording capacity of an optical disk can be
distinguished such that the difference in color between the
printing regions, prints other than characters and the numerals may
be applied to first printing region 151 and second printing region
152.
[0095] Further, to distinguish surfaces of an optical disk from
each other, in place of prints applied to printing regions,
information such as alphabets and numerals may be marked on a
substrate by a laser marker or the like. Further, marking may be
applied to only one surface of the optical disk.
[0096] With respect to optical disk 150 capable of recording
information on both surfaces, provided that both surfaces can be
distinguished from each other, and effects such as the generation
of a play in optical disk 150 at the time of clamping are not
generated, the printing region may be formed only one side of the
optical disk.
[0097] Further, in optical disk 150 according to the present
exemplified embodiment, first printing region 151 and film forming
region 107 are separated from each other. In the same manner,
second printing region 152 and film forming region 108 are
separated from each other. By disposing the printing region and the
film forming region such that these regions do not overlap with
each other, it is possible to prevent the deterioration of the film
forming region caused by intrusion of a printing material into a
film forming region.
[0098] In optical disk 150 of the present exemplified embodiment,
first printing region 151 is disposed at the position different
from film forming region 107. However, provided that there is no
effect on distinction in first printing region 151 and there is no
effect on recording in film forming region 107, first printing
region 151 and film forming region 107 may partially overlap with
each other. In the same manner, second printing region 152 is
disposed at the position different from film forming region 108.
However, provided that there is no effect on distinction in second
printing region 152 and there is no effect on recording in film
forming region 108, second printing region 152 and film forming
region 108 may partially overlap with each other. Further, when the
film forming region is formed of a plurality of films, only some
films may overlap with each other.
[3-2-2. Modification 2]
[0099] In optical disk 150 capable of recording information on both
surfaces, the positions of first printing region 151 and second
printing region 152 are not limited to the outer sides of
substrates 101, 102, that is, the recording surface sides of
substrates 101, 102. First printing region 151 and second printing
region 152 may be formed on inner sides of substrates 101, 102,
that is, the sides of substrates 101, 102 which are laminated to
each other.
[0100] FIG. 15A shows the example of optical disk 150 where first
printing region 151 and second printing region 152 are formed on
inner sides of substrates 101, 102, that is, the sides of
substrates 101, 102 which are laminated to each other. FIG. 15B
shows the example of optical disk 150 where first printing region
151 and second printing region 152 are formed on the sides of
substrates 101, 102 which are laminated to each other, and the
radial positions of first printing region 151 and second printing
region 152 overlap with first clamp region 105 and second clamp
region 106.
[0101] As described previously, substrates 101, 102 are made of a
transparent resin material such as polycarbonate and hence,
printing portions on first printing region 151 and second printing
region 152 can be visually recognized from the outside even when
printing portions are formed in the inside of the substrates.
[0102] In both examples shown in FIG. 15A and FIG. 15B, there is no
possibility that clamper 55 will be brought into contact with first
printing region 151 and second printing region 152 in the inside of
the substrates. Accordingly, it is possible to prevent the rupture
of first printing region 151 and second printing region 152 due to
projecting portions 111 of damper 55 and the generation of dust
caused by clamping first printing region 151 and second printing
region 152. Further, it is also possible to prevent a play which
may be generated in optical disk 150 at the time of clamping due to
a contact between projecting portions 111 of clamper 55 and uneven
portions of the printing portions on first printing region 151 and
second printing region 152. Still further, as shown in FIG. 15B,
there arises no problem even when the radial position of first
printing region 151 and the radial position of second printing
region 152 overlap with radial position of first clamp region 105
and hence, first printing region 151 and second printing region 152
can be widely formed.
[0103] First printing region 151 and second printing region 152
shown in FIG. 15A and FIG. 15B may be formed only on one side of an
optical disk so long as both surfaces can be distinguished from
each other. Although first printing region 151 and second printing
region 152 shown in FIG. 15A and FIG. 15B overlap with each other
with respect to the radial position, these printing regions may be
formed in a non-overlapping manner or may be formed in a state
where the printing regions are displaced from each other.
[3-3. Advantageous Effects]
[0104] As described above, in optical disk 150 according to the
present exemplified embodiment, in addition to the advantageous
effects of previously-mentioned first and second exemplified
embodiments, due to the formation of first rib 103 and second rib
104, when a plurality of optical disks 150 are stacked, it is
possible to prevent the occurrence of a case where a region which
stores and reproduces data is damaged due to the collision of the
film forming region of optical disk 100 on an upper side and the
film forming region of optical disk 150 on a lower side.
[0105] In separating stacked optical disks 150, it is possible to
prevent two film forming regions from being adhered to each other
due to a contact therebetween. Further, a gap formed between
stacked optical disks 150 can be increased by first rib 103 and
second rib 104 and hence, pawls 61 of separation arm 58 can be
easily inserted between the optical disks, thus facilitating the
optical disk separating operation.
[0106] When optical disk 150 is placed on a tray or the like in a
separation state, first rib 103 and second rib 104 are brought into
contact with a bottom surface of the tray. Accordingly, it is
possible to prevent the occurrence of the case where the film
forming region in which data is recorded is damaged due to a
contact between the film forming region and the bottom surface of
the tray or the occurrence of the case where a dust on the bottom
surface of the tray adheres to a region where data is recorded and
reproduced.
[0107] In optical disk 150, first clamp region 105 and second clamp
region 106 and film forming regions 107, 108 are formed such that
first clamp region 105 and second clamp region 106 do not overlap
with film forming regions 107, 108 and hence, it is possible to
prevent the rupture of film forming regions 107, 108 by projecting
portions 111 of clamper 55.
[0108] In optical disk 150, first clamp region 105, second clamp
region 106, first printing region 151 and second printing region
152 are formed such that first clamp region 105 does not overlap
with first printing region 151 and second clamp region 106 does not
overlap with second printing region 152 and hence, it is possible
to prevent the rupture of first printing region 151 and second
printing region 152 due to projecting portions 111 of damper 55 and
the generation of dust due to clamping first printing region 151
and second printing region 152. Further, it is also possible to
prevent a play which may be generated in optical disk 150 at the
time of clamping due to a contact between projecting portions 111
of clamper 55 and uneven portions of the printing portions on first
printing region 151 and second printing region 152.
[0109] Further, the printing portion is formed on first printing
region 151 and second printing region 152 of optical disk 150
capable of recording information on both surfaces and hence, the
front surface and the back surface of optical disk 150 can be
easily distinguished from each other.
Other Embodiments
[0110] (1)
[0111] The thin wall portion formed at the center of the substrate
in the optical disk according to the above-mentioned exemplified
embodiments is not limited to the above-mentioned configuration.
For example, even when the thin wall portion is configured as
follows, the optical disk can acquire substantially the same
advantageous effects as the above-mentioned exemplified
embodiments.
[0112] As shown in FIG. 16 which is a cross-sectional view, in
optical disk 200 capable of recording information on both surfaces,
a thin wall portion 1411 may include: inclined surface 149 (one
example of the inclined surface) which is inclined at a
predetermined angle; and vertical surface 1413 (one example of
non-inclined surface) which is continuously formed with an inner
diameter side of inclined surface 149 and is formed along an outer
diameter of through hole 140. In the same manner, thin wall portion
1412 may include: inclined surface 1410 (one example of the
inclined surface) which is inclined at a predetermined angle; and
vertical surface 1414 (one example of non-inclined surface) which
is continuously formed with an inner diameter side of inclined
surface 1410 and is formed along the outer diameter of through hole
140.
(2)
[0113] An optical disk capable of recording information on both
surfaces may include the configuration for distinguishing front and
back surfaces of the optical disk besides the above-mentioned
exemplified embodiments. For example, it may be possible to record
information for distinguishing a front surface and a back surface
of the optical disk by partially changing shapes of groove-like
tracks formed on a front-surface-side substrate and a
back-surface-side substrate respectively or by forming uneven pits
on the front surface and the back surface of the optical disk.
[0114] FIG. 17A is a perspective view of optical disk 170 (one
example of a disc-shaped information recording medium) as viewed
from a front surface of optical disk 170. FIG. 17B is a perspective
view of optical disk 170 as viewed from a back surface of optical
disk 170. Optical disk 170 is configured by laminating substrate
171 having a predetermined thickness and substrate 174 having a
predetermined thickness to each other. Optical disk 170 further
includes: center cylindrical portion 173 on a front surface side in
which through hole 172 is formed; and center cylindrical portion
175 on a back surface side in which through hole 172 is formed.
Substrate 171 and substrate 174 are formed by injection molding
using a transparent resin such as polycarbonate.
[0115] A recording film for recording information is formed on both
substrate 171 and substrate 174, and substrate 171 and substrate
174 are laminated to each other such that surfaces on which the
recording film is formed form outer sides. Numeral 176 indicates a
groove-like track or an uneven pit formed in substrate 171, and
information for distinguishing the front surface and the back
surface is recorded by partially changing a shape of the track or a
pattern of the uneven pit. In the same manner, numeral 177
indicates a groove-like track or an uneven pit formed in substrate
174, and information for distinguishing the front surface and the
back surface is recorded by partially changing a shape of the track
or by a pattern of the uneven pit.
[0116] Information in the optical disk includes two kind of
information, that is, information dedicated to reproduction which
is embedded in advance as described above, and information recorded
later by applying a laser beam. In general, information dedicated
to reproduction is reproduced prior to recorded information to be
recorded. Accordingly, by recording information for distinguishing
front and back surfaces of the substrate in advance as in the case
of the present exemplified embodiments, when information is
recorded on both surfaces and the surface on which information to
be reproduced first is determined, for example, it is possible to
readily recognize whether or not information on the correct surface
is being reproduced.
(3)
[0117] Further, in the above-mentioned exemplified embodiments,
optical disk capable of recording information on both surfaces is
formed by laminating two substrates. However, the optical disk may
include a single substrate where a recording film is formed on both
surfaces, and thin wall portions may be formed symmetrically in a
front-and-back direction. Further, by disposing first printing
region 151 and second printing region 152 on an inner peripheral
side, film forming region 107 and film forming region 108 can be
also disposed on the inner peripheral side and hence, the recording
regions can be widened.
(4)
[0118] In the above-mentioned exemplified embodiments, an optical
disk is exemplified as an example of a disc-shaped information
recording medium. However, the disc-shaped information recording
medium is not limited to the optical disk. For example, the present
invention is applicable to an opto-magnetic disk or other magnetic
discs provided that the disk is a disc-shaped information recording
medium.
(5)
[0119] The exemplified embodiments have been described heretofore
as examples of the technique according to this disclosure. For this
purpose, the attached drawings and the detailed description are
provided.
[0120] Accordingly, the components described in the attached
drawings and the detailed description may also include not only the
components necessary for solving the problems but also components
which are unnecessary for solving the problems in order to
exemplify the aforementioned techniques. Therefore, such
unnecessary components should not be immediately determined to be
necessary, for the reason that these unnecessary components are
described in the attached drawings and the detailed
description.
[0121] Further, the aforementioned embodiment is merely for
exemplifying the techniques according to this disclosure and,
therefore, various changes, replacements, additions, omissions and
the like can be made thereto within the scope of the claims and
scopes equivalent thereto.
[0122] The exemplified embodiments of the present invention are
applicable as a disc-shaped information recording medium or an
information recording and reproducing apparatus for the disc-shaped
information recording medium.
* * * * *