Note: Descriptions are shown in the official language in which they were submitted.
2~6~
TITI,~
HUB FOR OPTICAL DISK AND OPTICAL DISK
FIEI,D OF :~5~;1~
5This invention relates to hubs for optical disk and
optical disks having said hubs, and more particularly the
invention relates to hubs for optical disk and optical disks
having said hubs, both of them being so designed that when a
spindle of the optical disk driving device is fitted into the
hub of the optical disk, excellent lubricating properties or
slipping properties can be exhibited between the spindle and
a center hole of the hub, and no poor loading performance is
produced.
1~BACKGROUND OF THE INVENTION
Because of their characteristics such as large memory
capacity and portability, optical disks have a future
possibility of being used in a great variety of applications,
and in recent years extensive researches and developments of
the optical disks have been conducted.
Optical disks which have been made fit for practical use
include those of read-only type such as a compact disk (CD)
and CD-ROM, and those of the write-once type capable of
storing information but incapable of erasing the stored
2 2 ~ fi 3
inEorma~ion. Further, practical use of the rewritable
optical disks is begun.
Such optical disks as mentioned above are usually held
rotatably in a th-n flat case, and are often used as optical
disk cartridges.
When this optical disk cartridge is set on a carriage of
a recording and reproducing equipment, a spindle of a disk
drive is fitted with a hub of the optical disk. In this
case, the spindle is so designed that it is inserted into a
0 center hole of the hub.
Thereafter, the surface of the optical disk exposed
thrGugh the cartridge is irradiated with a laser beam,
whereby information is recorded in the disk or the recorded
information is reproduced therefrom.
1~ In such cases, however, the spindle sometimes cannot be
inserted smoothly into the center hole of the hub, or
frictional force produced between the surface of the spindle
and the inner peripheral surface of the center hole of the
hub becomes large. As the result, the spindle is damaged
sometimes when the center hole of the hub is made of a metal,
or when the center hole of the hub is made of a resin,
lubricating properties between the spindle and the center
hole of the hub b-ecome poor depending on the kind of resin
used, whereby a poor loading performance is sometimes
produced.
OBJECT OF THE INVENTION
The present invention has been made in view of the
circumstances as mentioned above, and an object of the
5 invention is to provide hubs for optical disk and optical
disks having said hubs, both of them being so designed that
when a spindle of the optical disk driving device is fitted
into the hub of the optical disk, improved sliding properties
or slipping properties can be exhibited between the spindle
and a center hole of the hub, whereby an excellent loading
performance is exhibited.
~IJMMARY OF THE INVENTION
The hubs for optical disk of the present invention
having a center hole into which a spindle of an optical disk
driving device is inserted, are characterized in that a
lubricant layer is provided in an opening edge of the center
hole of the hub or in the vicinity of said opening edge.
The optical disks of the present invent.ion are
charactexized ln that said disks are provided with a hub
having a center hole into which a spindle of an optical disk
driving device is inserted, said hub being provided with a
lubricant layer in an opening edge of said center hole of the
hub or in the vicinity of said opening edge.
The lubricant layer used in the hub of the optical disk
includes suitably those formed from lubricants, preferably
from silicone oil, silicone grease or silicone oil compound,
and preferably having a thickness of from 1 to 50,000 A.
S In the present invention, the lubricant layer is
provided in the opening edge of the center hole of the hub or
in the vicinity of said opening edge, for example, by
applying the lubricant thereto, hence sliding properties or
slipping characteristics are improved at the time when the
0 spindle is inserted into the center hole of the hub, thereby
preventing the spindle or hub from its damage.
It has been found by an experiment 20,000 times on
loading an upright drive with the optical disk of the
invention that the sliding properties between the spindle and
the center hole of the hub was excellent and no spin-up
troubles occurred.
BRIEF DE~RIPTION QF T~E DRAWINGS
Fig. 1 is a sectional view of one e~bodiment o~ the
optical disk of the present invention.
Fig. 2 is a sectional view of one embodiment of the
optical. disk of the invention.
Fig. 3 is a perspective view of one embodiment of the
hub viewed from the bottom, said hub is used in one
embodiment of the optical disk of the present invention.
Fig. 4 is a perspective view of the hub viewed from the
top, said hub is used in one embodiment of -the optic~l disk
of the invention.
Fig. 5 is an enlarged sectional view of essential parts
of a preferred embodiment of the first optical disk of the
invention and an optical disk driving device, said sectional
view showing the state wherein the optical disk is about to
be fitted on the driving device.
Fig. 6 is a sectional view of the third embodiment of an
0 optical disk oE the invention, said optical disk being a
laminated optical disk which has no such a concave portion as
in the optical disX of Fig. 1 provided for fitting an annular
metallic member to the outward edge face of the hub.
Fig. 7 is a sectional view of an optical disk of an air-
sandwich structure, said optical disk having no such aconcave portion as in the optical disk of Fig. 2 provided for
fitting an annular metallic member to the outward edge face
of the hub.
Fig. 8 is to show sectional view of an optical disk of
one embodiment of the invention, a disk cartridge and a disk
drive, respectively, and an enl.arged longitudinal sectional
view of a chamfered (broken) opening edge of the center hole
of the hub for inserting the spindle therethrough.
Fig. 9 is a front view of the optical disk cartridge
2~ shown in Fig. 8.
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Fig. 10 is to show sectional views of various opening
edges of the center hole of resinous hubs used in the optical
disk of the invention.
Fig. 11 is to show sectional views of various opening
edges of the center hole of metallic hubs used in the optical
disk of the invention.
Fig. 12 is a sectional view of an insert hub having
metallic ring formed in the center thereof.
Fig. 13 is s sectional view of a single-plate optical
dis~ of one embodiment of the invention.
Fig. 1~ is a sectional view of a single-plate optical
disk of one embodiment of the invention.
67 ... Hub, 77 ... Center hole, 100 ... Opening edge,
53,93 ... Spindle, 61,21 ... Optical disk
1 5
DET~ILED DESCRIPTION OE T~E INVENTION
The present invention is illustrated below with
reference to embodiments given in terms of their respective
drawings attached hereto.
Figs. 1 and 2 are to show individually a sectional view
of one embodiment of optical disk of the present invention.
Fig. 1 shows a laminated type optical disk provided with
a concave portion 81 in which an annular metallic member 67a
is engaged with an outward end face s6 of the hub, and Flg. 2
shows an air-sandwich type optical disk provided with the
same concave portion 81 as in the optical disk of Fig. 1.
The laminated type optical disk of the first embodiment
of the invention as shown in Fig. 1 is illustrated below in
5 detail.
In this connection, Fig. 3 is a perspective view showing
the hub used in the optical disk of the first embodiment
shown in Fig. 1 when viewed from the bottom, and Fig. 4 is a
perspective view of said hub when viewed from top.
Fig. 5 is an enlarged sectional view of essential parts
of the optical disk of one embodiment of the invention when
said optical disk is about to be fitted on an optical disk
driving device.
Fig. 6 is a sectional view of one embodiment of the
IS optical disk of the invention, said optical disk being a
laminated type optical disk which has no such a concave
portion 81 as in the optical disk of Fig. 1 provided for
fitting an annular metallic member 67a to the outward end
face s6 of the hub, and Fig. 7 shows an air-sandwich type
optical disk which has no such a concave portion 81 provided
on the outward end face of the hub as in the optical disk of
Fig. 2.
~ s shown in Fig. 1, the optical disk 61 of the first
embodiment of the invention is an laminated type optical disk
comprising two pieces of disk substrates 63 each having a
2 ~ 3 3
recording medium layer 63b on one side thereof, said disk
substrates 63 being laminated together so that said recording
medium layers is positioned between said disk substrates 63,
and two pieces of hubs 67 fitted individually in center
openings 65 of said disk substrates 63 through both sides
thereof.
Disk sub~
The disk substrates 63 comprises a resin substrate 63a
and a recording medium layer 63b laminated on one tinner)
side of said disk substrate 63. In this embodiment of the
invention, the disk substrates 63 both respectively have the
recording medium layers 63b thereon, but the recording medium
layer 63b may be formed only on one of the disk substrates
63.
The resin substrate 63a may be formed from any resinous
materials known hitherto, for example, resins commonly used
as substrate materials such as polymethyl methacrylate and
polycarbonate, and random copolymers of ethylene with
cycloolefins such as tetracyclododecene,
methylcyclotetradodecene and norbornene.
Desirable materials for the substrate used in the
present invention are resins having an intrinsic viscosity
[~1 of 0.05 - 10 dl/g, such as (a) cycloolefin random
copolymers of ethylene and a cycloolefin represented by the
following formula [1] and ~b) polyolefins comprising
9 2 ~
polyolefins formed by ring opening polymerizat:ion of the
cycloolefin represented by the following formula [11 or
hydrogenation products of -the polyolefins.
- General formula [1]
`"`[l]
R 4 R 5 R ~ R l R '
wherein n is O (zero) or 1, m is O (zero) or a positive
integer, R1 - R18 are individually hydrogen, halogen or
- hydrocarbon group. R15 - R1a may, linking together, form a
mono- or polycyclic, and R15 with R1fi or R17 with R18 may form
a divalent hydrocarbon group. The mono- or polycyclic
composed of R15 - R18 may have double bond.
The recording medium layer 63b comprises a recording
material layer or, if necessary, a laminate including one or
two or more layers selected from among a protective layer
comprising inorganic or organic materials (e.g. SiNx,
ultraviolet curing resin, etc.), enhancing layer, reflecting
layer, good heat conductive layer (e.g. Al alloy),
interference layer and reflection pre~enting layer, which are
laminated on the recording material layer and/or on the
reverse of said recording material layer, or alternatively
the recording medium layer 63 preferably comprises the
recording material layer laminated with the protective layer
comprising the organic material te.g. ultraviole-t curing
resin) or the inorganic material as the outermos-t layer.
Particularly, it is preferable that on the substrate 63a is
laminated the recording medium layer ~3b comprising a SiN
protective layer/recording material layer/SiN protective
layer/Al alloy layer/ultraviolet curing resin layer in this
order. The recording material layer may be formed from any
materials so long as they are optical recording materials,
including those used exc]usively for replay such as a compact
disk (CD) and CD-ROM, for those of the write-once type
capable of storing information but incapable of erasing
stored information or those for the rewritable type. In
addition, -there may be mentioned, for example, magnetooptical
recording materials containing a 3d transition metal and
rare-earth elements such as Tb Fe Co or containing 3d
tr~nsition metal, rare-earth metal and corrosion resistant
metal such as Tb Fe Co plus Pt or Pd; organic coloring
materials such as cyanine and naphthalocyanine dyes; low
melting metallic materials such as Te, Te-C-H and Te-Cr-C-H;
or disk substrates having formed thereon pits corresponding
to signals. Of these recording material layers mentioned
above, particularly preferred are magnetooptical recording
material layers.
The disk substrates 63 are bonded together by means of
an adhesive layer 6~c as shown in Fig. 1 (or Fig. 6), or
joined together through an outer peripheral spacer 68a and an
inner peripheral spacer 68b by means of an adhesive or
ultrasonic welding (air-sandwich type) as shown in Fig. 2 (or
Eig. 7).
In the present invention, an adhesive for bonding the
disk substrates and the hubs includes, a thermosetting
adhesive such as amino resin, phenol resin, resorcinol resin,
xylene resin, furan resin, epoxy resin, polyisocyanate,
unsa-turated polyester and acrylic resin; a thermoplastic
adhesive such as vinyl acetate type, acrylic type, ethylene
copolymer type, polyamide, polyester and polyurethane; a
rubber type adhesive such as polychloroprene, nitrile rubber,
reclaimed rubber, SBR type and natural rubber; and a
pressure-sensitive adhesive such as rubber type, acrylic
type, emulslon type, oligomer -type, hot-melt type,
thermosetting type and hygroscopic setting type; a hot-melt
adhesive such as water soluble type, reaction type, high~
temperature type and pressure-sentitive type; an
instantaneous adhesive such as cyanoacrylic type. The disk
substrates and the hubs may be bonded by ul-trasonic welding
or high-frequency welding. As preferred materials, there is
12 ~ 3
exemplified a UV-curing adhesive such as acrylic type and
epoxy type.
Further, as an adhesive for bonding both of substrates
or both of hubs, the adhesives mentioned above may be used
and water solble type, reaction type, high-temperature type
and the pressure~sensitive type of the hot-melt adhesives are
particularly preferred. From among the hot-melt adhesives,
those having at least 130C, particularly at least 140C of a
softening point are preferred. As the hot-melt adhesive,
0 there may be exemplified those having the following
composition.
a-olefin polymer 1 - 60 ~ by weight
(e.g. ethylene-propylene copolymer, polypropylene and
polyisobutylene)
Styrene type polymer 1 - 30 % by weight
Tackifier 30 - 95 % by weight
le.g. aliphatic cyclic resin having 300 - 5000 of number
average-molecular weight)
The hub 67 which is fitted in the central opening 65 of
the disk substrate 63 usually comprises a resin body 67b
having a column-like portion 71 and a flange portion 73
extended outward from an edge of said column-like portion 71.
The column-like portion 71 has a center hole 77
penetrating therethrough up to both end faces s6 and s7 of
said column-like portion 71, and a spindle 93 of a driving
1 3 2~6~
device 91 shown in Fig. 5 as will be mentioned later is
insertecl into the center hole 77.
In the optical disk of the embodiment of the present
invention as shown in Fig. 1, the resin body 67b which is a
5 part of the hub 67 has an annular groove 78 along the
circumference of the end face s7 of the column-like portion
71, and an annular metallic member ~metallic plate) 67a
embedded in the end face s6 of the column-like portion 71
having the flange portion 73 (see Fig. 4) . The metallic
l 0 member 67a is arranged so tha-t the center hole 77 is
positioned concentrically within a central opening 89 of said
metallic member 67a.
The central opening 89 of the metallic member 67a is
larger in radius than the center hole 77 of the resin body
15 67b, and there is a given distance between an inner edge end
of the central opening 89 and an inner peripheral por-tion s8
of the center hole 77.
Accordingly, in the column-like portion 71 of the resin
body 67b, the circumferential portions s9 and slO and the
inner peripheral portion s~ are all made of resin. The
metallic member 67a has an exposed face s12 between the
circumferential portion s9 and the outer circumferential
portion sll in the outward end face s6 of the hub 67
comprising the flange portion 73 and the column-like portion
25 71.
14 2~
Materials used for preparing the resin body 67b are not
limited particularly and may be any resins conventionally
used for hubs of optical disks. Concretely, there may be
used such materials as used in the aforementioned resin
substrate 63a, for example, polycarbonate, acrylic resin,
polyolefin, etc. Of these materials mentioned above,
particularly preferred is polycarbonate.
Materials used for preparing the metallic member
(metallic plate) 67a may be any metals so long as they are
attracted by magnets, particularly ferromagnetic materials
such as iron, nickel, cobalt, etc. or alloys thereof (SUS
430, etc.) are preferably usable.
In the present invention, -the hub may use a metallic
member having the exposed face s12 as mentioned above.
However, as shown in Fig. 11 (a~, the hub 67 may be entirely
composed of a magnetic metal of a thin ring form, or may be
such a hub comprising a cylindrical portion 767 extending
inward in the center hole 77 and a flange portion 73 as shown
in Fig. 11 (b), said hub being entirely composed of a
magnetic metal.
As shown in Fig. 12 (a), there may be used a metallic
member 701 capable of being attracted by a magnet member
provided on a turn table, which has a center hole 651 fi-tted
with the spindle of the driving device, and as shown in Fig.
12 (b), there may also be used a metallic member 701 capable
6 ~ ~
of being attracted by the magnet member provided on the turn
table of the driving device, which has the center hole 651
for the spindle of the driving device, said center hole 651
having a projected portion ex-tending inward inside the
centering hole 651. It is desirable that an outer peripheral
edge 702 of the metallic member 701 is embeded into -the resin
body 67b of the hub 67, and fastened to said resin body.
In the optical disk 61 of the present invention, it is
desirable that an opening edge 100 of the center hole 77 of
0 the hub 67 is chamfered tbroken) as shown in Fig. 5 or 8.
The chamfered opening edge 100 includes the opening
edges 100 extending in the form of an arc in -the direction of
opening end (i.n other words, being rounded off by radius: R
type) as shown in Fig. 1, 2 or 10 (a), extending straight in
the direction of opening end as shown in Fig. 10 (b-1), 6 or
7 and a bore diameter of said opening edge 100 is relatively
small tapered type, for example, having chamfer of 45 or
extending straight in the direction o:E opening end as shown
in Fig. 10 (b-2) and a bore diame-ter of said opening edge 100
2() is relatively large tapered type. The opening edge 100,
however, desirably is the chamfer of R type In the present
invention, in case that the opening edge of the center hole
of the hub is chamfered, it becomes easy to apply the
lubricant on the opening edge of the center hole or in the
vicinity of said opening edge and the loading properties of
16 ~ 3
the recording disks are improved since the layer of the
lubricant is capable of keeping stability for a long time and
the spindle is inserted smoothly.
In order to exhibit the effect obtained by the chamfer
of the opening edge of the hub center hole at its maximum, in
the chamfered edge of the R type, the radius thereof is
preferably not more than 0.2 mm, more preferably, 0.02 to 0.2
mm, and in the tapered type, two sides crossing at right
angles in a shaved sectional triangle individually has a
length preferably of not more than 0.2 mm, more preferably of
0.02 to 0.2 mm.
Preparation of hub
The hub 67 used in the optical disk of the present
invention may easily be prepared by insert molding technique,
wherein the metallic member 67a is placed in position within
a mold and a resin is then injected into the mold to obtain
the desired resin body 67b.
The hub 67 having a concave portion 81 in the outward
end face s6 as shown in Fig. 1 or 2 may be prepared, for
example, by a process wherein a resin hub body 67b having 1
or 2 or more concave portions 81 provided at equal interval
in the vicinity of the circumference of the outward end face
s6 is first prepared and then the metallic member ~7a having
1 or two or more engaging members 82 is fitted in the concave
portions 81 of the resin hub body 67a.
17
The optical disk 61 shown in Fig. 1 is prepared by
bonding the ]aminated disk substrate 63 to the hub 67, and
bonding the hubs 67 to each other. The adhesive layer 83 is
S formed in a gap x between the central opening 65 of the disk
substrate 63 and the column-like portion of the hub 67 fitted
to this central opening 65, in a gap y between the
circumferential portion of the central opening 65 and the
flange portion 73 applied along this circumferential portion,
0 and in a gap 7 between the inward end faces s7 of the hubs
67, and a groove 78 acts as a reservoir for the adhesive.
In the present invention, it is desirable to provide the
groove 78 from the standpoint of adhesive force, but this
groove 78 is nct essential and, depending on circumstances
1S the groove 78 may be omissible. In the present inven-tion, it
is desirable, from the standpoint of adhesion strength, to
form the adhesive layer 83 at the three portions x, y and z.
However, the adhesive layer 83 may be formed only at the
portion y or may be formed at the portions x and y or y and
z.
Lubricant lQYer
In the present invention, for example, in the optical
disk 61, a ].ubricant layer (not shown) is formed in the
opening edge 100 of the center hole 77 into which the tip
521a of the spindle 93 is inserted or in the vicinity of said
l8 2 ~
opening edge 100. In the present invention this lubricant
layer may have varying thickness depending on the kind oE the
lubricant used, but usually has a thickness o-f 1 to 50,000 A,
preferahly 5 to 20,000 ~, and especially 100 to 15,000 A, and
is formed by coating a lubricant, for example, silicone
grease.
In the present invention, it is desirable to use such
lubricants that they are transparent, non-volatile or
sparingly volatile and excellent in chemical stability,
though any known lubricants may be used. Such lubricants as
mentioned above include, for exampler silicone oil, silicone
grease (for example, silicone oil incorporated with viscosity
increasing agents ~thickeners) such as metallic soap, etc.,
and various additives such as oiliness improvers,
antioxidants, etc.), silicone oil compound (a product
obtained by mixing silicone oil with, for example, finely
divided silicon oxide powders etc. and, if necessary, various
additives), fatty acid esters, fluorocarbon, polyester type
lubricants containing fatty acid, petroleum waxes, mineral
oil waxes, metallic soap grease, Teflon type lubricants, etc.
Of these lubricants exemplified above, preferred are silicone
grease or silicone oil compounds.
The silicone grease used herein includes, for example,
silicone grease series G 30r G 31, G 40, G 41, G 420, G 501,
FG 720, G 330, G 340 and G 630 produced and sold by Shin-etsu
~9 2 ~ 3
Silicone K.K., and silicone grease SH 33, SH 41, SH 49, SH 45
and SG 34S1 produced and .sold by Toray Dow Corning Silicone
K.K.
The silicone oil compounds used herein include, for
example, HIVAC-G produced and sold by Shin-ets~l Silicone K.K.
and HVG produced and sold by Toray Dow Corning Silicone K.K.
The lubricant layer mentioned above may be formed in
position, for example, in an optical disk laid in an optical
disk cartridge as shown in Fig. 8, by first opening an open-
0 close shutter 513 of the cartridge case 510 and then fixingit with a clip, and then a given amount of the lubricant such
as silicone grease is applied to the opening edge 100 of the
entral opening of the hub or in the vicinity of said opening
edge, for example, by using applicator having a end portion
applied with the lubricant.
In that case, an excess lubricant such as silicone
grease attached to the opening edge 100, it is desirable to
wipe out said lubricant with a clean applicator. Further,
when silicone grease is attached to portions other than the
opening edge 100 or the vicinity thereof, it is also
desirable to wipe out said silicone grease with a new
applieator. The applieator onee used is desirably discarded.
Through the wiping operation as mentioned above, it is
possible to inhibit effectively the contamination of the
20 ~ 3
optical disk with the lubricant and the occurrence of errors
in the recording and reproducing operation of information.
In the embodiment of the optical disk of the invention,
the lubricant layer is formed in the opening edge 100 for -the
spindle 93 or in the vicinity thereof, hence the sliding or
slip characteristics between the spindle 93 and the center
hole 77 of the hub 67 can be improved.
The optical disk 61 of the invention, as illustrated
hereinbefore, has the lubricant layer provided on the surface
(tapered portion) of the central openiny 89 into which the
spindle 93 is inserted.
In the optical disk as shown in Fig. 1 or 2, the
metallic member 67a (or s12) is embedded in the column-like
portion 71 constituting the hub 67, and other portions of the
column-like portion (that is, opening circumferential
portions s9 and sll and inner peripheral portion s8 of the
center hole 77) are formed from resin. In the optical disk
as mentioned above, the spindle 93 is inserted into the
center hole provided the lubricant layer on the s~lrface of
the central opening 89 and having excellent slip
characteristics, hence the loading and unloading operation
becomes smooth and no poor loading performance occurs.
Accordingly, this optical disk 61 is optimum when used
in the automatic loading and unloading operation of -the disk
~5 on and off the disk drive (driving device) for several ten-
2 1
thousands to several hundred thousands times by virtue of anautochanger.
The optical disk 61 of the invention .is used by holding
and setting said disk on the driving device 91 as shown in
Fig. 5, while inserting the spindle g3 of the driving device
91 into the center hole 77 and attracting the metallic member
67a to a magnet 95 of the driving device 91.
Further, the optical disk 61 of one embodiment oE the
0 invention mentioned above may be used as an optical disk
cartridge by holding said disk rotatably within a cartridge
case 510 of a thin hollow case shape as shown in Fig. 8 or 9.
The cartridge case 510 in which the optical disk is
received is prepared, for example, by laminating together a
~5 pair of case forming member 510a and 510b made from a
synthetic resin so that a hollow portion 511 is formed. In
this cartridge case 510, an open window 512 through which a
part of the op-tical disk substrate is exposed externally on
both sides of said cartridge case 510. The cartridge case
510 mentioned above is provided with an open-close shutter
513 for the open window 512 fitted to said open window 512 so
as to be slidable reciprocatively in the direction of an
arrow shown in Fig. 9.
Further, in the cartridge case 510, an opening 514 is
formed through which a turn table 96 of the disk driving
22 2 ~
device is inserted, and along the circumference of this
opening 514 an inner peripheral rib 515 is formed in an inner
surface of the cartridge case 510 opposite to the optical
disk. This inner peripheral rib 515 is intended to inhibit
S "looseness" of the optical disk by narrowing relatlvely the
space between the inner peripheral rib 515 and the optical
disX.
The optical disk received in this disk cartridge 510 is
rotated by fitting it to the optical disk driving device
0 having the turn table 96. This turn table 96 has an annular
holding portion 523 formed so as to embrace the hub 67 and
the spindle 93 projecting from the center of the turn table,
tapering off to the tip portion 521a and going to be inserted
into the center hole 77 of the hub 67.
In the turn table 96, a magnet 524 is provided in order
to attract the metallic plate s12 o~ the hub 67 in a state
where the hub 67 is embraced by the annular holding portion
523 and the spindle 93 is inserted into the center hole 77,
and the hub 67 is fixed on the turn table 96 by means of this
magnet and this annular holding portion. When the turn table
96 is set to rotate, the optical disk rotates and the disk
substrate 63 exposed through the open window 512 is
irradiated with a laser beam, whereby information is recorded
or reproduced in and from the optical disk.
23 ~ 6 3
In order to demonstrate the effect oE the present
invention, the present inventor conducted 20,000 times an
experiment of loading the optical disk of the invention on
the upright drive, whereupon no spin-up trouble occurred.
The upright drive referred to above has a disk cartridge
loading aperture formed perpendicular to the ground, and the
disk cartridge is inserted longitudinally into said loading
aperture.
Furtherr the present inventor prepared the optical disk
0 which was applied silicone grease (silicone oil compound HVG
produced and sold by Toray Dow Corning Silicone K.K.) by the
above-mentioned procedure to a thickness of 1 ~m on the
opening edge (tapered portion) 100 of each center hole of 10
optical disks ~both sides make 20 faces) of Fig. 1, each of
which was received in the cartridge case 510 as shown in Fig.
8, and put the optical disks thus treated were individually
put to "upright loading test" 50 times per one side (both
sides make 100 times), whereupon the spindle got accurately
and quickly into the center hole 77 of the hub 67 in every
case, the turn table of the upright drive attracted surely
the hub 67 and the optical disk was set to spin up (the
optical disk which is at a standstill suddenly initiates to
rotate by interlocking with rotation of the turn table),
whereupon no poor loading performance occurred.
24 2 ~ 3
In the "upright loading test" mentioned above, Sony
Drive SMO-S 501 produced and sold by Sony Corporation was
used as a driving device.
The present inventor conducted 25,000 -times an
experiment (load/unload test) -to load the optical disk (see
Fig. 1) on an upright drive (SMO-S 501 produced and sold by
Sony Corporation), whereby no -trouble occurred.
In conducting the above experiment, the load/unload test
was carried out automatically using a robot ~RV-CMI produced
and sold by Mitsubishi Elect. Corp.).
The load/unload test referred -to above is intended to
mean a repetition of such loading operation as mentioned
below, wherein a robot was used.
That is, the robot is allowed to insert into the upright
drive the optical disk which is completely taken off from the
drive, whereby the thus inserted optical disk is fitted
automatically to said drive. The upright drive is then set
to initiate the spin-up of the thus fitted optical disk,
whereby the upright drive is brought to "READY STATE" wherein
~0 the recording and reproducing operation becomes possible, and
"BUSSY LAMP" provided in said upright drive to instruct a
quick rota-tion of the optical disk goes off. After the lamp
went off, the robot is allowed to press "EJECT BUTTON" for
instructing to take out the optical disk therefrom, -thereupon
the optical disk is ejected therefrom to appear partly. The
2 ~
robot is then allowed to draw out completely the partly
appeared optical disk from the upright drive, whereb~ the
test terminates one time. By "load/unload test" is meant
that such a test as mentioned above is carried out
5 repeatedly. The drive was set to sound the alarm when the
drive is not brought to the "READY STATE" 15 seconds after
the optical disk was inserted into the drive. The tact -time
for the test of one time was 22 seconds.
Such a load/unload test as mentioned above was conducted
25,000 times, whereupon no trouble such as poor loading
performance occurred at all. No trouble was observed in the
hub portion when the hub portion was inspected visually in
the middle of the load/unload test, that is, 100 times, 200
times, 500 times, 2300 times, 5000 times, 12000 times, 14700
times and 20600 times after initiation of said test.
The optical disk of the present invention provided at
predetermined portions with a lubricant layer comprising
silicone grease (called also a silicone grease layer) was
allowed to stand at 80C/dry for 6000 hours, and the optical
disk thus treated was then put to the load/unload test 25000
times, whereupon no trouble such as poor loading performance
occurred at all in the same manner as mentioned above. The
hub portion was visually inspected in the middle of the
load/unload test in the same way as above, whereupon no
~5 trouble was observed.
2~
2~6~
Furtner, the optical disk provided at the predetermined
portions with the silicone grease layer was allowed to stand
at 80C/RH 85-~ for 300 hours, and then put to the load/unload
test in the sa~e way as above, whereupon no stress crack oE
the hub of the optical disk occurred and no such poor loading
performance as the optical disk runs idle to make noise or
the inner peripheral surface of the hub is shaved was
observed.
It is needless to say that the present invention is in
0 no way limited to the examples mentioned above and it will be
understood that variations and modifications can be effected
within the spirit and scope of the invention. For example,
various lubricants other than those used in the foregoing
examples may be used, and the opening edge of the center hole
1~ of the hub may not have a chamfer, though it desirably has a
chamfer (is desirably chamfered). The form of chamfered edge
and the shape of the hub are not limited to those mentioned
in the foregoing examples and may ~e formed into various
shapes.
The optical disks and hubs for optical disk illustrated
hereinbefore are of the "laminated type" (see Figs. 1 and 2).
The optical disks of the "single plate type" and the hubs for
the same are illustrated hereinbelow.
The ~ptical disk 21 shown in Fig. 13 is an opti.cal disk
of the single plate type and has a disk substrate 23a and a
27
hub 27 which is inserted into a central opening 25 of -the
disk substrate 23a.
The disk subskrate 23a and a recording material layer to
be fo.rmed thereon are the same as in the optical disks of the
laminated type.
The central opening 25 o~ the disk substrate 23a is
fitted with the hub 27. In the same manner as in the hub 67
in the op-tical disk of Fig. 1, the hub 27 has a cylindrical
portion 31, and a resin body 27 comprising a flange portion
33 extending outward from one end of said cylindrical portion
31 and a bottom portion 35 blockading the other end of said
cylindrical portion 31. In the bottom portion 35 is formed a
center hole 37 into which a spindle of a driving device is
inserted, and a cylindrical boss portion 33 surrounding the
center hole 37 is formed.
On the outer surface of the bottom portion 35 of this
resin body 27b is embedded an annular metallic member 27a,
and this metalllc member is arranged so that the center hole
37 is located within a central opening 39 of said metallic
member. The central opening 39 oE the metallic member 27a
has a radius larger than that of the center hole 37 of the
resi.n body 27b, and the inner edge of the opening 39 is apart
from inner peripheral portion sl wi-th a given distance. In
the bottom portion 35 of the resin body 27b, the boss portion
38 is a part of the bottom portion 35, and accordingly
2~
2 ~
circumferential edge portions s2, s3 and an interperipheral
portion sl of the center hole 37 are all made of resin. The
metallic member 27 has an exposed portion s5 between the
circumferential edge portion s2 of the center hole and an
outer peripheral edge portion s4 on the outer surface of the
bottom portion 35.
Materials used for the resin body 27b and metallic
member 27a are the same as those mentioned above.
The hub 27 and optical disk 21 are prepared in the same
manner as above.
Further, as shown in Fig. l~, the optical disk 61 of the
present invention may have a hub 27 consisting of a resin
body 27b and a metallic member 701 capable of being attracted
~y the magnet member provided on the turn table of the
driving device, which has the center hole 37 for the spindle
of the driving device, said center hole 36 having a projected
portion extending inward the cylindrical portion 31 of the
resin body 27b. It is desirable that an outer peripheral
edge of the metallic member 701 is embeded into the resin
body 27b of the hub 27, and fastened to said resin body.
An opening edge 100 of the single plate type optical
disk 21 into which the spindle 93 is inserted has desirably a
chamfer (is desirably chamfered) in the same manner as in the
laminated type optical disk 61 mentioned before, and a
29
2 ~ 3
lubricant layer (not shown) is formed in the chamfered
opening edge 100 in the same manner as above.
EEEE~T OF THE IN~EN~ION
As stated hereinbefore, in the present invention the
lubricant layer is formed by coating a lubricant on the
opening edge of the center hole of the hub or in the vicinity
thereof, hence sliding properties or slip characteristics
between the spindle and the opening edge of the hub can be
improved, and the optical disk can be smoothly loaded on the
disk drive to effect recording and reproducing information in
and from the optical disk smoothly.
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