Disk holding device

A disk holding device of a thin design is provided which can positively hold disks of different thicknesses, and also can automatically align the disk. The disk holding device includes a plurality of claw-like members, a center hub receiving the claw-like members therein, resilient members which are received in the center hub, and respectively urge the claw-like members in a radial direction of a disk, a turntable for supporting the disk thereon, a cone ring which is provided at a lower side of the center hub, and is movable along an axis of a spindle shaft and an urging member urging the cone ring in a disk-unloading direction away from an upper surface of the turntable. The cone ring has a slanting portion for engagement with a center hole portion of the disk, and each claw-like member is received in the center hub in such a manner that the claw-like member is slidable in the radial direction of the disk, and is angularly movable in the disk-unloading direction. With this construction, a force, required for loading and unloading the disk, is small, and therefore the deformation and strain of the disk can be kept to a minimum. And, the disk holding mechanism and the disk alignment mechanism can be combined into an integral construction, thereby achieving a thin design of the disk holding device.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a disk holding device for holding a disk medium 
so as to rotate the same, the disk holding device being used in an optical 
disk drive unit which records and reproduces information relative to the 
disk medium by light or light-magnetism. 
2. Description of the Related Art 
Recently, remarkable progress has been made in techniques relating to of 
recording and reproducing information by the use of light. Examples of 
read-only optical devices include a so-called CD (compact disk), a CD-ROM 
and a laser disk. Read-write optical devices have now been extensively 
used in secondary memory devices of computers, rewritable filing devices 
and so on. Large-capacity optical disk are devices, such as DVDs (digital 
versatile disk), are expected to become a mainstream product in the 
future. 
There exist various optical disk standards having respective features. 
These have been developed to meet requirements for performance and also 
because of differences in the time of development of the technologies. 
However, the existence of the various optical disk standards and the 
sacrifice of their interchangeability are disadvantageous in the handling 
of these optical disks and the extension of the market. Particularly, CDs 
and DVDs, which both have created a large market in homes and so on, and 
have almost the same appearance in the form of a disk having a diameter of 
12 cm, are not optically interchangeable with each other. As a result, the 
DVD disk can not be reproduced by a CD player, and the opposite is the 
same. This is due to differences in (1) thickness of a disk plate (CD is 
1.2 mm thick, and DVD consists of two 0.6 mm-thick plates laminated 
together), (2) characteristics of objective lenses, (3) wavelength of 
laser beams to be used, and recording density (the DVD is higher in 
density than the CD). 
In the market, there has been an increasing requirement that the two 
different disks, that is, the CD and the DVD, which have different 
standards, respectively, should be used in a common disk drive. A 
conventional disk holding device, which has been provided to meet this 
requirement, and is capable of holding such two different optical disks, 
will now be described with reference to the drawings. Generally, 
conventional disk holding devices are classified into a clamp type 
(disclosed for example in Japanese Patent No. 1509217) Japanese Patent 
Application No. 63-60459), in which a disk is clamped and held between two 
mechanism portions, and a self-holding type in which, when a disk is 
placed on a table, its holding mechanism holds the disk. In order to 
achieve a small-size and thin design of the disk drive unit, the 
self-holding type is advantageous. The disk holding device of the 
self-holding type will be described below. 
FIG. 25 is a view showing the construction of the conventional disk holding 
device of the self-holding type. In FIG. 25, a disk holding mechanism 
portion 30 capable of self-holding a disk 23 will be described. In FIG. 
25, a spindle motor 34 is broadly divided into a turntable unit 36 for 
holding the disk 23 and a drive portion 40 for rotating the disk 23. 
Reference is first made to the turntable unit 36. When holding the disk 23, 
claw-like members 26 first interfere with an inner peripheral edge of the 
disk 23. The claw-like members 26 are provided at at least three portions 
of a turntable 21. Each of the claw-like members 26 is urged radially 
outwardly (that is, toward the outer periphery) by a resilient member 27, 
and bosses (not shown), provided respectively on opposite sides of the 
claw-like member 26, are supported respectively by guides (not shown) of a 
center hub 25. 
On the other hand, the drive portion 40 mainly constitutes a magnetic 
circuit, and consists of a rotor yoke 37, magnets 38, a coil 39, a back 
yoke 42, and a bearing metal unit 41 supporting a spindle shaft 24 
press-fitted into the turntable 21. The spindle shaft 24 is rotatably 
supported on a thrust bearing 46. Hall elements 47 are mounted on an FPC 
48 provided on the surface of the back yoke 42, and are opposed to the 
magnets 38, respectively. In this embodiment, although the spindle motor 
is of the peripherally-opposed type, it may be of the surface-opposed type 
in which case the same functions are achieved. 
FIGS. 26A and 26B are illustrations of the operation of the disk holding 
mechanism portion 30 of FIG. 25. In FIGS. 26A and 26B, for loading the 
disk 23, the disk 23 is pressed respectively against rounded portions 26b 
of the claw-like members 26 (provided at at least three portions of the 
turntable 21) from the upper side, and is placed on the turntable 21. At 
this time, each claw-like member 26 is retracted by the disk 23 against 
the bias of the resilient member 27 to slide toward the inner periphery of 
the center hub 25 along the guides in the center hub 25. 
Thus, the inner peripheral edge of the disk 23 moves past the claw-like 
members 26 while pressing the rounded portions 26b of these claw-like 
members 26. The disk 23 is pushed until it is brought into intimate 
contact with a slip sheet 22 bonded to the turntable 21. 
When the inner peripheral edge of the disk 23 thus moves past the claw-like 
members 26, the claw-like members 26 are extended or projected under the 
influence of the resilient members 27, so that a lower slanting surface of 
the rounded portion 26 of each claw-like member 26 abuts against the inner 
peripheral edge of the disk 23. As a result, the disk 23 is self-held by 
the claw-like members 26 provided respectively at at least three portions 
of the turntable 21. At this time, even if the disk 23 is eccentric with 
respect to the spindle shaft 24, the disk 23 is held by the urging force 
of the claw-like members 26 held against the disk 23, and is rotated by 
the drive portion 40. 
Next, a disk holding device of the clamp type will be described, and a 
countermeasure to the above-noted eccentricity will also be described. 
FIG. 27 is a view showing the construction of the disk holding device of 
the clamp type. A turntable unit 36 for clamping a disk 23 will be 
described with reference to FIG. 27. In FIG. 27, a center boss 45 is 
provided at the center of a magnet clamper 44 having a magnet (not shown) 
embedded therein. The center boss 45 is engaged with a spindle shaft 24. 
When the magnet clamper 44 is closed, the magnet in the magnet clamper 44 
produces a magnetic attraction force relative to a ferromagnetic member 
(e.g. iron plate) embedded in a cone ring 28. The precision of the center 
position of the disk is maintained by the center boss 45 of the magnet 
clamper 44. The disk 23 is pressed against a turntable 21 uniformly over 
an entire surface thereof. 
A disk alignment mechanism portion for aligning the disk 23 so as to 
overcome the above eccentricity problem will be described with reference 
to FIG. 27. The turntable unit 36, having the disk alignment mechanism 
portion 31 mounted therein, is mounted on the spindle shaft 24. More 
specifically, the spindle shaft 24 is press-fitted in the turntable 21. 
The cone ring 28 is slidably mounted on the turntable 21, and is urged in 
a disk-unloading direction by a return coil spring 29. The sliding 
movement of the cone ring 28 is limited by a C-ring 43. That surface of 
the cone ring 28 for engagement with the inner peripheral edge of the disk 
23 is formed into a substantially conical surface which is tapered, that 
is, decreasing in diameter progressively in the disk-unloading direction. 
First, the disk 23 is placed on the disk alignment mechanism portion 31 of 
the above construction, and when the magnet clamper 44 is closed, the 
surface of the disk 23 is pressed against the turntable 21 as described 
above, and during this operation, the inner peripheral edge of the disk 23 
slides along the conical surface of the cone ring 28. As a result, the 
disk 23 can be aligned while being accurately held in position. 
In order that the above conventional disk holding devices can hold a CD and 
a DVD different in plate thickness from each other, and also can have a 
small-size and thin design, it is necessary that the disk holding device 
can self-hold the disk while aligning the disk. However, the reduction of 
the thickness of the turntable (base member) adversely affects the 
rigidity and the rotation accuracy particularly when the turntable is made 
of a resin material. Moreover, when the mechanism portion capable of 
self-holding and aligning the disk is mounted on the turntable, it has 
been difficult to reduce the thickness of the disk holding device in a 
direction of the thickness of the disk. 
Under these circumstances, the disk holding device has now been required to 
be capable of holding a CD and a DVD and also to have such a small-size 
and thin design as to be mounted in a mobile computer. 
SUMMARY OF THE INVENTION 
The present invention solves the above problems. It is an object of this 
invention to provide a disk holding device which can easily load and 
unload disks (e.g. a CD and a DVD) of different thicknesses and inner 
diameters, and can stably rotate the disk in a positively-loaded 
condition, and can be formed into a small-size and thin design with a 
simple mechanism. 
To solve the problems according to the present invention, there is provided 
a disk holding device which comprises a plurality of claw-like members, a 
center hub receiving the claw-like members therein, resilient members 
which are received in the center hub, and respectively urge the claw-like 
members in a radial direction of a disk, a turntable for supporting the 
disk thereon, a cone ring which is provided at a lower side of the center 
hub, and is movable along an axis of a spindle shaft, and an urging member 
urging the cone ring in a disk-unloading direction away from an upper 
surface of the turntable. The cone ring has a slanting portion for 
engagement with a center hole portion of the disk, and each claw-like 
member is received in the center hub in such a manner that the claw-like 
member is slidable in the radial direction of the disk, and is angularly 
movable in the disk-unloading direction. 
With this construction, the disk holding device can positively self-hold 
the selected disk with a proper holding force, and also can automatically 
align the disk even if the disks to be loaded have different thicknesses 
and different inner peripheral edge configurations. A force, required for 
loading and unloading the disk, is small, and therefore the deformation 
and strain of the disk can be kept to a minimum. Further, the disk holding 
mechanism and the disk alignment mechanism can be combined into an 
integral construction, thereby achieving a thin design of the disk holding 
device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
(First Embodiment) 
FIG. 1 is a cross-sectional view of a first embodiment of a disk holding 
device of the present invention. In the sheet of FIG. 1, a left side on a 
central spindle shaft 24 shows a condition before a disk is loaded whereas 
a right side on spindle shaft 24 shows a condition after the disk is 
loaded. FIG. 2 is a plan view of the disk holding device of FIG. 1. In 
FIGS. 1 and 2, a disk alignment mechanism portion 131 for aligning the 
disk 23, and a disk holding mechanism portion 130 for self-holding the 
disk 23 are mounted on a turntable unit 136. A drive portion 40 comprises 
the same mechanism as described above for the conventional drive portion 
40. The three kinds of mechanisms are combined together to form an 
integral construction. The drive portion 40 identical to the conventional 
drive portion will not be described in detail. 
The disk alignment mechanism portion 131 comprises a cone ring 128 and a 
return coil spring 129. FIGS. 3A and 3B show the cone ring 128 on an 
enlarged scale. As shown in FIGS. 1 to 3B, the cone ring 128 is disposed 
at a lower side of the disk holding mechanism portion 130. The cone ring 
128 is slidably mounted on a turntable 121. A slip sheet 122 for imparting 
an appropriate sliding friction torque to the disk 23 is bonded to a 
predetermined outer peripheral portion of the turntable 121, an inner 
periphery of this predetermined outer peripheral portion being radially 
spaced 12 mm from the center of the turntable 121 while its outer 
periphery is radially spaced 14 mm from the center. 
The cone ring 128 is urged in a disk-unloading direction by the return coil 
spring 129. The return coil spring 129 acts between a recessed portion 
(which defines a lower limit of the sliding movement of the cone ring 128) 
of the turntable 121 and a recessed portion in a reverse side of the cone 
ring 128. The return coil spring 129 is wound into a conical shape (see 
FIG. 1). The upward sliding movement of the cone ring 128 is limited by a 
center hub 125. With this construction, it is not necessary to provide the 
sliding movement limitation member, such as a C-ring, heretofore required, 
and therefore the disk alignment mechanism portion 131 of the present 
invention has a simple construction, and its manufacturing process is 
simplified, and the cost can be reduced. 
That surface of the cone ring 128 for engagement with the inner peripheral 
edge of the disk 23 is formed into a tapering (slanting) surface or 
portion 128a of a substantially conical shape decreasing in diameter 
progressively in the disk-unloading direction. Therefore, the position of 
the center of the disk is regulated by the tapering portion 128a engaged 
with the inner peripheral edge of the disk 23. With this construction, 
even if there are variations in the inner diameter of the disk 23, this 
inner diameter variation can be absorbed by the tapering portion 128a. The 
inner peripheral edge of the disk 23 engages the tapering portion 128a, 
and also engages claw-like members 126 (described later). With this 
arrangement, the disk 23 is aligned, and also is held on the turntable 
121. 
As shown in FIGS. 1 and 2, in the disk holding mechanism portion 130, the 
claw-like members 126 are arranged, for example, at three regions of the 
outer peripheral portion of the center hub 125, respectively, and are 
circumferentially spaced 120 degrees from one another. FIGS. 4A to 4D show 
the claw-like member 126 on an enlarged scale, and FIGS. 5A to 5D show the 
center hub 125 on an enlarged scale. 
In FIGS. 1, 2, 4A to 4D and 5A to 5D, the claw-like member 126 of a 
generally cross-shape has bosses 126 formed respectively on opposite sides 
thereof, and an engagement projection 126c formed at its rear end. A 
distal end portion of the claw-like member 126 has a slanting portion 126b 
decreasing the thickness progressively toward its distal end (that is, 
toward the outer periphery of the disk), and a ball end portion 126d of a 
semi-spherical shape. The claw-like member 126 is made, for example, of a 
resin. 
Center hub windows 125a are formed respectively in three portions of the 
center hub 125 spaced circumferentially 120 degrees from one another. 
Guide grooves 125b are formed at a reverse side of the center hub window 
125a, and an engagement projection 125c is provided at a radially-inner 
end of the center hub window 125a. The bosses 126a of each claw-like 
member 126 are engaged respectively in the guide grooves 125b of the 
associated center hub window 125a. The claw-like member 126 is supported 
on the center hub 125, with the bosses 126a engaged respectively in the 
guide grooves 125b, in such a manner that the claw-like member 126 is 
slidable in the radial direction of the disk, and also is angularly 
movable about the radially-outermost portions of the guide grooves 125b in 
a direction perpendicular to the disk surface. 
A resilient member 127 extends between each engagement projection 125c of 
the center hub 125 and the engagement projection 126c of the associated 
claw-like member 126, and is received in the center hub 125. The resilient 
member 127 comprises, for example, a compression spring. Spaces 135 for 
allowing the bending of the resilient members 127 are formed respectively 
in those portions of the turntable 121 disposed respectively beneath the 
three resilient members 127. Therefore, each claw-like member 126 is urged 
toward the outer periphery of the disk by the resilient member 127, so 
that the bosses 126a are engaged respectively in the radially-outermost 
portions of the guide grooves 125b in a stand-by condition. 
As shown in FIG. 7, the turntable unit 136 of the above construction can be 
formed into a total thickness of not more than 3.8 mm (for example, 3.5 
mm), and more specifically the dimension of its disk-unloading side 
portion, measured from the disk-mounting surface (that is, the upper 
surface of the slip sheet 22), is not more than 2.5 mm (for example, 2.25 
mm), and the dimension of its disk-loading side portion (close to the 
turntable 121), measured from the disk-mounting surface, is not more than 
1.3 mm (for example, 1.25 mm). 
The disk loading and unloading operations of the turntable unit 136 of the 
above construction will now be described. FIG. 6 is an enlarged, 
cross-sectional view of the disk holding device, showing a condition 
before the disk is loaded, and FIG. 7 is an enlarged, cross-sectional view 
of the disk holding device, showing a condition after the disk is loaded, 
and FIGS. 8A and 8B are views explanatory of the disk loading and 
unloading operations. In FIGS. 1, 6, 8A and 8B, for loading the disk 23, 
the operator first presses the disk 23 against the disk holding mechanism 
portion 130. As a result, the disk 23 is pressed against the slanting 
portions 126b of the three claw-like members 126 from the upper side, and 
is loaded onto the turntable 121. At this time, each of the claw-like 
members 126 is pushed and retracted by the disk 23 against the bias of the 
resilient member 127 to slide toward the inner periphery of the disk 23 
along the guide grooves 125b. 
When the disk 23 is further pushed, the inner peripheral edge of the disk 
23 moves past the ball end portions 126d of the claw-like members 126. 
During this operation, a lower edge of the inner peripheral edge of the 
disk 23 abuts against the tapering portion 128a of the cone ring 128. When 
the disk 23 is further pushed, the cone ring 128 is moved downward against 
the bias of the return coil spring 129, and at the same time the position 
of the center of the disk 23 is regulated by the tapering portion 128a 
(that is, the automatic alignment of the disk 23 is effected). The return 
coil spring 129 is wound into a spiral configuration, and therefore when 
the disk 23 is pushed or pressed down, a compression space of the coil 
spring will not limit a retraction stroke of the cone ring 128. 
The disk 23 is further pushed until it is brought into intimate contact 
with the slip sheet 122 bonded to the turntable 121. During this 
operation, the ball end portions 126d move past the disk 23 in the 
direction of the thickness of this disk, so that each claw-like member 126 
is projected to slide along the guide grooves 125b toward the outer 
periphery of the disk 23 under the influence of the resilient member 127. 
As a result, the ball end portions 126b of the claw-like members 126 abut 
against an upper edge of the inner peripheral edge of the disk 23, thereby 
holding the disk 23 on the turntable 121 under the influence of the 
resilient members 127. Thus, merely by pressing the disk 23 against the 
disk holding mechanism portion 130 by the operator and then by pushing the 
disk 23, the automatic alignment and the self-holding can be completed. 
Next, the unloading or removal of the disk 23 will be described with 
reference to FIGS. 1, 7, 8A and 8B. First, the operator lifts the disk 23 
in the unloading direction. As a result, the ball end portions 126d are 
subjected to an upwardly-lifting force. The bosses 126a of each claw-like 
member 126 are engaged respectively in the radially-outermost portions of 
the guide grooves 125b, and are angularly moved about the 
radially-outermost portions of the guide grooves 125b in a direction 
perpendicular to the disk surface (see arrows in FIGS. 8A and 8B). At this 
time, the engagement projection 126c of each claw-like member 126 is 
angularly moved toward the turntable 121, and also the resilient member 
127 is flexed or bent, and this angular movement and this flexing are both 
effected in the space 135. Therefore, the angular movement of the ball end 
portion 126d is not limited at all, and the disk 23 can be easily detached 
and removed from the turntable unit 136. 
As described above in detail, when the force is applied to back the 
claw-like member 126, the claw-like member 126 is retracted to slide in 
the radial direction of the disk, and when the force to remove the disk 23 
is applied, the claw-like member 126 is angularly moved upwardly about the 
radially-outermost portions of the guide grooves 125b in the direction 
perpendicular to the disk surface. The resilient member 127 can be flexed 
or bent downwardly. Namely, each claw-like member 126 is received in the 
center hub 125, and is slidable in the radial direction of the disk, and 
is angularly movable. With this construction, the disk holding mechanism 
portion 130 can be formed into a thin design, and also the operator can 
effect the automatic alignment and self-holding of the disk with the 
simple operation. Also, since the disk 23 can be easily removed with a 
small force, an undue force will not be applied to the disk. 
Next, urging means, which can replace the resilient members 127, will be 
described. FIG. 9 is a cross-sectional view of a disk holding device using 
this urging means, and FIG. 10 is a plan view thereof. In FIGS. 9 and 10, 
a disk alignment mechanism portion 131 is mounted on a turntable unit 136, 
and a disk holding mechanism portion 150 is mounted coaxially with the 
disk alignment mechanism portion 131. This basic construction is identical 
to that described above for FIG. 1, and therefore explanation of the 
turntable unit 136 and the disk alignment mechanism portion 131 will be 
omitted. 
The disk holding mechanism portion 150 comprises a center hub 155 (serving 
as a main component), claw-like members 156, and an O-ring 152. Center hub 
windows 155a are formed, for example, in three portions of the center hub 
155, respectively, and are circumferentially spaced 120 degrees from one 
another. A reverse side of the center hub window 155a has the same 
construction as described above for FIG. 1. 
Each claw-like member 156 has bosses 156a engaged respectively in guide 
grooves 155b, and is supported on the center hub 155 in such a manner that 
it is slidable in the radial direction of the disk, and also is angularly 
movable about radially-outermost portions of the guide grooves 155b in a 
direction perpendicular to the disk surface. A distal end portion of the 
claw-like member 156 has the same configuration as described above for 
FIGS. 4A to 4D. 
The configuration of a radially-inner end portion of the center hub window 
155a and the configuration of a radially-inner end portion of the 
claw-like member 156 are different from those described above for FIGS. 1 
and 4A to 4D. The O-ring 152 in the form of an annular elastic ring having 
a substantially circular cross-section is provided at the radially-inner 
portions of the center hub windows 155a. The radially-inner end of the 
claw-like member 156 is extended to abut against the O-ring 152. An inner 
peripheral surface of the O-ring 152 is held in contact with an O-ring 
stopper 153, and hence is prevented from displacement. Therefore, the 
O-ring 152 is provided between the center hub 155 and the O-ring stopper 
153. More specifically, the difference between this construction and the 
construction of FIG. 1 is that the O-ring 152 performs the same function 
as the resilient members 127 of FIG. 1 do. 
The disk holding mechanism 150 of the above construction, in which the 
O-ring 152 is used instead of the resilient members 127, achieves a 
self-retaining function totally similar to that described above. In this 
case, the number of the component parts is smaller, and also an assembling 
and adjusting process can be made simpler as compared with the disk 
holding mechanism portion using the resilient members 127, and therefore 
there can be provided the inexpensive disk holding mechanism portion. 
(Second Embodiment) 
FIG. 11 is a partially cross-sectional view of a second embodiment of a 
disk holding device of the invention. FIG. 12 is a plan view of the disk 
holding device of FIG. 11. FIG. 13 is an enlarged, cross-sectional view 
showing a claw-like member 226 before a disk is loaded. In FIG. 11, a 
right side on a central spindle shaft 24 is a cross-sectional view of the 
disk holding device, showing a condition before the disk is loaded whereas 
a left side on the spindle shaft 24 is a side-elevational view showing a 
condition after the disk is loaded. 
A disk alignment mechanism portion 231 for aligning the disk 23 is mounted 
on a turntable unit 236. A disk holding mechanism portion 230 for 
self-holding the disk 23 is mounted coaxially on the spindle shaft 24, and 
is disposed on the disk alignment mechanism portion 231. As in the first 
embodiment, the two kinds of mechanism portions are combined together to 
form an integral construction. 
On the other hand, a drive portion 40 has the same construction as that of 
the first embodiment and the conventional device, and therefore identical 
portions will be designated by identical reference numerals, respectively, 
and explanation thereof will be omitted. 
The disk alignment mechanism portion 231 comprises a cone ring 228 and a 
return coil spring 229. FIGS. 14A and 14B are enlarged views showing the 
cone ring 228. As shown in detail in FIGS. 14A and 14B, projected portions 
228b of the cone ring 228 are disposed in an extension of a tapering 
portion 228a of the cone ring 228, and are provided respectively at three 
regions of the outer peripheral portion of the disk holding mechanism 
portion 230, and extend in a circumferential direction. The amount of 
projection of each protected portion 228b is about 20% of the overall 
thickness of the cone ring 228. The cone ring 228 is disposed at a lower 
side of the disk holding mechanism portion 230. The cone ring 228 is 
slidably mounted on a turntable 221, and the whole of the cone ring 228 is 
movable in a direction perpendicular to the disk surface. A slip sheet 222 
for imparting an appropriate sliding friction torque to the disk 23 is 
bonded to a predetermined outer peripheral portion of the turntable 221, 
an inner periphery of this predetermined outer peripheral portion being 
radially spaced 12 mm from the center of the turntable 221 while its outer 
periphery is radially spaced 14 mm from the center. 
The return coil spring 229 acts between a recessed portion (which defines a 
lower limit of the sliding movement of the cone ring 228) of the turntable 
221 and a recessed portion in a reverse side of the cone ring 228. 
Therefore, the cone ring 228 is urged in a disk-unloading direction by the 
return coil spring 229. The return coil spring 229 is wound into a conical 
shape (see FIG. 11). The upward sliding movement of the cone ring 228 is 
limited by a center hub 225. 
With this construction, it is not necessary to provide any limitation 
member, such as a C-ring, heretofore required, and therefore the disk 
alignment mechanism portion 231 of the invention has a simple 
construction, and its manufacturing process is simplified, and the cost 
can be reduced. Also, the influence of the diameter of the return coil 
spring 229, which would be encountered when pushing the cone ring 228 a 
full stroke, is eliminated. 
That surface of the cone ring 228 for engagement with the inner peripheral 
edge of the disk 23 is formed into a tapering (slanting) surface or 
portion 228a of a substantially conical shape decreasing in diameter 
progressively in the disk-unloading direction. Here, as shown in FIGS. 13, 
14A and 14B, if the maximum region of sliding movement of the cone ring 
228 (in a thrust direction when loading the disk) is set to 0.5 mm, the 
good aligning effect is achieved (that is, the alignment is effected in a 
best-balanced manner) when the angle of inclination of the tapering 
portion 228a with respect to a plane (horizontal plane) perpendicular to 
the spindle shaft 24 is set to the range of between 68.7.degree. and 
88.7.degree., and the optimum inclination angle is 78.7.degree.. The inner 
peripheral edge of the disk 23 engages the tapering portion 228a, and 
further depending on the configuration of the inner peripheral edge, it is 
positively brought into engagement with the claw-like members 226 through 
the projected portions 228b formed in the extension of the tapering 
portion 228a. 
With this construction, even if there are variations in the inner diameter 
of the disk 23, this inner diameter variation can be absorbed by the 
tapering portion 228a. Therefore, the disk 23 is aligned, and also is held 
on the turntable 221. 
As shown in FIGS. 11 and 12, in the disk holding mechanism portion 230, the 
claw-like members 226 are arranged, for example, at three regions of the 
outer peripheral portion of the center hub 225, respectively, and are 
circumferentially spaced 120 degrees from one another. FIGS. 15A to 15C 
show the claw-like member 226 on an enlarged scale, and FIGS. 16A to 16D 
show the center hub 225 on an enlarged scale. 
In FIGS. 11, 12, 13 and 15A to 15C, the claw-like member 226 of a generally 
cross-shape has bosses 226 formed respectively on opposite sides thereof, 
and an engagement projection 226e formed at its rear end. A distal end 
portion of the claw-like member 226 has a slanting portion 226b decreasing 
the thickness progressively toward its distal end (that is, toward the 
outer periphery of the disk). If the angle of inclination of the slanting 
portion 226b with respect to the plane (horizontal plane) perpendicular to 
the spindle shaft 24 is set to the range of between 130.degree. and 
150.degree., a good disk-loading effect is achieved, and the optimum 
inclination angle is 140.degree.. A projected distal end portion 226c of 
the claw-like member 226 forms a curved line of a modified oval 
cross-section (see FIGS. 15A to 15C), and includes a reversely-slanting 
surface disposed generally perpendicular to the slanting surface 226b, and 
a lower projected portion 226d defined by a surface extending from the 
reversely-slanting surface. The amount of projecting of the lower 
projected portion 226d is about 10% of the overall thickness of the 
claw-like member 226. The claw-like member 226 is made, for example, of a 
resin. 
With this configuration of the claw-like member 226 having the lower 
projected portion 226d, when the thinnest one of the disks, which can be 
used in a disk drive unit, is loaded, this disk can be positively held by 
the lower projected portions 226d of the claw-like members 226. And 
besides, with this construction of the disk holding mechanism portion 230, 
the overall thickness of this mechanism portion 230 can be reduced, and 
also a force, required for removing or unloading the optical disk 23, can 
be reduced. 
Center hub windows 225a are formed respectively in three portions of the 
center hub 225 spaced circumferentially 120 degrees from one another. 
Guide grooves 225b are formed at a reverse side of the center hub window 
225a, and an engagement projection 225c is provided at a radially-inner 
end of the center hub window 225a. The bosses 226a of each claw-like 
member 226 are engaged respectively in the guide grooves 225b of the 
associated center hub window 225a. The claw-like member 226 is supported 
on the center hub 225, with the bosses 226a engaged respectively in the 
guide grooves 225b, in such a manner that the claw-like member 226 is 
slidable in the radial direction of the disk, and also is angularly 
movable about the radially-outermost portions of the guide grooves 225b in 
a direction perpendicular to the disk surface. 
A resilient member 227 extends between each engagement projection 225c of 
the center hub 225 and the engagement projection 226e of the associated 
claw-like member 226, and is received in the center hub 225. The resilient 
member 227 comprises, for example, a compression spring. Spaces 235 for 
allowing the bending of the resilient members 227 are formed respectively 
in those portions of the turntable 221 disposed respectively beneath the 
three resilient members 227. Therefore, each claw-like member 226 is urged 
toward the outer periphery of the disk by the resilient member 227, so 
that the bosses 226a are engaged respectively in the radially-outermost 
portions of the guide grooves 225b in a stand-by condition. 
As shown in FIG. 11, the turntable unit 236 of the above construction can 
be formed into a total thickness of not more than 4.0 mm (for example, 
3.75 mm), and more specifically the dimension of its disk-unloading side 
portion, measured from the disk-mounting surface (that is, the upper 
surface of the slip sheet 222), is not more than 2.7 mm (for example, 2.5 
mm), and the dimension of its disk-loading side portion (close to the 
turntable 221), measured from the disk-mounting surface, is not more than 
1.3 mm (for example, 1.25 mm)(not shown but similar with the showing of 
FIG. 7). 
The disk loading and unloading operations of the turntable unit 236 of the 
above construction will now be described. FIG. 17 is a view showing the 
disk loading and unloading operations by the disk holding device of FIG. 
11. The correlation between the disk holding mechanism portion 230 and the 
disk alignment mechanism portion 231 of the invention, as well as the 
operation of the claw-like members 226 during the loading and unloading of 
the disk 23, will be described in detail with reference to FIGS. 11, 13 
and 17. 
First, the disk loading operation will be described. The operator presses 
the disk 23 against the disk holding mechanism portion 230 (FIG. 17(a)). 
As a result, the disk 23 is pressed against the slanting portions 226b of 
the three claw-like members 226 from the upper side, and is loaded onto 
the turntable 221. At this time, each of the claw-like members 226 is 
pushed and retracted by the disk 23 against the bias of the resilient 
member 227 to slide toward the inner periphery of the disk 23 along the 
guide grooves 225b (FIG. 17(b)). 
When the disk 23 is further pushed, the inner peripheral edge of the disk 
23 passes past the projected distal end portions 226c of the claw-like 
members 226. During this operation, a lower edge of the inner peripheral 
edge of the disk 23 abuts against the tapering portion 228a of the cone 
ring 228. When the disk 23 is further pushed, the cone ring 228 is moved 
downward against the bias of the return coil spring 229, and at the same 
time the position of the center of the disk 23 is regulated by the 
tapering portion 228a (that is, the automatic alignment of the disk 23 is 
effected). The return coil spring 229 is wound into a spiral 
configuration, and therefore when the disk 23 is pushed or pressed down, a 
compression space of the coil spring will not limit a retraction stroke of 
the cone ring 228. 
The disk 23 is further pushed until it is brought into intimate contact 
with the slip sheet 222 bonded to the turntable 221. During this 
operation, the projected distal end portion 226c pass past the disk 23 in 
the direction of the thickness of this disk, so that each claw-like member 
226 is projected to slide along the guide grooves 225b toward the outer 
periphery of the disk 23 under the influence of the resilient member 227. 
At this time, if the disk 23 has a standard thickness, the 
reversely-slanting surfaces and projected distal end portions 226d (each 
continuous with the associated reversely-slanting surface) of the 
claw-like members 226 abut against an upper edge of the inner peripheral 
edge of the disk 23, thereby holding the disk 23 on the turntable 221 
under the influence of the resilient members 227 (FIG. 17(c)). On the 
other hand, if the disk 23 has a smaller thickness, the projected distal 
end portion 226d of each claw-like member 226 abuts against the upper edge 
of the inner peripheral edge of the disk 23, and further is brought into 
engagement with the upper surface of the disk 23, thereby holding the disk 
23 on the turntable 221 (FIG. 17(d)). Thus, merely by pressing the disk 23 
against the disk holding mechanism portion 230 by the operator and then by 
pushing the disk 23, the automatic alignment and the self-holding can be 
completed. 
Next, the unloading or removal of the disk 23 will be described. First, the 
operator lifts the disk 23 in the unloading direction. As a result, the 
reversely-slanting surface and projected distal end portion 226d 
(continuous therewith) of each claw-like member 226 are subjected to an 
upwardly-lifting force. The bosses 226a of each claw-like member 226 are 
engaged respectively in the radially-outermost portions of the guide 
grooves 225b, and the claw-like member 226 is angularly moved about the 
radially-outermost portions of the guide grooves 225b in a direction 
perpendicular to the disk surface (see arrows in FIGS. 17(e) and 17(f)). 
At this time, the engagement projection 226e of each claw-like member 226 
is angularly moved toward the turntable 221, and also the resilient member 
227 is flexed or bent, and this angular movement and this flexing are both 
effected in the space 235. Therefore, the angular movement of the 
reversely-slanting surface and projected distal end portion 226d 
(continuous therewith) of the claw-like member 226 is not limited at all, 
and the disk 23 can be easily detached and removed from the turntable unit 
236 (FIG. 17(g)). 
As described above in detail, when the force to push the claw-like member 
226 back is applied, the claw-like member 226 is retracted to slide in the 
radial direction of the disk, and when the force to remove the disk 23 is 
applied, the claw-like member 226 is angularly moved upwardly about the 
radially-outermost portions of the guide grooves 225b in the direction 
perpendicular to the disk surface. The resilient member 227 can be flexed 
or bent downwardly. Namely, each claw-like member 226 is received in the 
center hub 225, and is slidable in the radial direction of the disk, and 
is angularly movable. With this construction, the disk holding mechanism 
portion 230 can be formed into a thin design, and also the operator can 
effect the automatic alignment and self-holding of the disk with the 
simple operation. And besides, since the disk 23 can be easily removed 
with a small force, an undue force will not be applied to the disk. 
Next, the balance between the force of the aligning function and the force 
of the self-holding function in the above operation will be described in 
further detail. As shown in FIG. 11, the disk 23 is mounted on the slip 
sheet 222, bonded to the turntable 221, while maintaining a certain static 
friction coefficient. As a result, a slip force, withstanding an angular 
acceleration developing when the disk 23 is rotated, is produced. If this 
slip force is too large or too small, the disk holding device can not 
properly function. This slip force is produced by the holding force with 
which the three claw-like members 226 are pressed against the upper edge 
portion of the center hole in the disk 23. The larger the holding force 
becomes, the larger the slip force becomes. 
This holding force is also influenced by the pushing force applied 
uniformly to the lower edge portion of the center hole in the disk 23 by 
the cone ring 228. With the increase of the holding force, the force of 
the urging means (for example, the spring force of the return coil spring 
229), urging the cone ring 228 in the disk-unloading direction, must be 
increased; otherwise, the disk can not be aligned in a well-balanced 
manner. 
Therefore, with respect to the relationship of these three forces, the 
spring force of the compressed resilient members 227, required to 
self-hold the disk by the three claw-like members 226, is set to 200 
gf.+-.50 gf. Then, in order to press the cone ring 228 uniformly against 
the disk, the spring force of the return coil spring 229 is set to 100 
gf.+-.50 gf, and further the slip force of the disk is set to 200 gf.+-.50 
gf. By doing so, these forces, acting on the disk, can be well balanced. 
Next, modified urging means, which can replace the return coil spring 229 
in the disk alignment mechanism portion 231, will be described. FIG. 18 is 
an enlarged, cross-sectional view of a disk holding device using this 
modified urging means. The urging means of FIG. 18 differs from the urging 
means of FIG. 11 in that instead of the return coil spring 229, a wave 
washer 229a is provided between a turntable 221 and a cone ring 228. The 
other constituent elements are the same as those of FIG. 11, and the 
operation of the urging means and the operation of the cone ring 228 are 
generally similar to those in the first embodiment. 
Features, obtained by the use of this wave washer 229a, will be described. 
The wave washer 229a has such a wavy configuration that the bottom of each 
wave thereof is held in contact with a recessed portion of the turntable 
221 while the top (crest) of each wave thereof is held in contact with a 
lower side of the cone ring 228. The wave height between the bottom and 
top of the wave satisfies the range of movement of a disk alignment 
mechanism portion 231, that is, a region (0.5 mm) of sliding movement of 
the cone ring 228 in a direction of the axis thereof. Another feature, 
obtained by the use of the wave washer 229a, is that an optimum number of 
waves of the wave washer can be selected. More specifically, in this 
embodiment, there are provided three claw-like members 226 and three 
slanting portions 228a of a cone ring 228. Therefore, if the number of the 
crests of the waves (that is, the number of the waves) of the wave washer 
229a is set to a multiple of 3, load points of the cone ring 228 are urged 
or pushed uniformly over the entire periphery thereof. The number of the 
waves is not limited to the above number, but it can be set to the range 
of 3 to 6, in which case also the load points of the cone ring 228 are 
urged uniformly over the entire periphery thereof. In this case, of 
course, the urging force is set to a value equal to the spring force (100 
gf.+-.50 gf) of the above-mentioned return coil spring 229. The 
deformation of the waves, which produces this urging force, is effected 
between the recessed portion of the turntable 221 and the lower side of 
the cone ring 228, and therefore the region (0.5 mm) of sliding movement 
of the cone ring 228 in the axial direction is not affected at all. 
Therefore, with the thin-design construction, the self-holding and the 
automatic alignment of the center hole portion of the disk can be 
effected. 
Next, another modified urging means, which can replace the return coil 
spring 229 in the disk alignment mechanism portion 231, will be described. 
FIG. 19 is an enlarged, cross-sectional view of a disk holding device 
having this modified urging means. The urging means of FIG. 19 differs 
from the urging means of FIG. 11 in that instead of the return coil spring 
229, magnets 229b are provided between a turntable 221 and a cone ring 
228. The other constituent elements are the same as those of FIG. 11, and 
the operation of the urging means and the operation of the cone ring 228 
are generally similar to those in the first embodiment. 
Features, obtained by the use of the magnets 229b, will be described. In 
FIG. 19, the magnets 229a are arranged in such a manner that their 
surfaces of the same pole (for example, their surfaces each having a N 
pole or a S pole) are opposed to each other. Also, the magnets 229b are 
arranged to provide such an air gap as to enable a disk alignment 
mechanism portion 231 to achieve its function. Under no load (that is, in 
a condition in which the disk is not loaded), a magnetic repulsion force 
of the magnets 229b is set to 100 gf.+-.50 gf as described above for the 
spring force of the abovementioned return coil spring 229. The magnet 229b 
comprises an annular ferromagnetic body, and may be magnetized over an 
entire circumference thereof, or may be magnetized at regions spaced 
circumferentially from one another. Alternatively, sector-shaped 
ferromagnetic pieces may be arranged at equal intervals in the 
circumferential direction. With this construction, the load points of the 
cone ring 228 are urged uniformly over the entire periphery thereof. 
Therefore, with the thin-design construction, the self-holding and the 
automatic alignment of the center hole portion of the disk can be 
effected. 
(Third Embodiment) 
FIG. 20 is a partially cross-sectional view of a third embodiment of a disk 
holding device of the invention. In FIG. 20, a right side on a central 
spindle shaft 24 is a side-elevational view of the disk holding device, 
showing a condition before the disk is loaded whereas a left side on the 
spindle shaft 24 is a cross-sectional view showing a condition after the 
disk is loaded. 
A disk alignment mechanism portion 331 for aligning the disk 23 is mounted 
on a turntable unit 336. A disk holding mechanism portion 330 for 
self-holding the disk 23 is mounted coaxially on the spindle shaft 24, and 
is disposed on the disk alignment mechanism portion 331. As in the first 
embodiment, the two kinds of mechanism portions are combined together to 
form an integral construction. 
On the other hand, a drive portion 40 has the same construction as that of 
the first embodiment and the conventional device, and therefore identical 
portions will be designated by identical reference numerals, respectively, 
and explanation thereof will be omitted. 
The disk alignment mechanism portion 331 comprises a cone ring 328 and a 
wave washer 329a. FIGS. 21A and 21B are enlarged views showing the cone 
ring 328. As shown in detail in FIGS. 21A and 21B, projected portions 328b 
of the cone ring 328 are disposed respectively in extensions of slanting 
portions 328a of the cone ring 328, and extend in a disk-unloading 
direction. The projected portions 328b are provided respectively at three 
regions of the outer peripheral portion of the disk holding mechanism 
portion 330, and extend in a circumferential direction. The length of a 
slanting surface of each projected portion 328b is about one to two times 
larger than the thickness of the disk. The cone ring 328 is disposed at a 
lower side of the disk holding mechanism portion 330. The cone ring 328 is 
slidably mounted on a turntable 321, and the whole of the cone ring 328 is 
movable in a direction perpendicular to the disk surface. A slip sheet 322 
for imparting an appropriate sliding friction torque to the disk 23 is 
bonded to a predetermined outer peripheral portion of the turntable 321, 
an inner periphery of this predetermined outer peripheral portion being 
radially spaced 9 mm from the center of the turntable 321 while its outer 
periphery is radially spaced 14 mm from the center. 
Next, description will be made of an example in which the wave washer 329a 
is used as urging means in the disk alignment mechanism portion 331. FIG. 
20 differs from FIG. 11 in that instead of the return coil spring 229, the 
wave washer 329a is provided between the turntable 321 and the cone ring 
328. The wave washer 329a has such a wavy configuration that the bottom of 
each wave thereof is held in contact with a recessed portion of the 
turntable 321 while the top (crest) of each wave thereof is held in 
contact with a lower side of the cone ring 328. The wave height between 
the bottom and top of the wave satisfies the range of movement of the disk 
alignment mechanism portion 331, that is, a maximum region (0.6 mm) (the 
expected stroke for the standard disk is not more than about 1/2 of the 
disk thickness, and is 0.4 mm) of sliding movement of the cone ring 328 in 
a direction of the axis thereof. Therefore, the cone ring 328 is urged in 
the disk-unloading direction. The sliding movement of the cone ring 328 is 
limited by a center hub 325. By the use of the wave washer 329a, an 
optimum number of waves of the wave washer can be selected. More 
specifically, in this embodiment, there are provided three claw-like 
members 326 and the three slanting portions 328a of the cone ring 328 as 
in the embodiment of FIG. 12. Therefore, if the number of the crests of 
the waves (that is, the number of the waves) of the wave washer 329a is 
set to a multiple of 3, load points of the cone ring 228 are urged or 
pushed uniformly over the entire periphery thereof. The number of the 
waves is not limited to the above number, but it can be set to the range 
of 3 to 6, in which case also the load points of the cone ring 228 are 
urged uniformly over the entire periphery thereof. The deformation of the 
waves, which produces this urging force, is effected between the recessed 
portion of the turntable 321 and the lower side of the cone ring 328, and 
therefore the maximum region (0.6 mm) of sliding movement of the cone ring 
328 in the axial direction is not affected at all. Therefore, with the 
thin-design construction, the self-holding and the automatic alignment of 
the center hole portion of the disk can be effected. 
With the above construction, it is not necessary to provide any limitation 
member, such as a C-ring, heretofore required, and therefore the disk 
alignment mechanism portion 331 of the present invention has a simple 
construction, and its manufacturing process is simplified, and the cost 
can be reduced. Also, the influence of the diameter of the return coil 
spring 329, which would be encountered when pushing the cone ring 328 to 
an end of the maximum sliding region, is eliminated. 
Those surfaces of the cone ring 328 for engagement with the inner 
peripheral edge of the disk 23 are formed respectively into the slanting 
portions 328a each defined by part of a substantially conical shape 
decreasing in diameter progressively in the disk-unloading direction. The 
slanting portions 328a will now be described in detail with reference to 
FIGS. 21A and 21B. The device is so designed that the disk can be loaded 
with the maximum pushing (loading) stroke of 0.6 mm. If the maximum region 
of sliding movement of the cone ring 328 (in a thrust direction when 
loading the disk) is set to 0.6 mm, a good aligning effect is achieved 
(that is, the alignment is effected in a best-balanced manner) when the 
angle of inclination of the slanting portion 328a with respect to a plane 
(horizontal plane) perpendicular to the spindle shaft 24 is set to the 
range of between 68.7.degree. and 88.7.degree., and the optimum 
inclination angle is 78.7.degree.. The inner peripheral edge of the disk 
23 engages the slanting portions 328a, and further depending on the 
configuration of the inner peripheral edge, it is positively brought into 
engagement with the claw-like members 326 through the projected portions 
328b formed respectively in the extensions of the slanting portions 328a. 
As described above, each of the slanting portions 328a is defined by part 
of a substantially conical surface. However, depending on a desired touch 
obtained when loading the disk, the slanting portion 328a may be formed 
into part of a spherical surface in such a manner that the angle of a line 
tangential to the surface of the slanting portion 328a is within the range 
of the above inclination angle. In this case, similar effects can be 
achieved. The surface of the slanting portion 328a may be formed of metal 
or a resin. A material of a low friction coefficient, such as Teflon 
(polytetrafluoroethylene), may be bonded to the surface of the slanting 
surface 328a. These modifications can be effected in order to adjust the 
touch obtained when loading the disk. 
With the above construction, even if there are variations in the inner 
diameter of the disk 23, this inner diameter variation can be absorbed by 
the slanting portions 328a. Therefore, the disk 23 is aligned, and also is 
held on the turntable 321. 
As shown in FIG. 12 (showing the second embodiment) and FIG. 20, in the 
disk holding mechanism portion 330 of this embodiment, the claw-like 
members 326 are arranged, for example, at three regions of the outer 
peripheral portion of the center hub 325, respectively, and are 
circumferentially spaced 120 degrees from one another. FIGS. 22A to 22D 
show the claw-like member 326 on an enlarged scale, and FIGS. 23A to 23D 
show the center hub 325 on an enlarged scale. 
In FIGS. 20 and 23A to 23D, the claw-like member 326 of a generally E-shape 
has bosses 326a formed respectively on opposite sides thereof, and an 
engagement projection 326e formed at its rear end. A distal end portion of 
the claw-like member 326 has a slanting portion 326b decreasing the 
thickness progressively toward its distal end (that is, toward the outer 
periphery of the disk). The slanting portion 326b forms a slanting surface 
slanting gently toward the distal end from an apex of a semi-spherical 
surface continuous with the opposite side surfaces. If the angle of 
inclination of the slanting portion 326b with respect to a plane 
(horizontal plane) perpendicular to the spindle shaft 24 is set to the 
range of between 140.degree. and 160.degree., a good disk-loading effect 
is achieved, and the optimum inclination angle is 150.degree.. 
A projected distal end portion 326c of the claw-like member 326 forms a 
curved surface (see FIGS. 22A to 22D) having an apex into which the upper, 
lower, right and left surfaces merge. The projected distal end portion 
326c has a reversely-slanting flat lower surface 326d disposed generally 
perpendicular to the slanting surface 326b, and this reversely-slanting 
flat surface 326d extends to the lower end of the claw-like member 326. 
With respect to the overall length of the reversely-slanting surface 326d, 
it is extended from the body of the claw-like member 326 by an amount 
equal to about 35% of the thickness of this body which corresponds to the 
thickness of the projected distal end portion 326c. If the angle of 
inclination of the reversely-slanting surface 326d with respect to the 
plane (horizontal plane) perpendicular to the spindle shaft 24 is set to 
the range of between 100.degree. and 128.degree., a good disk loading 
effect is achieved, and the optimum inclination angle is 114.degree.. 
With this configuration of the claw-like member 326 having the 
reversely-slanting surface 326d, the reversely-slanting surfaces 326d of 
the claw-like members 326 cooperate with the slanting portions 328a of the 
cone ring 328 to positively hold the inner peripheral edge portion of the 
disk 23 to thereby effect the automatic alignment thereof. Also, thanks to 
the reversely-slanting surfaces 326d, each formed over the entire 
thickness of the claw-like member 326, and the slanting surfaces of the 
projected portions 328b of the cone ring 328, even if there are variations 
in the inner diameter of the disk and the thickness of the inner 
peripheral edge portion of the disk, these variations can be absorbed. 
Therefore, the disk 23 is aligned, and is held on the turntable 321. With 
this construction of the disk holding mechanism portion 330, the overall 
thickness of this mechanism portion 330 can be reduced, and also a force, 
required for removing or unloading the optical disk 23, can be reduced. 
Center hub windows 325a are formed respectively in three portions of the 
center hub 325 spaced circumferentially 120 degrees from one another. 
Guide grooves 325b are formed at a reverse side of the center hub window 
325a, and an engagement projection 325c is provided at a radially-inner 
end of the center hub window 325a. A bottom projected portion 325d, 
projecting in a terrace-like manner, is provided at the bottom of the 
radially-outer end portion of the center hub window 325a. The bosses 326a 
of each claw-like member 326 are engaged respectively in the guide grooves 
325b of the associated center hub window 325a. The claw-like member 326 is 
supported on the center hub 325, with the bosses 326a engaged respectively 
in the guide grooves 325b, in such a manner that the claw-like member 326 
is slidable in the radial direction of the disk, and also is angularly 
movable about the radially-outermost portions of the guide grooves 125b 
(and the radially-innermost portion of the bottom projected portion 325d) 
in a direction perpendicular to the disk surface. When the bosses 326a 
slide respectively along the guide grooves 325b, the bottom projected 
portion 325d serves as a guide, and when loading the disk 23, the bottom 
projection portions 325d function to support the pressing force applied to 
the claw-like members 326 from the upper side. When unloading or removing 
the disk 23, the bottom projected portion 325d serves as a pivot point 
about which the bosses 326a are angularly moved. When the bottom projected 
portion 325d is provided at the radially-outer end portion of the center 
hub window 325a as described above, it achieves the intended functions, 
but the position of provision of the bottom projected portion 325d is not 
limited to the radially-outer end portion of the center hub window 325a, 
and it may be formed on the center hub 325 over the entire circumference 
thereof. In this case, the configuration of the center hub 325 is simpler, 
and the molding of the center hub 325 can be effected more easily. 
A resilient member 327 extends between each engagement projection 325c of 
the center hub 325 and the engagement projection 326e of the associated 
claw-like member 326, and is received in the center hub 325. The resilient 
member 327 comprises, for example, a compression spring. Spaces 335 for 
allowing the bending of the resilient members 327 are formed respectively 
in those portions of the turntable 321 disposed respectively beneath the 
three resilient members 327. Therefore, each claw-like member 326 is urged 
toward the outer periphery of the disk by the resilient member 327, so 
that the bosses 326a are engaged respectively in the radially-outermost 
portions of the guide grooves 325b (and the radially-innermost portions of 
the bottom projected portions 325d in a stand-by condition). 
As shown in FIG. 7, the turntable unit 336 of the above construction can be 
formed into a total thickness of not more than 3.8 mm (for example, 3.5 
mm), and more specifically the dimension of its disk-unloading side 
portion, measured from the disk-mounting surface (that is, the upper 
surface of the slip sheet 322), is not more than 2.5 mm (for example, 2.25 
mm), and the dimension of its disk-loading side portion (close to the 
turntable 321), measured from the disk-mounting surface, is not more than 
1.3 mm (for example, 1.25 mm). 
The disk loading and unloading operations of the turntable unit 336 of the 
above construction will now be described. FIGS. 24A and 24B are views 
showing the disk loading and unloading operations by the disk holding 
device of FIG. 20. The correlation between the disk holding mechanism 
portion 330 and the disk alignment mechanism portion 331 of the invention, 
as well as the operation of the claw-like members 326 during the loading 
and unloading of the disk 23, will be described in detail with reference 
to FIGS. 20 to 24B. 
First, the disk loading operation will be described. The operator presses 
the disk 23 against the disk holding mechanism portion 330 (FIG. 24A(a)). 
As a result, the disk 23 is pressed against the slanting portions 326b of 
the three claw-like members 326 from the upper side, and is loaded onto 
the turntable 321. At this time, each of the claw-like members 326 is 
pushed by the disk 23, while supported by the bottom projected portion 
325d, to be retracted against the bias of the resilient member 327 to 
slide toward the inner periphery of the disk 23 along the guide grooves 
325b (FIG. 24A(b)). 
When the disk 23 is further pushed, the inner peripheral edge of the disk 
23 moves past the projected distal end portions 326c of the claw-like 
members 326. During this operation, a lower edge of the inner peripheral 
edge of the disk 23 abuts against the slanting portions 328a of the cone 
ring 328. When the disk 23 is further pushed, the cone ring 328 is moved 
downward against the bias of the wave washer 329a, and at the same time 
the position of the center of the disk 23 is regulated by the slanting 
portions 328a (that is, the automatic alignment of the disk 23 is 
effected). 
At this time, since the number of the waves of the wave washer 329a is set 
to a multiple of the number of the claw-like members 326, the load points 
of the cone ring 328 are urged uniformly over the entire periphery 
thereof. Also, since the deformation of the waves is effected between the 
recessed portion of the turntable 321 and the lower side of the cone ring 
328, the region of sliding movement of the cone ring 328 in the axial 
direction (that is, the retraction stroke) is not affected at all. 
The disk 23 is further pushed until it is brought into intimate contact 
with the slip sheet 322 bonded to the turntable 321. During this 
operation, the projected distal end portion 326c pass past the disk 23 in 
the direction of the thickness of this disk, so that each claw-like member 
326 is projected to slide along the guide grooves 325b toward the outer 
periphery of the disk 23 under the influence of the resilient member 327. 
At this time, if the disk 23 has a standard thickness or a smaller 
thickness, the reversely-slanting surfaces 326d of the claw-like members 
326 and the slanting portions 328a of the cone ring 328 abut against the 
upper and lower edges of the inner peripheral edge of the disk 23, thereby 
holding the disk 23 on the turntable 321 and also effecting the automatic 
alignment. Particularly in this third embodiment, the reversely-slanting 
surface 326d of each claw-like member 326 and each slanting portion 328a 
of the cone ring 328 both have the respective long extension portions, and 
therefore abut against the upper and lower edges of the inner peripheral 
edge of the disk 23, so that the claw-like members 326 will not slide onto 
the upper surface of the disk 23 (FIG. 24A(c)). Thus, merely by pressing 
the disk 23 against the disk holding mechanism portion 330 by the operator 
and then by pushing the disk 23, the automatic alignment and the 
self-holding can be completed. 
Next, the unloading or removal of the disk 23 will be described. The 
operator lifts the disk 23 in the unloading direction (FIG. 24B(d)). As a 
result, the reversely-slanting surface 326d of each claw-like member 326 
is subjected to an upwardly-lifting force. The bosses 326a of each 
claw-like member 326 are angularly moved about an axis on the bottom 
projected portion 325d in a direction perpendicular to the disk surface 
(see an arrow in FIG. 24B(e)). At this time, the engagement projection 
326e of each claw-like member 326 is angularly moved toward the turntable 
321, and also the resilient member 327 is flexed or bent, and this angular 
movement and this flexing are both effected in the space 335. At the same 
time, the reversely-slanting surface 326d is pushed by the disk 23, and is 
retracted to slide along the guide grooves 325b toward the inner periphery 
of the disk against the bias of the resilient member 327. Therefore, the 
angular movement of the reversely-slanting surface 326d of the claw-like 
member 326 is not limited at all, and the disk 23 can be easily detached 
and removed from the turntable unit 336. After the disk 23 is removed, 
each claw-like member 326 is returned to its stand-by position (FIG. 
24B(f)). 
As described above in detail, when the force is applied to push back the 
claw-like member 326, the claw-like member 326 is retracted to slide in 
the radial direction of the disk, and when the force to remove the disk 23 
is applied, the claw-like member 326 is angularly moved in the 
disk-unloading direction about the bottom protected portion 325d. The 
resilient member 327 can be flexed or bent downwardly. Namely, each 
claw-like member 326 is received in the center hub 325, and is slidable in 
the radial direction of the disk, and is angularly movable in the 
disk-unloading direction. With this construction, the disk holding 
mechanism portion 330 can be formed into a thin design, and also the 
operator can effect the automatic alignment and self-holding of the disk 
with the simple operation. And besides, since the disk 23 can be easily 
removed with a small force, an undue force will not be applied to the 
disk. 
Next, the balance between the force of the aligning function and the force 
of the self-holding function in the above operation will be described in 
further detail. As shown in FIG. 20, the disk 23 is mounted on the slip 
sheet 322, bonded to the turntable 321, while maintaining a certain static 
friction coefficient. As a result, a slip force, withstanding an angular 
acceleration developing when the disk 23 is rotated, is produced. If this 
slip force is too large or too small, the disk holding device can not 
properly function. This slip force is produced by the holding force with 
which the three claw-like members 326 are pressed against the upper edge 
portion of the center hole in the disk 23. The larger the holding force 
becomes, the larger the slip force becomes. 
This holding force is also influenced by the pushing force applied 
uniformly to the lower edge portion of the center hole in the disk 23 by 
the cone ring 328. With the increase of the holding force, the force of 
the urging means (for example, the spring force of the wave washer 329a), 
urging the cone ring 328 in the disk-unloading direction, must be 
increased; otherwise, the disk can not be aligned in a well-balanced 
manner. 
Therefore, with respect to the relationship of these three forces, the 
spring force of the compressed resilient members 327, required to 
self-hold the disk by the three claw-like members 326, is set to 200 
gf.+-.50 gf. Then, in order to press the cone ring 328 uniformly against 
the disk, the spring force of the wave washer 329a is set to 100 gf.+-.50 
gf, and further the slip force of the disk is set to 200 gf.+-.50 gf. By 
doing so, these forces, acting on the disk, can be well balanced. 
In this third embodiment, the urging means, urging the cone ring 328, 
comprises the wave washer 329a. However, in this embodiment, the same 
effects can be achieved even if a return coil spring or magnets are used 
as in the second embodiment. Therefore, explanation of such modification, 
using the return coil spring or the magnets, will be omitted.