Disk support device having deformation limiting member

A disk support device for supporting a disk having a central hub, a central support hole and a rotatable drive shaft, a turntable fixedly mounted on the rotatable drive shaft and having a hole for supporting the disk on one surface thereof with the rotatable drive shaft inserted in the central support hole in the disk, a leaf spring having one end fixed to an opposite surface of the turntable and supporting a positioning pin remotely from the one end thereof, the positioning pin projecting under the resiliency of the leaf spring through the hole in the turntable for engagement in the support hole in the disk, and a stopper fixed to the opposite surface of the turntable in spaced relation thereto, the leaf spring being interposed between the opposite surface of the turntable and the stopper for being subjected to a limited extent of deformation.

BACKGROUND OF THE INVENTION 
The present invention relates to a disk support device for supporting and 
driving a small-size disk such as a 3.5-inch magnetic disk, and more 
particularly to a disk support device capable of accurately positioning a 
disk at the time it is supported thereon. 
One conventional type of disk support device is illustrated in FIGS. 1 and 
2 of the accompanying drawings. The disk support device serves to drive a 
flexible magnetic disk which is 3.5 inches across. 
The disk support device includes a rotatable drive shaft 1 which is rotated 
by a brushless motor (not shown) rotating at a constant speed, and a 
turntable 2 fixed to an upper end portion of the rotatable drive shaft 1. 
The rotatable drive shaft 1 has an upper end 1a projecting beyond an upper 
surface of the turntable 2. The turntable 2 has a hole 2a and an 
internally threaded hole 2b. A leaf spring 3 is mounted on a lower surface 
of the turntable 2 and has a central recess 3a defined therein and a 
support hole 3b defined in an end thereof. The leaf spring 3 has a 
positioning pin 4 fixed to an opposite end thereof. The rotatable drive 
shaft 1 is inserted in the recess 3a in the leaf spring 3. A fastening 
screw 5 is inserted through the support hole 3b threadedly into the 
internally threaded hole 2b to secure the corresponding end of the leaf 
spring 3 to the lower surface of the turntable 2. The positioning pin 4 
projects upwardly out of the hole 2a beyond the upper surface of the 
turntable 2. 
FIGS. 3 and 4 illustrate the manner in which a flexible magnetic disk 6 is 
mounted on the disk support device shown in FIGS. 1 and 2. Designated at 7 
is a hub secured to a central portion of the magnetic disk 6. As shown in 
FIG. 3, the hub 7 has a central support hole 7a and another support hole 
7b. When the magnetic disk 6 is mounted on the disk support device, the 
end 1a of the rotatable drive shaft 1 is inserted in the central support 
hole 7a and the positioning pin 4 is inserted in the other support hole 
7b. 
In operation, the turntable 7 is rotated clockwise in the direction of the 
arrow A by the rotatable drive shaft 1 to thereby rotate the hub 7 and the 
magnetic disk 6 in the direction of the arrow A. A magnetic head (not 
shown) is pressed against the magnetic disk 6 to record or reproduce 
information. 
While the magnetic head is pressed against the magnetic disk 6, a 
resistance is imposed from the magnetic disk 6 on the magnetic head to 
bring an edge of the support hole 7b in the hub 7 into abutment against 
the positioning pin 4, which is then subjected to a force in the direction 
of the arrow B. Therefore, the positioning pin 4 tends to be tilted 
through an angle .alpha., thus deforming the leaf spring 3 as shown in 
FIG. 4. 
When this happens, the hub 7 is displaced off the properly mounted position 
on the turntable 2. In general, one-pulse index signals are recorded at 
given positions on the magnetic disk in magnetic disk recording apparatus. 
The positions where such index signals are recorded must be accurate in 
order to ensure compatibility among the magnetic disk recording apparatus. 
If the magnetic disk 6 is displaced off position with respect to the 
turntable 2 as described above, then index signals will be generated at 
different positions, and compatibility among the magnetic disk recording 
apparatus will be lost. 
SUMMARY OF THE INVENTION 
With the prior art shortcoming in view, it is an object of the present 
invention to provide a disk support device of a simple construction which 
is capable of positioning a magnetic disk accurately with respect to a 
turntable. 
According to the present invention, there is provided a disk support device 
for supporting a disk having a central hub having a central support hole 
and a support hole includes a rotatable drive shaft, a turntable fixedly 
mounted on the rotatable drive shaft and having a hole for supporting the 
disk on one surface thereof with the rotatable drive shaft inserted in the 
central support hole in the disk, a leaf spring having one end fixed to an 
opposite surface of the turntable and supporting a positioning pin 
remotely from the one end thereof, and a stopper fixed to the opposite 
surface of the turntable in spaced relation thereto, the leaf spring being 
interposed between the opposite surface of the turntable and the stopper 
for being subjected to a limited extent of deformation. When the turntable 
is rotated, the deformation of the leaf spring is limited to prevent the 
positioning pin from being unduly tilted with respect to the turntable. 
The above and other objects, features and advantages of the present 
invention will become more apparent from the following description when 
taken in conjunction with the accompanying drawings in which a preferred 
embodiment of the present invention is shown by way of illustrative 
example.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 5 and 6 illustrate a disk support device according to the present 
invention. 
The disk support device of the present invention includes a rotatable drive 
shaft 11 which is rotated by a brushless motor (not shown) which is driven 
to rotate at a constant speed, and a turntable 12 fixed to an upper end 
portion of the rotatable drive shaft 11. The rotatable drive shaft 11 has 
an upper end 11a projecting beyond an upper surface of the turntable 12. 
The turntable 12 has a hole 12a and an internally threaded hole 12b, and 
also has a recess 12c defined in an outer peripheral surface thereof. A 
leaf spring 13 is mounted on a lower surface of the turntable 12 and has a 
central recess 13a defined therein and a support hole 13b defined in an 
end thereof. The leaf spring 13 has a crank-shaped finger 13c extending in 
an opening of the recess 13a, and a positioning pin 14 fixed as by staking 
to an opposite end of the leaf spring 13. An auxiliary plate 15 is 
disposed below the leaf spring 13 and is composed of a thick metal sheet 
which will not be easily deformed under external forces applied thereto. 
The auxiliary plate 15 has a support hole 15a in one end thereof and a 
stopper 15b bent from an opposite end thereof, there being a recess 15c 
defined in an edge adjacent to the stopper 15b. 
When the leaf spring 13 the auxiliary plate 15 are mounted on the lower 
surface of the turntable 12, the rotatable drive shaft 11 is inserted in 
the recess 13a in the leaf spring 13 and positioned in the recess 15c in 
the auxiliary plate 15. A fastening screw 15 is inserted through the 
support holes 15a, 13b threadedly into the internally threaded hole 12b to 
secure the leaf spring 13 and the auxiliary plate 15 to the lower surface 
of the turntable 12. The positioning pin 14 projects upwardly out of the 
hole 12a beyond the upper surface of the turntable 12. The stopper 15b of 
the auxiliary plate 15 is spaced from the lower surface of the turntable 
12, with the finger 13c interposed between the lower surface of the 
turntable 12 and the stopper 15b. 
To a flexible magnetic disk 6 to be mounted on the disk support device, 
there is centrally fixed a hub 7 (FIG. 7) having a central support hole 7a 
and another support hole 7b defined therein. 
Operation of the disk support device thus constructed is as follows: 
When the magnetic disk 6 is to be mounted on the disk support, the hub 7 is 
placed on the upper surface of the turntable 12 (FIGS. 7 and 8). At this 
time, the distal end 11a of the rotatable drive shaft 11 projecting from 
the turntable 12 is inserted in the central support hole 7a. The 
positioning pin 14 is held against the lower surface of the hub 7 and has 
its distal end disposed back in the turntable 12 with the leaf spring 13 
being flexed. As the turntable 12 starts rotating and the positioning pin 
14 reaches the support hole 7b in the hub 7, the positioning pin 14 is 
inserted into the support hole 7b and projects upwardly beyond the upper 
surface of the hub 7 under the resilient force of the leaf spring 13. 
Thereafter, the positioning pin 14 drives the hub 7 to rotate the magnetic 
disk 6 in the direction of the arrow A in FIG. 7. 
Since a magnetic head is pressed against the magnetic disk 6 during 
operation of the magnetic recording and reproducing apparatus, as 
described above, the magnetic disk 6 is subjected to a resistance to 
rotation thereof, and hence the hub 7 imposes a force in the direction of 
the arrow B in FIG. 7 on the positioning pin 14. Therefore, the leaf 
spring 13 tends to be twisted, but is twisted only to a limited extent 
since the finger 13c of the leaf spring 13 is engaged by the stopper 15b 
of the auxiliary plate 15. As a consequence, the positioning pin 14 is 
tilted by the force applied in the direction B through an angle .beta. 
which is much smaller than the angle .alpha. shown in FIG. 4. The angle 
.beta. is determined solely by the dimensions of the finger 13c and the 
stopper 15b. Therefore, by keeping the angle .beta. in a range 
corresponding to an allowable error of the positional accuracy of the 
index signals recorded on the magnetic disk 6, the positions where the 
index signals are generated are rendered accurate. Desired compatibility 
amonth the recording and reproducing apparatus is thus ensured. 
Although in the illustrated embodiment the leaf spring 13 has the finger 
13c which is interposed between the lower surface of the turntable 12 and 
the stopper 15b, the stopper 15b may be of a greater area and spaced from 
the turntable 12 with only a small spacing therebetween, and the leaf 
spring 13 may be disposed as a whole between the turntable 12 and the 
stopper 15b for limited movement therebetween. 
With the arrangement of the present invention, the positioning pin is 
tilted only through a minimum angle smaller than a certain critical angle 
when the pisitioning pin is subjected to a force tending to resist the 
rotation of the magnetic disk. The magnetic table is thus positioned 
accurately on the turntable, and hence the positions of the index signals 
recorded on the magnetic disk are accurately determined with respect to 
the turntable. The index signals are always generated at the same 
positions in different magnetic recording and reproducing apparatus, which 
are therefore rendered compatible with each other. The construction for 
ensuring the above positional accuracy is simple since the positioning pin 
is prevented from being unduly tilted by the stopper disposed below the 
leaf spring. 
Although a certain preferred embodiment has been shown and described, it 
should be understood that many changes and modifications may be made 
therein without departing from the scope of the appended claims.