Disk drive device having a swingable lever carrying pin and positioned in a space between a rotary plate and a magnetic member mounted on the rotary plate

A disk drive device incorporated in a disk apparatus has a rotary plate mounted on a rotary drive shaft and a magnet mounted on the rotary plate. A recess is formed in the lower surface of the magnet or the upper surface of the rotary plate. A swingable lever having a first end portion pivotally connected to the rotary plate is accommodated in the recess. A second end portion of the swingable lever carries a disk drive pin movably disposed in an opening formed in the magnet. Before the disk drive pin engages with a drive pin engagement hole of a disk, the disk drive pin is depressed in a direction parallel to the axis of the rotary drive shaft by the disk magnetically attracted by the magnet toward the rotary plate. At this time, the second end portion of the swingable lever resiliently deforms away from the magnet. The rotary plate is formed therein with an opening for receiving the deformed second end portion of the swingable lever, thus allowing the thickness of the entire device to be reduced.

BACKGROUND OF THE INVENTION 
The present invention relates to a device for driving and thus rotating a 
disk (hereinafter referred to as "a disk drive device") which is 
incorporated in a disk apparatus. 
A conventional disk drive device of this type has a structure such as that 
disclosed in, e.g., Japanese Patent Unexamined Publication No. 64-78462. 
To describe the outline of the conventional device, a rotary plate is 
mounted on a rotary drive shaft and integrally rotatable therewith. A 
swingable lever has its proximal end portion pivotally supported by the 
lower surface of the rotary plate in such a manner that the lever is also 
movable in the axial direction of the rotary drive shaft. The swingable 
lever is urged by a spring toward the rotary plate. A drive pin is 
provided on a distal end portion of the swingable lever and extends 
through a hole formed in the rotary plate and also through another hole 
formed in a magnet mounted on the rotary plate so as to magnetically 
attract a disk. 
When a disk is placed on the rotary plate with a central hole of the disk 
fitted onto the rotary drive shaft, the disk is magnetically attracted by 
the magnet. In this condition, a drive pin engagement hole formed in the 
disk at a position eccentric to the center of the disk is not aligned with 
the drive pin. Therefore, the drive pin is pushed downward by the disk, so 
that the drive pin and the swingable lever are lowered from the disk 
against the force of the spring. When the rotary drive shaft is rotated by 
a motor of the disk apparatus, the rotation causes the rotary plate and 
the swingable lever to rotate. The disk, however, is held by a magnetic 
head of the apparatus and does not rotate until the drive pin engages with 
the drive pin engagement hole of the disk. This engagement causes the 
torque of the rotary plate to be transmitted through the drive pin to the 
disk, thereby causing the disk to rotate. 
In the conventional disk drive device, the swingable lever is, as described 
above, supported by the lower surface of the rotary plate in such a manner 
as to be movable in the axial direction of the rotary shaft so that the 
drive pin of the swingable lever is engageable with the drive pin 
engagement hole of the disk. This arrangement requires clearances to be 
provided in order to prevent unnecessary contact between the swinging 
lever and other component parts, thus making it impossible to reduce the 
thickness of the entire device. The conventional device has another 
drawback that a costly spring for applying spring force to the swinging 
lever is required. 
SUMMARY OF THE INVENTION 
The present invention has been made to eliminate such drawbacks of the 
conventional device. An object of the present invention is to provide a 
disk drive device constructed such that the swinging lever is accommodated 
within the thickness of the disk attracting magnet and/or the rotary 
plate, thereby enabling a reduction in the thickness of the entire device 
and such that the structure of the device is simplified to reduce the 
production cost. 
According to the present invention, there is provided a device for driving 
a disk of the type that has a central hole and a disk drive pin engagement 
hole at a position radially spaced from the central hole, the device 
comprising: a rotary drive shaft engageable with the central hole of the 
disk; a rotary plate mounted on the rotary drive shaft in such a manner as 
to be rotatable together with the rotary drive shaft; a magnet mounted on 
one of the major surfaces of the rotary plate in such a manner as to be 
rotatable together with the rotary plate, the magnet being capable of 
magnetically attracting the disk; means defining a space between the 
rotary plate and the magnet; and a swingable lever accommodated in the 
space and pivotally connected, at a first portion adjacent a first end of 
the lever, to the rotary plate. The magnet has an opening formed therein 
at a position adjacent to a first end of the space. The swingable lever 
has a disk drive pin provided thereon at a second portion adjacent a 
second end of the lever, the disk drive pin being engageable with the disk 
driven pin engagement hole of the disk and being movably disposed in the 
opening of the magnet. At least the second end portion of the swingable 
lever is resiliently deformable in such a manner as to deflect away from 
the magnet when the disk drive pin is depressed in a direction parallel to 
the axis of the rotary drive shaft by the disk when the same is 
magnetically attracted by the magnet. The rotary plate has receptacle 
means for receiving the deformed portion of the swingable lever which 
includes the second end portion. 
As described above, the swingable lever carrying the disk drive pin is 
accommodated by the means which define a space between the rotary plate 
and the magnet which are disposed in contact with each other, while the 
rotary plate has the receptacle means for receiving at least the distal 
end portion of the swingable lever which elastically deforms or deflects 
when the disk drive pin is depressed in a direction parallel to the rotary 
drive shaft by the disk when the same is magnetically attracted by the 
magnet. This arrangement permits the swingable lever to elastically deform 
without requiring any separate space to be provided in the drive in 
addition to the dimension of the total of the thickness of the rotary 
plate and that of the magnet. Therefore, the present invention makes it 
possible to reduce the thickness of the entire disk drive device, to 
simplify the structure of the device and to reduce the production cost. 
The above and other objects, features, and advantages of the present 
invention will be more apparent from the following description with 
reference to the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
An embodiment of the present invention will be described with reference to 
FIGS. 1 and 2. 
A rotary drive shaft 1 has an end portion engageable with two adjacent 
sides of a square central hole of a disk (not shown). A circular hub 2 is 
secured to the end portion of the shaft 1 which extends through the hub 2. 
The hub 2 has an outer peripheral portion to which the inner peripheral 
edge portion of a central hole 3a of a rotary plate 3 is secured, so that 
the rotary plate 3 is rotatable integrally with the rotary drive shaft 1. 
An annular magnet 4 for magnetically attracting a disk is mounted on the 
upper surface of the rotary plate 3 and has a central hole 4a whose inner 
peripheral edge contacts the outer periphery of the hub 2. A space 5 for 
accommodating a swingable lever 8 is defined between the magnet 4 and the 
rotary plate 3 at a position spaced radially outwardly from the rotary 
drive shaft 1. 
In the embodiment illustrated in FIGS. 1 and 2, the space 5 comprises a 
recess formed in the lower surface (the surface facing the rotary plate 3) 
of the magnet 4. As indicated by the broken lines in FIG. 1, the recess 5 
is of an arcuate shape. The magnet 4 has a notch 6 (serving as an opening 
of the magnet) formed in the inner peripheral edge of the central hole 4a 
of the magnet 4 and communicating with a first end of the recess 5. On the 
other hand, the rotary plate 3 has formed therein an opening 7 aligned 
with the notch 6 and a part of the length of the arcuate recess 5. Within 
the recess 5, a first end portion of the swingable lever 8 is pivotally 
supported by a shaft 9 protruding from the rotary plate 3 in parallel with 
the rotary drive shaft 1, with the second end of the lever 8 projecting 
into both of the notch 6 of the magnet 4 and the opening 7 of the rotary 
plate 3. The swingable lever 8 is formed of a plate spring member (e.g., a 
sheet of stainless steel or phosphor bronze having a thickness of 08 to 
0.20 mm) so that the lever 8 has a flexibility imparted thereto. A drive 
pin 10 parallel with the rotary drive shaft 1 is provided on and projects 
from the upper surface of the distal end (the second end) of the swingable 
lever 8. The drive pin 10 extends through the notch 6 of the magnet 4. 
The drive pin 10 is provided to drive a disk and, for this purpose, is 
engageable with two adjacent sides of a square, drive pin engagement hole 
formed in the disk at a position eccentric to the center of the disk. In 
order to achieve such engagement, the swingable lever 8 and the drive pin 
10 are pivotally movable through a certain angle about the axis of the 
shaft 9. The outermost position of the pivotal movement is defined by a 
stopper 11 projecting from a part of the radially outer edge of the 
opening 7 of the rotary plate 3, the stopper 11 consisting of a portion of 
the rotary plate 3 cut and raised at that part of the opening 7. On the 
other hand, the innermost position of the pivotal movement is defined by 
another stopper 12 formed by the radially inner edge of the recess 5 in 
the lower surface of the magnet 4. 
Although not shown, the innermost position of the pivotal movement of the 
swingable lever 8 and the drive pin 10 about the shaft 9 may alternatively 
be defined by the outer peripheral edge of the hub 2. The outermost 
position of the pivotal movement may alternatively be defined by a portion 
11a of the magnet 4, as shown in FIG. 3. Specifically, in the modification 
shown in FIG. 3, the portion 11a of the magnet 4 projects into the opening 
7 of the rotary plate 7, thereby constituting a stopper. The structure of 
the device may be such that the distal end of the swingable lever 8 is 
narrowed, and the drive pin 10 provided on the narrowed end is allowed to 
abut against the radially inner and outer stoppers. 
The operation of the embodiment having the above-described construction 
will be described below. 
When the central hole of a disk is fitted onto the rotary drive shaft 1 and 
the position of the disk relative to the rotary plate 3 is thus 
determined, the disk is magnetically attracted by the magnet 4 against the 
hub 2. In this position, the drive pin engagement hole of the disk is not 
aligned with the drive pin 10. Therefore, the drive pin 10 is depressed by 
the lower surface of the disk, thereby causing the swingable lever 8 to 
deflect downwardly, so that the drive pin 10 and the distal end of the 
lever 8 are lowered into the opening 7 of the rotary plate 3. 
Subsequently, the rotary drive shaft 1, the rotary plate 3, the swingable 
lever 8 and other associated members are rotated. However, the disk, which 
is held by the magnetic head (not shown) of the disk apparatus, does not 
rotate until the drive pin 10 slides on the lower surface of the disk into 
alignment with the drive pin engagement hole of the disk. Upon this 
alignment, the drive pin 10 is forced into the drive pin engagement hole 
by the elasticity of the swingable lever 8, more specifically, the ability 
of the lever 8 to recover its original shape. This is followed by the 
engagement of the rotary drive shaft 1 and the drive pin 10 with two 
adjacent sides of the central hole of the disk and those of the drive pin 
engagement hole of the disk, respectively. The engagement causes the disk 
to rotate. 
As described above, according to the foregoing embodiment of the present 
invention, when the disk is magnetically attracted by the magnet 4, the 
swingable lever 8 deflects, causing the drive pin 10 and the distal end 
portion of the lever 8 to be lowered into the opening 7 of the rotary 
plate 3. Therefore, the space required to permit the movement of the lever 
8 in the axial direction of the rotary drive shaft 1 can be reduced to the 
minimum necessary dimension, thereby making it possible to reduce the 
thickness of the entire device. 
Next, a second embodiment of the present invention will be described with 
reference to FIG. 4. 
The second embodiment is substantially the same in construction and 
operation as the first embodiment except that, in contrast to the first 
embodiment where the space for accommodating the swingable lever 8 
comprises a recess formed in the lower surface of the magnet 4, the space 
in the second embodiment comprises a recess formed in the upper surface 
(the surface facing the magnet 4) of the rotary plate 3. In FIG. 4, the 
component parts of the second embodiment corresponding to those of the 
first embodiment are denoted by the same reference numerals to omit the 
description thereof. 
It will be apparent from the description given above that similar effect 
can be achieved in the case where the space for accommodating the 
swingable lever comprises a recess formed partly in the upper surface of 
the rotary plate 3 and partly in the lower surface of the magnet 4.