Compact disk drive for use with laptop computer

A compact disk drive includes a rotary head actuator or voice coil motor for a head arm assembly formed with flexures. The baseplate for the drive is formed with recesses to contain the voice coil motor and a lower flexure whereby the depth of the drive is reduced. The magnet housing for the voice coil motor is contoured and located in a corner of the baseplate, and the head arms are oriented so that the length of the drive is reduced.

FIELD OF THE INVENTION 
This invention relates to a compact disk drive such as used with a laptop 
or notebook computer. 
BACKGROUND OF THE INVENTION 
Description of the Prior Art 
A major objective of present day data processing technology is to reduce 
the size and cost of systems while increasing data handling capability and 
reliability. Data processors or computers typically include one or more 
disk drives. A laptop computer which needs to be portable, and therefore 
compact and light in weight, generally has a single compact disk drive 
which comprises, inter alia, at least one magnetic disk, a drive motor, 
magnetic heads and a head actuator. The head actuator generally is a voice 
coil motor that rotates the heads to selected data tracks on the surface 
of the storage disk. In prior art disk drive assemblies, the form factors 
allowed ample length so that the voice coil motor could be large enough to 
meet the desired performance specifications, especially average access 
time. The length of the disk drive assembly is thus driven by the need for 
space for the voice coil motor. The voice coil motor of the head actuator 
uses a magnet housing which occupies substantial space in prior art disk 
drives. Also prior art construction employs separate components for the 
magnetic yoke which is susceptible to resonant vibrations at the mating 
surfaces. In the event of failure of the head actuator, the actuator 
components need to be removed and replaced separately which is 
time-consuming. 
With the development of laptop and notebook portable computers, disk drive 
designs have been modified and thus deviate from conventional designs that 
have standard form factors. The departure from standard form factors has 
allowed reduction in size and weight of the disk drive. Nevertheless 
further reduction in size and weight is still desirable to realize the use 
of minimal space in a laptop or notebook computer. 
Conventionally magnetic disks are made with highly polished aluminum 
substrates on which a thin magnetic layer is deposited. Aluminum 
substrates are subject to damage due to head crashes which may occur when 
the heads are track seeking across the surface of the disk. It is 
desirable to use a material for a disk substrate that provides better 
performance and reliability, and allows the heads to fly closer to the 
disk surfaces so that data density can be increased. 
Known prior art disk drives generally assemble the magnetic disk to the 
drive motor by means of bolts or screws. This type of assembly is time 
consuming and requires proper alignment and is subject to tight mechanical 
tolerances. With the use of bolts or screws, removal and replacement of a 
damaged disk involves intensive labor cost and unduly long down time. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a compact disk drive which is 
significantly reduced in in overall length and depth while maintaining a 
relatively high level of performance. 
Another object of this invention is to provide a compact disk drive having 
a magnetic disk that allows the heads to fly closer to the disk surfaces 
and affords an improved resistance to damage that may be caused by head 
crashes. 
Another object is to provide a compact disk drive wherein resonant 
vibrations are minimized and higher track densities are attained. 
According to this invention, the configuration of a compact disk drive 
affords a significant reduction in the overall length and depth of the 
disk drive. The disk drive comprises a magnetic disk formed with a glass 
substrate. The magnetic disk is seated on a spindle for rotation by a 
drive motor. The disk is clamped by a clamping ring to connect to the 
drive motor by engagement of threaded portions of the drive motor and the 
clamping ring. The clamping ring and housing for the motor are made of 
stainless steel and have a substantially similar thermal coefficient of 
expansion. 
A rotatable head arm assembly supports at least two diverging flexures on 
which magnetic transducers are mounted, as is well known. The pivot point 
of the rotary head arm actuator or voice coil motor, to which the head 
assembly is coupled, is located close to a longitudinal side at the corner 
of a rectangular baseplate on which the drive assembly is seated. The head 
arm, when in home position, is aligned substantially parallel to a 
longitudinal side of the baseplate. This arrangement saves space that is 
lost with diagonal orientation of the head arm, as practised in the prior 
art. 
An integrally formed housing for the permanent magnet of the voice coil 
motor, which has been formed by metal-injection molding fabrication as a 
one piece component, eliminates the need for separate supports for 
opposing plates of the magnetic yoke structure, as used in the prior art. 
Such supports found in prior art drives require fasteners that consume 
volume within the disk drive. The single piece magnet housing of this 
invention eliminates undesirable resonances and higher track densities are 
thus obtained. 
In keeping with this invention, the entire actuator is disposed within a 
contoured recess in the baseplate. Also, the lower head arm flexure is 
located within a second contoured recess in the baseplate. The recesses 
allow the lower head flexure and the voice coil motor to be positioned in 
a plane below the major surface of the baseplate on which the disk drive 
assembly is seated. In this way, the depth of the disk drive assembly is 
significantly reduced. 
In one embodiment, crash stops in the form of posts or screws are provided 
to limit the extent of travel of the rotary head arm. In an alternative 
embodiment, the housing for the permanent magnet of the voice coil motor, 
which is contoured to be reduced in size, is formed with a crash stop 
portion to limit the travel of the head assembly in one direction. A 
second crash stop, in the form of a post or projecting screw, is spaced 
from the crash stop formed with the magnet housing to limit the rotary 
motion of the head assembly in the other direction of travel. 
Air flow slots are disposed at the bottom of the baseplate for cooling the 
drive during operation and an air filter is provided to maintain a clean 
ambient environment. A slot in the baseplate allows passage of the 
electrical cable and circuit leads from the head flexures and 
preamplifiers for connection to the computer and power supply so that data 
can be recorded on the disk and read out.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates a prior art disk drive assembly which includes a 
magnetic disk 10 and a head arm assembly 12 that is coupled to a rotary 
head actuator or voice coil motor 14. The inner diameter 80 of the disk 
defines the central aperture of the disk which enables seating of the disk 
to a motor spindle. The disk surface is disposed between the inner 
diameter and the outer diameter 81. The line 70 defines the longitudinal 
side of the baseplate 22. Air slots 48 are provided to allow air 
circulation. A swage hole 72 is used for attaching the head suspension and 
flexure 16. During operation of the disk drive, the head arm 12 turns 
about a pivot center 73. The head arm assembly 12 includes at least one 
flexure 16 and a head slider 18 which supports magnetic transducers. The 
actuator assembly including its magnet housing 20 is oriented so that the 
head arm assembly 12 is diagonally disposed relative to the rectangular 
geometry of the baseplate 22 on which the drive is mounted. It is apparent 
that an area 24 of unused space is lost in the corner of the baseplate 
where the actuator magnet housing 20 is located. 
With reference to FIG. 2, the compact disk drive of this invention is 
illustrated wherein a rotary actuator 26 is positioned so that its pivot 
point is close to a longitudinal side 75 of a baseplate 28. The centerline 
C/L of the head arm and flexure passes through a swage hole 77. The 
centerline defines the longitudinal direction of the head arm and is 
parallel to the baseplate edge defined by the line 75. As shown in FIGS. 
5A and 5B, an integral ball bearing pivot support 50 for the rotary 
actuator 26 is shown. The support 50 is located adjacent to a housing 30 
for the magnet of the actuator 26. This design allows the removal of the 
entire actuator from the drive as a subassembly. Integral supports 52 are 
also provided for the magnetic yoke structure of the actuator. The one 
piece construction eliminates the need for separate supports for the 
opposing plates of the magnetic yoke structure, which would require 
fasteners that occupy space within the disk drive. 
The magnet housing 30 is contoured so that the area at the corner of the 
baseplate 28 is occupied and effectively used. The head arm assembly 32 is 
mounted to the actuator 26 so that in its home position the head arm 
assembly 32 extends substantially parallel to the longitudinal dimension 
of the baseplate 28. The head assembly 12 includes an upper flexure 34 and 
lower flexure 36, as shown in the side view of FIG. 4. Each flexure 34 and 
36 has a microslider 38 attached to a suspension 40 at the end of the 
flexure. The head arm is preferably made of magnesium and the suspensions 
40 are relatively short so that the polar mass moment of inertia of the 
head actuator 26 is reduced and the volume requirement of the voice coil 
motor is reduced. 
The magnetic disk 42 used with the disk drive of this invention is 
preferably made with a glass substrate on which a thin magnetic film is 
deposited. The relatively smooth glass disk 42 allows the head to fly 
closer and is more durable than the aluminum disks commonly used in terms 
of start-stop characteristics and shock resistance. 
The flexures 34 and 36 provide a predetermined gram load so that the heads 
fly at a specified height range from the recording surfaces of the 
magnetic disk 42, in a well known manner. One flexure 34 is disposed over 
an upper surface of the disk 42 and the second head flexure 36 is located 
below the bottom surface of the disk 42. In accordance with this 
invention, the lower flexure 36 is located in a recess 94 (see FIG. 6) 
that is formed in the baseplate 28. The lower flexure 36 and its 
suspension 40 and microslider 38 are thus disposed below the upper surface 
96 of the baseplate 28 that faces the disk 42. In addition, the voice coil 
motor 26 is contained within a second recessed portion 95 of the baseplate 
28. Thus a significant decrease in depth is realized by recessing these 
components of the compact disk drive resulting in reduced height 
dimensions 92 and 93. By virtue of providing the recesses, the lower 
flexure 36 and the voice coil motor do not project beyond the plane of the 
upper surface of the baseplate 28. In this manner, the depth of the disk 
drive can be minimized. For a disk drive employing a 2.5 inch disk, the 
depth of the drive assembly can be made to be about 15 mm. (millimeters) 
or less. 
The magnet housing 30 is formed from stainless steel having a thermal 
coefficient of expansion substantially the same as the steel housing of 
the disk drive motor. Variations in ambient temperature do not adversely 
affect disk drive operation. 
A significant reduction in the length of the disk drive is achieved by the 
novel arrangement of the drive motor 58 and the spindle to which the disk 
is mounted relative to the pivot point of the rotary head actuator. The 
length of the disk drive is significantly reduced by locating the pivot 
point of the rotary head actuator close to the corner of the baseplate, 
which is made possible by the contoured shape of the magnet housing 30. As 
a result of the design and configuration of the disk drive disclosed 
herein, a very compact drive assembly about 88 mm. long, 70 mm. wide and 
15 mm. deep or smaller can be produced for use in a portable computer. 
Crash stops 44 for the head actuator are located at the front end of the 
actuator adjacent to the heads, and spaced from the voice coil motor area 
so that space is not wasted. By mounting the voice coil motor in a 
contoured recess of the baseplate, space is made available for electronic 
components beneath the baseplate, thereby reducing the overall height of 
the drive. 
During operation of the disk drive, the rotational speed of the disk 42 is 
reduced substantially from the conventional 3600 rpm whereby the heads can 
fly closer to the surfaces of the glass disk 42. The 2.5" disk drive 
disclosed herein can store more than 120 megabytes. 
An aperture 46 is provided to allow making external connection with the 
computer electronic circuitry by the flexible electrical cable coupled to 
the heads and the preamplifier circuit. Air slots 48 allow air cooling and 
circulation through an air filter to maintain a clean environment within 
the drive assembly. 
When assembling the disk drive components, the disk motor is securely 
fastened within an aperture of the baseplate with a threaded portion 
extending above the baseplate. After seating the magnetic disk to the 
motor spindle, a spacer ring is placed over the disk 42 around the 
extending outer threaded portion at the outer periphery. A circular 
clamping element 56 having a threaded portion at the inner periphery is 
engaged securely with the spindle by mere rotation of the clamping 
element. A gasket is positioned over the clamp along the periphery 59 of 
the baseplate 28 and a protective cover is fastened to the baseplate 
thereby enclosing the drive assembly, with the connection plug for 
transferring data signals between the head circuits and the computer 
exposed. 
It should be understood that the invention is not limited to the use of a 
single disk only in a disk drive but may include two or more disks with 
additional magnetic heads. Other parameters including materials and 
dimensions than those described above may be used to implement the 
invention.