This invention relates to disk drive systems, and relates more particularly
to such disk drive systems having a low height or profile, improved serviceability,
reliability and removability without sacrificing capacity or performance.
Over the past ten years, disk drive devices for use in computer systems
have been dramatically shrinking in size. One of the factors responsible for this
rapid progress has been the ability to reduce the space required to house the electronic
components of the devices, made possible principally through very large scale integration
of the electronic circuitry. Additionally, substantial advances have been made in
reducing the size of the major mechanical components of disk drive devices such
as the motor which rotates the disk or disks, the flexure mounting mechanism for
the read/write heads and the actuator mechanism which moves the heads to different
track positions on the disk surfaces.
With the increasing popularity of portable, laptop, notebook and smaller
desktop personal computers employing disk drives, the pressure to reduce the volume
of the disk drive enclosure without sacrificing the capacity, performance and cost
of the storage device is significant. A hard disk drive manufacturer must supply
a product having a very high linear bit density and radial track density in a device
that is resistant to shock and vibration, is temperature and environment tolerant,
is producible in high volume at a reasonable cost, has high throughput performance,
and has a storage capacity that meets the increasing data storage requirements of
the computer system market. In most small computer systems, the size of the keyboard
and the visual display or monitor will dictate the mandatory X and Y dimensions
for the system. This means that the most critical disk drive dimension that can
be controlled is the height or Z dimension of the drive.
The relatively recent introduction of 2.5 inch (6.35 cm) and 1.8 inch
(4.57 cm) "form factor" disk drives has been a response to this demand for high
capacity, low volume storage for the smaller types of computers. Representative
examples of prior art disk drive designs directed to the 2.5 inch (6.35 cm) and
1.8 inch (4.57 cm) form factor drives are the following.
U.S. Patent 5,025,335, Stefansky, shows a disk drive employing a 2.5
inch (6.35 cm) disk in a housing whose length is described as equal to the width
of a conventional 3.5 inch (8.89 cm) disk drive (4 inches 10.16 cm) and whose width
is approximately one half the length of a 3.5 inch (8.89 cm) drive (2.75 inches
(6.98 cm)). In an embodiment with one disk in the housing, the height of the unit
is 0.68 inches (1.73 cm), with a printed circuit board containing the drive electronics
mounted adjacent to and outside the bottom of the housing.
U.S. Patent 5,025,336, Morehouse et al, discloses a reduced height
disk drive with a single 2.5 inch (6.35 cm) disk therein, the drive housing having
a width of approximately 2.8 inches (7.11 cm), a length of approximately 4.0 inches
(10.16 cm) and an overall height no greater than 0.63 inches (1.60 cm). The patent
attributes this reduced height to the use in the disk enclosure of disk spin motors,
actuators and head flexures of smaller height. This drive utilizes a printed circuit
board with the drive electronics therein disposed below the base which supports
the disk and actuator and outside the disk enclosure.
U.S. Patent 4,933,785, Morehouse et al, shows a drive containing at
least two 2.5 inch (6.35 cm) disks therein, with the printed circuit board containing
the device electronics mounted below and spaced from the disk enclosure.
U.S. Patent 5,038,239 Vettel et al., discloses a disk drive in which
the electronic circuits are disposed mounted on a number of circuit cards which
are mounted in different areas in the drive housing, with interconnections between
the multiplicity of cards.
U.S. Patent 4,317,146 discloses a disc drive assembly as part of compact
magnetic disc storage system which includes a 3-dimensional enclosure comprising
a sealed volume and a circuit volume and with at least one disc disposed inside
the sealed volume and a printed circuit board arrangement disposed in the circuit
volume outside the sealed volume. However, the relationship between the enclosure
and the printed circuit board within the cited document is disadvantageously limited
as compared with the present invention.
The present invention provides a disk drive assenbly as defined in
In the prior art disk drives discussed above, the printed circuit
board or boards are placed above or below, or both above and below, the disk or
disks, outside the drive enclosure. This results in problems with electrostatic
charges which may be placed on the electronic components as a result of human hands
touching the components when inserting or removing the disk drive assembly from
its mounting in the using computer.
In the present invention, placement of all of the electronic components
inside the small enclosure totally protects the electronic components from damage
from human handling. This design configuration results in a cartridge-like device
with a compact, smooth rectangular configuration, making it very suitable for use
as a removable type device, without any modification. At the same time, this invention
provides for mounting of the printed circuit board or boards in the enclosure in
a manner which permits its or their removal therefrom for replacement or repair
without the need to remove the entire disk drive assembly from the computer.
Additionally, by mounting the flexible cables associated with the
circuit board totally within the enclosure, the circuits in these cables are shielded
from external electromagnetic interference (EMI). Further, the HDA is placed in
a separate sealed compartment inside the enclosure to prevent contaminants from
reaching the disk surfaces and causing head crashes.
The disk storage device of this invention can be used in workstations,
desktop and portable computers, notebooks and peripheral devices such as facsimile
machines, laser printers, oscilloscopes, instruments, etc., where minimum dimensional
volume is critical, but where no degradation of capacity, performance and/or cost
The present invention provides an extremely thin disk drive, with
a 0.350-inch (0.89 cm) high profile for a single disk enclosure, a 0.500-inch (1.27
cm) high profile for a two disk enclosure, 0.750-inch (1.9 cm) high profile for
a four disk configuration and a 1.00 inch (2.54 cm) high profile for a six disk
configuration. In representative configurations utilizing 3.5 inch (8.89 cm) disks,
the disk drive system of this invention may have a width of approximately 4 inches
(10.16 cm) and a length of approximately 5.75 inches (14.6 cm) regardless of the
number of disks utilized in the enclosure. An embodiment of this invention having
two 3.5 inch (8.89 cm) disks therein weighs approximately 10 ounces, while a similar
version utilizing magnesium parts for the housing weighs approximately 8 ounces.
When 3.5 inch (8.89 cm) disks are employed in the invention, a formatted
capacity of 240 megabytes (MB) is obtained with a two disk embodiment, a formatted
capacity of 120 MB is obtained with a one disk embodiment, and a formatted capacity
of 480 MB results from a four disk configuration. If 2.5 inch (6.35 cm) or 1.8 inch
(4.57 cm) diameter disks are employed using the configuration of the present invention,
comparable low profiles can be obtained.
- Fig. 1 is an exploded perspective view showing the major components of the disk
drive of this invention employing two disks;
- Fig. 2 is a top plan view, partially cut away and with the enclosure cover removed,
of the disk drive shown in Fig. 1;
- Fig. 3 is a bottom plan view of the cover for the disk enclosure;
- Fig. 4 is a perspective view of the assembled disk drive enclosure with the
circuit board removed therefrom.
- Fig. 5 is a side view, partly in cross section, along plane 5-5 of Fig. 2;
- Fig. 6 is a cross sectional side view similar to Fig. 5 of an embodiment of
the invention employing one disk;
- Fig. 7 is a block diagram of the circuit chip elements making up a nine chip
embodiment of the invention; and
- Fig. 8 is a block diagram of the circuit chip elements of an embodiment where
a number of the functions of different chips in Fig. 7 have been integrated into
a single chip.
The exploded perspective view of Fig. 1 shows a disk drive system
in accordance with this invention employing two recording disks. The drive system
is mounted in an enclosure 11 having a base member 11a on which the main elements
of the drive are mounted. Within enclosure 11 are mounted a pair of disks 13a, 13b,
and an actuator assembly including three actuator arms 14a, 14b, 14c which carry
flexure members 17a, 17b, 17c and 17d to support transducing heads at the ends thereof
for reading and writing on the concentric tracks on the recording surfaces of disks
13a, 13b. As been shown in Fig. 5, upper arm 14a carries a head 16a mounted on flexure
member 17a for reading and writing on the upper surface of disk 13a, while lower
arm 14c carries a head 16d on a flexure 17d for reading and writing on the lower
surface of disk 13b. Arm 14b carries a pair of heads 16b, 16c on flexures 17b, 17c
for reading and writing on the lower surface of disk 13a and the upper surface of
disk 13b, respectively.
Referring again to Fig. 1, arms 14a, 14b, 14c move as a unit in an
arcuate or rotary motion around a pivot journal 18 in response to the electromagnetic
interaction between a current-carrying coil 19 and a pair of permanent magnetic
members 21a, 21b. Magnet 21a, as best seen in Fig. 2, is secured to a mounting plate
22a which in turn is fixed to base 11a, while magnet 21b (Fig. 3) is secured to
a mounting plate 22b which is fixed to top cover 11b. When top cover 11b is secured
to base 11a to form a sealed enclosure, magnets 21a, 21b are positioned on opposite
sides of coil 19 and suitably polarized to provide the required flux direction to
interact magnetically with coil 19 and produce motion of the actuator. By mounting
magnets 21a, 21b directly to the bottom and top members of the housing, there is
no need for the use of standoff spacers to separate and support the magnets as in
many prior art disk drives.
The actuator mechanism is positioned on base member 11a in a raised
shoulder portion 11n and is secured to member 11a by a screw extending through an
opening in member 11a and engaging a tapped opening in the bottom of the actuator
Coil 19 is mounted on the actuator on the side of journal 18 opposite
to that of arms 14a, 14b, 14c. As is well known in the art, the actuator operates
to move heads 16a, 16b, 16c and 16d to different radial track positions relative
to the surfaces of disks 13a, 13b in response to positioning signals supplied to
coil 19. Two crash-stop members 23a, 23b are located on either side of coil 19 at
the extreme limits of desired movement of the actuator. A magnetic pin 24 attached
to coil 19 and extending therefrom engages pin 23a or 23b at the limit of actuator
travel in each direction to act as a physical stop. Stop member 23a includes a resilient
material to absorb the impact from pin 24 when coil 19 moves to the extreme outer
position. Magnetic pin 24 member also is magnetically attracted to metal stop member
23b when adjacent thereto to magnetically latch the actuator in a "parked" position,
as is well known in the art.
Disks 13a, 13b are rotated by a spindle motor 26 which is mounted
on a flange 20 which in turn is anchored to base 11a by screws 25. Flange 20 has
a cut out portion 20a underlying head 16d and flexure 17d to permit free movement
of these elements across the lower surface of disk 13b. In one embodiment, two .0315-inch
(0.08 cm) thick thin film magnetic disks 13a, 13b are mounted for rotation by the
spindle motor and are separated by a spacer ring 30. The two disks are rigidly mounted
on the spindle by a disk clamp 28 which is secured to the upper surface of spindle
motor 13 by screws 31.
In accordance with a major feature of this invention, the majority
of the electronic circuitry for the disk drive is mounted on both sides of a single
circuit board which is disposed in the same envelope as the disks in the enclosure.
As best seen in Fig. 2, this printed circuit board 41 contains a number of electric
components mounted on both sides of the board. The electronic components of the
disk drive system on one side of board 41 are represented in Figs. 1 and 2 by reference
numerals 1-6 and 9, and those on the other side of board 41 are shown in dotted
outline in Fig. 2 as elements 7 and 8. The function of these components will be
discussed in detail below in connection with Fig. 7.
From Figs. 1 and 2 it can be seen that the layout of the disk drive
system of this invention is configured such that, unlike prior art disk drives,
the actuator mechanism of the drive is positioned near one side and at one end of
base 11a, thereby resulting in sufficient space in which to locate board 41 near
that one end and at the other side of base 11a. This is a major feature of this
invention in that it permits board 41 to be positioned in the same envelope as the
disks and in essentially the same plane as the disk in the case of a one disk embodiment
shown in Fig. 6, or in a plane between disks 13a, 13b in the case of a two disk
embodiment illustrated in Figs. 1 and 5, thereby resulting in the very low height
profile of the drive system. This permits obtaining the very thin envelope or enclosure
necessary for many small computer devices, without sacrificing capacity, performance,
In accordance with this invention, the different electronic components
on board 41 are positioned in proximity to the elements in the drive to which they
relate. For example, component 5 on board 41 may be a circuit for controlling the
disk drive actuator and it can be seen that this component is positioned closely
adjacent coil 19 of the actuator mechanism. Similarly, circuit components 3 and
4 on board 41 contain analog read/write circuitry for processing signals to and
from read/write heads 16. The digital portion of the electronic circuitry on the
upper surface of board 41 includes component 1 for processing digital signals present
in the disk drive system. A feature of the invention is that component 7, located
on the underside of board 41 and also containing digital processing circuitry, is
aligned physically on board 41 with component 1, as represented by the dashed outline
of component 7 in Fig. 2, so as to minimize the path length between components 1
and 7 and facilitate their interconnection.
As seen in Fig. 2, circuit board 41 provides for supplying signals
to the disk spindle motor 26, coil 19 of the actuator, and read/write heads 16 through
a connector cable 42 which plugs into terminals in a member 45 in board 41. Signal
cables from connector 42 may include a group of lines 43 which supply power to spindle
motor 26, while another group of signal lines 44 are connected to the read/write
heads and the actuator mechanism including coil 19. Signal lines 43 and 44 extend
under the bottom of lower disk 13b to connect their respective circuits to the spindle
motor and actuator mechanism, respectively.
The read/write portion of signal lines 44 preferably includes preamplifier
circuitry in the form of a chip 46 for providing preamplification of the read signals
from heads 16. After passing under disk 13b, signal lines 44 are in the form of
a flexible cable which connects to coil 19 and heads 16. As shown in Figs. 1 and
2, the flexible cable 44 is configured in a serpentine manner in this area to minimize
the undesired torque produced on the actuator mechanism by the cable.
External electrical connections are made to the circuitry on board
41 through a connector block 47 which mates with an external connector cable (not
shown) to provide for the interchange of signals between the disk drive system and
the using system. By maintaining the flex cable within the drive enclosure, the
cable is protected from damage which could otherwise occur during opening of the
container in which the disk drive system is shipped. Additionally, by being disposed
within the drive enclosure, the flex cable is shielded from EMI when the disk drive
is in operation and signals are present in the conductors in the flex cable.
An air filter 33 is located in one corner of the cover 11b (Fig. 3)
for maintaining a clean environment within the enclosure. This may be in the form
of an air filter 33 through which air is forced in response to rotation of disks
13a, 13b. Filter 33 may be a container of low air resistance fiber sold under the
name Filtrete Filter Media by Minnesota Mining & Manufacturing. To insure that
the filter has optimum efficiency, the air pressure at the inlet side of the filter
is increased relative to the filter outlet pressure. To accomplish this, a vane
32a (Figs. 1 and 2), and vane 32b (Fig. 3), both of which are preferably formed
as part of bottom portion 11a and enclosure cover 11b, respectively, are located
in the air path. When bottom portion 11a and top cover 11b are assembled, vane members
32a, 32b are disposed opposite each other to direct air flow as represented by the
arrows. This configuration causes the air entering filter 31 at a pressure P1 to
exceed the filter outlet pressure P2, thereby insuring maximum efficiency.
Cover 11b and base 11a are designed to hermetically isolate the HDA
from the circuit board area by means of a continuous gasket 11d (Figs. 1 and 3)
which acts to seal the HDA area when cover 11b and base 11a are secured together
by screws 11e which extend through cover 11b to engaged tapped supports 11f formed
in base 11a.
When cover 11b is assembled on base 11a, the actuator mechanism and
the disks and spindle motor may be anchored against tilt by screws 11g and llh.
Screw 11g extends through an opening in cover 11b to engage a tapped opening in
the stationary portion around actuator pivot 18, while screw 11h similarly engages
a tapped opening in the stationary center portion of spindle motor 26. As seen in
Fig. 3, the portions of cover 11b above disk clamp 28 and the actuator mechanism
may be slightly hollowed out to accommodate these elements.
An opening 11j in base 11a (Figs. 1 and 2) is provided for access
to transducers 16 during the trackwriting operation when the disk drive is initially
assembled. A similar opening 11k is provided in top cover 11b (Figs. 1 and 4) for
access during trackwriting. After completion of the trackwriting operation, openings
11j and 11k are sealed to insure the hermetic seal of the HDA area.
To facilitate mounting the disk drive in a position desired by the
user, pairs of tapped openings 11m are provided around the periphery of cover 11b.
These openings do not extend through cover 11b and can be used for mounting screws
to position the disk drive in a desired location in the using system.
As shown in Fig. 4, circuit board 41 may be inserted in and removed
from housing 11 without the need to disassemble the housing. Board 41 is guided
into and supported in the housing by grooves 11c formed in the side walls of cover
11b. When board 41 is fully inserted, connector 45 mates with connector 42 in the
housing to provide the necessary electrical connections. When inserted, board 41
is maintained in position by screws 49 which extend through openings in the corners
of bottom member 11a to engage tapped openings 41a in board 41. Screws 49, when
engaged, also serve the functions of anchoring the corners of bottom member 11a
to the housing assembly and acting as an electrical ground connection.
For removal of board 41, screws 49 are removed and an opening (not
shown) may be provided on the end of board 41 to permit a user to engage the opening
with a tool and remove the board for replacement or repair. If desired, a hinged
or otherwise movable door may be provided for the opening in housing 11 through
which board 41 extends so as to close the housing when board 41 is inserted.
Fig. 5 shows that in a two disk embodiment, board 41 is disposed in
a plane between the planes of the recording surfaces of disks 13a and 13b. Fig.
6 illustrates an embodiment of the invention in a drive employing one disk. This
embodiment employs a single disk 13a' having heads 16a', 16d' cooperating with its
upper and lower surfaces, respectively. Except for the height of the actuator and
disk spin motor and the reduced envelope height, the elements of this configuration
are generally the same as those in the two disk embodiment of Figs. 1-5. From Fig.
6 it can be seen that board 41' is disposed in essentially the same plane as the
surface of single disk 13a'. Additionally, in the case of embodiments employing
more than two disks, the circuit board can be positioned in a plane which is between
the planes of the recording surfaces of the disks or can be aligned with the plane
of the surface of one of the disks. This is in contrast to the prior art in which
the circuit board or boards are positioned above or below, or both above and below,
the plane or planes of the surfaces of the disks.
The embodiment described above for a disk drive incorporating two
disks employed nine circuit chips mounted on board 41. As shown in the block diagram
of Fig. 7, these chips may have the following functions. Chip 1 may provide the
functions of a sequencer/error correction code (ECC) element, servo timing buffer
controller and AT interface. Chip 2 provides random access memory which may be in
the form of a static buffer RAM, type M51008VP manufactured by Mitsubishi. Chip
3 provides the read/write electronics control and may be a type Reach 1 manufactured
by AT&T. Chip 4 is a synthesizer associated with read/write control chip 3 and
of the type SC84038 manufactured by Sierra Semiconductor. Chip 5 provides positioning
signals to the actuator voice coil motor (VCM) and may be of a type 8932 manufactured
by Allegro Microsystems. Chip 6 provides the power to drive spindle motor 26 and
may be of the type 8902 manufactured by Allegro Microsystems. Chip 7 is a microcontroller/servo
processor type Z86C94 manufactured by Zilog Inc. Chip 8 is a firmware ROM of 32K
bytes of any suitable type such as a 27C256 manufactured by Microchip. Chip 9 is
a read/write filter type 8011 from Silicon Systems, Inc.
However, as shown in the block diagram of Fig. 8, the number of chips
required can be reduced by combining functions which were separately implemented
in the embodiment of Fig. 7. By integration techniques, for example, the buffer
RAM and the controller and microprocessor elements can be combined into a multi-chip
module (MCM). Further, the functions of the spindle motor power chip 5 and the VCM
actuator positioning current chip 6 can be combined into a single chip. Additionally,
the function of the read/write control chip 3 and the synthesizer chip 4 can be
merged into a single chip. Similarly, by further integration of functions into a
multichip module, the total chip count can be reduced to three chips.
It will be seen that the structure of this invention provides a disk
drive having an extremely low height or profile by virtue of the disposition of
the printed circuit board in the same enclosure as the HDA and either in substantially
the same plane as a disk in a single disk housing or located in a plane between
the planes of the surfaces of the disks in a multi-disk housing. At the same time,
the location of the circuit board within the enclosure housing protects the circuit
components from handling damage and the buildup of electrostatic charges from human
contact with the components. Further, the flex cable is protected by the enclosure
housing from physical damage and from the effects of EMI.
The disk drive configuration of this invention provides many advantages
over conventional disk drives of its type. The present drive may be employed as
a single removable, replaceable drive in a notebook computer system or used as multiple
drives in computer systems, such as laptops and desktops, which require larger data
storage capacity than can be provided in a single 200 MB drive. Further, a single
drive used in a notebook computer may be removed therefrom by a user and mounted
for use in a laptop or desktop computer, thereby permitting the user to transfer
data from one computer system to another with a minimum of time and effort.