U.S. patent application number 09/779262 was filed with the patent office on 2001-07-05 for disk drive enclosure.
Invention is credited to Glorioso, Scott R., Jehu, Erica M., Kass, Daniel H., Tarr, Morton H., Westland, Clifford G..
Application Number | 20010006453 09/779262 |
Document ID | / |
Family ID | 22619665 |
Filed Date | 2001-07-05 |
United States Patent
Application |
20010006453 |
Kind Code |
A1 |
Glorioso, Scott R. ; et
al. |
July 5, 2001 |
Disk drive enclosure
Abstract
Noise is reduced in a disk drive enclosure by using vibration
damping materials on the inside surface of the enclosure. These
materials and their placement on the inside surface of the
enclosure reduce noise without thermally insulating the disk drive.
A temperature controlled fan may be used to remove heat by
convection while generating a minimum amount of noise. The
connection between the disk drive and the external connector of the
disk drive enclosure is made more reliable by using a printed
circuit board instead of a cable. Because a printed circuit board
has a fixed location and fixed layout, variability among disk drive
enclosures can be minimized. Also, errors in manufacturing of the
disk drive enclosure can be reduced. To facilitate the use of the
disk drive in a stripe set, the disk drive enclosure has a set of
mechanical interlocks that permit the enclosures to be stacked
vertically. In one embodiment, the mechanical interlocks are
constructed in a manner that permits stacking in unlocked and
locked configurations. The locked configuration may be made
permanent using an additional locking mechanism. These mechanical
interlocks also may be used to support the enclosure on a desktop.
The mechanical interlocks also may be constructed so that they can
slide on a rail, permitting the enclosure to be used in a rack
mount. The rack mount also may be provided with a quick-release
mechanism that interacts with the mechanical interlocks to hold the
disk drive enclosure in the rack mount.
Inventors: |
Glorioso, Scott R.;
(Littelton, MA) ; Kass, Daniel H.; (Maynard,
MA) ; Westland, Clifford G.; (Chelmsford, MA)
; Jehu, Erica M.; (Andover, MA) ; Tarr, Morton
H.; (Bolton, MA) |
Correspondence
Address: |
AVID TECHNOLOGY, INC.
AVID TECHNOLOGY PARK, ONE PARK WEST
ATTENTION: CATHY J. SAMRA
TEWKSBURY
MA
01876
US
|
Family ID: |
22619665 |
Appl. No.: |
09/779262 |
Filed: |
February 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09779262 |
Feb 8, 2001 |
|
|
|
09170386 |
Oct 13, 1998 |
|
|
|
Current U.S.
Class: |
361/679.34 ;
361/679.58; G9B/33.003; G9B/33.024; G9B/33.031; G9B/33.041 |
Current CPC
Class: |
G11B 33/08 20130101;
G11B 33/125 20130101; H05K 2201/09236 20130101; H05K 2201/10189
20130101; H05K 2201/09727 20130101; H05K 1/0216 20130101; G11B
33/022 20130101; G11B 33/144 20130101 |
Class at
Publication: |
361/685 ;
361/687 |
International
Class: |
G06F 001/16; H05K
005/00; H05K 007/00 |
Claims
What is claimed is:
1. A disk drive enclosure, comprising: a housing for enclosing a
disk drive; a first plurality of mechanical interlocks mounted on a
first side of the housing; a second plurality of mechanical
interlocks mounted on a second side of the housing opposite the
first side of the housing; wherein each of the first and second
plurality of mechanical interlocks has a top portion having a
surface complementary to a surface of a bottom portion of the
mechanical interlock, such that the top portion of a first
mechanical interlock and the bottom portion of a second mechanical
interlock are slidably connectable in a first direction and when
connected prohibit movement of the mechanical interlocks with
respect to each other in second and third directions orthogonal to
the first direction.
2. The disk drive enclosure of claim 4, wherein the top portion has
top face and the bottom portion has a bottom face such that the top
face of the top portion of a first mechanical interlock supports
the bottom face of the bottom portion of a second mechanical
interlock when enclosures on which the first and second mechanical
interlocks are attached are vertically aligned and stacked.
3. The disk drive enclosure of claim 4, wherein each of the first
and second plurality of mechanical interlocks has portion having a
surface complementary to a surface of a support in a rack, such
that the portion of the mechanical interlock and the support in the
rack are slidably connectable in a first direction and when
connected prohibit movement of the mechanical interlock with
respect to support in second and third directions orthogonal to the
first direction.
4. The disk drive enclosure of claim 4, further comprising: a
locking mechanism having a first movable member mounted on the
first side of the housing.
5. A disk drive enclosure for mounting in a rack having a support,
comprising: a housing for enclosing a disk drive; a first plurality
of mechanical interlocks mounted on a first side of the housing; a
second plurality of mechanical interlocks mounted on a second side
of the housing opposite the first side of the housing; wherein each
of the first and second plurality of mechanical interlocks has
portion having a surface complementary to a surface of the support
in the rack, such that the portion of the mechanical interlock and
the support in the rack are slidably connectable in a first
direction and when connected prohibit movement of the mechanical
interlock with respect to support in second and third directions
orthogonal to the first direction.
6. A mechanical interlock for use with a disk drive enclosure
comprising a top portion, a bottom portion and a section connecting
the top portion to the bottom portion, wherein the top portion has
a surface complementary to a surface of the bottom portion, such
that the top portion of a first mechanical interlock and the bottom
portion of a second mechanical interlock are slidably connectable
in a first direction and when connected prohibit movement of the
mechanical interlocks with respect to each other in a second and
directions orthogonal to the first direction.
7. The mechanical interlock of claim 16, wherein the top portion
has top face and the bottom portion has a bottom face such that the
top face of the top portion of a first mechanical interlock
supports the bottom face of the bottom portion of a second
mechanical interlock when enclosures on which the first and second
mechanical interlocks are attached are vertically aligned and
stacked.
8. A rack mount for a disk drive enclosure having at least one bay
for receiving the disk drive enclosure, and comprising: a support
mechanism having edges shaped to engage an interlock on the disk
drive enclosure to guide the disk drive enclosure into the bay; a
spring loaded block shaped to engage the interlock on the disk
drive enclosure so as to permit the interlock to pass the blocks in
a first direction and to prohibit passage of the interlock in a
second direction opposite the first direction; and a user-operable
member constructed to move the spring loaded block to permit
passage of the interlock in the second direction to permit removal
of the disk drive enclosure from the rack mount.
Description
[0001] This is a divisional of patent application Ser. No.
09/170,386, filed Oct. 13, 1998, pending.
BACKGROUND
[0002] A disk drive for a computer commonly is placed in an
enclosure in order to, for example, protect or cool the disk drive.
An enclosure commonly includes one or more external electrical
connectors that are connected inside the enclosure by a cable to
the disk drive. An enclosure may be constructed to be placed in
rack equipment or may be constructed to be placed on a desktop.
[0003] Advances in disk drive technology that provide greater
storage density and access speeds also are accompanied by problems
caused by higher power consumption and revolutions per minute of
the disk drive. These problems include increased heat and increased
noise. Techniques for reducing noise tend to be thermally
insulating and thus increase heat around a disk drive. Techniques
for reducing heat by convection, such as rotating fans, tend to
create noise. The use of conduction to dissipate heat, such as by a
heat sink, often is ineffective to adequately cool the disk drive,
because integrated circuits in a disk drive generally do not have a
heat conduction path from within the disk drive to a heat sink.
[0004] Other reliability problems are associated with the cable
that connects the disk drive to the external connector of the
enclosure. For example, the impedance of a cable is affected by its
proximity to both devices within the enclosure and the enclosure
itself. Because a cable may be placed in many locations within an
enclosure, the impedance of the cable can vary significantly from
enclosure to enclosure. Single-ended small computer systems
interface (SCSI) signals and low voltage differential (LVD) signals
are particularly sensitive to such variations in impedance. The
cable also can become loose after manufacturing, or can be
installed incorrectly.
[0005] Another reliability problem arises when data is striped,
i.e., a data word is divided and written in parallel, to a set of
disk drives. Such a set of disk drives is called a stripe set.
After data is stored on a stripe set, the order of the disks in the
stripe set must be maintained in order to maintain data integrity.
The exact physical arrangement of the disk drive enclosures for the
stripe set, for example in a stack, ideally would be maintained in
order to ensure data integrity. Some users actually resort to using
adhesive tape or other physical measures to bind the set of disk
drive enclosures together.
[0006] These problems are particularly undesirable in computing
environments where high reliability and low noise are expected,
such as in professional multimedia authoring studios. Computer
systems in such environments typically use a large amount of disk
capacity, particularly if the disks are used for storing audio and
video information. The large number of disks both creates a
significant amount of noise and increases concern for
reliability.
SUMMARY
[0007] Noise is reduced in a disk drive enclosure by using
vibration damping materials on the inside surface of the enclosure.
These materials and their placement on the inside surface of the
enclosure reduce noise without thermally insulating the disk drive.
A temperature controlled fan may be used to remove heat by
convection while generating a minimum amount of noise.
[0008] The connection between the disk drive and the external
connector of the disk drive enclosure is made more reliable by
using a printed circuit board instead of a cable. Because a printed
circuit board has a fixed location and fixed layout, variability
among disk drive enclosures can be minimized. Also, errors in
manufacturing of the disk drive enclosure can be reduced.
[0009] To facilitate the use of the disk drive in a stripe set, the
disk drive enclosure has a set of mechanical interlocks that permit
the enclosures to be stacked vertically. In one embodiment, the
mechanical interlocks are constructed in a manner that permits
stacking in unlocked and locked configurations. The locked
configuration may be made permanent using an additional locking
mechanism. These mechanical interlocks also may be used to support
the enclosure on a desktop. The mechanical interlocks also may be
constructed to slide on a rail, permitting the enclosure to be used
in a rack mount. A rack mount configuration also may be provided
with a quick-release mechanism that interacts with the mechanical
interlocks to hold the disk drive enclosure in the rack mount.
[0010] Accordingly, in one aspect, a disk drive enclosure has a
housing for enclosing a disk drive. A vibration dampening material
is applied to the inside surface of the housing. A temperature
sensor is mounted inside the housing adjacent to the disk drive.
The temperature sensor has an output to provide an electrical
signal indicative of ambient temperature in the housing. A control
circuit has an input connected to the output of the temperature
sensor and an output to provide a control signal as a function of
the temperature sensor. A fan has an input connected to the control
signal and is responsive to the control signal to rotate at a speed
corresponding to the control signal. In one embodiment, the control
signal varies according to the temperature in the housing within a
range of temperatures, whereby the speed of the fan is variable
according to the control signal. In another embodiment, a threshold
circuit has an input connected to the output of the temperature
sensor and an output to provide an alarm signal indicating one of a
plurality of ranges in which the temperature is sensed. An
indicator has an input connected to the output of the threshold
circuit and is responsive thereto to provide a visual indication of
the range in which the temperature is sensed.
[0011] In another aspect, the disk drive enclosure has a housing
for enclosing a disk drive. A first plurality of mechanical
interlocks is mounted on a first side of the housing. A second
plurality of mechanical interlocks is mounted on a second side of
the housing opposite the first side of the housing. Each of the
first and second plurality of mechanical interlocks has a top
portion having a surface complementary to a surface of a bottom
portion of the mechanical interlock, such that the top portion of a
first mechanical interlock and the bottom portion of a second
mechanical interlock are slidably connectable in a first direction.
When connected, the mechanical interlocks prohibit movement of the
mechanical interlocks with respect to each other in second and
third directions orthogonal to the first direction. In one
embodiment, the top portion has top face and the bottom portion has
a bottom face such that the top face of the top portion of a first
mechanical interlock supports the bottom face of the bottom portion
of a second mechanical interlock when enclosures on which the first
and second mechanical interlocks are attached are vertically
aligned and stacked. In another embodiment, each of the first and
second plurality of mechanical interlocks has portion having a
surface complementary to a surface of a support in a rack, such
that the portion of the mechanical interlock and the support in the
rack are slidably connectable in a first direction and when
connected prohibit movement of the mechanical interlock with
respect to support in second and third directions orthogonal to the
first direction. In still another embodiment, a locking mechanism
has a first movable member and is mounted on the first side of the
housing. In another aspect, a disk drive enclosure, for mounting in
a rack having a support, has a housing for enclosing a disk drive.
A first plurality of mechanical interlocks is mounted on a first
side of the housing. A second plurality of mechanical interlocks is
mounted on a second side of the housing opposite the first side of
the housing. Each of the first and second plurality of mechanical
interlocks has portion having a surface complementary to a surface
of the support in the rack, such that the portion of the mechanical
interlock and the support in the rack are slidably connectable in a
first direction and when connected prohibit movement of the
mechanical interlock with respect to support in second and third
directions orthogonal to the first direction.
[0012] In another aspect, a printed circuit board is constructed
for use in connecting a first connector on a disk drive to a second
and third connectors on a disk drive enclosure, wherein the first
connector has a plurality of pins providing a plurality of
corresponding signals, and wherein the second and third connectors
each receive the plurality of corresponding signals, The printed
circuit board includes a plurality of layers of material. A
plurality of traces are placed in a layout on the layers of
material, wherein each trace corresponds to one of the plurality of
signals from the first connector, wherein the plurality of signals
includes an acknowledge signal and a request signal, and wherein
the trace for the acknowledge signal and the trace for the request
signal are the same length. In one embodiment, the plurality of
signals includes a termination power signal, and wherein the trace
for the termination power signal is thicker than the traces for the
other signals. In another embodiment, the impedance of the traces
for the acknowledge and request signals is 90.sub.--6 Ohms. In
still another embodiment, the impedance of the traces for the
plurality of signals is 90.sub.--10 Ohms. In yet another
embodiment, a first connector is attached to a first surface of the
printed circuit board and a second connector is attached to the
printed circuit board on a second surface opposite the first
surface. In yet another embodiment, a first connector is attached
to a first surface of the printed circuit board, and a second
connector is attached to the first surface of the printed circuit
board. A temperature sensor also may be mounted on the printed
circuit board, which has an output to provide an electrical signal
indicative of ambient temperature around the temperature sensor. A
control circuit may be mounted on the printed circuit board which
has an input connected to the output of the temperature sensor and
an output to provide a control signal as a function of the
temperature sensor.
[0013] In another aspect, a mechanical interlock for use with a
disk drive enclosure has a top portion, a bottom portion and a
section connecting the top portion to the bottom portion, wherein
the top portion has a surface complementary to a surface of the
bottom portion, such that the top portion of a first mechanical
interlock and the bottom portion of a second mechanical interlock
are slidably connectable in a first direction and when connected
prohibit movement of the mechanical interlocks with respect to each
other in a second and directions orthogonal to the first direction.
The top portion has top face and the bottom portion has a bottom
face such that the top face of the top portion of a first
mechanical interlock supports the bottom face of the bottom portion
of a second mechanical interlock when enclosures on which the first
and second mechanical interlocks are attached are vertically
aligned and stacked.
[0014] Another aspect is a rack mount for a disk drive enclosure
having at least one bay for receiving the disk drive enclosure. The
rack mount has a support mechanism having edges shaped to engage an
interlock on the disk drive enclosure to guide the disk drive
enclosure into the bay. One or more spring loaded blocks, shaped to
engage the interlock on the disk drive enclosure, permit the
interlock to pass the blocks in a first direction and prohibit
passage of the interlock in a second direction opposite the first
direction. A user-operable member is constructed to move the spring
loaded block to permit passage of the interlock in the second
direction to permit removal of the disk drive enclosure from the
rack mount.
[0015] In other aspects, the printed circuit board connector, and
its various embodiments, are combined with the heat and noise
reduction techniques. In another aspect, the mechanical interlocks
for making and stacking the enclosures and its various embodiments
are combined with the heat and noise reduction techniques. The heat
and noise reduction techniques also may be used in combination with
both the printed circuit board connector and the mechanical
interlocks for stacking and racking the enclosures.
BRIEF DESCRIPTION OF THE DRAWING
[0016] In the drawing,
[0017] FIG. 1 is an exploded perspective view of a disk drive in an
enclosure;
[0018] FIG. 2 is a block diagram of thermal sensing and fan control
circuit;
[0019] FIG. 3 is a more detailed circuit diagram of one embodiment
of the thermal sensing and fan control circuit of FIG. 2;
[0020] FIG. 4 is a block diagram of the circuit of FIG. 2 further
including a temperature indicator;
[0021] FIG. 5 is a more detailed circuit diagram of the circuit of
FIG. 4;
[0022] FIG. 6 is a graph of a typical transfer function for the
circuits of FIGS. 3 and 5;
[0023] FIG. 7 is a circuit diagram of one embodiment of the printed
circuit board connector;
[0024] FIGS. 8A-E are a layout diagram for one embodiment of the
printed circuit board connector of FIG. 7 and including the control
circuit of FIG. 6;
[0025] FIG. 9 is a perspective view of a mechanical interlock for
stacking enclosures;
[0026] FIG. 10 is a side elevational view of a mechanical interlock
for stacking enclosures;
[0027] FIG. 11 is a cross-sectional side view of a mechanical
interlock for stacking enclosures;
[0028] FIG. 12 is a perspective view of two unconnected drive
enclosures;
[0029] FIG. 13 is a perspective view of two connected drive
enclosures;
[0030] FIG. 14 is a perspective view of a rack for mounting an
enclosure;
[0031] FIG. 15 is a perspective view of a rack with an enclosure
mounted therein; and
[0032] FIG. 16 is a top view of a mechanism permitting quick
release of the enclosure from a rack.
DETAILED DESCRIPTION
[0033] The following detailed description should be read in
conjunction with the attached drawing in which similar reference
numbers indicate similar structures.
[0034] Noise is reduced in a disk drive enclosure by using
vibration damping materials on the inside surface of the enclosure.
These materials and their placement on the inside surface of the
enclosure reduce noise without thermally insulating the disk drive.
A temperature controlled fan may be used to remove heat by
convection while generating a minimum amount of noise. One
embodiment of an enclosure with such noise and heat reduction will
be first described in connection with FIGS. 1-6.
[0035] FIG. 1 is an exploded perspective view of a disk drive
enclosure in one embodiment. The enclosure has a housing which, in
this embodiment, is in four pieces. The housing pieces may be made
of any material that is sufficiently hard and impact resistant for
the environment in which the enclosure is used. Example materials
include sheet metal, such as aluminum or steel, or hard plastic.
The housing includes a base 100. A top portion 104 formed in "c"
shape connects to the base 100. A front 108 and back 106 complete
the enclosure. The base 100, front 108 and back 106 may be one
piece. The front 108 has an air inlet 118. Back 106 has an air
outlet 116.
[0036] A disk drive 102 is connected to the base 100 through a
bracket 111 that has mounts 110 and 112. The bracket 111 is
attached to the base 100. A power supply 124 also is mounted to the
base 100 and also is a source of heat in the enclosure. The disk
drive produces heat and noise, which are generally related to the
power consumption and revolutions per minute of the disk drive
motor. The disk drive 102 may be, for example, a Cheetah 9 or
Cheetah 18 disk drive from Seagate Technology, Inc., of Scotts
Valley, Calif. Such a disk drive complies with the small computer
systems interface (SCSI) standard, and uses a low voltage
differential (LVD) signal. This disk drive has a capacity of 9 to
18 gigabytes (GB) and a rotation speed of 7200 to 10000 revolutions
per minute. It should be understood that many other types of disk
drive may be used, and the invention is not limited to the type of
interconnect, capacity of the disk drive, or other characteristics
of the disk drive.
[0037] The base 100, when made of heat conducting material such as
metal, acts a heat sink for the disk drive. In particular, the two
mounting bracket 111 that connects to the disk drive at opposite
ends along the sides of the disk drive through mounts 110 and 112
dissipates heat from the disk drive by conduction to the
enclosure.
[0038] Heat also may be dissipated by convection, which should be
used because integrated circuits within the disk drive often do not
have a heat conduction path from the circuit to the housing of the
disk drive itself. Heat convection is provided by a fan 114 which
is shown located at the front 108 of the enclosure, between the
disk drive 102 and the front 108 of the enclosure. The fan 114 also
is mounted to the base 100 of the enclosure. To minimize the amount
of noise produced by the fan while maximizing air flow, the fan
should be selected so that its size is the maximum allowable to fit
within the enclosure. Using a ball-bearing type fan or brushless DC
motor also minimizes the amount of noise generated by the fan,
reduces power consumption and increases reliability. A fan that
meets these characteristics is available from Comair Rotron of San
Ysidro, Calif., under the product name Flight 60 LT. This fan is
rated at 23.2 CFM at 12 volts. It should be understood that the
invention is not limited to the use of a particular fan, fan
dimensions, fan type, or fan specifications.
[0039] The fan motor rotates about an axis to move blades that in
turn cause air to flow. The direction of rotation and the
orientation of the blades controls the direction of airflow. The
fan may be positioned to draw air through an inlet, over the disk
drive, through the fan and out an outlet in the enclosure.
Alternatively, the fan may draw air through an inlet, through the
fan, over the disk drive and out the outlet in the enclosure. In
the former configuration, the temperature sensor should be placed
between the disk drive and the fan. In that latter configuration,
the temperature sensors should be placed between the disk drive and
the outlet. In general, the temperature sensor should be adjacent
to the disk drive and adjacent to the side of the disk drive that
is closest to the outlet.
[0040] The fan is controlled by a circuit (not shown) that may be
mounted on a printed circuit board 120. The fan may be controlled
according to temperature sensed adjacent the disk drive. A
temperature sensor 122, such as a thermistor, is mounted adjacent
the disk drive and in the path of airflow that comes in a direction
from the disk drive, rather than towards the disk drive. The fan
may be controlled to operate at a lower speed at lower
temperatures, thus reducing the amount of noise generated by the
fan. In this manner, the temperature sensor detects the approximate
ambient temperature of the disk drive.
[0041] The control circuit for the fan will be described in more
detail below in connection with FIGS. 2-6.
[0042] Referring now to FIG. 2, the temperature sensing control
circuit for the fan will now be described. FIG. 2 is a block
diagram of such a circuit. The temperature sensor 130 reacts to
ambient temperature to generate an output signal 132 that is a
function of the detected temperature. Different temperature sensors
are selected for temperatures in different ranges. Ideally, the
temperature sensor should have an operating range between
10.degree. C. and 70.degree. C. In the embodiment described below,
a thermistor is used as the temperature sensor.
[0043] The output of the temperature sensor is received by an input
to a voltage control circuit 134. The voltage control circuit 134
also has an input for receiving a certain minimum value 136,
indicative of a minimum voltage which it should provide as an
output. The output 138 of the voltage control circuit is dependent
upon the specified minimum voltage and the temperature sensed by
the temperature sensor. The output of the voltage control circuit
is then applied to the fan.
[0044] Referring now to FIG. 3, a detailed circuit diagram of one
embodiment of the temperature control signal of FIG. 2 will now be
described. In FIG. 3, the temperature sensor is a thermistor 200,
or thermally sensitive resistor, which is connected to a source
voltage 202 (e.g., 12 volts). An example thermistor is a negative
temperature coefficient (NTC) thermistor Part No. LM5001-5,
available from Dale Electronics, Inc. of Columbus, Nebr., which has
a nominal impedance of about 5000 (5K) ohms, but which varies from
8.375K ohms to 0.5K ohms over a temperature range of 10.degree. C.
to 70.degree. C. A positive temperature coefficient (PTC)
thermistor also could be used, with appropriate changes to the
control circuit. It should be understood that the invention is not
limited to any particular thermistor.
[0045] The thermistor is connected to a common voltage 204 through
an RC circuit 206 having a resistor 208 (e.g. 100K ohms) and a
capacitor 210 (e.g., 0.1 .mu.F) connected electrically in parallel.
The voltage (Vt) at node 212 between thermistor 200 and RC circuit
206 is applied to the positive input of an operational amplifier
214. Example commercially available operational amplifiers include
the TL082, LM358 or LM1558 operational amplifiers available from
several sources, such as National Semiconductor Corporation of
Santa Clara, Calif. The negative input of the operational amplifier
is the voltage (Vo) from a voltage divider 216, having two
resistors 218 (with impedance R2) and 220 (with impedance R3)
connected in serial between the source voltage 202 and common
voltage 204. A feedback connection from the output of the
operational amplifier 214 to its negative terminal is provided by
an RC circuit 222 including a resistor 224 (with impedance R4) and
capacitor 226 (e.g., 0.1 .mu.F) connected electrically in parallel.
The output of operational amplifier 214 also is connected to a
voltage regulator 228. A suitable voltage regulator is Part No.
LM1117T, available from National Semiconductor Corporation of Santa
Clara, Calif., or other sources. The input of the voltage regulator
228 is connected to the source voltage 202 and a terminal of a
resistor 230 (e.g., 100K ohms) connected between the output of
operational amplifier 214 and the source voltage 202. Its output
voltage (Vf) is provided to the fan.
[0046] In the circuit shown in FIG. 3, the output voltage Vf of the
voltage regulator is described by the following equations:
Vf=(Vt-Vo)Av+1.25V
Av=1+(R4/((R2+R3)/R2R3))
[0047] Given the temperature-to-voltage characteristics of the
thermistor, the voltage Vo may be set by selecting impedances for
resistors R2, R3 and R4 such that the desired output voltage Vf is
obtained from the voltage regulator 228. The maximum output voltage
Vf should be set to occur at a temperature lower than the maximum
temperature specified for reliable operation of the disk drive.
[0048] FIG. 4 illustrates another embodiment of the control circuit
for the fan that also provides a high temperature indicator signal
144. This signal may be used to signal an alarm to a user or to the
computer system. For example, the signal may be used to illuminate
a light emitting diode (LED) 142 on the enclosure to indicate that
the recommended operating temperature of the disk drive has been
exceeded. The high temperature indicator signal is generated as a
function of the temperature signal 132 or 132' by a threshold
circuit 140. The temperature signal may come from the thermistor as
indicated at 132 or from the fan control circuit as indicated at
132'. The threshold circuit 140 receives a signal 148 indicative of
the threshold temperature indicate the operating range of the disk
drive.
[0049] Referring now to FIG. 5, a detailed circuit diagram of one
embodiment of the temperature control signal of FIG. 4 will now be
described. FIG. 5 adds to the circuit of FIG. 3 a second operation
amplifier 232 with a positive input that connects to the output of
operational amplifier 214 through resistor 234 and to the output of
operational amplifier 232 through resistor 236, to provide
hysteresis. The negative input of operational amplifier 232 is
connected to node 238 between a resistor 240 and RC circuit 242
connected in serial between source 202 and common 204. The RC
circuit 242 includes resistor 244 and capacitor 246 (e.g., 0.1
.mu.F). The output of operational amplifier 232 controls a light
emitting diode (not shown) through a control circuit 248 which
provides an LED output 250. The control circuit 248 includes three
NAND Schmitt triggers 252, 254 and 256 of which the combined
outputs provide the current to drive the output LED 250. The input
to the Schmitt triggers 252 through 256 is provided by the output
of a NAND Schmitt trigger 258, which is configured to be an
oscillator. The first input of Schmitt trigger 258 is connected to
a node 260 between resistors 262 and 264 connected in serial
between the output of operational amplifier 232 and common 204,
which implements a voltage divider. The second input of Schmitt
trigger 258 is provided by a feedback circuit through resistor 266,
and is also connected to common 204 via capacitor 268 (e.g., 0.33
.mu.F). The resistors 234, 236, 240, 244, 260, 264 and 266 may have
an impedance, for example of 100K ohms.
[0050] Characteristics of the circuits shown in FIGS. 3 and 5 are
illustrated by the graph of FIG. 6. As temperature of the disk
drive increases up to temperature t1, the fan is off. As the
temperature increases above t1, the fan is turned on, but at a low
speed. Ultimately, the top speed of the fan is reached by
temperature t2. If the ambient temperature near the disk drive
continues to increase, the temperature ultimately reaches
temperature t3 that indicates the limit of the desired operating
range of the disk drive. At this temperature, the threshold circuit
140 in FIG. 4 generated the high temperature signal. Using such a
fan control circuit, the fan is used on when the detected ambient
temperature is such that heat should be dissipated. If the fan is
operating at its maximum speed and the temperature continues to
increase, the user or computer system is alerted to the excessive
temperature. The temperatures t1, t2 and t3 vary with the fan and
disk drive used. As a result, the selection of various components
for use in the circuits shown in FIGS. 3 and 5 is application
dependent.
[0051] Having now described the heat dissipation in the enclosure,
noise reduction will now be described again in reference to FIG. 1.
Noise within the disk drive enclosure is created by vibrations from
the disk drive and fan. By using a temperature controlled fan, and
the largest fan that fits in the enclosure, the amount of noise
produced by the fan is minimized. The vibrations from the disk
drive and fan propagate through the walls of the enclosure itself,
the disk drive and fan to create audible sound, typically in the
range of 1 kHz to 4 kHz.
[0052] The mechanical vibrations in the walls of the enclosure may
be reduced by applying a vibration damping material to the inside
surface of the housing. The vibration damping material ideally
covers as much of the surface area as practical, and any mounting
brackets of the disk drive and fan. At a minimum, the material is
applied to the inside surface of the base and top of the housing.
The vibration damping material also may be applied to the front and
back of the housing. By using a vibration damping material applied
to the housing, the disk drive is not insulated; heat still may be
dissipated from the disk drive by convection. Vibrational damping
materials also may be used in any connectors between the fan and
the base of the enclosure.
[0053] In a vibration damping material, vibrational energy is
converted into heat rather than sound. An example vibration damping
material is a styrene-butyadine-rubber based mastic with an
aluminum constraining layer. Such a material is advantageous
because it is both thin and effective at reducing noise. One
example of such a material is a material sold under the trademark
Dynamat Super by Dynamic Control of Hamilton, Ohio. This material
has a pressure sensitive adhesive on one side. Because it may be
die-cut and easily installed, it is cost-effective to use. This
material has a thickness of about 0.060 inches. This material has
an acoustic loss factor of about 0.10 to 1.5 depending on the
ambient temperature and frequency range of the vibrations. It
should be understood that the invention is not limited to any
particular vibration damping material. Other damping materials
having similar noise reduction properties also may be used.
[0054] Reducing noise from sound waves in the air in the enclosure
is more difficult because the disk drive enclosure has air inlets
118 and outlets 116 to permit heat convection to dissipate heat
from the enclosure. In particular, the fan draws air into and
forces air out of the disk drive enclosure. In order to reduce
sound waves exiting the enclosure through the outlet, the printed
circuit board 122 is placed in a vertical orientation as shown in
FIG. 1. Alternatively, a baffle also may be placed between the
outlet and the disk drive if the printed circuit board is placed in
a horizontal orientation. Also, in order to reduce sound waves from
the fan, a muffler 126 (shown in FIG. 1) may be used. The area
between the baffle and the fan may be filled with sound absorbing
material, such as vibration damping material or foam, to reduce
noise from the fan.
[0055] Having now described noise and heat reduction, other
improvements to the enclosure will now be described.
[0056] The connection between the disk drive and the external
connector of the disk drive enclosure is improved by using a
printed circuit board instead of a cable. In particular, because a
printed circuit board has a fixed location and fixed layout,
variability among disk drive enclosures is minimized. Also, errors
in manufacturing of the disk drive enclosure are reduced. Such a
connector is described in connection with FIGS. 7 and 8A-E.
[0057] Referring now to FIG. 7, a circuit diagram for a printed
circuit board connector will now be described. The disk drive has a
connector to which a connector 400 attaches. The disk drive
enclosure has two connectors to which connectors 402 and 404
attach. The connectors 400, 402 and 404 are mounted on the printed
circuit board. Connector 402 is an input; connector 404 is an
output. In a configuration such as shown in FIG. 7, several SCSI
disk drive devices may be daisy chained together.
[0058] The actual signals provided by the disk drive which pass
through connectors 402 and 404 and defined by the SCSI standard. In
this embodiment the signals are low voltage differential (LVD)
signals. The eighteen differential data signals (thirty-six signal
lines) are known as DB0-15 (data bus) and DBP0-P1 (data bus
parity). There are also nine differential control signals labeled
as: ATN (attention), BSY (bus is busy), ACK (acknowledge), RST
(reset), MSG (message), SEL (select), C.+-.D (control or data), REQ
(request), and I.+-.O (in/out).
[0059] On connectors 402 and 404, the ATN (attention) signals are
separated from other signals by ground pins on the connector.
Connectors 400, 402 and 404 also have a differential sense signal
which is interconnected among the connectors. Similarly, reserved
signal lines and termination power signal lines also are
interconnected between connectors 402 and 404. Connector 400 also
provides an active signal 408 that may be provided to a light
emitting diode on the face of the disk drive enclosure to signal
activity of the disk drive. SCSI identifier signals (SCSI.+-.ID0-3)
also may be routed on the circuit board to a different connector
that provides signals from a SCSI identification switch, such as a
push button rotary switch mounted on the front of the disk drive
enclosure, indicating these identifiers to the disk drive. The
other signals RMT.+-.START, DLYD.+-.START and SYNC need not be
used.
[0060] Given the circuit diagram for the connectors as shown in
FIG. 7, these circuits may be implemented using a printed circuit
board instead of a cable, which provides various benefits. The
printed circuit board provides a more definite connection between
the disk drive and the enclosure. Also, the printed circuit board
reduces the variability among devices that would otherwise be
present if cables were used.
[0061] When routing this circuit on a printed circuit board,
several constraints are applied to the traces to maximize
performance. These constraints are as follows:
[0062] 1) a thick trace is used for the termination power
signals;
[0063] 2) the traces for the ACK (acknowledge) and REQ (request)
signals are the same length;
[0064] 3) the impedance of the traces for the ACK (acknowledge) and
REQ (request) signals is 90.+-.6 Ohms; and
[0065] 4) the impedance of the remaining traces is 90.+-.10
Ohms.
[0066] One embodiment of the printed circuit board on which both
the circuit of FIG. 5 and the circuit of FIG. 7 are provided, is
shown in FIGS. 8A-8E. FIG. 8A illustrates the silkscreen on the
primary side of the board and indicates the placement of the
electronic components of FIG. 5, other connectors, and the
connectors of FIG. 7. FIG. 8B illustrates a first layer of traces.
The traces for the acknowledge and request signals are illustrated
by reference to the connector pins for these signals. In
particular, the +REQ signal is on pin 29 of the 68 pin connectors
and pin 52 of the 80 pin connector, as indicated at 410. The -REQ
signal is on pin 63 of the 68 pin connectors and pin 12 of the 80
pin connector, as indicated at 412. The +ACK signal is on pin 24 of
the 68 pin connectors and pin 57 of the 80 pin connector, as
indicated at 414. The -ACK signal is on pin 58 of the 68 pin
connectors and pin 17 of the 80 pin connector, as indicated at 416.
FIG. 8C illustrates the ground plane which is the second layer.
FIG. 8D illustrates the power plane which is the third layer. FIG.
8E illustrates a second layer of traces, which is the fourth layer.
The printed circuit board has a set of through holes for each
connector 400', 402', and 404' that are mounted to the printed
circuit board. The actual location of these connectors on a printed
circuit board depends on the location of the disk drive connector
and the connectors on the enclosure. The embodiment shown in FIGS.
8A-E is for a printed circuit board that is placed horizontally
within the disk drive enclosure. The three connectors are mounted
on the same surface of the printed circuit board. In an alternative
embodiment, the printed circuit is placed vertically within the
enclosure. In this embodiment, the connector to the disk drive is
mounted on the surface of the printed circuit board opposite the
connectors to the enclosure.
[0067] By using the printed circuit board as a connector, other
circuits inside the disk drive enclosure also may be mounted on the
printed circuit board. In particular, the temperature sensor may be
mounted on the printed circuit board. The fan control circuit also
may be mounted on the printed circuit board.
[0068] Having now described the printed circuit board connector,
features of the enclosure that permit stacking of multiple
enclosures, or placement of the enclosure in a rack, will now be
described in connection with FIGS. 9-15. To facilitate the use of
the disk drive in a stripe set, the disk drive enclosure may have a
set of mechanical interlocks that permit the enclosures to be
stacked vertically in either an unlocked or a locked formation. The
locked configuration may be made permanent using an additional
locking mechanism. These mechanical interlocks also may be used to
support the enclosure on a desktop. The mechanical interlocks also
may be constructed so that they can slide on a rail, permitting the
enclosure to be used in a rack mount. The rack mount also may be
provided with a quick-release mechanism that interacts with the
mechanical interlocks to hold the disk drive enclosure in the rack
mount.
[0069] Referring now to FIGS. 9-11, one embodiment of a mechanical
interlock will now be described. Four of these mechanical
interlocks are attached to the sides of the disk drive enclosure.
The mechanical interlock has a portion 450 that is used to attach
the mechanical interlock to the enclosure. In this embodiment, a
hooked member 452 inserts into the disk drive enclosure and a hole
454 permits a screw to attach the mechanical interlock to the
enclosure. The shape of the region 450 and the manner of attaching
it to the enclosure are not significant to the present invention.
The mechanical interlock connects two enclosures by mating the top
portion 456 of one mechanical interlock with the bottom portion 458
of the other mechanical interlock. The top portion has a surface or
shape 460 that is complementary to the surface or shape 462 of the
bottom portion. The mechanical interlock may be made of any
suitably strong material, such as a blend of 50% PVC and 50% ABS
plastic.
[0070] In one configuration, the top portion has top face and the
bottom portion has a bottom face such that the top face of the top
portion of a first mechanical interlock supports the bottom face of
the bottom portion of a second mechanical interlock when enclosures
on which the first and second mechanical interlocks are attached
are vertically aligned and stacked. This configuration provides an
unlocked stack of disk drive enclosures.
[0071] The shapes on the mechanical interlock also permit a locked
configuration. In particular the shapes of the mechanical interlock
are such that the bottom portion 458 of one mechanical interlock
and the top portion 456 of another mechanical interlock are
slidably connectable in a first direction, such as shown in FIGS.
12 and 13. In FIG. 12, a first enclosure 500 is placed on top of a
second enclosure 502. The mechanical interlocks 504 on the first
enclosure engage with the mechanical interlocks 506 on the second
enclosure when the first enclosure is slid on top of the second
enclosure. When connected, as shown in FIG. 13, movement of the
mechanical interlocks with respect to each other in a direction
orthogonal to the direction of sliding is prohibited. In this
embodiment, the shape 462 is a "c" shape whereas the shape 460 is a
"-" shape. By using these shapes, movement in the vertical
direction 510 is prohibited, thus connecting the enclosures on
which these mechanical interlocks are mounted. Lateral movement in
one direction 512 also is prohibited. With such mechanical
interlocks on both sides of the enclosure, lateral movement in both
directions 512 and 514 is limited.
[0072] As shown in FIGS. 9 through 11, the mechanical interlock
also may have a detent 464 on the top portion 456 that interacts
with a complementary detent 466 in the bottom portion to maintain
the connection between two mechanical interlocks. Any other
mechanism may be used to maintain the connection between the two
mechanical interlocks. For example, a piece attached to one
enclosure may rotate and mate with a complementary piece on another
enclosure. This rotated piece may be secured to the other
enclosure, for example by using a screw.
[0073] Also shown in FIGS. 12 and 13 are a handle 508, rotating
counter 520 that may be used to provide the SCSI identifier signals
to the disk drive and an LED display 522 to indicate the status of
the disk drive. FIGS. 14 and 15 illustrate how the enclosure shown
in FIGS. 12 and 13 also may be used in a rack configuration. A rack
mount, shown in FIG. 14, has a faceplate 300 that can be attached
to a rack by any suitable attachment through holes 302. One or more
bays 304 receive an enclosure. The embodiment shown in FIGS. 14 and
15 accepts two drive enclosures independently. The enclosure is
placed through openings in the faceplate into bays 304 so that the
bottom portion of each mechanical interlock engages with the edge
of a plate 308. Alternatively, two rails may be provided on the
rack mount to engage the mechanical interlocks in order to support
the sides of the enclosure. The plate or the rails may terminate
with a detent 310 that prevents the enclosure from sliding off the
end of the plate or rails. The enclosure as mounted in the rack
mount is shown in FIG. 15. A quick release mechanism 312, operated
using button 314 also may be provided.
[0074] The quick release mechanism is described in connection with
FIG. 16, which is a bottom view of a rack mount, illustrating the
quick release mechanism underneath the support or rails for the
disk drive enclosure. The quick release mechanism includes two arms
600 and 602, each of which supports a corresponding block 604, 606
(also shown at 312 in FIGS. 14 and 15). Each block (e.g., 604), has
a sloped surface 608 that extends from the side of the support or
rail. The length of the sloped surface 608 that extends from the
rail increases from the front of the rack mount to the back of the
rack mount. The blocks 604 and 606 each are connected to a
corresponding spring 610, 612, which are attached to the support.
The spring acts to force the blocks in a direction as indicated at
614 and 616, respectively. Many configurations of one or more
springs can provide such a force, and the invention is not limited
to the configuration shown in FIG. 16. Each arm 600 and 602 is
connected to a rotating connector 618, which rotates about an axis
620. A third arm 622 also is connected to the rotating connector
618 at one end, and to the button 624 (314 in FIGS. 14 and 15) on
the other end.
[0075] When a disk drive enclosure is slid into a bay on the rack
mount, the mechanical interlocks push the blocks 604 and 606 out of
the way, then are stopped at the end of the rails by the detents as
shown in FIG. 15. The force from the mechanical interlocks on the
blocks causes the connector 618 to rotate about axis 620. After the
mechanical interlocks pass the blocks 604 and 606, the springs 610
and 612 force the block back to their original position, thus
retaining the enclosure and preventing the enclosure from moving
backward. To remove the enclosure, button 624 is pressed, causing
the connector 618 to rotate about axis 620, thus pulling blocks 604
and 606 inward. The disk drive enclosure then may be removed. The
springs 610 and 612 force the button and blocks back to their
original positions. This quick release mechanism allows fast
installation and removal of a disk drive enclosure.
[0076] The combination of heat and noise reduction, a printed board
circuit connector and mechanical interlocks provides a disk drive
enclosure that is particularly suited to multimedia production
environments by reducing noise and improving reliability. The
ability to place such enclosures in a stack (in either an unlocked
or a locked configuration), in a rack or on a desktop improves its
portability and simplifies maintenance of data integrity of striped
data.
[0077] Having now described a few embodiments, it should be
apparent to those skilled in the art that the foregoing is merely
illustrative and not limiting, having been presented by way of
example only. Numerous modifications and other embodiments are
within the scope of one of ordinary skill in the art and are
contemplated as falling within the scope of the invention.
* * * * *