U.S. patent application number 09/833216 was filed with the patent office on 2001-11-22 for disk speed profile method and device.
Invention is credited to Drouin, David.
Application Number | 20010043425 09/833216 |
Document ID | / |
Family ID | 22171091 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010043425 |
Kind Code |
A1 |
Drouin, David |
November 22, 2001 |
Disk speed profile method and device
Abstract
A system having a storage device including read/write heads for
repositioning the read/write heads from a parking location to a
position adjacent a surface of a magnetic disk, the storage device
includes a spindle motor coupled to the magnetic disk, for
accelerating the magnetic disk to at least a first number of
revolutions per time period while the read/write heads are
positioned at the parking location, and a solenoid control coupled
to the read/write heads and to the spindle motor, for biasing the
read/write heads towards the position adjacent the surface of the
magnetic disk after the magnetic disk reaches the first number of
revolutions per time period, wherein the spindle motor maintains a
rotation of the magnetic disk at less than a second number of
revolutions per time period before the read/write heads are
positioned adjacent the surface of the magnetic disk, and wherein
the spindle motor rotates the magnetic disk at a third number of
revolutions per time period after the read/write heads are
positioned adjacent the surface of the magnetic disk.
Inventors: |
Drouin, David; (Milpitas,
CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Family ID: |
22171091 |
Appl. No.: |
09/833216 |
Filed: |
April 10, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09833216 |
Apr 10, 2001 |
|
|
|
09082418 |
May 20, 1998 |
|
|
|
Current U.S.
Class: |
360/75 ;
360/73.03; G9B/19.046; G9B/21.003; G9B/21.021; G9B/21.027;
G9B/5.181; G9B/5.187 |
Current CPC
Class: |
G11B 5/54 20130101; G11B
19/28 20130101; G11B 21/02 20130101; G11B 21/12 20130101; G11B
5/5521 20130101; G11B 21/22 20130101 |
Class at
Publication: |
360/75 ;
360/73.03 |
International
Class: |
G11B 021/02; G11B
015/46 |
Claims
What is claimed is:
1. A method for unloading read/write heads from a surface of a
magnetic disk, the magnetic disk coupled to a spindle motor,
comprising the steps of: using the spindle motor to rotate the
magnetic disk at approximately a first number of revolutions per
minute; positioning the read/write heads adjacent the surface of
the magnetic disk; receiving a head unload signal; using the
spindle motor to rotate the magnetic disk at approximately a second
number of revolutions per minute in response to the head unload
signal; after a first predetermined amount of time after the step
of receiving the head unload signal, biasing the read/write heads
towards an outer edge of the magnetic disk; and after a second
predetermined amount of time after the step of receiving the head
unload signal, using the spindle motor to dynamically brake the
magnetic disk from approximately the second number of revolutions
per minute.
2. The method of claim 1 wherein the step of biasing the read/write
heads further comprises the step of biasing the read/write heads
onto a load/unload ramp.
3. The method of claim 1 wherein the second number of revolutions
per minute is greater than the first number of revolutions per
minute.
4. The method of claim 1 wherein the first number of revolutions
per minute is greater than the second number of revolutions per
minute.
5. The method of claim 1 further comprising the step of: before the
step of biasing the read/write heads towards the outer edge of the
magnetic disk, biasing the read/write heads towards an inner edge
of the magnetic disk.
6. A method for repositioning read/write heads from a parking
location to a position adjacent a surface of a magnetic disk, the
magnetic disk coupled to a spindle motor, comprising the steps of:
receiving a read/write heads load signal; using the spindle motor
to rotate the magnetic disk at least a first number of revolutions
per time period, in response to the read/write heads load signal;
thereafter using the spindle motor to maintain rotation of the
magnetic disk at less than a second number of revolutions per time
period, the second number greater than the first number; biasing
the read/write heads towards the position adjacent the surface of
the magnetic disk after the step of using the spindle motor to
rotate the magnetic disk and during the step of using the spindle
motor to maintain rotation of the magnetic disk; and using the
spindle motor to rotate the magnetic disk at a third number of
revolutions per time period, after the step of biasing the
read/write heads, the third number greater than the second
number.
7. The method of claim 6 wherein the step of biasing the read/write
heads comprises the step of unloading the read/write heads from a
load/unload ramp.
8. The method of claim 6 wherein the step of using the spindle
motor to rotate the magnetic disk a third number of revolutions per
time period includes the step of using the spindle motor to
accelerate the magnetic disk.
9. The method of claim 6 wherein the first number of revolutions
per time period is approximately 1000 revolutions per second.
10. The method of claim 9 wherein the second number of revolutions
per time period is approximately 1500 revolutions per second.
11. A system having a storage device including read/write heads for
repositioning the read/write heads from a parking location to a
position adjacent a surface of a magnetic disk, the storage device
further comprising: a spindle motor coupled to the magnetic disk,
for accelerating the magnetic disk to at least a first number of
revolutions per time period while the read/write heads are
positioned at the parking location; and a solenoid control coupled
to the read/write heads and to the spindle motor, for biasing the
read/write heads towards the position adjacent the surface of the
magnetic disk after the magnetic disk reaches the first number of
revolutions per time period; wherein the spindle motor maintains a
rotation of the magnetic disk at less than a second number of
revolutions per time period before the read/write heads are
positioned adjacent the surface of the magnetic disk, and wherein
the spindle motor rotates the magnetic disk at a third number of
revolutions per time period after the read/write heads are
positioned adjacent the surface of the magnetic disk.
12. The system of claim 11 wherein the parking location is on a
load/unload ramp.
13. The system of claim 11 wherein the solenoid control is also for
loading the read/write heads onto the magnetic disk.
14. The system of claim 11 wherein the second number of revolutions
per time period is greater than the first number of revolutions per
time period.
15. The system of claim 14 wherein the third number of revolutions
per time period is greater than the second number of revolutions
per time period.
16. The method of claim 11 wherein the first number of revolutions
per time period is approximately 1000 revolutions per second.
17. The method of claim 11 wherein the second number of revolutions
per time period is approximately 1500 revolutions per second.
18. The system of claim 11 wherein the parking location is located
at an inner crash stop.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to removable storage
devices for electronic information. More particular, the present
invention provides a technique including an apparatus and methods
for the movement and operation of a storage device including a
magnetic head used to read and write data into a removable
disk.
[0002] Consumer electronics including television sets, personal
computers, and stereo or audio systems, have changed dramatically
since their availability. Television was originally used as a stand
alone unit in the early 1900's, but has now been integrated with
audio equipment to provide video with high quality sound in stereo.
For instance, a television set can have a high quality display
coupled to an audio system with stereo or even "surround sound" or
the like. This integration of television and audio equipment
provides a user with a high quality video display for an action
movie such as STARWARS.TM. with "life-like" sound from the high
quality stereo or surround sound system. Accordingly, the clash
between Luke Skywalker and Darth Vader can now be seen as well as
heard in surround sound on your own home entertainment center. In
the mid-1990's, computer-like functions became available on a
conventional television set. Companies such as WebTV of California
provide what is commonly termed as "Internet" access to a
television set. The Internet is a world wide network of computers,
which can now be accessed through a conventional television set at
a user location. Numerous displays or "wet sites" exist on the
Internet for viewing and even ordering goods and services at the
convenience of home, where the act of indexing through websites is
known as "surfing" the web. Accordingly, users of WebTV can surf
the Internet or web using a home entertainment center.
[0003] As merely an example, FIG. 1 illustrates a conventional
audio and video configuration, commonly termed a home entertainment
system, which can have Internet access. FIG. 1 is generally a
typical home entertainment system, which includes a video display
10 (e.g., television set), an audio output 20, an audio processor
30, a video display processor 40, and a plurality of audio or video
data sources 50. Consumers have often been eager to store and play
back prerecorded audio (e.g., songs, music) or video using a home
entertainment system. Most recently, consumers would like to also
store and retrieve information, commonly termed computer data,
downloaded from the Internet.
[0004] Music or audio have been traditionally recorded on many
types of systems using different types of media to provide audio
signals to home entertainment systems. For example, these audio
systems include a reel to reel system 140, using magnetic recording
tape, an eight track player 120, which uses eight track tapes, a
phonograph 130, which uses LP vinyl records, and an audio cassette
recorder 110, which relies upon audio cassettes. Optical storage
media also have been recognized as providing convenient and high
quality audio play-back of music, for example. Optical storage
media exclusively for sound include a digital audio tape 90 and a
compact disk 10. Unfortunately, these audio systems generally do
not have enough memory or capacity to store both video and audio to
store movies or the like. Tapes also have not generally been used
to efficiently store and retrieve information from a personal
computer since tapes are extremely slow and cumbersome.
[0005] Audio and video have been recorded together for movies using
a video tape or video cassette recorder, which relies upon tapes
stored on cassettes. Video cassettes can be found at the local
Blockbuster.TM. store, which often have numerous different movies
to be viewed and enjoyed by the user. Unfortunately, these tapes
are often too slow and clumsy to store and easily retrieve computer
information from a personal computer. Additional video and audio
media include a laser disk 70 and a digital video disk 60, which
also suffer from being read only, and cannot be easily used to
record a video at the user site. Furthermore, standards for a
digital video disk have not been established of the filing date of
this patent application and do not seem to be readily establishable
in the future.
[0006] From the above, it is desirable to have a storage media that
can be used for all types of information such as audio, video, and
digital data, which have features such as a high storage capacity,
expandability, and quick access capabilities.
[0007] A typical storage device includes a storage media including
a magnetic disk and a read/write head for reading data from the
magnetic disk. In a normal, operating mode, the read/write heads
are positioned above the data storage portion of the magnetic disk.
More particularly, the read/write heads "fly" above the surface of
the magnetic disk and never physically touch the data storage
portion of the magnetic disk.
[0008] Upon power-down of a typical storage device, the read/write
heads are typically moved from a position above the data storage
portion of the magnetic disk to a safe position. This safe position
is typically not above the storage portion, but at a landing region
located at either the inner or outer diameter of the disk; a head
load/unload ramp, often located outside the outer diameter of the
disk; and the like.
[0009] If the read/write heads are not reliable moved to a safe
position after power-off, the read/write heads may move around the
storage device causing damage to the data storage portions of the
magnetic disk resulting in data loss, causing misalignments to the
read/write heads, causing damage to the read/write head elements,
and causing other types of damage. The potential damage with
storage devices based upon magneto-resistive (MR) read/write heads
is significant due to the high cost of MR heads compared to the
storage device and their more delicate nature.
[0010] Present methods for unloading of read/write heads include
either maintaining the rotational speed of the magnetic disk at the
same speed used for conventional operation while unloading the
heads or allowing the magnetic disk to slow down at its own pace
while unloading the heads. Another method includes removing a drive
voltage from the spindle motor and using a Back Electro-Motive
Force (back EMF, VBEMF, VEMF) voltage generated by the spindle
motor to power the heads to the safe position.
[0011] One concern about relying upon present methods is that
because the initial radial positions of the MR heads is
unpredictable, the amount of force applied by flex cables coupled
to actuator arms is unpredictable, and the load/unload ramp
resistance is unpredictable. Further, because the height at which
the read/write heads fly over the magnetic disk is non-linearly
related to the speed of rotation of the magnetic disk, the position
of the read/write heads on the load/unload ramp vary. This causes
problems when loading heads onto the magnetic disk.
[0012] Another concern is that the read/write heads are not always
reliably unloaded. This occurs because the amount of energy applied
to the read/write heads is typically not regulated or controlled.
For example, when relying upon a back EMF, where a spindle motor
has a great deal of internal resistance, the spindle motor may
spin-down faster than designed to do resulting in a back EMF energy
that is lower than predicted. As a result of the lower back EMF
energy, the read/write heads may not be reliably unloaded.
[0013] Upon power-up of a typical storage device, the read/write
heads are typically moved from the safe position to a position
above the data storage portion of the magnetic disk.
[0014] If the read/write heads are not carefully loaded onto the
magnetic disk, the read/write heads may bounce on the magnetic disk
again causing damage to the data storage portions of the magnetic
disk resulting in data loss, misalignments to the read/write heads,
damage to the read/write head elements, particulate generation and
contamination, and other types of damage.
[0015] Concerns about present head loading methods include that the
height at which the read/write heads fly over the surface of the
magnetic disk is often unpredictable, thus when the heads are
loaded, the heads may oscillate and touch the magnetic disk. As
noted previously, because the position of the heads on the
load/unload ramp vary at power-off, the speed of the magnetic disk
at the moment the heads are loaded is unpredictable.
[0016] Thus what is required are methods and apparatus for
providing more reliable loading and unloading of read/write heads
in order to protect the read/write heads as well as the disk
media.
SUMMARY OF THE INVENTION
[0017] According to the present invention, a technique including
methods and a device for providing a single type of media for
electronic storage applications is provided. In an exemplary
embodiment, the present invention provides a methods and apparatus
for unloading of MR heads from the surface of removable media.
[0018] According to an embodiment of the present invention, a
method for unloading read/write heads from a surface of a magnetic
disk, the magnetic disk coupled to a spindle motor includes the
steps of using the spindle motor to rotate the magnetic disk at
approximately a first number of revolutions per minute, positioning
the read/write heads adjacent the surface of the magnetic disk, and
receiving a head unload signal. The technique also includes the
steps of using the spindle motor to rotate the magnetic disk at
approximately a second number of revolutions per minute in response
to the head unload signal, after a first predetermined amount of
time after the step of receiving the head unload signal, biasing
the read/write heads towards an outer edge of the magnetic disk,
and after a second predetermined amount of time after the step of
receiving the head unload signal, using the spindle motor to
dynamically brake the magnetic disk from approximately the second
number of revolutions per minute.
[0019] According to another embodiment, a method for repositioning
read/write heads from a parking location to a position adjacent a
surface of a magnetic disk, the magnetic disk coupled to a spindle
motor, includes the steps of receiving a read/write heads load
signal, and using the spindle motor to accelerate the magnetic disk
typically from zero to approximately a first number of revolutions
per time period, in response to the read/write heads load signal.
The steps of biasing the read/write heads towards a position
adjacent the surface of the magnetic disk, when the magnetic disk
rotates at approximately the first number of revolutions per time
period, and using the spindle motor to rotate the magnetic disk at
approximately a second number of revolutions per time period, after
the read/write heads are positioned adjacent the surface of the
magnetic disk are also performed.
[0020] According to yet another embodiment of the present
invention, a system having a storage device including read/write
heads for repositioning the read/write heads from a parking
location to a position adjacent a surface of a magnetic disk, the
storage device includes a spindle motor coupled to the magnetic
disk, for accelerating the magnetic disk to at least a first number
of revolutions per time period while the read/write heads are
positioned at the parking location, and a Voice Coil Motor (VCM
driver) coupled to the read/write heads and to the spindle motor,
for biasing the read/write heads towards the position adjacent the
surface of the magnetic disk after the magnetic disk reaches the
first number of revolutions per time period, wherein the spindle
motor maintains a rotation of the magnetic disk at less than a
second number of revolutions per time period while the read/write
heads are positioned adjacent the surface of the magnetic disk, and
wherein the spindle motor rotates the magnetic disk at a third
number of revolutions per time period after the read/write heads
are positioned adjacent the surface of the magnetic disk.
[0021] The present invention provides a more reliable method for
providing the described functions. Depending upon the embodiment,
the present invention provides at least one of these if not all of
these benefits and others, which are further described throughout
the present specification.
[0022] Further understanding of the nature and advantages of the
invention may be realized by reference to the remaining portions of
the specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 illustrates a conventional audio and video
configuration;
[0024] FIG. 2 illustrates a system according to an embodiment of
the present invention;
[0025] FIG. 3 includes a detailed block diagram of a system 200
according to an embodiment of the present invention;
[0026] FIGS. 4A and 4B illustrate a storage unit according to an
embodiment of the present invention;
[0027] FIGS. 5A-5F illustrate simplified views and a storage unit
for reading and/or writing from a removable media cartridge;
[0028] FIG. 6 illustrates a functional block diagram of an
embodiment of the present invention;
[0029] FIG. 7 illustrates a functional block diagram of a circuit
for unloading read/write heads from the magnetic disk and onto a
loading/unloading ramp;
[0030] FIG. 8 illustrates a block diagram of a method for unloading
heads according to an embodiment of the present invention;
[0031] FIGS. 9a and 9b illustrate typical time profiles of
embodiments of the present invention;
[0032] FIG. 10 illustrates a block diagram of a method for
unloading heads according to an embodiment of the present
invention;
[0033] FIGS. 11a-b illustrate typical time profiles of embodiments
of the present invention; and
[0034] FIGS. 12a and 12b illustrate other time profiles of
embodiments of the present invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0035] System Overview
[0036] FIG. 2 is a simplified block diagram of a system according
to an embodiment of the present invention. This embodiment is
merely an illustration and should not limit the scope of the claims
herein. The system 150 includes the television display 10, which is
capable of Internet access or the like, the audio output 20, a
controller 160, a user input device 180, a novel storage unit 190
for storing and accessing data, and optionally a computer display
170. Output from system 150 is often audio and/or video data and/or
data that is generally input into audio processor 30 and/or video
processor 40.
[0037] The storage unit includes a high capacity removable media
cartridge, such as the one shown in FIGS. 5B & 5C, for example.
The removable media cartridge can be used to record and playback
information from a video, audio, or computer source. The cartridge
is capable of storing at least 2 GB of data or information. The
cartridge also has an efficient or fast access time of about 13 ms
and less, which is quite useful in storing data for a computer. The
cartridge is removable and storable. For example, the cartridge can
store up to about 18 songs, which average about 4 minutes in
length. Additionally, the cartridge can store at least 0.5 for
MPEGII-2 for MPEGI full length movies, which each runs about 2
hours. Furthermore, the cartridge can be easily removed and stored
to archive numerous songs, movies, or data from the Internet or the
like. Accordingly, the high capacity removable media provides a
single unit to store information from the video, audio, or
computer. Further details of the storage unit are provided
below.
[0038] In an alternative embodiment, FIG. 3 is a simplified block
diagram of an audio/video/computer system 200. This diagram is
merely an illustration and should not limit the scope of the claims
herein. The system 200 includes a monitor 210, a controller 220, a
user input device 230, an output processor 240, and a novel
electronic storage unit 250 preferably for reading and writing from
a removable media source, such as a cartridge. Controller 220
preferably includes familiar controller components such as a
processor 260, and memory storage devices, such as a random access
memory (RAM) 270, a fixed disk drive 280, and a system bus 290
interconnecting the above components.
[0039] User input device 230 may include a mouse, a keyboard, a
joystick, a digitizing tablet, a wireless controller, or other
graphical input devices, and the like. RAM 270 and fixed disk drive
280 are mere examples of tangible media for storage of computer
programs and audio and/or video data, other types of tangible media
include floppy disks, optical storage media such as CD-ROMs and bar
codes, semiconductor memories such as flash memories,
read-only-memories (ROMs), ASICs, battery-backed volatile memories,
and the like. In a preferred embodiment, controller 220 includes a
'586 class microprocessor running Windows95.TM. operating system
from Microsoft Corporation of Redmond, Wash. Of course, other
operating systems can also be used depending upon the
application.
[0040] The systems above are merely examples of configurations,
which can be used to embody the present invention. It will be
readily apparent to one of ordinary skill in the art that many
system types, configurations, and combinations of the above devices
are suitable for use in light of the present disclosure. For
example, in alternative embodiments of FIG. 2, for example, video
display 10 is coupled to controller 220 thus a separate monitor 210
is not required. Further, user input device 230 also utilizes video
display 10 for graphical feedback and selection of options. In yet
other embodiments controller 220 is integrated directly into either
audio processor 20 or video processor 30, thus separate output
processor 240 is not needed. In another embodiment, controller 220
is integrated directly into video display 10. Of course, the types
of system elements used depend highly upon the application.
[0041] Detailed Description
[0042] Referring now to FIGS. 4A and 4B, a storage unit according
to the present embodiment can be an external disk drive 310 or
internal disk drive 320 unit, which shares many of the same
components. However, external drive 310 will include an enclosure
312 adapted for use outside a personal computer, television, or
some other data manipulation or display device. Additionally,
external drive 310 will include standard I/O connectors, parallel
ports, and/or power plugs similar to those of known computer
peripheral or video devices.
[0043] Internal drive 320 will typically be adapted for insertion
into a standard bay of a computer. In some embodiments, internal
drive 310 may instead be used within a bay in a television set such
as HDTV, thereby providing an integral video system. Internal drive
320 may optionally be adapted for use with a bay having a form
factor of 3 inches, 2.5 inches, 1.8 inches, 1 inch, or with any
other generally recognized or proprietary bay. Regardless, internal
drive 320 will typically have a housing 322 which includes a
housing cover 324 and a base plate 326. As illustrated in FIG. 4B,
housing 324 will typically include integral springs 328 to bias the
cartridge downward within the receiver of housing 322. It should be
understood that while external drive 310 may be very different in
appearance than internal drive 320, the external drive will
preferably make use of base plate 326, cover 324, and most or all
mechanical, electromechanical, and electronic components of
internal drive 320.
[0044] Many of the components of internal drive 320 are visible
when cover 322 has been removed, as illustrated in FIG. 5A. In this
exemplary embodiment, an actuator 450 having a voice coil motor 430
positions first and second heads 432 along opposed recording
surfaces of the hard disk while the disk is spun by spindle drive
motor 434. A release linkage 436 is mechanically coupled to voice
coil motor 430, so that the voice coil motor effects release of the
cartridge from housing 422 when heads 432 move to a release
position on a head load ramp 438. Head load ramp 438 is preferably
adjustable in height above base plate 426, to facilitate aligning
the head load ramp with the rotating disk.
[0045] A head retract linkage 440 helps to ensure that heads 432
are retracted from the receptacle and onto head load ramp 438 when
the cartridge is removed from housing 422. Head retract linkage 440
may also be used as an inner crash stop to mechanically limit
travel of heads 432 toward the hub of the disk.
[0046] Base 426 preferably comprise a stainless steel sheet metal
structure in which the shape of the base is primarily defined by
stamping, the shape ideally being substantially fully defined by
the stamping process. Bosses 442 are stamped into base 426 to
engage and accurately position lower surfaces of the cartridge
housing. To help ensure accurate centering of the cartridge onto
spindle drive 434, rails 444 maintain the cartridge above the
associated drive spindle until the cartridge is substantially
aligned axially above the spindle drive, whereupon the cartridge
descends under the influence of cover springs 428 and the downward
force imparted by the user. This brings the hub of the disk down
substantially normal to the disk into engagement with spindle drive
434. A latch 446 of release linkage 436 engages a detent of the
cartridge to restrain the cartridge, and to maintain the
orientation of the cartridge within housing 422.
[0047] A cartridge for use with internal drive 320 is illustrated
in FIGS. 5B and 5C. Generally, cartridge 460 includes a front edge
462 and rear edge 464. A disk 666 (see FIG. 5F) is disposed within
cartridge 460, and access to the disk is provided through a door
568. A detent 470 along rear edge 464 of cartridge 460 mates with
latch 446 to restrain the cartridge within the receptacle of the
drive, while rear side indentations 472 are sized to accommodate
side rails 444 to allow cartridge 460 to drop vertically into the
receptacle.
[0048] Side edges 574 of cartridge 460 are fittingly received
between side walls 576 of base 526, as illustrated in FIG. 5D. This
generally helps maintain the lateral position of cartridge 460
within base 426 throughout the insertion process. Stops 578 in
sidewall 576 stop forward motion of the cartridge once the hub of
disk 666 is aligned with spindle drive 534, at which point rails
444 are also aligned with rear indents 472. Hence, the cartridge
drops roughly vertically from that position, which helps accurately
mate the hub of the disk with the spindle drive.
[0049] FIG. 5F also illustrates a typical first position 667 of VCM
668 and a typical second position 669 in response to different
current pulses applied by a motor driver. As a result, read/write
heads 632 ate repositioned relative to disk 666 as shown.
[0050] FIG. 6 illustrates a simplified functional block diagram of
an embodiment of the present invention. FIG. 6 includes a buffer
700, a control store 710, a read data processor 720, a controller
730, motor drivers 740, a voice coil motor 750, a spindle motor
760, and read/write heads 770. Controller 730 includes interface
module 780, an error detection and correction module 790, a digital
signal processor 800, and a servo timing controller 810. Voice coil
motor 750 preferably corresponds to current pulses applied by voice
coil motor 430 in FIG. 5A, spindle motor 760 preferably corresponds
to spindle drive motor 434 in FIG. 5A, and read/write heads 770
preferably correspond to read/write heads 432 on actuator arm 450
in FIG. 5A.
[0051] As illustrated in FIG. 6, buffer 700 typically comprises a
conventional DRAM, having 16 bits.times.64 K, 128 K, or 256 K,
although other sized buffers are also envisioned. Buffer 700 is
typically coupled to error detection and correction module 790.
Buffer 700 preferably serves as a storage of data related to a
specific removable media cartridge. For example, buffer 700
preferably stores data retrieved from a specific removable media
cartridge (typically a magnetic disk), such as media composition
and storage characteristics, the location of corrupted locations,
the data sector eccentricity of the media, the non-uniformity of
the media, the read and write head offset angles for different data
sectors of the media and the like. Buffer 700 also preferably
stores data necessary to compensate for the specific
characteristics of each removable media cartridge, as described
above. Buffer 700 typically is embodied as a 1 Meg DRAM from Sanyo,
although other vendors' DRAMs may also be used. Other memory types
such as SRAM and flash RAM are contemplated in alternative
embodiments. Further, other sizes of memory are also
contemplated.
[0052] Control store 710 typically comprises a readable memory such
as a flash RAM, EEPROM, or other types of nonvolatile programmable
memory. As illustrated, typically control store 710 comprises a 8
to 16 bit.times.64 K memory array, preferably a flash RAM by Atmel.
Control store 710 is coupled to DSP 800 and servo timing controller
810, and typically serves to store programs and other instructions,
as well as data for DSP 800 and servo timing controller 810.
Preferably, control store 710 stores access information that
enables retrial of the above information from the media and
calibration data.
[0053] Read data processor 720 typically comprises a Partial
Read/Maximum Likelihood (PRML) encoder/decoder. PRML read channel
technology is well known, and read data processor 720 is typically
embodied as a 81M3010 chip from MARVELL company. Other read data
processors, for example from Lucent Technologies are contemplated
in alternative embodiments of the present invention. As
illustrated, read data processor 720 is coupled to error detection
and correction module 790 to provide ECC and data transport
functionality.
[0054] Interface module 780 typically provides an interface to
controller 220, for example. Interfaces include a small computer
standard interface (SCSI), an IDE interface, parallel interface,
PCI interface or any other known or custom interface. Interface
module 780 is typically embodied as an AIC-8381B chip from Adaptec,
Incorporated. Interface module 780 is coupled to error detection
and correction module 790 for transferring data to and from the
host system.
[0055] Error detection and correction module 790 is typically
embodied as a AIC-8381B chip from Adaptec, Incorporated. This
module is coupled by a read/write data line to read data processor
720 for receiving read data and for ECC. This module is also
coupled to read data processor 720 by a now return to zero (NRZ)
data and control now return to zero line. Other vendor sources of
such functionality are contemplated in alternative embodiments of
the present invention.
[0056] DSP 800 typically provides high-level control of the other
modules in FIG. 6. DSP 800 is typically embodied as a AIC-4421A DSP
from Adaptec, Inc. As shown, DSP 800 is coupled to read data
processor 720 to provide control signals for decoding signals read
from a magnetic disk. Further, DSP 800 is coupled to servo timing
controller 810 for controlling VCM 750 and spindle motor 760. Other
digital signal processors can be used in alternative embodiments,
such as DSPs from TI or Motorola.
[0057] Servo timing controller 810 is typically coupled by a serial
peripheral port to read data processor 720 and to motor drivers
740. Servo timing controller 810 typically controls motor drivers
740 according to servo timing data read from the removable media.
Servo timing controller 810 is typically embodied in a portion of
DSP 800.
[0058] Motor driver 740 (or Voice Coil Motor driver) is typically
embodied as a L6260L Chip from SGS-Thomson. Motor driver 740
provides signals to voice coil motor 750 and to spindle motor 760
in order to control the reading and writing of data to the
removable media.
[0059] Spindle motor 760 is typically embodied as an 8 pole Motor
from Sankyo Company. Spindle motor 760 typically is coupled to a
center hub of the removable media as illustrated in FIG. 4 and
rotates the removable media typically at rates from 4500 to 7200
revolutions per minute. Other manufacturers of spindle motor 760
and other rates of revolution are included in alternative
embodiments.
[0060] VCM 750 is a conventionally formed voice coil motor.
Typically VCM 750 includes a pair of parallel permanent magnets,
providing a constant magnetic field. VCM 750 also includes an
actuator having a voice coil (a solenoid), and read/write heads.
Read/write heads are typically positioned near the end of the
actuator arm, as illustrated in FIG. 5A. The voice coil is
typically electrically coupled to motor driver 740. VCM 750 is
positioned relative to the magnetic disk in response to the amount
of electric current flowing through the voice coil. FIG. 5F
illustrates a typical first position 667 of VCM 668 and a typical
second position 669 in response to different electric current from
motor driver 740. As a result, read/write heads 632 are
repositioned relative to disk 666 as shown.
[0061] In a preferred embodiment of the present invention
read/write heads are separate heads that utilize magneto resistive
technology. In particular, the MR read/write heads. Typically a
preamplifier circuit is coupled to the read/write heads.
[0062] In the preferred embodiment of the present embodiment the
removable media cartridge is comprises as a removable magnetic
disk. When reading or writing data upon the magnetic disk the
read/write heads on the end of the actuator arm "fly" above the
surface of the magnetic disk. Specifically, because the magnetic
disk rotates at a high rate of speed, typically 5400 rpm, a
negative pressure pulls the read/write heads towards the magnetic
disk, until the read/write heads are typically 0.001 millimeters
above the magnetic disk.
[0063] FIG. 7 illustrates a functional block diagram of a
embodiment of the present invention. FIG. 7 includes a more
detailed block diagram of motor driver 740 above, including a
solenoid control 860, and a spindle driver 870 each responsive to a
power-on signal 885.
[0064] The solenoid 890 represents the voice coil described as part
of the VCM 750 above and includes terminals 900 and 910. In one
embodiment, solenoid control 860 is the primary control mechanism
for positioning of MR heads anywhere above the magnetic disk. In
alternative embodiments, solenoid 890 may be coupled to a separate
power-on solenoid control by the same or different terminals for
conventional power-on operation of solenoid 890 and the actuator
arm.
[0065] In FIG. 7, the spindle driver 870 provides the drive voltage
to the spindle motor to rotate the magnetic disk. During
conventional data storage or retrieval, the drive voltage having a
drive period is provided to spindle motor and is relatively
constant such that the magnetic disk spins at approximately the
same number of revolutions per time unit (per second, per minute,
and the like).
[0066] In response to an active power-off signal 880, the spindle
driver 870 modifies the voltage and the period of time it is
applied to the spindle motor to thereby modify the rotation speed
of the magnetic disk from a first number of revolutions per minute
to a second number of revolutions per minute. In one embodiment,
power-off signal 880 signal is asserted (active high) upon a
power-off condition and is de-asserted (active low) otherwise. In
alternative embodiments, the polarities are reversed.
[0067] In response to the active power-off signal 880, after a
first delay, solenoid control 860 within VCM driver 740 applies
controlled current pulses to solenoid 890 in VCM 750, as will be
described below. In response to the controlled current pulses, MR
heads are smoothly removed from the magnetic disk and preferably
unloaded onto a load/unload ramp.
[0068] In other embodiments, solenoid control 860 monitors the
speed of the spindle motor after the active power-off signal 880,
and when the speed of the spindle motor has reached the second
number of revolutions per minute, solenoid control 860 applies the
controlled pulses to solenoid 890.
[0069] After a second delay, spindle driver 870 reduces the
rotation speed of the magnetic disk to an idle rotation speed,
typically a full stop. Dynamic braking/driver block 850 provides
additional dynamic braking of the magnetic disk if desired.
[0070] In response to an active power-on signal 885, the spindle
driver 870 asserts a drive voltage having a drive period so as to
increase the rotation speed of the magnetic disk to at least a
first number of revolutions per second. In one embodiment, power-on
signal 885 signal is asserted (active high) upon a power-on
condition and is de-asserted (active low) otherwise. In alternative
embodiments, the polarities are reversed.
[0071] In response to the active power-on signal 885, after a first
delay, solenoid control 860 within VCM driver 760 applies
controlled current pulses to solenoid 890, within VCM 750, as will
be described below. In response to the controlled current pulses,
MR heads are smoothly unloaded onto the magnetic disk.
[0072] In other embodiments, solenoid control 860 is coupled to the
spindle motor and monitors the speed of the spindle motor, and, as
will be discussed below, when the speed of the spindle motor has
stabilized at the first number of revolutions per second, solenoid
control 860 applies the controlled current pulses to solenoid
890.
[0073] After a second delay, spindle driver 870 increases the
rotation speed of the magnetic disk to a second number of
revolutions per second, typically an operating speed.
[0074] In the embodiment in FIG. 7, dynamic braking/driver block
850, solenoid control 860, spindle driver 870, and other functional
components are embodied within voice coil motor driver 740. In one
embodiment, voice coil motor driver 740 is an L6260L chip from
SGS-Thomson. Other motor driver chips from other vendors are also
usable in alternative embodiments of the present invention.
[0075] FIG. 8 illustrates a block diagram of a method for unloading
heads according to an embodiment of the present invention.
[0076] Initially, the read/write (MR) heads fly above the magnetic
disk at a first number of revolutions per minute (rpm or other time
unit), step 1000. In the present embodiment, this first number is
approximately 5400 rpm. This speed is typically the rotation speed
where the MR heads read from or write to the magnetic disk. In
other embodiments this speed may be different, for example 7200
rpm.
[0077] Next, upon detection of a power-off signal 880, step 1010,
spindle driver 870 applies a voltage of a certain period of time to
spindle motor 760 such that the speed of the spindle motor 760 is
adjusted from the first number of rpms until a second number of
rpms (a parking speed) is reached, step 1020. The rate of change
may be linear, or otherwise. In the present embodiment, this second
number is typically smaller than the first number. For example,
when the first number is approximately 5400 rpm, the second number
may be approximately 700 rpm.
[0078] In alternative embodiments, the second number may be larger
than the first number. For example, when the first number is
approximately 5400 rpm, the second number may be above
approximately 7000 rpm.
[0079] In one embodiment of the present invention, determining when
the second number of rpms has been reached is performed directly by
monitoring the speed of the spindle motor 760.
[0080] In another embodiment, the rate of acceleration or
deceleration of the spindle motor is known ahead of time. Thus, the
amount of time it takes the spindle motor to speed up from 5400 rpm
to 7000 rpm or other speed in response to a drive voltage can be
accurately estimated. Similarly, the amount of time it takes the
spindle motor to slow down from 5400 rpm to 700 rpm or any other
speed in response to a drive voltage can also be accurately
estimated. Thus, in one embodiment of the present invention, it is
assumed the second number of rpms has been reached in step 1030
after a first period of time after step 1020.
[0081] After the second number of rpms has been reached, step 1030,
solenoid control 860 applies a stream of current pulses to solenoid
890 in VCM 750 such that the MR heads are moved at a constant
velocity on the magnetic disk, step 1040. A typical velocity is
approximately 3 inches/second. This step preferably also unloads
the MR head onto the load/unload ramp, or moves the MR head to a
landing region. The method of moving the MR head can be performed
using the invention described in pending application Ser. No. ,
Attorney Docket No. 18525-001810, entitled MR Head Unload
Technique, assigned to the same assignee, incorporated by reference
for all purposes.
[0082] In one embodiment, the second number of rpms is referred to
as the parking speed, and when the parking speed is reached, the
spindle motor maintains the number of rpms at approximately the
parking speed. In another embodiment, after the parking speed is
reached, the spindle motor continues to decelerate at its own pace.
In another embodiment, after the parking speed is reached, the
spindle motor continues to decelerate at its own pace, but is
prevented from dropping below a predetermined floor speed while the
MR heads are being unloaded. For example, if the parking speed is
700 rpm, while the MR head is being unloaded, the spindle motor is
allowed to continually slow down but is not allowed to drop below a
floor speed of 500 rpm.
[0083] In one embodiment of the present invention, determining when
the MR heads are unloaded onto the head load/unload ramp is
performed directly by monitoring the back EMF voltage of solenoid
890 in the VCM 750. In another embodiment, the MR heads are
considered unloaded a predetermined amount of time after no more
data is read from the MR heads.
[0084] In yet another embodiment of the present invention, it is
assumed the MR heads have been unloaded after a second period of
time after solenoid control 860 applies a current pulse to solenoid
890 in step 1040. In such an embodiment, the rate of movement of
the MR heads is known ahead of time, thus, the amount of time it
takes the MR heads to move from any position on the magnetic disk
to the load/unload ramp can be accurately estimated. In another
embodiment, when the current pulses applied to VCM 750 are very
large, it can be assumed that the MR heads have stopped moving on
the load/unload ramp, or have hit a stop on the load/unload
ramp.
[0085] After the MR head has been unloaded, step 1050, the speed of
the spindle motor can be slowed to a complete stop, step 1060. In
the present invention, dynamic braking can also occur in this
step.
[0086] FIG. 9a and 9b illustrate typical time profiles of
embodiments of the present invention. In FIG. 9a, profile 1070
illustrates the profile of the speed of the magnetic disk in
revolutions per minute versus time. Profile 1075 illustrates the
position of the MR head versus time using the same time base as
profile 1070. Time periods 1080-1120 are also illustrated.
[0087] Time period 1080 represents a typical operating condition of
the present invention. During time period 1080, the magnetic disk
operates at an operating speed, (for example 5400 rpm) and the MR
head is located above a data storage portion of the magnetic disk.
Next, a signal such as an eject disk signal, a power-off signal,
and the like occurs, and during time period 1090, the magnetic disk
is slowed to a parking speed of 700 rpm. The magnetic disk is then
kept spinning at 700 rpm for time period 1100. As disclosed above,
in other embodiments of the present invention, the parking speed
may vary, further the parking speed may be greater than the first
number of rpms.
[0088] After the magnetic disk stabilizes at 700 rpm, the MR head
is moved from above the magnetic disk and unloaded onto a
load/unload ramp during time period 1110. In the present
embodiment, the MR head is controlled to be moved at approximately
a constant velocity, as shown, whether the MR head is located at
the inner diameter (I.D.), the outer diameter (O.D.) of the
magnetic disk, or in between.
[0089] In one embodiment described above, time period 1100 (a hold
time) ends after it is detected that the MR heads are unloaded onto
the load/unload ramp. In another embodiment, time period 1100 is an
amount of time that is predetermined based upon the known
characteristics of the MR head movement.
[0090] After the MR heads have been unloaded, the magnetic disk is
slowed from approximately 700 rpm to an idle rpm (0 rpm) during
time period 1120.
[0091] In the present embodiment, time period 1090 is on the order
of 2-3 seconds, time period 1110 is on the order of less than 450
milliseconds. It is envisioned that the duration of the above time
periods may vary by user design, depending upon the physical
characteristics of the storage unit, and the like.
[0092] FIG. 9b, illustrates an embodiment where the parking speed
varies within a range and where the MR heads are pre-positioned
prior to being unloaded. In FIG. 9b, the MR heads are moved to the
O.D. at the same time the disk is slowed during time period 1090,
i.e., prepositioned prior to being unloaded. Because the MR head is
closer to the load/unload ramp, the unloading time 1110' is
typically shorter and time period 1100' is also typically
shorter.
[0093] As illustrated in FIG. 9b, the spindle speed can vary within
a range of 700-500 rpm, in this example, while the MR head is being
unloaded. Because the spindle speed can slow down while unloading
the MR head, the time period 1120 can also be shorter.
[0094] FIG. 10 illustrates a block diagram of a method for loading
heads according to an embodiment of the present invention.
[0095] Initially, the read/write (MR) heads are parked on the
load/unload ramp and the magnetic disk is idle, step 1140.
[0096] Next, upon detection of a power-on signal 885, step 1150,
spindle driver 870 applies a voltage of a certain time period to
spindle motor 760 so that the speed of the spindle motor is
accelerated to at least a first number of rpms (a loading speed),
step 1160. In one embodiment this first number is approximately
1000 rpm, in another embodiment the first number is approximately
7200 rpm, and the like. The rate of change can be linear, and the
like.
[0097] In one embodiment of the present invention, determining when
the first number of rpms has been reached is performed directly by
monitoring the speed of the spindle motor 760.
[0098] In another embodiment, the response of the spindle motor 760
to the voltage pulses is known ahead of time. Thus, the amount of
time it takes the spindle motor 760 to speed up from idle to 1000
rpm or to 7200 rpm in response to a drive voltage can be accurately
determined. Thus, in one embodiment of the present invention, it is
assumed the first number of rpms has been reached in step 1170 a
first period of time after spindle driver 870 applies a voltage in
step 1160.
[0099] After the first number of rpms (the loading speed) has been
reached, step 1170, solenoid control 860 applies current pulses to
solenoid 890 in VCM 750 such that the MR heads are loaded onto the
magnetic disk from the load/unload ramp, step 1180. A typical
constant velocity is approximately 3 inches/second. The method of
moving the MR head smoothly and with reduced audible noise can be
performed by the invention described in application Ser. No.
Attorney Docket No. 18525-001810, described above.
[0100] In one embodiment, when the loading speed is reached, the
spindle motor maintains the number of rpms at approximately the
loading speed. In another embodiment, after the loading speed is
reached, the spindle motor continues to accelerate at its own pace.
In another embodiment, after the loading speed is reached, the
spindle motor continues to accelerate at its own pace, but is
prevented from increasing above a predetermined ceiling speed while
the MR heads are being loaded. For example, if the parking speed is
approximately 1000 rpm, while the MR head is being loaded, the
spindle motor speeds up but does rise above a ceiling speed of
approximately 1500 rpm.
[0101] In one embodiment of the present invention, determining when
the MR heads are unloaded onto the head load/unload ramp is
performed directly by determining if the MR heads detect any data
from the magnetic disk.
[0102] In yet another embodiment of the present invention, it is
assumed the MR heads have been loaded after a second period of time
after solenoid control 860 applies a voltage to solenoid in step
1160. In such an embodiment, the rate of movement of the MR heads
is known ahead of time, thus, the amount of time it takes the MR
heads to move from the load/unload ramp to the magnetic disk can be
accurately estimated. In one embodiment, the amount of time is
estimated to be for loading of the MR heads and repositioning the
MR heads to approximately the middle of the magnetic disk.
[0103] After the MR head has been loaded, step 1190, the speed of
the spindle motor is brought to a second number of rpms, an
operating speed, step 1200. In one embodiment, the operating speed
is approximately 5400 rpm, although other speeds are usable.
[0104] FIGS. 11a and 11b illustrate typical time profiles of
embodiments of the present invention. In FIG. 11a, profile 1220
illustrates the profile of the speed of the magnetic disk in
revolutions per minute versus time. Profile 1225 illustrates the
position of the MR head versus time using the same time base as
profile 1220. Time periods 1230-1270 are also illustrated.
[0105] Time period 1230 represents a typical rest condition of the
present invention. During time period 1230, the magnetic disk is
typically idle, and the MR head is located on a load/unload ramp.
Next, a signal such as an disk insert signal, a power-on signal,
and the like occurs, and during time period 1240, the magnetic disk
is accelerated to approximately 1000 rpm. The magnetic disk is then
kept spinning at approximately 1000 rpm for time period 1250. In
other embodiments of the present invention, the number-of rpms may
vary and be larger than the operating number of rpms.
[0106] After the magnetic disk reaches at approximately 1000 rpm,
the MR head is moved from the load/unload ramp loaded onto any
position on the magnetic disk during time period 1260. In the
present embodiment, the MR head is controlled to be moved at
approximately a constant velocity as shown. As disclosed above, in
one embodiment of the present invention, the time period 1250 is
estimated and is longer than time period 1260.
[0107] After the MR heads have been loaded onto the magnetic disk,
the magnetic disk is accelerated to the operating speed, such as
5400 rpm, during time period 1270.
[0108] In the present embodiment, time period 1240 is approximately
300 milliseconds, time period 1250 is approximately 450
milliseconds, and time period 1270 is approximately 3 seconds. It
is envisioned that the duration of the above time periods may vary
by user design, depending upon the physical characteristics of the
storage unit, and the like.
[0109] FIG. 11b, illustrates an embodiment where the loading speed
varies within a range. As illustrated, the spindle speed can vary
within a range of 1000-1500 rpm, in this example, while the MR head
is being loaded. Because the spindle can accelerate to the ceiling
speed, the time period 1270' is typically shorter.
[0110] Conclusion
[0111] In the foregoing specification, the invention has been
described with reference to specific exemplary embodiments thereof.
Many modifications or changes are readily envisioned in alternative
embodiments of the present invention, for example parking of the MR
heads onto the load/unload ramp may include different parking
speeds or reverse-forward parking, discussed below.
[0112] FIG. 12a illustrates an embodiment where the parking speed
(7200 rpm) is higher than the operating speed (5400 rpm). It has
been determined that in some embodiments, having a higher parking
speed provides a more consistent MR head height from the magnetic
disk thus facilitating unloading.
[0113] In the embodiment in FIG. 12b, the MR heads are moved to a
position between the O.D. and the ID, the middle diameter (M.D.),
at the same time the disk is slowed during time period 1090.
Because the MR heads are unloaded from the same position, the MD,
the MR heads are more consistently parked upon the load/unload
heads. When the MR heads are initially located near the OD, this
technique is called reverse-forward parking, as the MR heads are
first moved away from the load/unload ramp (reverse), and then
moved toward the load/unload ramp (forward). Further information
regarding the general concept of reverse-forward parking of MR
heads upon power down is disclosed in pending application Ser. No.
, Attorney Docket 18525-002210, filed entitled Reverse-Forward
Power-Off Method and Device for Electronic Storage Apparatus,
assigned to the same assignees. Application Ser. No. is
incorporated by reference for all purposes. In other embodiments,
other positions other than the M.D. can be used.
[0114] The embodiment in FIG. 12b also includes the parking speed
range concept discussed above. Other combinations of the above
techniques shown in FIGS. 9a-b, 11a-b, 12a-b, etc. may be
advantageously used in other embodiments of the present
invention.
[0115] In other embodiments, the velocity of read/write head
movement may vary between on-disk movements and off-disk movements.
Thus, the slopes of the lines in FIGS. 9a-b, 11a-b, and 12a-b may
vary from those shown.
[0116] The presently claimed inventions may also be applied to
other areas of technology such as mass storage systems for storage
of video data, audio data, textual data, program data, or any
computer readable data in any reproducible format.
[0117] The specification and drawings are, accordingly, to be
regarded in an illustrative rather than a restrictive sense. It
will, however, be evident that various modifications and changes
may be made thereunto without departing from the broader spirit and
scope of the invention as set forth in the claims.
* * * * *