U.S. patent number RE35,269 [Application Number 08/223,789] was granted by the patent office on 1996-06-11 for portable computer hard disk protective reflex system.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Liam D. Comerford.
United States Patent |
RE35,269 |
Comerford |
June 11, 1996 |
Portable computer hard disk protective reflex system
Abstract
A protective reflex system for a portable computer hard disk
initiates protective action before the hard disk suffers the shock
of an impact in the event they fall from, for example, a user's
lap. A three axis accelerometer is mounted in the portable
computer. The output of the accelerometer is continuously monitored
by a dedicated processor. In the event of an acceleration event
within a preset range of values, the dedicated processor passes a
high priority interrupt to the central processing unit of the
portable computer and then proceeds to park the disk heads.
Alternately, the interrupt routine of the central processing unit
may also cause the park operation. In addition to park operation, a
brake operation may be performed by either the dedicated processor
or the central processing unit.
Inventors: |
Comerford; Liam D. (Carmel,
NY) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
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Family
ID: |
24476702 |
Appl.
No.: |
08/223,789 |
Filed: |
April 6, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
618192 |
Nov 26, 1990 |
05227929 |
Jul 13, 1993 |
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Current U.S.
Class: |
360/75;
714/799 |
Current CPC
Class: |
G11B
5/5582 (20130101); G11B 19/043 (20130101); G11B
21/12 (20130101); G06F 11/004 (20130101); G11B
33/08 (20130101); G11B 33/10 (20130101) |
Current International
Class: |
G11B
5/55 (20060101); G11B 33/08 (20060101); G11B
33/00 (20060101); G11B 33/10 (20060101); G11B
021/20 (); G06F 011/00 () |
Field of
Search: |
;360/75,105,106,97.02
;371/4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0175839 |
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Apr 1986 |
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EP |
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2187031 |
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Aug 1987 |
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GB |
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Other References
H R. Ottesen; "Apparatus for Detecting and Correcting Excessive
Vibration in a Disk File", IBM Technical Disclosure Bulletin, vol.
30, No. 6, Nov. 1987, p. 81..
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Primary Examiner: Psitos; Aristotelis
Assistant Examiner: Wilson; James T.
Attorney, Agent or Firm: Whitham, Curtis, Whitham &
McGinn Percello; Louis J.
Claims
I claim:
1. A protective reflex system for a portable computer hard disk
which initiates protective action before the hard disk suffers
.[.the.]. .Iadd.a .Iaddend.shock of an impact, said hard disk
.[.having.]. .Iadd.including .Iaddend.at least .[.a.]. one head
flying above at least one .[.motor driven.]. .Iadd.motor-drive
.Iaddend.rotating disk and said portable computer .[.having.].
.Iadd.including .Iaddend.a central processing unit, said protective
reflex system comprising:
a three axis accelerometer mounted in the portable computer and
generating signals proportional to accelerations along three axes;
and
a dedicated processor for continuously monitoring said
accelerometer signals and computing an acceleration vector, said
dedicated processor further comparing a .[.scaler.]. .Iadd.scalar
.Iaddend.value of said acceleration vector to a preset range of
values .[.close to 1G.]. corresponding to a free fall condition and
passing a high priority interrupt to the central processing unit of
the portable computer when said .[.scaler.]. .Iadd.scalar
.Iaddend.value falls within said preset range;
one of said dedicated processor .[.or.]. .Iadd.and .Iaddend.said
central processing unit calling a routine to park said at least one
head of the hard disk .[.rapidly.]. before the hard disk suffers
.[.the.]. .Iadd.a .Iaddend.shock of an impact.
2. The protective reflex system recited in claim 1 wherein one of
said dedicated processor .[.or.]. .Iadd.and .Iaddend.said central
processing unit further calls a routine to brake .[.the.]. .Iadd.a
.Iaddend.rotation of said hard disk.
3. The protective reflex system recited in claim 2 wherein said
dedicated processor calls the routine to park said at least one
head of the hard disk .[.rapidly.]. while said central processing
unit calls the routine to brake the rotation of said hard disk,
said routines .Iadd.to park and to brake .Iaddend.being processed
simultaneously in parallel by said dedicated processor and said
central processing unit.
4. The protective reflex system recited in claim 1 wherein said
hard disk further .[.has.]. .Iadd.includes .Iaddend.a frame and
said accelerometer is mounted on said frame.
5. The protective reflex system recited in claim 1 wherein said
dedicated processor calls the routine to park said at least one
head of the hard disk .[.rapidly.]..
6. A .[.reflexive.]. method for protecting a portable computer hard
disk by initiating protective action before the hard disk suffers
.[.the.]. .Iadd.a .Iaddend.shock of an impact, said hard disk
.[.having.]. .Iadd.including .Iaddend.at least .[.a.]. one head
flying above at least one .[.motor driven.]. .Iadd.motor-driven
.Iaddend.rotating disk.Iadd., a three-axis accelerometer and a
dedicated processor .Iaddend.and said portable computer
.[.having.]. .Iadd.including .Iaddend.a central processing unit
.[.and being further provided with a three-axis accelerometer and a
dedicated processor.]., said reflexive method comprising the steps
of:
monitoring.Iadd., .Iaddend.by said dedicated processor.Iadd.,
.Iaddend.signals from said accelerometer proportional to
accelerations along three axes;
computing.Iadd., .Iaddend.by said dedicated processor.Iadd.,
.Iaddend. an acceleration vector and comparing a .[.scaler.].
.Iadd.scalar .Iaddend.value of said acceleration vector to a preset
range of values .[.close to 1G.]. corresponding to a free fall
condition and passing a high priority interrupt to the central
processing unit of the portable computer when said .[.scaler.].
.Iadd.scalar .Iaddend.value .[.exceeds.]. .Iadd.falls within
.Iaddend.said preset range; and
parking.Iadd., .Iaddend.by said dedicated processor or said central
processing unit.Iadd., .Iaddend.said at least one head of the hard
disk .[.rapidly.]. before the hard disk suffers .[.the.]. .Iadd.a
.Iaddend.shock of an impact.
7. The .[.reflexive.]. method recited in claim 6 further comprising
the step of braking by one of said dedicated processor .[.or.].
.Iadd.and .Iaddend.said central processing unit .[.the.]. .Iadd.a
.Iaddend.rotation of said hard disk.
8. The .[.reflexive.]. method recited in claim 7 wherein said step
of parking said at least one head of the hard disk .[.rapidly.]. is
performed by said dedicated processor while said step of braking
the rotation of said hard disk is performed by said central
processing unit, said steps .Iadd.of parking and braking
.Iaddend.being performed simultaneously in parallel by said
dedicated processor and said central processing unit.Iadd.,
respectively.Iaddend..
9. The .[.reflexive.]. method recited in claim 6 wherein said step
of parking said at least one head of the hard disk .[.rapidly.]. is
performed by said dedicated processor. .Iadd.10. A storage device
comprising:
a moving storage medium;
at least one head positioned in transducing relationship with
respect to said moving storage medium; and
a system for protecting the storage device, said system
comprising:
an accelerometer, operatively coupled to the storage device, for
generating a signal proportional to an acceleration of the storage
device;
means for comparing a magnitude of said signal to a predetermined
magnitude, said predetermined magnitude being associated with a
shock of an impact; and
means for repositioning said at least one head responsive to said
magnitude of said signal generated by said accelerometer being
greater than said predetermined magnitude and prior to said storage
device suffering a shock of an impact. .Iaddend. .Iadd.11. The
storage device of claim 10, wherein said means for repositioning
places said at least one head in a protective position. .Iaddend.
.Iadd.12. The storage device of claim 10, wherein said means for
repositioning parks said at least one head over a portion of said
moving storage medium not containing data previously written to
said
moving storage medium. .Iaddend. .Iadd.13. The storage device of
claim 10, wherein said means for repositioning parks said at least
one head in a nontransducing position. .Iaddend. .Iadd.14. A
storage device comprising:
a moving storage medium;
at least one head positioned in transducing relationship with
respect to said moving storage medium; and
a system for protecting the storage device, said system
comprising:
a three-axis sensing device coupled to the storage device, for
generating a signal proportional to an acceleration of the storage
device;
means for comparing a magnitude of said signal to a predetermined
magnitude, said predetermined magnitude being associated with a
shock of an impact; and
means for moving said at least one head positioned in transducing
relationship with respect to said moving storage medium responsive
to said magnitude of said signal being greater than said
predetermined magnitude and prior to said storage device suffering
a shock of an impact. .Iaddend. .Iadd.15. The storage device of
claim 14, wherein said means for moving positions said at least one
head to a nontransducing position. .Iaddend. .Iadd.16. The storage
device of claim 14 wherein said means for moving parks said at
least one head over a portion of said moving storage medium not
containing data previously written to said moving storage medium.
.Iaddend. .Iadd.17. A storage device comprising:
a moving storage medium;
at least one head movably positioned in transducing relationship
with respect to said moving storage medium; and
a system for protecting the storage device, said system
comprising:
a three-axis sensing device coupled to the storage device, for
generating a signal proportional to an acceleration of the storage
device;
means for comparing a magnitude of said signal to a predetermined
magnitude, said predetermined magnitude being associated with a
shock of an impact; and
means for stopping movement of at least one of said moving storage
medium and said at least one head, responsive to said magnitude of
said signal being greater than said predetermined magnitude and
prior to said storage
device suffering a shock of an impact. .Iaddend. .Iadd.18. A method
of protecting data stored on a hard disk drive, said hard disk
drive including at least one disk having a portion of the disk
storing data, at least one transducing head positioned in
transducing relation with respect to said at least one disk, an
accelerometer and a microprocessor, said method comprising the
steps of:
comparing a signal from said accelerometer to a predetermined range
of levels, said predetermined range of levels being associated with
a shock of an impact; and
moving said at least one transducing head in response to said
signal from said accelerometer being within said predetermined
range of levels and prior to said hard disk drive suffering a shock
of an impact. .Iaddend. .Iadd.19. The method of protecting data of
claim 18, wherein the step of moving said at least one transducing
head includes a step of parking said at least one transducing head
off said at least one disk. .Iaddend. .Iadd.20. The method of
protecting data of claim 18, wherein the step of moving said at
least one transducing head includes a step of parking said at least
one transducing head off the portion of said disk storing data.
.Iaddend. .Iadd.21. A storage device comprising:
a moving storage medium;
at least one head movably positioned in transducing relationship
with respect to said moving storage medium; and
a system for protecting the storage device, said system
comprising:
a three-axis accelerometer, operatively coupled to the storage,
device, for generating a signal proportional to an acceleration of
the storage device;
means for comparing a magnitude of said signal to a predetermined
magnitude, said predetermined magnitude being associated with a
shock of an impact; and
means for interrupting an operation of the storage device
responsive to said magnitude of said signal being greater than said
predetermined magnitude and prior to said storage device suffering
a shock of an impact. .Iaddend. .Iadd.22. The storage device of
claim 21, wherein said means for interrupting includes means for
interrupting an operation of said at least one head. .Iaddend.
.Iadd.23. The storage device of claim 22, wherein said means for
interrupting includes means for interrupting a write operation of
said at least one head. .Iaddend. .Iadd.24. The storage device of
claim 21, wherein said means for interrupting includes means for
stopping a movement of at least one of said moving storage medium
and said at least one head. .Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to protection systems for
computer hard disk drives in portable computers and, more
particularly, to, a reflexive system for parking the heads of a
hard disk and, optionally, stopping the spinning of the magnetic
media platters in the event the computer is dropped.
2. Description of the Prior Art
Portable personal computers (PCs) have become more and more
popular. Part of this popularity is due to providing portable
computer with much the same power and features of desk top
workstations. Among these features are hard disks which are now
quite common in portable computers.
Portable computers are subject to forms of failure which are not a
problem for desk top workstations. They can run out of power and
they can be dropped. While this latter jeopardy is a threat to
every component in the system, it is the hard disk drive which has
the lowest threshold of failure in the event the computer is
dropped. This component is so vulnerable to shock because it is
dependent on the maintenance of a very small gap between the drive
heads and the disk platters. The size of this gap is a key factor
in the quantity of data which can be stored on the disk. In
general, the smaller the gap, the more the data which can be
stored. Thus, small, and hence vulnerable, gap dimensions are the
rule for hard disks. The technology routinely used to obtain small
gap height is aerodynamic. The head is literally flown over the
platter surface to place the heads as close to the platters as
possible without allowing contact. If the head were to contact the
platter, the result could be both the destrucuon of the head and
the removal of magnetic material (and hence data) from the
platter.
Disk manufacturers recognize this hazard and attempt to address it
by shock mounting their drives, by publishing the G-force limits
their drives can tolerate, and by providing a position in which the
heads may be "parked" in which the drive can tolerate accelerations
which are far greater than are tolerable when the heads are
"loaded".
The prior an addresses two kinds of events which may destroy the
data integrity or hardware integrity of a hard disk. One of these
event types is electrical power failure. This problem is addressed,
for example, in U.S. Pat. No. 4,786,995 to Stupeck et al., U.S.
Pat. No. 4,831,469 to Hanson et al., and U.S. Pat. No. 4,866,554 to
Stupeck et al. In each of these patents, the energy stored in the
motion of the disk heads is tapped by using the disk spindle motor
as a generator. The power derived from this source is used to
retract the disk head. Electromagnetic braking of the spindle is
also contemplated. Provisions are made by one invention to shut
down in the event of other voltage faults beside that of power
failure.
The second event type is physical or mechanical impact. In U.S.
Pat. No. 4,040,103 to White, an accelerometer is used to detect the
magnitude and direction of a shock so that the hard disk head
flying height can be adjusted. This adjustment is possible because
the accelerometer is mounted on the disk driver frame while the
drive itself is mounted to that frame by shock absorbers. The time
delay for shock transmission supplied by the shock absorbers allows
the flying height correction to be calculated prior to the shock
arriving at the disk head.
In U.S. Pat. No. 4,862,298 to Genheimer et al., impact detection is
used to generate a write-fault signal to the computing system. This
signal is used to prevent data destruction by off-track writes and
to cause head retraction in the event of severe impacts. This
device relies on the fact that the read and write operations on
disk drives involve sectors of significant extent so that if an
impact is detected, it is very likely that it will occur in the
course of a sector operation rather than at its very end. The
system is thus expected to have the time required to abort the read
or write operation without storing or retrieving corrupted
data.
The problems with each of these techniques is that remedial action
is taken after the failure or impact has occurred and may be too
late to prevent damage. In the case of impact, what is needed is a
system which can anticipate the possibility of impact and take
protective action before the impact actually occurs.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
protective reflex system for a portable computer hard disk which
initiates protective action before the hard disk suffers the shock
of an impact.
It is a further object of the invenuon to provide, in a portable
computer, a means by which hard disk drives in the active,
un-parked state may be protected from possible destruction in the
event they fall from, for example, a user's lap.
According to the present invention, a three axis, quick response
accelerometer is mounted in the portable computer. The output of
the accelerometer is continuously monitored by a dedicated
processor. In the event of an acceleration within a preset range of
values close to IG, the dedicated processor passes a high priority
interrupt to the central processing unit of the portable computer
and proceeds to park the disk heads. The interrupt handler routine
simultaneously performs those actions which that computer may need
to perform to deal with the loss of disk availability.
Alternatively, the interrupt routine of the central processing unit
may also perform the park operation. In addition, the dedicated
processor or the central processing unit may cause a brake
operation to be performed to slow or stop the rotation of the hard
disk. Preferably, the park and brake operations are performed
simultaneously in parallel by the dedicated processor and the
central processing unit.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, aspects and advantages will be
better understood from the following detailed description of a
preferred embodiment of the invention with reference to the
drawings in which:
FIG. 1 is a perspective view of a portable computer of the type
commonly having a hard disk;
FIG. 2 is a funcnonal block diagram showing the components of the
protective reflex system according to the invention; and
FIG. 3 is a flow diagram illustrating the logic of the computer
control program for the protective reflex system of the
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Referring now to the drawings, and more particularly to FIG. 1,
there is shown a typical portable personal computer (PC) 10,
sometimes referred to a laptop computer. The configuration shown
includes a system unit case 12 to which is attached a hinged liquid
crystal display (LCD) 14 that folds down for attachment to a
keyboard 16 for transportation. On the right side of the system
case 12, there is a 31/2 floppy disk drive 18 and within the case
is a hard disk drive (not shown).
The portable PC shown in FIG. I is merely for purposes of
illustration. Portable PCs are configured in a variety of different
ways. For example, the system unit case 12 may be integrated under
and in one unit with the keyboard 16 with the LCD display hinged at
the back of this integrated unit. Alternatively, the system unit
case 12 may be integrated behind the display 14 with the keyboard
16 detachable from the face of the display. Moreover, the display
may be a gas plasma panel or other so-called "flat screen" display
rather than an LCD, and while it is typical for portable PCs to
have at least one floppy disk drive, such as the disk drive 18
shown in FIG. 1, the location of that disk drive may be at the
front of the computer or other convenient location. The point is
that no matter what the outside physical configuration of the
portable computer, many are now being equipped with a hard disk
drive and due to the portability of the computer, the hard disk
drive is in jeopardy of damage or destruction due to the shock of
an impact, such as caused by the computer being dropped.
The time required to park a disk drive head is on the order of
three times the average seek time. This is in the range of 50 to
200 milliseconds. assuming that the current track is known and that
the head is parked with a seek operation. The time required to fall
a distance of one foot is 250 milliseconds. The present invention
is a system which will protect hard disks in portable computers by
sensing the IG acceleration of a fall and causing the disk heads to
park in that event.
According to the invention, a three-axis accelerometer is mounted
within the computer system case 12, preferably as a component part
of the hard disk and mounted to the frame of the hard disk. As
shown in FIG. 2, the accelerometer 22 provides output signals for
each of the three axes to a dedicated processor 24 which
continuously monitors the acceleration signals, computes the
resultant acceleration vector and compares the scaler magnitude of
the acceleration vector with a preset range of values. The preset
range is chosen to represent an acceleration that would suggest an
impending impact. In the event that a value in the preset range for
acceleration is calculated, the dedicated processor 24 generates a
high priority interrupt to the central processor unit (CPU) 26 of
the portable computer and proceeds to park the disk heads of the
hard disk 28 rapidly and, optionally, to brake the hard disk's
rotation. The interrupt handler of the CPU 26 simultaneously
performs those actions which that computer and operating system may
be able to perform to deal with the loss of disk availability.
Alternatively, the interrupt routine of the CPU 26 may initiate the
disk park and brake operations, as indicated by the dotted lines in
FIG. 2. An advantage of having, for example, the dedicated
processor 24 perform the park subroutine while the CPU 26 performs
the brag subroutine is that the two subroutines can be processed
simultaneously by the two processors in parallel.
Turning now to FIG. 3 there is shown a flow diagram of the logic of
the protective reflex system just described. The process starts by
inputting the three acceleration inputs to the dedicated processor
24, as represented by function block 31. The dedicated processor 24
computes the acceleration vector, as represented by function block
32. The scaler value of the acceleration vector is compared with
the preset range of values in decision block 33. When the value of
the calculated acceleration falls within the range continuously for
a period suggesting a fall is in progress, the dedicated processor
24 generates a high priority interrupt to the CPU 26, as
represented by the function block 34. In operation block 35,
depending on the specific implementation of the invention, either
the dedicated processor 24 or the CPU 26 calls the park subroutine
which causes the heads of the hard disk 28 to be parked
rapidly.
At this point in the flow diagram, the main reflexive action, i.e.,
parking of the heads, has been accomplished. Further action can
optionally be taken to enhance the protective system according to
the invention. In addition to calling the park subroutine, a motor
braking subroutine may be called, as indicated by operation block
36. Again, this subroutine may be called by either the CPU 26 or
the dedicated processor 2A. The system then awaits resumption of
normal operations, as indicated by decision block 37. Further
variations might include testing for a disk drive motor stopped
condition followed by a power down procedure.
While the inention has been described in terms of a single
preferred embodiment with optional features, those skilled in the
art will recognize that the invention can be pracueed with
modification within the spirit and scope of the appended
claims.
* * * * *