Slider lifter

A slider lifter including a support structure, a flexure arm and a resilient means cantilevered from the support structure, and a shape memory alloy element operatively connected between the support structure and the resilient means, wherein the shape memory alloy element has a martensitic condition and an austenitic condition. The shape memory alloy element in one of the martensitic and austenitic conditions cooperates with the resilient means to elastically deform the flexure arm from an undeformed position to a deformed position. The shape memory alloy element in the other of the martensitic and austenitic conditions cooperates with the resilient means to both move away from the fexure arm, thereby allowing the flexure arm to return towards its undeformed position. It is most preferred that when the resilient means moves away from the flexure arm, the flexure arm and the resilient means are not in contact. This allows the flexure arm to return to its completely undeformed position.

BACKGROUND OF THE INVENTION 
This invention relates to the field of slider lifters and more particularly 
relates to slider lifters incorporating shape memory alloys. 
Various electromechanical devices have been proposed utilizing shape memory 
alloys. Among these are: Perry U.S. Pat. No. 3,483,360; Willson U.S. Pat. 
No. 3,594,674; Willson et al U.S. Pat. Nos. 3,613,732; 3,634,803; and 
3,652,969; Du Rocher U.S. Pat. Nos. 3,676,815 and 3,707,694; Hickling U.S. 
Pat. No. 3,849,756; Clarke U.S. Pat. No. 3,872,415; Jost et al U.S. Pat. 
No. 3,968,380; Melton et al U.S. Pat. No. 4,205,293; Brubaker U.S. Pat. 
No. 4,517,543; and Sims U.K. Patent Application 2,026,246A. 
These devices typically take advantage of the shape memory effect to trip a 
switch or break a contact upon reaching a critical temperature. 
The phenomenon of shape memory is, of course, well known. The ability to 
possess shape memory is a result of the fact that the shape memory alloy 
undergoes a reversible transformation from an austenitic state to a 
martensitic state with a change in temperature. An article made of such an 
alloy is easily deformed from its original configuration to a new 
configuration when cooled below the temperature at which the alloy is 
transformed from the austenitic state to the martensitic state. The 
temperature at which this transformation begins is usually referred to as 
the M.sub.s temperature and the temperature at which this transformation 
is complete is the M.sub.f temperature. When an article thus deformed is 
warmed to the temperature at which the alloy starts to revert back to 
austenite, referred to as the A.sub.s temperature, the deformed object 
will begin to return to its original configuration. The reversion of the 
alloy will be complete upon reaching the A.sub.f temperature. 
The shape memory alloys that have been used with the above actuators are 
usually either copper-based or nickel/titanium-based. These alloys are 
well known to those skilled in the art. 
Those who are familiar with computers are aware of so-called Winchesters 
which are units for storing data on hard discs. The units basically 
consist of a disc drive unit, a hard disc and a read/write head or slider 
for retrieving data from the hard disc. The slider is typically 
cantilevered over the hard disc from a supporting structure by a flexure 
arm. Other types of disc drive units are configured in a similar manner. 
The slider rests on a landing zone on the disc while the power is off. In 
operation, the drive unit is powered up and the disc begins to rotate. 
After the disc reaches a certain speed, the slider rises up slightly off 
the landing zone due to small air currents which push up on the slider. 
However, until the slider rises, there is considerable friction associated 
with head drag on the disc which causes wear to the slider and the disc. 
When the unit is powered down, the same friction occurs until the disc 
stops rotating. 
In order to accommodate this friction, the discs are coated with a 
protective layer and lubricants are applied. Additionally, the discs often 
require a landing zone where no data can be stored. Consequently, the 
amount of data that can be stored on a disc is reduced. Too, a larger disc 
drive motor is required to overcome the adverse frictional effects and a 
motor brake is often necessary to stop the rotation of the disc when the 
motor is turned off to reduce frictional wear. 
It can thus be appreciated that it would be desirable to raise the slider 
during power up and keep it raised during power down so as to eliminate 
the adverse effects of friction. 
Accordingly, in Japanese Patent Application No. 57-222046 and Yaeger et al 
U.S. Pat. No. 4,551,974, it has been proposed to utilize shape memory 
alloys to cause the slider to be raised or lowered. In each of these 
references, the shape memory alloy element works in conjunction with a 
biasing means which also happens to be the flexure arm. 
The difficulty with these references, most apparent with the Japanese 
reference, is that alteration of the characteristics of the flexure arm is 
required to make the device work. The lack of commercial success of these 
devices is due, at least in part, to this fact. Disc drive manufacturers 
are loathe to change any aspect of the flexure arm. The reason for this 
attitude is that the combined flexure arm and slider are very sensitive as 
to their loading and airfoil characteristics. A great deal of time and 
effort has gone into their design. Accordingly, any design that requires 
the assistance of the flexure arm, and thus a redesign of the flexure arm 
as well, is looked upon with disfavor. 
Therefore, it is an object of the invention to have a device to raise and 
lower the slider without adversely affecting the flexure arm. 
It is a further object of the invention to have such a device which is 
simple in design and economical to produce. 
These and other objects of the invention will become more apparent after 
referring to the following description considered in conjunction with the 
accompanying drawings. 
BRIEF SUMMARY OF THE INVENTION 
There is disclosed according to the invention a slider lifter comprising a 
support structure, a flexure arm and a resilient means cantilevered from 
the support structure, and a shape memory alloy element operatively 
connected between the support structure and the resilient means, wherein 
the shape memory alloy element has a martensitic condition and an 
austenitic condition. The shape memory alloy element in one of the 
martensitic and austenitic conditions cooperates with the resilient means 
to elastically deform the flexure arm from an undeformed position to a 
deformed position. The shape memory alloy element in the other of the 
martensitic and austenitic conditions cooperates with the resilient means 
to both move away from the flexure arm, thereby allowing the flexure arm 
to return towards its undeformed position. 
It is most preferred that when the resilient means moves away from the 
flexure arm, the flexure arm and the resilient means are not in contact. 
This allows the flexure arm to return to its completely undeformed 
position. 
As will become more apparent hereafter the slider lifter according to the 
invention performs its function without adversely affecting the design 
characteristics of the flexure arm.

DETAILED DESCRIPTION OF THE INVENTION 
According to one aspect of the invention there is disclosed a slider lifter 
comprising a support structure, a flexure arm and a resilient means 
cantilevered from the support structure, and a shape memory alloy element 
operatively connected between the support structure and the resilient 
means with the shape memory alloy element having a martensitic condition 
and an austenitic condition. The shape memory alloy element in one of the 
martensitic and austenitic conditions cooperates with the resilient means 
to elastically deform the flexure arm from an undeformed position to a 
deformed position. The shape memory alloy element in the other of the 
martensitic and austenitic conditions cooperates with the resilient means 
to both move away from the flexure arm, thereby allowing the flexure arm 
to return towards its undeformed position. 
It is most preferred that the shape memory element and resilient means 
further cooperate so that when the shape memory alloy element is in the 
other of the martensitic and austenitic conditions, the resilient means 
and shape memory alloy element move away from the flexure arm so that the 
flexure arm and the resilient means are not in contact. This allows the 
flexure arm to return to its completely undeformed position. 
There is disclosed according to the invention another aspect of the 
invention. Thus, there is a slider lifter comprising a support structure, 
a flexure arm and a resilient means cantilevered from the support 
structure, and a shape memory alloy element operatively connected between 
the support structure and the resilient means, the shape memory alloy 
element having a martensitic condition and an austenitic condition. The 
shape memory alloy element in the martensitic condition allows the 
resilient means to contact and elastically deform the flexure arm from an 
undeformed position to a deformed position. The shape memory alloy element 
in the austenitic condition elastically deforms the resilient means away 
from the flexure arm, thereby allowing the flexure arm to return towards 
its undeformed position. 
Referring to the drawings in more detail and particularly referring to 
FIGS. 1 to 3 there is shown the slider lifter according to the invention. 
For clarity, a disc is not shown in place. The slider lifter 10 has a 
suitable support structure generally indicated by 12 which is connected to 
other structure (not shown) of a disc drive unit. There is a flexure arm 
14 and a resilient means 16 cantilevered from the support structure 12. 
The flexure arm 14 is the standard flexure arm which is typically used in 
the manufacture of Winchester disc drives. At the end of the flexure arm 
14 is the slider 18 or read/write head. The resilient means 16, as shown 
in FIG. 1 is a leaf spring; however, it is contemplated within the scope 
of the invention that the resilient means may take other forms. 
The slider lifter 10 further comprises a shape memory alloy element 24 
which is operatively connected between the support structure 12 at 26 and 
the resilient means 16 at 28. As shown in FIGS. 1 to 3, the shape memory 
alloy element may take other forms as will become apparent hereafter. The 
shape memory alloy element has a martensitic condition and an austenitic 
condition. 
The support structure generally consists of moveable carriage 19, plate 20, 
insulating spacer 21 and screw 22. Flexure arm 14 and resilient means 16 
are trapped between the insulating spacer 21 and the carriage 19. The 
shape memory alloy element 24 is attached, e.g. by soldering, to plate 20. 
Similarly, the shape memory alloy element 24 may be attached also to 
resilient means 16 by soldering. The insulating spacer 21 is preferably 
made from a rigid, non-conducting material such as nylon 6,6, high density 
polyethylene or ceramic material. In the preferred embodiment, plate 20 is 
molded into insulating spacer 21. Screw 22 secures the insulating spacer 
21 to the carriage 19; however, screw 22 passes through resilient means 16 
without making electrical contact therewith. Screw 22 only makes contact 
between the insulating spacer 21 and the carriage 19 so as not to 
electrically short out the plate 20 and resilient means 16. 
There is additionally an insulating coating 23 applied to the bottom 
surface of the resilient means 16 to prevent the resilient means 16 from 
electrically shorting against the flexure arm 14 or carriage 19. This 
insulating coating 23 is commonly sprayed on the surface of the resilient 
means 16 and may be, for example, TEFLON.RTM. (TEFLON is 
tetrafluoroethylene and is a product of E. I. DuPont de Nemours). 
Furthermore, the insulating coating 23 acts as a lubricating means between 
resilient means 16 and flexure arm 14 when they are in contact, thereby 
preventing frictional debris from being generated and interferring with 
the operation of the disc drive in general. 
Extending from the back of the slider lifter 10 are electrical leads 30 
which lead to a suitable power source 32 and switch 31. One lead is 
attached to tab 25 of plate 20. The other lead is attached to tab 27 of 
resilient means 16. When switch 31 is closed, current flows through shape 
memory alloy element 24. 
Referring now to FIG. 3 the shape memory alloy element 24 is in the 
martensitic condition and thus in its weakened state. The resilient means 
16 is designed so that it can overcome the strength of the martensitic 
shape memory alloy element. Since the shape memory alloy element 24 can 
not restrain the movement of the resilient means 16 the resilient means is 
allowed to contact the flexure arm 14 and elastically deform it from an 
undeformed position to a deformed position. At this point the slider 18 is 
removed from the disc 34. 
Referring now to FIG. 2, the shape memory alloy element 24 is caused to 
transform to its austenitic condition. The transformation occurs due to 
the heating, by resistance, of the shape memory alloy element. The heating 
is supplied by the power source 32 which is activated when the power to 
the disc drive is turned on by closing switch 31. When the shape memory 
alloy element 24 is in the austenitic condition the element 24 elastically 
deforms the resilient means 16 away from the flexure arm 14. This occurs 
because when the shape memory alloy element goes through the 
transformation from martensite to austenite, the element's dimensions 
change from the lengthened, deformed state in FIG. 3 to the shortened, 
undeformed state in FIG. 2. When the shape memory alloy element 24 is in 
the austenitic condition, it has greater strength than the resilient means 
16. Accordingly, the shape memory alloy element is able to pull the 
resilient means 16 away from the flexure arm 14. The flexure arm 14 is 
then able to return towards its undeformed position. As shown in FIG. 2 
this undeformed position is with the slider resting on, or just above, the 
surface of the disc for its normal read/write operation, depending on the 
speed of the disc. 
As is apparent the flexure arm 14 and the resilient means 16 are 
resiliently opposed to one another. It is preferred that the resilient 
means 16 exerts a greater biasing force than the flexure arm 14 so that in 
the absence of the shape memory alloy element 24 the resilient means 16 
elastically deforms the flexure arm 14. That is, the flexure arm and the 
resilient means work in opposition to one another so that unless the 
resilient means is somehow restrained by the shape memory alloy element 
the resilient means will push the flexure arm into its deformed position. 
In this deformed position the slider is removed from the surface of the 
disc. 
As stated earlier when the shape memory alloy element 24 is in the 
austenitic condition it elastically deforms the resilient means 16 away 
from the flexure arm 14. It is most preferred that when the resilient 
means 16 is so deformed that the flexure arm 14 and the resilient means 16 
(and the shape memory alloy element 24 as well) are not in contact at all. 
This allows the flexure arm 14 to return to its completely undeformed 
position. This is important because when the flexure arm returns to its 
undeformed position it is left completely unrestrained by the resilient 
means as well as the shape memory alloy element. Thus the loading and 
airfoil characteristics of the flexure arm and slider 18 will be 
unaffected by the lifting mechanism of the slider lifter. 
While the Figures only show one slider lifter per disc, it is of course 
understood that there will normally be two slider lifters per disc--one 
above the disc and one below it. For clarity, the slider lifter above the 
disc is not shown. If more than one slider is used on a given disc side, 
then a separate slider lifter may be used for each slider. It is similarly 
within the scope of the invention that a single slider lifter could be 
adapted to lift multiple sliders. 
While many shape memory alloys will be suitable for the shape memory alloy 
element it is preferred that the shape memory alloy element be made from a 
nickel/titanium-based shape memory alloy. Among the preferred alloys are 
the nickel/titanium/copper alloys disclosed in Harrison U.S. Pat. No. 
4,565,589 (which is incorporated by reference herein) and the binary 
alloys such as 49.4 Nickel/50.6 Titanium (in atomic percent). 
As is apparent in this embodiment of the invention it is necessary that a 
small maintenance level of current be directed through the shape memory 
alloy element so as to maintain the slider in the proper position while 
the power is on. However, this is not considered to be a serious 
disadvantage. 
A further aspect, according to the invention, relates to a slider lifter 
comprising a support structure, a flexure arm and a resilient means 
cantilevered from the support structure, and a shape memory alloy element 
operatively connected between the support structure and the resilient 
means. The shape memory alloy element has a martensitic condition and an 
austenitic condition. The shape memory alloy element while in the 
austenitic condition elastically deforms the resilient means and the 
flexure arm from an undeformed position to a deformed position. The shape 
memory alloy element while in the martensitic condition is deformed by the 
resilient means and the resilient means moves away from the flexure arm, 
thereby allowing the flexure arm to return towards its undeformed 
position. 
Referring again to the Figures and particularly referring to FIGS. 4 and 5 
there are shown side views of this embodiment of the slider lifter 110. As 
will be appreciated this slider lifter has the same basic components of 
the slider lifter discussed previously except the operation of the various 
cooperating elements is slightly different. Thus the slider lifter 110 
comprises the support structure, generally indicated by 12, and a flexure 
arm 14 and a resilient means 16 cantilevered from the support structure 
12. Similarly the slider lifter 110 further comprises a shape memory alloy 
element 124 operatively connected between the support structure 12 and the 
resilient means 16. The shape memory alloy element has a martensitic 
condition and an austenitic condition. 
As mentioned above the flexure arm 14 is the standard flexure arm that is 
typically used in disc drives such as Winchesters. The resilient means 16, 
as shown in FIGS. 4 and 5, is a leaf spring but may be other resilient 
means as will be apparent to one skilled in the art. 
The difference in this embodiment of the slider lifter 110 is in the 
cooperation of the shape memory alloy element 124 and the resilient means 
16. Referring particularly to FIG. 5 the shape memory alloy element 124 
has transformed to the austenitic condition due to power from power source 
32 being directed through the shape memory alloy element 124 thereby 
resistantly heating the element so as to cause the transformation. The 
shape memory alloy element 124 lengthens so as to push upon and 
elastically deform the resilient means 16 which in turn pushes upon the 
flexure arm 14 causing the deformation of the flexure arm from an 
undeformed position to a deformed position. The flexure arm 14 is moved 
away from the disc 34 so that the slider 18 is removed from surface 
contact with the disc 34. When power is turned off to the shape memory 
alloy element it cools down and transforms to the martensitic condition. 
At this point, as shown in FIG. 4, the resilient means 16 can overcome the 
weakened martensitic condition of the shape memory alloy element 124 and 
deform it. The shape memory alloy element 124 no longer being in its high 
strength condition cannot keep the resilient means 16 against the flexure 
arm 14. The resilient means 16 is then able to move away from the flexure 
arm 14. The flexure arm 14, no longer being restrained by the shape memory 
alloy element 124 and the resilient means 16 is able to return to its 
undeformed position wherein the slider rests on, or nearly on, the surface 
of the disc to perform its read/write function. 
In the earlier embodiments of the slider lifter as shown in FIGS. 1 to 3, 
the shape memory alloy element was a wire or other similar element. 
However, in the embodiment as shown in FIGS. 4 and 5, it is necessary for 
the shape memory alloy element to have a different form so as to be able 
to push upon the resilient means. This being the case the shape memory 
alloy element could be in the form of, for example, a rod which would just 
be a wire having a thickened cross section. 
Alternatively, as shown in FIGS. 6 and 7, the shape memory alloy element 
224 could be in the shape of a bow with the ends of the bow attached to 
the support structure and the resilient means 16. The bow would straighten 
out, or nearly straighten out upon reaching its austenitic transformation 
temperature. Except for the different shape memory alloy element 224, the 
operation of the slider lifter 210 in FIGS. 6 and 7 is identical to the 
slider lifter 110 in FIGS. 4 and 5. In any case, other forms of the shape 
memory alloy element will come to those who are skilled in the art. These 
other forms are nevertheless contemplated within the scope of the 
invention. 
Referring now to FIGS. 8 and 9, there is shown a further embodiment of the 
slider lifter 310. This embodiment of the slider lifter is similar to the 
slider lifter 10 shown in FIGS. 1 to 3 except the positions of the 
resilient means and shape memory alloy element are flipped over. The 
operation of the slider lifter 310, however, is similar to slider lifters 
110 and 210 discussed previously. That is, the resilient means 316 and 
flexure arm 14 are both cantilevered from the support structure, generally 
indicated by 12. The shape memory element 324 is operatively connected 
between the support structure at 326 and the resilient means at 328. In 
this embodiment, however, plate 20 shown in FIGS. 1 to 7 is no longer 
necessary. Rather, plate 320 is inserted between insulating space 21 and 
flexure arm 14. Then, shape memory alloy element may be attached, e.g. by 
soldering, to plate 320. The leads 30 would be connected to tab 327 of 
resilient means 316 and tab 325 of plate 320. Resilient means 316 at least 
at its distal end and plate 320 would need an insulated coating 23, as 
discussed previously, to avoid shorting out against the flexure arm 14. 
When switch 31 is closed, as shown in FIG. 9, the shape memory alloy 
element 324 tranforms to its austenitic condition and contracts. In so 
doing, it pulls resilient means 316 into contact with flexure arm 14 and 
deforms the flexure arm 14 from an undeformed position to a deformed 
position. When power to the slider lifter 310 is turned off by opening 
switch 31, the shape memory alloy element 324 transforms to its 
martensitic condition. Resilient means 316 is then able to overcome the 
shape memory alloy element 324 and move away from the flexure arm as shown 
in FIG. 8. The flexure arm 14 is then able to return towards its 
undeformed position. 
When the shape memory alloy elements 124, 224 and 324 (of FIGS. 4 to 9) are 
in the martensitic condition and when the resilient means 16 is thus able 
to move away from the flexure arm 14 it is most preferred that the flexure 
arm and the resilient means are not in contact. This allows the flexure 
arm to return to its completely undeformed position. As mentioned above, 
when the flexure arm is allowed to return to its completely undeformed 
position it is not in contact with the resilient means or the shape memory 
alloy element. Thus the loading and airfoil characteristics of the flexure 
arm and slider are not adversely affected by the slider lifter structure 
according to the invention. 
Again, while the shape memory alloy elements 124, 224 and 324 may be made 
from a variety of shape memory alloys it is preferred that they be made 
from a nickel/titanium-based shape memory alloy such as the binary and 
ternary alloys mentioned above. 
In the embodiments of the invention shown in FIGS. 4 to 9, the slider rests 
on the disc when there is no power to the disc drive. At power on (switch 
31 is closed) the slider is lifted from the surface of the disc before the 
disc motor is actually started. The slider is then lowered (power to the 
slider lifter is turned off) when the disc attains proper operating speed. 
There is no power applied to the slider lifter during normal operation of 
the disc drive. 
As will be apparent to those skilled in the art the advantages of all the 
embodiments of the invention are many. Some of these advantages, for 
purposes of illustration and not of limitation, are a smaller disc motor 
can be used because power from the motor is not used to overcome static 
and startup friction associated with slider drag on the disc. Too, the 
need to stop the motor quickly is removed if there is no slider/disc 
friction. Thus, it is possible to eliminate the motor brake. Similarly, 
disc lubricants are not necessary since the slider never touches the disc. 
As a side benefit fewer contaminates are introduced since slider/disc 
friction is eliminated. Finally, the storage capacity of the disc can be 
increased by a substantial amount by eliminatinq the landing zone which is 
normally present on the disc. 
It cannot be too strenuously emphasized that the many advantages of the 
invention have been accomplished without alteration of the characteristics 
of the flexure arm. As noted previously disc drive manufacturers are 
loathe to change any aspect of the flexure arm since the combined flexure 
arm and slider are very sensitive as to their loading and airfoil 
characteristics. A great deal of time and effort has gone into the design 
of the flexure arm and therefore modifications of the flexure arm will not 
usually be tolerated. Applicant, however, has devised a very advantageous 
design without alteration of this flexure arm. 
It will be apparent to those skilled in the art having regard to this 
disclosure that other modifications of this invention beyond those 
embodiments specifically described here may be made without departing from 
the spirit of the invention. Accordingly, such modifications are 
considered within the scope of the invention as limited solely by the 
appended claims.