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Патент USA US3060443

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Oct- 23, 1962
Filed March 28, 1961
United States Patent 0 "ice
Patented Get. 23, 1962
, problem of variations in the dynamic, elastic or ?uid
Roger K. Lee, Jr., Watertown, and William J. German,
Swampscott, Mass., assignors to Laboratory For Elec
tronics, lne, Boston, Mass, a corporation of Dela
Filed Mar. 28, 1961, Ser. No. 98,883
6 Claims. (Cl. 346--74)
forces mentioned hereinbefore.
Therefore, it is a primary object of this invention to
provide a magnetic recorder having self-actuated means
for adjusting the spacing between a ?exible magnetic disc
and a plurality of radially disposed magnetic transducers.
Another object of the invention is to provide a mag
netic recorder using a ?exible magnetic disc, the cross
sectional shape of the disc being adjustable in operation to
This invention pertains generally to data processing ap 10 compensate for variations in the parameters alfecting such
cross-sectional shape.
paratus and particularly to a magnetic recording device
Still another object of this invention is to provide a
utilizing a ?exible storage medium and a plurality of mag
magnetic recorder incorporating the advantages of the
netic transducers.
foregoing objects without adding appreciably to the com
Certain types of magnetic records known to the art op
erate on the principle that positioning of a number of 15 plexity of the device.
These and other objects of the invention are attained
magnetic transducers with respect to a storage medium
generally by disposing a ?exible magnetic disc adjacent
may be attained in operation by mounting the transducers
to a stabilizing plate in which a plurality of radially dis
in a stabilizing plate and then rotating the storage me
posed magnetic transducers are mounted, rotating the
dium to ?x the distance between the recording medium
and the transducers. The recording medium may con 20 disc so as to create a differential in pressure across the two
sides thereof, whereby air, or some other ?uid, is moved
sist of a plastic membrane-like disc, having a magnet~
izable surface which serves as a magnetic store and is
properly spaced from the transducers when the dynamic,
elastic and ?uid forces on the disc are brought into equi
A magnetic recorder using a membrane-like disc is
shown in the presently co~pending application Serial No.
25,995, entitled “Magnetic Disc Storage Device,” ?led
May 2, 1960, and assigned to the same assignee as the
assignee of this application. In the just-cited application,
any desired radial distribution of the ?uid forces acting
on a ?exible disc is established and balanced against the
dynamic and elastic forces acting on the disc during op
eration. When an equilibrium between the dynamic,
from the central portions of the disc outwardly thereof,
and means for recirculating at least a portion of the air
arriving at the periphery of the disc so that the distribu
tion of the ?uid forces acting on the disc is regulated in
accordance with any arbitrarily selected function of the
radius of the disc, thereby changing the cross-sectional
shape of the disc to adjust the spacing between the mag
netic disc and each one of the magnetic transducers.
For a more complete understanding of the invention,
reference is now made to the following detailed descrip
tion of a preferred embodiment of the invention illus
trated in the accompanying drawing in which the single
FIGURE is a simpli?ed cross-sectional view of a mag
elastic and ?uid forces acting on each unit area of the 35 netic recorder made in accordance with the invention.
As may be seen in the drawing, the magnetic recorder
disc exists, the pro?le, or cross-sectional shape, of the disc
approximates an ideal pro?le, or cross-sectional shape,
and each one of a plurality of magnetic transducers ra
dially disposed with respect to the disc operates With sub
stantially equal ef?ciency.
Although satisfactory results may be obtained follow
ing the disclosure of the cited application, it is highly de
sirable that improved ways be provided to adjust the pro
preferably comprises an enclosure 10 so shaped and
adapted as to support a ?exible disc positioning and ro
tating assembly, 12, a number of magnetic transducers 14
40 (only one of which is shown) and a disc cross-sectional
shaping assembly generally indicated by the numeral 16.
The enclosure 10 consists of a base 17 having a sub
stantially ?at stabilizing surface, a depression 21 prefer
?le of a ?exible disc in a magnetic recorder. Experience 45 ably formed centrally of the base 17. The enclosure it}
is completed by a cover 23 attached in any convenient
has proven, for example, that great care must be taken to
way to the base 17.
ensure the constancy of the elastic and dynamic forces
The disc positioning and rotating assembly \12. includes
acting on the disc. Otherwise, even relatively small and
an electric motor 25 mounted on the cover 23 and ener
virtually uncontrollable variations in either the physical
characteristics of the disc (which change the elastic forces 50 gized through leads 27. The rotor of electric motor 25
is extended to form a shaft 29 to which a pair of ?anges
on the disc) or the speed at which the disc is rotated
(which change the dynamic forces on the disc) cause un
3'1, 33 are connected to hold a ?exible recording disc 35'
expectedly large variations in the cross-sectional shape
of the disc during operation. Such variations, of course,
coaxially in alignment with the depression 21 in the base
The disc cross-sectional shaping assembly 16 comprises
in turn are re?ected in equally large variations in the 55
an initial pressure regulating system 36 which controls the
spacing between the disc and associated magnetic trans
pressure of any ?uid in the depression 21, as described in
ducers, resulting in unforseen changes in amplitude of the
more detail in the co-pending application of Pearson et al.,
signal of the latter elements. Such changes in signal am
Serial No. 853,373, ?led November 16, 1959, now aban
plitude must, in many cases, be compensated by adjust
ment of the circuitry associated with the transducers and 60 doned. Brie?y though, the initial pressure regulating sys
tem comprises means, including a fluid inlet 37, a pipe
are, in any event, to be avoided whenever possible.
39, a valve 41 and a ?uid outlet 43 whereby a predeter
It has also been found that the various forces acting on
mined differential in ?uid pressure may, in operation, be
a ?exible disc in a magnetic recorder are inter-related in
established between the environmental ?uid within the
such an extremely complex manner that a complete re
enclosure N and the depression 21. Included in the disc
design is required whenever it is desired to make even
minor changes in the pro?le of the disc, the material of
the disc or the speed of rotation of the disc. Obviously,
65 cross-sectional shaping assembly 16 (in addition to the
initial ?uid pressure regulating system 36) is a ?uid pres
sure regulating system 44 for regulating the ?uid pressure
it would be extremely advantageous if means could be pro
gradient radially of the flexible recording disc 35. The
vided for adjusting the pro?le of a ?exible disc in opera
tion so as to permit at least moderate changes in any 70 just mentioned system includes a plurality of movable
parameter and still attain satisfactory results. Such
means would, of course, also minimize the gravity of the
?uid inlets 45 disposed adjacent to and outside the periph
ery of the ?exible recording disc 35 and rotatably sup
ported on the base 17. A lever 47 attached to each one
one surface of the stabilizing plate to create a ?uid stream
of the ?uid inlets 45 makes each element adjustable with
respect to the periphery of the ?exible recording disc 35.
A pipe 49 is attached between the outer end of each ?uid
intake 45. The second side of each pipe 49 in turn is con
?owing spirally outwardly along. the surface of the mem
brane, means disposed adjacent the periphery of the mem
brane in the ?uid stream to intercept a predetermined por
tion thereof, and means for recirculating such intercepted
nected to a ?uid outlet 53 in the base 17 so as to com
municate with the stabilizing surface 19, as illustrated.
2. Apparatus as in claim 1 wherein the ?uid is a gas
In operation, the electric motor 51 is energized to ro
and the second last named means includes means for
tate the shaft 2‘), the ?anges 31, 33 and the ?exible re
throttling the gas and the means for recirculating the in
cording disc 35. Rotation of the ?exible disc 35 in turn 10 tercepted gas includes means passing through the surface
creates a partial vacuum in the depression 21, causing
of the stabilizing plate to introduce the intercepted and
?uid to ?ow through the ?uid inlet 37, the pipe 39, the
throttled gas into the gas stream.
"alve 41, and thence in to the depression 21, until an
3. A magnetic recorder utilizing a plurality of magnetic
equilibrium condition is attained in which condition the
transducers coacting with a recording disc rotating in a
dynamic, elastic and ?uid pressures operating on the ?ex
?uid, each one of the plurality of magnetic transducers
ible recording disc 35 are balanced. As the ?exible re
being spaced from a surface of the recording disc and at
cording disc 35 speeds up, or after it has been brought up
a different distance from the axis of rotation thereof, com
to its ?nal operating speed, its cross-sectional shape may
prising, a ?exible disc having a magnetizable surface, a
be adjusted by orienting the ?uid intake 45. A closed
stabilizing plate, means for coaxially mounting the ?exible
self adjusting control loop is thus created whereby the 20 disc and the stabilizing plate in a ?uid, means for mount
amount of ?uid intercepted by the ?uid intake 45 deter
ing each one of the plurality of magnetic transducers
mines the amount of ?uid entering into the ?uid stream
?ush with the surface of the stabilizing plate facing the
between the ?exible recording disc 35 and the stabilizing
magnetizable surface of the ?exible disc and at a different
surface 19 of the base 17 through the ?uid outlet 53.
distance from the center thereof, means for rotating the
Consequently, the equilibrium condition of the dynamic,
?exible disc to generate a ?uid ?ow in a space de?ned by
elastic and ?uid forces acting on each unit area of the
the magnetizable surface and the stabilizing plate, the
?exible recording disc 35 radially outwardly of the open
direction of ?uid ?ow being spirally outwardly from a
ing of the ?uid outlet 53 may be ?xed by the particular
central portion of the ?exible disc to the periphery there
orientation of the ?uid intake 45 ?xed with respect to the
of and the velocity of the ?uid in the ?ow being a func
periphery of the ?exible recording disc 35. The equi 30 tion of distance along the spiral path thereof, and means
librium condition of the dynamic, elastic and ?uid forces
for recirculating a portion of the moving ?uid arriving at
on each unit area of the ?exible recording disc 35, in
the periphery of the ?exible disc.
turn, determines the cross-sectional shape, or pro?le, of
4. A magnetic recorder as in claim 3 wherein the
that element. Since the individual ones of the magnetic
means for recirculating a portion of the moving ?uid ar
transducers 14 are mounted ?ush with the surface 19 of
riving at the periphery of the ?exible disc includes at least
the base 17, it follows then that the spacing between each
one ?uid intake disposed adjacent the periphery of the
one of the magnetic transducers is dependent upon the
?exible disc, means for orienting the ?uid intake with re
cross-sectional shape of the ?exible recording disc 35.
spect to the direction of ?uid ?ow emanating from the
Further, in view of the teachings of application Serial No.
space de?ned by the ?exible disc and the stabilizing plate,
25,995 cited hereinbefore, it follows that the spacing be
and means for directing the ?uid intercepted by the ?uid
tween each one of the magnetic transducers 14 and the
?exible recording disc 35 may be made to increase in
proportion to the distance of each transducer from the
center of rotation of the disc.
intake back into the ?uid ?oW.
5. A magnetic recorder as in claim 4 wherein the ?uid
is a gas.
6. In a magnetic recorder wherein a ?exible disc hav
It will become immediately apparent to those having 45 ing a magnetizable surface is rotated at a short distance
skill in the art that more than one ?uid pressure regulat
from a stabilizing plate until the dynamic, elastic and ?uid
ing system 44 may be used so as to attain even greater
forces acting on each unit volume of the ?exible disc are
?exibility in the range of adjustment of the cross-sec
in equilibrium to cause the ?exible disc to assume a pre
tional shape of the ?exible recording disc 35. It will also
determined shape wherein the distance between a surface
be recognized that the position of the ?uid outlet 53 may 50 of the stabilizing plate and the magnetizable surface in
be varied at will, either radially of the ?exible recording
creases radially of the ?exible disc, means for adjusting
disc 35 along the base 17 or on the side of the disc re
the ?uid pressure gradient radially of the ?exible disc,
moved from the surface 19.
comprising the sub-combination of means for introducing
In view of the variations of the invention just described
the ?uid at a constant pressure through the aperture in
and other equally obvious modi?cations not described, the
the annular stabilizing plate into the space de?ned by a
invention should not be limited to the illustrated embodi
surface of the stabilizing plate and the magnetizable sur
ment thereof, but rather by the spirit and scope of the
face, ?uid intake means disposed in the path of the ?uid
appended claims.
?ow adjacent the periphery of the ?exible disc, means for
What is claimed is:
throttling the ?uid intake means, and means for recir
1. Apparatus for adjusting the cross-sectional shape of
culating the ?uid entering the ?uid intake means through
a membrane in a ?uid comprising a stabilizing plate,
at least a portion of the space de?ned by the surface of
means for rotating the membrane in the ?uid and close
the stabilizing plate and the magnetizable surface of the
to the stabilizing plate, means adjacent the axis of rota
?exible disc.
tion of the membrane for introducing the ?uid at a con
No references cited.
trolled rate into the space de?ned by the membrane and
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