U.S. patent number RE32,180 [Application Number 06/672,139] was granted by the patent office on 1986-06-10 for composite sheets constituting electromechanical transducers and transducers equipped with such sheets.
Invention is credited to Claude Hennion, Jacques Lewiner.
United States Patent |
RE32,180 |
Lewiner , et al. |
June 10, 1986 |
Composite sheets constituting electromechanical transducers and
transducers equipped with such sheets
Abstract
.[.The invention relates to a flexible composite sheet designed
to constitute an undersheet behaving as an electromechanical
transducer in order to detect the apnea of subjects lying on it.
This sheet comprises, in addition to a foil sensitive to pressure
in the sense of electromechanical transduction (an electret or
polarized piezoelectric foil), two film electrodes and two
protective foils. Spacing shims are glued to the two foils against
which they are juxtaposed. When the sensitive foil is an electret,
the shims are directly interposed between the sensitive foil and
one of the two electrodes. When the sensitive foil is a polarized
piezo-electric foil, the shims are directly interposed between one
of the electrodes and the corresponding external protective
foil..]. .Iadd.An apnea monitor/alarm consists of an electronic
monitor circuit to actuate an alarm responsive to the output of a
sheet-like electromechanical transducer. The transducer consists of
an electret or polarized piezoelectric foil responsive to pressure
to generate corresponding electrical signals, two film electrodes,
and two protective foils. Shims are glued to two of the foils for
spacing. If an electret sensor foil is used, the shims are directly
interposed between the sensitive foil and one of the electrodes. If
the sensitive foil is a polarized piezoelectric foil, the shims are
directly interposed between one of the electrodes and the
corresponding external protective foil. .Iaddend.
Inventors: |
Lewiner; Jacques (92210 Saint
Cloud, FR), Hennion; Claude (75005 Paris,
FR) |
Family
ID: |
9238512 |
Appl.
No.: |
06/672,139 |
Filed: |
November 15, 1984 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
228716 |
Jan 27, 1981 |
04359726 |
Nov 16, 1982 |
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Foreign Application Priority Data
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Feb 12, 1980 [FR] |
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8003093 |
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Current U.S.
Class: |
340/573.1;
307/400; 310/800; 340/666; 600/534; 600/595; 73/862.046 |
Current CPC
Class: |
A61B
5/1036 (20130101); A61B 5/113 (20130101); A61B
5/6892 (20130101); H01L 41/08 (20130101); H01L
41/1132 (20130101); Y10S 310/80 (20130101); A61B
2562/0247 (20130101) |
Current International
Class: |
A61B
5/103 (20060101); A61B 5/113 (20060101); A61B
5/11 (20060101); H01L 41/08 (20060101); H01L
41/113 (20060101); G08B 021/00 () |
Field of
Search: |
;340/666,573
;200/85A,85R,86A,86R ;310/800,338 ;307/400
;128/782,721,712,671 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Swann, III; Glen R.
Attorney, Agent or Firm: Larson and Taylor
Claims
We claim:
1. Relatively flexible and extended composite sheet, constituting
an electromechanical transducer and comprising a foil sensitive to
pressure in the sense of electromechanical transduction, said
pressure sensitive foil being interposed between two conductive
foils or electrodes themselves covered exeternally with protective
foils, said composite sheet also comprising, between the pressure
sensitive foil and one of the protective foils, spacing shims of
which the two opposite surfaces are glued respectively to the two
opposite adjacent areas.
2. Sheet according to claim 1, wherein the sensitive foil is
permanently electrically charged and creates an external electrical
field, and the shims are directly interposed between said sensitive
foil and one of the two electrodes.
3. Sheet according to claim 1, wherein the sensitive foil comprises
a piezo-electric foil permanently electrically polarized and
interposed contiguously between the two electrodes, the shims are
directly interposed between one of these electrodes and the
corresponding external protective foil.
4. Sheet according to claim 1, wherein the shims re self-adhesive
on the said surfaces.
5. Sheet according to claim 1, wherein the areas on which the shims
are glued are treated previously so as to facilitate this
gluing.
6. Sheet according to claim 5, wherein said previous treatment is
by electrical discharge.
7. Sheet according to claim 5, wherein said previous treatment
comprises deposition of a thin layer of a suitable substance for
enhancing said gluing.
8. Sheet according to claim 1, wherein the shims have a thickness
comprised between 0.1 and 1 mm, a width comprised between 1 and 10
mm and a mutual spacing comprised between 5 and 100 mm.
9. Rectangular mattress construction incorporating a composite
sheet according to claim 1, whose sides are comprised respectively
between 10 and 30 cm and between 20 and 50 cm.
10. Sheet according to claim 1, wherein the various layers are
constituted of transparent materials.
11. Electromechanical transducer comprising a composite sheet
according to claim 1, and output means connected electrically to
the two electrodes of said sheet.
12. Electrochemical transducer according to claim 11, including
alarm means connected to said output means so as to activated
thereby. .Iadd.
13. An Apnea monitor comprising:
a composite sheet of sufficient area to underlie a baby
comprising:
a piezoelectric foil;
electrodes covering opposite surfaces of said piezoelectric
foil;
cover layers overlying each of said electrodes; and
spacing means, located between one of said cover layers and the
corresponding electrode and affixed to said one cover layer and
said corresponding electrode at a plurality of locations, for
providing a plurality of compartments between said one cover layer
and said corresponding electrode such that portions of the
piezoelectric foil which lie adjacent these compartments will be
reversibly lengthened when a pressure force is applied to the
composite sheet at the corresponding compartments, said
compartments being distributed substantially uniformly over the
area of said piezoelectric foil; and
a monitor means, connected to said electrodes, for monitoring
electrical signals produced in response to changes in the
piezoelectric foil, whereby rhythmic movements of a baby will
rhythmically lengthen and relax said portions of said piezoelectric
foil so as to produce an electrical signal in response to said
rhythmic movements which is monitored by said monitor means.
.Iaddend. .Iadd.14. An Apnea monitor as claimed in claim 13,
wherein said monitor means includes alarm means for producing an
alarm output when the electrical signal monitored by said monitor
means is interrupted for a period longer than a predetermined
threshold period.
.Iaddend. .Iadd.15. An Apnea monitor comprising:
a sheet of piezoelectric foil of sufficient area to underlie a
baby;
electrodes covering opposite surfaces of said foil;
means providing a spaced shim support for portions of said foil
while leaving other portions unsupported, and shim support being
adhesively secured to one of the electrodes;
the unsupported portions being distributed substantially uniformly
over the area of said foil;
a monitor;
and leads connecting said electrodes to said monitor;
whereby the biological functions of a baby will rhythmically
lengthen and relax said unsupported portions of said foil to
produce a signal, corresponding to said biological functions, on
said electrodes which is transmitted to said monitor. .Iaddend.
.Iadd.16. A monitor for monitoring biological movements of a living
being, said monitor comprising:
(a) a composite sheet comprising:
a relatively flexible piezoelectric foil:
a pair of electrode members located on opposite sides of said
piezoelectric foil;
a cover member overlying at least one of said electrode members;
and
spacing means, located between the piezoelectric foil and one of
said members, for providing a plurality of spaces between said
piezoelectric foil and said one member such that a portion of the
piezoelectric foil which lies adjacent a said space will be
reversibly lengthened and thinned when a pressure force is applied
to said composite sheet at the corresponding space; and
(b) a monitor means, connected to said electrodes, for monitoring
electrical signals produced in response to changes in the
piezoelectric foil whereby biological movements of the living being
will lengthen and relax at least some of said portions of said
piezoelectric foil so as to produce an electrical signal in
response to said movements which is monitored by said monitor
means. .Iaddend. .Iadd.17. A monitor as claimed in claim 16 wherein
at least one surface of said spacing means is secured to the
surface adjacent thereto. .Iaddend. .Iadd.18. A monitor as claimed
in claim 16 wherein said electrode members comprise metallic foils
secured to opposite surfaces of said piezoelectric foil and said
cover member comprises a protective foil, said spacing means being
secured to one of said electrode foils and to said protective foil.
.Iaddend. .Iadd.19. A monitor as claimed in claim 16 wherein said
spaces comprises chambers distributed substantially uniformly over
the area of said piezoelectric foil. .Iaddend. .Iadd.20. A monitor
as claimed in claim 16, wherein said monitor means includes alarm
means for producing an alarm output when the electrical signal
monitored by said monitor means is interrupted for a
period longer than a predetermined threshold period. .Iaddend.
.Iadd.21. A monitor for monitoring the movements of a living being,
said monitor comprising:
(a) an electromechanical transducer comprising:
a relatively flexible piezoelectric foil;
a pair of electrode members located on opposite sides of said
piezoelectric foil; and
space defining means for defining a plurality of spaces adjacent
portions of said piezoelectric foil such that a said portion of the
piezoelectric foil will be reversibly depressed and lengthened when
a pressure force is applied to the transducer at the corresponding
space; and
(b) a monitor means, connected to said electrodes, for monitoring
electrical signals produced in response to changes in the
piezoelectric foil whereby movements of the living being will
reversibly lengthen said portions of said piezoelectric sheet so as
to produce an electrical signal in response to said movements for
monitoring by said monitor means. .Iaddend. .Iadd.22. A monitor as
claimed in claim 21 wherein said transducer comprises a composite
sheet and said space defining means comprise spacing shim means for
spacing said piezoelectric foil from one component of said
composite sheet so as to define said spaces therebetween. .Iaddend.
.Iadd.23. A monitor as claimed in claim 22, wherein said one
component comprises a cover sheet which overlies one of said
electrodes. .Iaddend. .Iadd.24. In a monitor for monitoring the
biological movements of a living being, a transducer
comprising:
a piezoelectric foil;
an electrode on each side of said foil, and
means for creating reversible depressions in said foil at selected
positions distributed around the area of said foil in response to
biological stimuli produced by a living being in contact with said
film.
.Iaddend. .Iadd.25. A transducer according to claim 24 in which
said depression creating means comprises:
shim means underlying said piezoelectric foil, said shim means
creating a chamber at each of said selected locations under the
piezoelectric foil into which a portion of said foil can be
depressed in response to stimuli produced by a living being in
contact with said transducer on the side of said transducer remote
from said shim means. .Iaddend. .Iadd.26. A transducer according to
claim 25 further comprising:
a protective sheet surrounding a composite formed by said foil,
said electrodes and said shim means;
and means for affixing said shim means to at least one of said
elements of said composite and to said protective sheet. .Iaddend.
.Iadd.27. A method of monitoring biological functions of a living
body comprising the steps of:
placing against a portion of the living body a transducer
comprising a piezoelectric foil having electrodes on each surface
thereof and having shim means distributed over the surface of said
foil for creating a plurality of locations at which portions of
said foil can be reversibly lengthened and thinned;
and utilizing the voltage generated between said electrodes
responsive to the reversibly thinning of said foil at least one of
said locations so as
to monitor biological functions of the living body. .Iaddend.
.Iadd.28. A monitor for monitoring the movements of a living being,
said monitor comprising:
(a) a relatively flexible transducer composite comprising:
an electret foil;
electrodes located on opposite sides of said electret foil;
a protective cover overlying at least one said electrodes; and
spacing means, affixed to the components of said composite lying
adjacent thereto at a plurality of locations, for providing a
plurality of compartments within said composite such that when a
pressure force is applied to the composite at the corresponding
compartments, the portions of the electret foil which lie adjacent
these compartments produce an electrical output; and
(b) monitor means, connected to said electrodes, for monitoring
electrical signals produced by said electret foil, whereby
movements of a living being will cause pressure forces to be
applied to said portions of said electret foil so as to produce a
resultant electrical output signal in response to said movements
which is monitored by said monitor means. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The invention relates to composite sheets constituting
electromechanical transducers and more particularly those, of these
sheets, which have a certain flexibility and extend over a
relatively large area, this area being preferably of the order of
several square decimeters.
The invention is also directed to transducers equipped with such
composite sheets.
It is known that these transducers permit the transformation into
variations of an electrical voltage, of the pressure variations
which are exerted locally on the sheet and/or the local
deformations of this sheet.
The composite sheets concerned comprise essentially for this
purpose a dielectric foil "sensitive" to pressure in the sense of
electromechanical transduction, which foil is permanently
electrically charged or carries a permanent electrical
polarisation, interposed between two electrodes or electrically
conducting films themselves covered externally with two protective
foils, and the transducers equipped with these composite sheets
include, in addition to the latter, electrical exploitation means
and possibly warning means connected to the two electrodes of said
composite sheets.
An interesting application of these transducers, to which the
invention relates preferably, but not exclusively, is the detection
of apnea, the monitoring of the biologic functions (respiration,
cardiac rhythm, . . . ), particularly in nurslings.
Draw-sheets or undersheets are constituted for this purpose, by
means of the composite sheets concerned, which are interposed
between a mattress and the subject to be watched, lying down,
sitting or supported on the mattress: the respiratory movements of
this subject cause cyclic local variations in the pressure exterted
on this draw-sheet, which variations are manifested by similar
cyclic variations of an electrical voltage, and the exploitation
means are arranged so as to activate the alarm when said cyclic
variations of voltage cease for a time which exceeds a threshold
estimated as dangerous or having a form differing excessively from
a form considered as normal.
It is a particular object of the invention to improve the fidelity
and reliability of transducers of the type concerned.
GENERAL DESCRIPTION OF THE INVENTION
To this end, composite sheets of the above type are essentially
characterized in that they comprise, between the sensitive foil and
one of the protective foils, separating shims of which the two
opposite surfaces are glued respectively to the two adjacent facing
areas.
In preferred embodiments, recourse is had in addition to one and/or
the other of the following features:
in the case where the sensitive foil is permanently electrically
charged and creates an external electrical field, the shims are
directly interposed between this sensitive foil and one of the two
electrodes, which forms chambers bounded by this electrode, this
sensitive foil and these shims,
in the case where the sensitive foil is a permanently electrically
polarized piezo-electrical foil and interposed contiguously between
the two electrodes, the shims are directly interposed between one
of these electrodes and the corresponding external protective foil,
which forms chambers bounded by this electrode, this protective
foil and these shims,
the shims are made self-adhesive on their two surfaces,
the areas to which the shims are glued are previously treated so as
to facilitate this adhesion, notably by electronic or ionic
bombardment, or again by the deposition of a thin layer of a
material, such as chromium, offering a good grip to the glues,
the shims are constituted by a grid,
the shims are constituted by a perforated continuous foil,
the shims are constituted by parallel strips,
the shims are constituted by spaced studs,
the shims have a thickness comprised between 0.1 and 1 mm, a width
comprised between 1 and 10 mm and a mutual spacing comprised
between 5 and 100 mm,
the composite sheet constitutes a rectangular undersheet for
nurslings of which one of the sides is comprised between 10 and 30
cm and the other side between 20 and 50 cm.
The invention comprises, apart from these main features, certain
other features which are preferably used at the same time and which
will be more explicitly considered below.
In the following, two preferred embodiments of the invention will
be described with reference to the accompanying drawings, given, of
course, as non-limiting Examples.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 of these drawings, shows in perspective view, with portions
broken away, one embodiment of a draw-sheet constructed according
to the invention.
FIG. 2 shows on a larger scale, in cross-section, a portion of this
draw-sheet.
FIG. 3 shows on a still larger scale, in cross-section, a detail of
said portion.
FIG. 4 shows similarly to FIG. 2 a modification of a portion of a
draw-sheet also according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Included in the pad or draw-sheet A is a dielectric foil 1
interposed between two foils, films or elecrically conducting
layers 2 and 3, denoted below by the word "electrodes".
The foil 1 is selected so that it is "sensitive" in the sense of
electromechanical transduction, that is to say that it is capable
of converting the pressure variations applied locally to it into
variations of the electrical voltage collected at the terminals of
the two electrodes 2 and 3.
To this end, foil 1 is advantageously constituted of a plastics
material such as polypropylene, P.T.F.E., poly(fluorinated
ethylene-propylene) or again a polymer or copolymer based on
polyvinylidene fluoride, its thickness being preferably comprised
between 5 and 50 microns.
This foil 1 is permanently electrically polarized or is permanently
electrically charged at least in the vicinity of 1.sub.1 of its
surfaces, by positive and/or negative charges which are shown
diagrammatically by the sign--in FIG. 2.
In the latter case (permanent electrical charge), the foil 1
creates an external electrical field and it is kept separated, at
least in part, from one of the electrodes 3 by insulating gaps, as
is visible in FIG. 2.
In the other case (permanent electrical polarization), shown
diagrammatically in FIG. 4, the foil 1 possesses piezo-electrical
properties and it is contiguously enveloped by the two electrodes 2
and 3.
Each of the electrodes 2 and 3 is advantageously constituted by
surface metallization of a foil of plastics material.
In the case of the charged sensitive foil (FIG. 2), one 2 of these
electrodes is attached to this foil 1 whilst the other electrode 3,
held slightly separated from said foil 1 by any desirable means, is
attached to an additional plastics foil 4.
In the case of the polarized sensitive foil 1 (FIG. 4), the two
electrodes 2 and 3 are attached respectively to the two surfaces of
this foil 1.
The assembly of the three foils 1, 2 and 3 is itself positioned
between two external protective foils 5 and 6, whose thickness is
advantageously comprised between 0.1 and 0.5 mm, constituted of an
electrically insulating flexible material.
These protective foils 5 and 6 extend beyond the assembly of the
three foils 1, 2 and 3 and their projecting margins 7 and 8 (FIG.
1) are assembled against one another so as to provide a seal with
respect to impurities, notably by gluing or heat welding.
The draw-sheet A, formed by the flexible sheet composed of the
superposed foils 1, 2, 3, 5 and 6, has the general shape of a
rectangle whose sides measure repectively between 10 and 30 cm and
between 20 and 50 cm when used as a draw-sheet for nurslings.
Each of the electrodes 2 and 3 is connected by means of leads 9 and
10 to a suitable exploitation or output unit 11--advantageously of
an electronic type with C-MOS circuits--adapted to activate a
sound, visual or the like alarm device 12.
For the application of the pad or draw-sheet A concerned with the
detection of apnea of a subject resting of this draw-sheet, the
activation of the warning system 12 is automatically ensured when
the oscillations, of the voltage between the electrodes 2 and 3,
due to the normal respiration of said subject, are interruped for a
period longer than a predetemined threshold, which can be adjusted
at will and can be equal, for example, to 10 or 30 seconds or have
a form departing to an excessive extent from a form considered as
normal.
There is provided, in addition, according to the invention, a
plurality of separating shims 13 interposed between the sensitive
foil 1 and one, 6, of the outer protective foils, the two opposite
surfaces of the shims being glued respectively to the areas of foil
against which they are juxtaposed.
The shims 13 concerned may be formed of any desirable shapes and
materials.
They can be in the form of grids or trellises formed from flat
crossed elements united preferably at their crossing points so as
not to create local overthicknesses, or again in the form of a
perforated continuous foil, or in that of parallel flat strips, or
of spaced flat studs, of square, rectangular, circular of the like
cross-section.
Their constituent material may be insulating or electrically
conducting: it is then selected so that the shims do not run the
risk of tearing the flexible foils against which they are
glued.
With this same aim of avoiding such tears, it will be advantageous
in certain cases to avoid too sharp edges or points on the
shims.
The dimensions of these shims 13, considered in a plane
perpendicular to that of the composite sheet such as that in which
FIG. 3 is traced, are preferably comprised
between 0.1 and 1 mm for the thickness,
between 1 and 10 mm for the width,
and between 5 and 100 mm for the mutual spacing.
The gluing of the shims 13 against the facing foil areas is ensured
by means of a thin layer of adhesive material 14.
Such a layer is advantageously applied in advance on each shim 13
surface, for example by spraying, so that the positioning of these
shims may be very easily effected by self-adhesion.
In view of their very slight thicknesses, for example of the order
of some tenths of microns, the electrodes 2, 3 and adhesive layers
14 have been represented by thick lines in FIG. 2 and 4: FIG. 3 on
a larger scale enables them to be seen best.
To facilitate the gluing of the shims 13 to the facing foil areas,
it may be advantageous to treat these areas previously, notably by
electronic or ionic (electrical discharge) bombardment, or again by
local deposition (under vacuum or otherwise) of a thin layer of a
material, such as chromium, offering good compatibility with the
glues.
In the first embodiment relating to the use of a charged sensitive
foil 1, which has been illustrated in FIGS. 2 and 3, the shims 13
are directly inserted between the charged surface 1.sub.1 of this
foil and the facing electrode 3: it is these shims which hold
surface 1.sub.1 spaced from the electrode 3 and bound between them
well defined chambers or compartments 15.
In the second embodiment relating to the use of a polarised
piezoelectric foil 1, which has been illustrated in FIG. 4, the
shims 13 are interposed directly between one, 3, of the electrodes
attached against this foil 1 and the corresponding protective foil
6, again defining between these elements well defined chambers or
compartments 16.
In each case, the double gluing of the shims according to the
invention ensures a particularly accurate operation of the
transducer:
in the first case, it is certain that the variations of the
distance between the charged surface 1.sub.1 and the facing
electrode 3 are due exclusively to the deformations, of this
electret and/or of this electrode, which develope at the level of
the different compartments 15 defined between successive shims: in
other words, there is no question here that the individual
distortions exploited for monitoring purposes involve surface
portions, of the composite sheet, covering pluralities of
neighbouring shims, even variable numbers of such shims, as would
be the case if there were a possiblity of ungluing between these
shims and the areas of the foil against which they are
juxtaposed;
in the second case, the pressure variations exerted locally on the
foil 1 are manifested by elastically reversible depressions of the
portions, of this foil, positioned opposite the compartments 16,
within these compartments, which lengthens, and hence thins these
portions: it is especially these reversible thinnings which are
converted into electrical variations exploited for monitoring
purposes; due to the gluing concerned, said thinnings correspond
only the depressions indicated whereas an absence of gluing of the
shims would make possible slippages of the foil along these shims,
able to denature the characteristics of these depressions.
As is itself evident, and as emerges besides from the foregoing,
the invention is in no way limited to those of its methods of
application and embodiments which have been more especially
contemplated; it encompasses, on the contrary, all
modifications.
In particular, the spacing shims could be formed by molding with
one of the foils against which they are intended to be glued,
constituting, for example, projecting ribs on the inner surface in
FIG. 4.
In the same way, the spacing shims could be arranged so as to
permit a flow of air on the outside of the composite sheet to the
cavities 15 and in the reverse direction.
Similarly, any one of the two composite structures described above
could be double:
it would be possible for this purpose to let comprise in common the
electrode 3 of FIG. 2 by two structures of the type illustrated in
said FIG. 2 and to apply symetrically two shim-electret-other
electrode-protective foil assemblies to respectively the two
surfaces of this electrode 3, the latter then being itself
splitable and constituted by metallisation of the two surfaces of
the additional foil 4,
it would also be possible to apply to each of the surfaces of the
shims 13 of FIG. 4 the assembly of a foil 1 metallised on its two
surfaces and coated externally with a protective sheet.
In each of these two latter modifications, the two outer electrodes
of the "doubled" structure obtained may be connected together and
constitute an electrostatic shielding for the composite sheet.
In another modification, the various layers of the composite sheet
may be constituted of transparent materials, so that the composite
sheet is itself transparent.
In another modification, the electrodes 2 and 3 are divided into
several electrically disjointed areas, so as to permit localisation
on the composite sheet of the region which is deformed and where
the pressure is exerted.
* * * * *