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EP 2 207 190 B9 |
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CORRECTED EUROPEAN PATENT SPECIFICATION |
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Note: Bibliography reflects the latest situation |
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Correction information: |
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Corrected version no 1 (W1 B1) |
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Corrections, see Claims DE |
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Corrigendum issued on: |
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24.09.2014 Bulletin 2014/39 |
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Mention of the grant of the patent: |
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04.06.2014 Bulletin 2014/23 |
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Date of filing: 08.01.2009 |
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International Patent Classification (IPC):
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Resilient device
Gefederte Vorrichtung
Dispositif élastique
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Designated Contracting States: |
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DE |
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Date of publication of application: |
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14.07.2010 Bulletin 2010/28 |
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Proprietor: Epcos AG |
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81669 München (DE) |
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Inventors: |
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- Steeneken, Peter Gerard
5551 PW
Valkenswaard (NL)
- Bielen, Jeroen
6584 AK Molenhoek (NL)
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Representative: Epping - Hermann - Fischer |
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Patentanwaltsgesellschaft mbH
Schloßschmidstraße 5 80639 München 80639 München (DE) |
| (56) |
References cited: :
US-A1- 2003 042 117
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US-B1- 6 360 035
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| Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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Field of the invention
[0001] The present invention relates to perpendicularly moving resilient devices for application
e.g. in MEMS devices.
Description of the related art
[0002] Conventional resilient devices (e.g. springs having a fixed cross-section) or spring
elements used in MEMS devices can suffer from high stress levels being restricted
to small areas of such devices. As a result, these high-stress areas often form the
geometrical starting point for later failure.
[0003] Therefore, what is needed is a resilient device with improved geometrical shape to
reduce the maximum stress level and that is less prone to failure due to e.g. plastic
deformation, fatigue, or mechanical overstraining in general.
[0004] The document "
US 2003/042117 A1" discloses a resilient device according to the preamble of claim 1.
Summary of the invention
[0005] The present invention provides a resilient device of length L, variable width w(x)
and variable thickness t(x) comprising a first longitudinal section of length l1 having
an area moment of inertia I(0 <= x <= l1) and having a first distal end at x = 0,
a second longitudinal section of length l2 having a constant area moment of inertia
I(l1 < x <= l1 + l2) and being attached to the first longitudinal section, a third
longitudinal section of length l3 having an area moment of inertia I(l1 + l2 < x <=
l1 + l2 + l3) and being attached to the second longitudinal section and having a second
distal end at x = L, where the area moment of inertia of the first longitudinal section
decreases monotonically from x = 0 to x = l1, the area moment of inertia of the third
longitudinal section increases monotonically from x = l1 + l2 to x = l1 + l2 + l3.
Here, x denotes the position along a longitudinal axis of the resilient device and
l1 + l2 + l3 equals the total length L of the resilient device, and x, l1, l2, l3,
L, w and t are real numbers larger than zero. It has to be clarified that the resilient
device is restricted to follow a curved path i.e. trajectory. Then x refers to the
linear position along the trajectory.
[0006] The area moment of inertia I
x of a straight beam following the x-axis is defined as:

where dA denotes an differential elemental area and y denotes the perpendicular distance
from the x-axis to the element dA. Each short section of a resilient device following
a curved trajectory can locally be approximated as a section of a straight beam. As
the tendency to kink for a perpendicularly moving resilient device does not directly
depend on the geometrical details of such a device but only to the area moment of
inertia I, there are degrees of freedom to design the geometrical details of a resilient
device while restricting the area moment of inertia to a desired value.
[0007] Here the wording monotonically decreasing / increasing means that the first or the
third longitudinal section may comprise subsections where the respective area moment
of inertia is constant.
[0008] In a preferred embodiment the area moment of inertia at least one of the first longitudinal
section and the third longitudinal section decreases/increases strictly monotonically
within its respective longitudinal section.
[0009] Furthermore combinations of subsection of monotonical and strictly monotonical decrease
/ increase within each respective section are possible.
[0010] In another preferred embodiment of the present invention, the resilient device's
cross-section has at every longitudinal position x a mainly rectangular shape. Then
the cross-sectional area is the product of the width w and the thickness t. Such shaped
devices make it easy to calculate the ratio of width w and thickness t in order to
get the desired area moment of inertia. To be more precise, the area moment of inertia
is then:

[0011] In order to further avoid local high-stress areas at the edges of a resilient device,
it is preferred that the resilient device comprises chamfered lateral edges.
[0012] It is further preferred to keep the thickness t of the resilient device constant
over the whole device. If the shape of the cross section is kept constant the width
w of the device is the only adjustable parameter. Having a constant thickness is preferred
because it simplifies the manufacturing process, especially in the case of MEMS devices.
[0013] It is further preferred that the area moment of inertia decreases linearly within
the first longitudinal section and increases linearly within the third longitudinal
section. As the tendency to kink is proportional to the length of the effective lever
and reciprocal to the area moment of inertia, such a resilient device's tendency to
kink keeps nearly constant over its longitudinal axis at an approximately constant
stress level.
[0014] In another preferred embodiment, the resilient device is stiffly connected with one
of its distal ends to an anchor element. Such a resilient device can be part of a
MEMS device.
[0015] When the resilient device is part of a MEMS device, it is preferred that one of its
distal ends is connected to a movable element. The other end can be connected to an
anchor element. Whether the resilient device has a constant thickness or not, the
width w can vary from 25% to 100% of the maximum width in the first and in the third
longitudinal section. In a preferred physical embodiment the width w can vary from
15 to 60 µm in the first and in the third longitudinal section. In another preferred
embodiment, the width can vary in the first and in the third section from 20 to 40
µm. The length of the second longitudinal section can be zero. Then the first and
the third longitudinal section are attached to each other directly. In another preferred
embodiment, the width of the resilient device does not extend below 40% of the maximum
width over the whole length of the device.
[0016] The resilient device can comprise metal, especially an aluminum comprising alloy,
or an inorganic dielectric or a ceramic or it can comprise a plastic.
[0017] It is especially preferred that such a resilient device used in a MEMS device connects
a fixed external anchor element of the MEMS device with a suspension element of a
movable element. The movable element can have mainly rectangular or trapezoid shape,
can be a membrane of rectangular or trapezoid shape, and can have sharp or chamfered
corners or lateral edges.
[0018] In a preferred embodiment, four of such resilient devices are used in a MEMS device
comprising a mainly rectangular shaped movable element that is flexibly suspended
between two fixed external anchor elements by means of the four resilient devices,
wherein, on each of two opposing sides of the movable element, two of the resilient
devices are connected with one of their distal ends to a respective one of two sides
of a respective one of the anchor elements each. The respective other distal ends
of the resilient devices are then connected to respective suspension elements of the
movable element. The resilient devices not necessarily follow a straight path. They
also can follow an arbitrarily shaped trajectory as long as the area moment of inertia
follows the requirements at each point of the trajectory. The resilient device thus
can have a curved structure / shape although no lateral stress is applied, i.e. the
device is in its stand-by position.
[0019] Another preferred embodiment concerns a MEMS device comprising a trapezoid shaped
movable element being flexibly connected to two external anchor elements by means
of two resilient devices. Then, on each of two opposing non-parallel sides of the
movable element, one of the resilient devices is connected with one of its distal
ends to a respective anchor element while the respective other distal end of the respective
resilient device is connected to a suspension element of the movable elements.
[0020] Suspension elements of the movable elements can be realized by a special means for
mounting a resilient device to a movable element. Apart from that, the wording suspension
element can also just refer to a part of the movable element where the resilient device
is bound to.
Brief description of the drawings
[0021] The present invention will become fully understood from the detailed description
given herein below and the accompanying drawings. In the drawings,
- FIG. 1
- illustrates a resilient device comprising a first, a second and a third longitudinal
section,
- FIG. 2
- illustrates a top view on a known resilient device,
- FIG. 3
- shows a top view on a known resilient device consisting only of the first and the
third longitudinal section,
- FIG. 4
- illustrates a cross-sectional view on a resilient device consisting of the first and
the third longitudinal section, each with a non-linear increase or decrease in thickness,
- FIG. 5
- illustrates a cross-section of a resilient device having chamfered lateral edges,
- FIG. 6
- illustrates four known resilient devices being connected between anchor elements and
suspension elements of a movable element,
- FIG. 7
- illustrates four resilient devices having a curved trajectory and connecting a movable
element to anchor elements,
- FIG. 8
- illustrates an element of a MEMS device having a trapezoid movable element being suspended
by two resilient devices.
Detailed description
[0022] FIG. 1 illustrates a resilient device RD of length L having a first longitudinal
section LS1, a second longitudinal section LS2 of constant width and thickness, and
a third longitudinal section LS3. The beginning of the first longitudinal section
LS1 and the end of the third longitudinal section LS3 mark the distal ends DE of the
resilient device RD. The width w of the first longitudinal section LS1 decreases strictly
monotonically while the width of the third longitudinal section increases strictly
monotonically. The thickness t is constant over the total length L.
[0023] FIG. 2 illustrates a top view of a resilient device comprising a first longitudinal
section LS1 having length l1 and a second longitudinal section LS2 of constant width
w having length l2 and a third longitudinal section LS3 of length l3. The total length
of the resilient device L equals the sum l1 + l2 + l3 of the lengths of the first,
second and third longitudinal sections. In this embodiment, the width of the first
longitudinal section LS1 decreases linearly with increasing position x and the width
of the third longitudinal section LS3 increases linearly with increasing position
x.
[0024] FIG. 3 illustrates a resilient device comprising only the first longitudinal section
LS1 and the third longitudinal section LS3, i.e. the length of the second longitudinal
section equals zero. Analog to FIG. 2, the width w decreases linearly in longitudinal
section LS1 and increases linearly in longitudinal section LS3. Here, the total length
of the resilient device equals the sum of the lengths l1 + l3 of the first LS1 and
the third LS3 longitudinal section.
[0025] In the following figures, an assumption is made that the resilient device extends
towards the x-direction while the width extends towards the y-direction and the thickness
extends towards the z-direction of a Cartesian coordinate system.
[0026] FIG. 4 illustrates a cross-section being parallel to the x-axis of the resilient
device comprising a first longitudinal section LS1 and a third longitudinal section
LS3 where the thickness t decreases not linearly with increasing x and the thickness
t increases not linearly with increasing x in longitudinal section LS3 (thickness).
[0027] FIG. 5 illustrates a cross-sectional view of a resilient device showing a cross-section
parallel to the yz-plain having a mainly or rectangular cross-section with chamfered
longitudinal edges CLE and having thickness t and width w. The dotted line indicates
the strict rectangular shape while the continuously curved line indicates the deviation
from the strict rectangular shape i.e. it indicates a shape with chamfered lateral
edges. As the deviation may be sufficiently small a person skilled in the art will
recognize that the cross section can still be regarded as a rectangular cross section.
[0028] FIG. 6 illustrates a structure that may be part of a MEMS device comprising two anchor
elements AE, a movable element ME, that may be a membrane M, four suspension elements
SE, two of them mounted to a first side, the other two mounted to the opposite side
of the movable element ME. Four resilient devices RD connect suspension SE elements
to anchor elements AE. On each of the opposing sites of the movable element ME, two
resilient devices RD are connected with one of their distal ends DE to one of the
two suspension elements, and with their other distal end (DE) to one common anchor
element. As the distal ends of the resilient devices are supposed to be dislocated
parallel (or antiparallel) to the z-direction, the movable element can be dislocated
towards the positive side of the z-direction or the negative side or can be tilted,
i.e. one end of the movable element is moved towards the negative direction of the
z-axis and the other end of the movable element is moved towards the positive direction
of the z-axis. Analog, the movable element ME can also oscillate with elongations
towards the z-direction.
[0029] FIG. 7 illustrates a variation of the structure of FIG. 6 having four resilient devices
RD following not a straight path but a curved trajectory TR each. One distal end DE
of the resilient device RD is connected to one of two anchor elements AE while the
other distal end DE of the resilient device RD is connected to a movable element ME
at a suspension element SE. FIG. 7 shows four resilient devices RD. In the figure
however, for simplicities sake, notations are only made exemplarily for one resilient
device. The suspension element SE can be formed by one distal end DE of the resilient
device RD or the point where the distal end DE is mounted to the movable element ME.
In this case, the movable element and the resilient device are fabricated as one single
piece and/or in one common production step.
Especially when special requirements have to be fulfilled in view of highly stressed
connections between the resilient device and the movable element, then special enforcement
means can be applied to the connection point between the resilient device and the
movable element. This could, for example, be a special variation in thickness of the
movable element ME or of the resilient device at the denoted distal end DE.
[0030] FIG. 8 illustrates another embodiment where two resilient devices RD, having a curved
trajectory TR, connect non-parallel sides of a trapezoid movable element ME to two
anchor elements AE. When comparing FIG. 8 to FIG. 7, it can be seen that in FIG. 8
the resilient devices are directly mounted to an edge of the movable element, while
in FIG. 7, the resilient devices are not directly connected to the edge of the movable
element leaving a gap GP between the mounting area and the edge of the movable element
ME. Any of these two cases can be preferred in any of both structures. The size of
the gap GP depends on the modes of translation or torsion respectively of the movable
elements. When designing MEMS devices comprising resilient devices connecting movable
elements to anchor elements, the size of this gap gives the engineer another degree
of freedom. The engineer has the opportunity, for example, to influence the value
of a torque resulting at the suspension element, i.e. the area where the resilient
device is mounted to the movable element.
[0031] The present invention refers to resilient devices for perpendicular movement having
lower maximum stress levels. The basic concept does not depend on details concerning
geometric details of the resilient devices. Further, the invention is not restricted
by the embodiments or the accompanying figures. Alternative embodiments are also possible
according to the appended claims 1-15.
List of reference symbols:
[0032]
- AE:
- Anchor element
- CLE:
- Chamfered lateral edge
- CS:
- Cross section
- DE:
- Distal end
- GP:
- Gap
- L:
- length of RD
- LE:
- Lateral edge
- LS1:
- First longitudinal section
- LS2:
- Second longitudinal section
- LS3:
- Third longitudinal section
- M:
- membrane
- MD:
- MEMS device
- ME:
- Movable element
- RD:
- Resilient device
- SE:
- Suspension element
- t:
- thickness of RD
- TR:
- Trajectory
- w:
- width of RD
1. Resilient device (RD)
having a length L, a variable width w(x), and a variable thickness t(x), comprising
- a first longitudinal section (LS1) of length l1 having a area moment of inertia
I (0< = x < = l1) and having a first distal end (DE) at x = 0,
- a second longitudinal section (LS2) of length l2 having a constant area moment of
inertia I (l1 < x < = l1 + l2) and being attached to the first longitudinal section
(LS1),
- a third longitudinal section (LS3) of length l3 having a area moment of inertia
I (l1 + l2 < x < = l1 + l2 + l3) and being attached to the second longitudinal section
(LS2) and having a second distal end (DE) at x = L, where
- the area moment of inertia of the first longitudinal section (LS1) decreases monotonically
from x = 0 to x = l1,
- the area moment of inertia of the third longitudinal section (LS3) increases monotonically
from x = l1 + l2 to x = l1 + l2 + l3,
- l1 + l2 + l3 = L and x, l1, l2, l3, L, w and t are real numbers > 0,
characterized in that the resilient device follows a curved path along the length L and x refers to the
linear position along the path.
2. Resilient device of claim 1, wherein
- the area moment of inertia of the first longitudinal section (LS1) decreases strictly
monotonically from x = 0 to x = l1 or
- the area moment of inertia of the third longitudinal section (LS3) increases strictly
monotonically from x = l1 + l2 to x = l1 + l2 + l3.
3. Resilient device of one of claims 1 or 2, wherein at every longitudinal position x
the cross section (CS) has a rectangular shape of a cross sectional area a (x) = w(x)
*t (x).
4. Resilient device of one of claims 1 to 3, wherein the thickness t(x) is constant over
the whole device.
5. Resilient device of one of claims 1 to 4
wherein the area moment of inertia I(x) decreases linearly with increasing x in the
first longitudinal section (LS1) and increases linearly in the third longitudinal
section (LS3).
6. Resilient device of one of claims 1 to 5, having a distal end (DE) stiffly connected
to an anchor element (AE).
7. Resilient device of one of claims 1 to 6, the device being part of a MEMS-device (MD).
8. Resilient device of claim 7, having a distal end (DE) connected to a movable element
(ME) of the MEMS-device (MD).
9. Resilient device of one of claims 1 to 8, the width w(x) of which varying from 15
µm to 60 µm in the first (LS1) and third (LS3) longitudinal section.
10. Resilient device of one of claims 1 to 9, wherein the second longitudinal section
has a length l2 (LS2) equaling zero.
11. Resilient device of one of claims 1 to 10, whose width w(x) varies between 0.4*wmax and 1.0*wmax in the interval 0 < = x < = L wherein wmax is the maximum value of width w(x).
12. Resilient device of one of the claims 1 to 11, whose longitudinal sections (LS1, LS2,
LS3) comprise one of a metal, an inorganic dielectric, a ceramic, an Al containing
alloy and a plastic.
13. Resilient device of one of claims 1 to 12, for use in a MEMS device (MD), the resilient
device (RD) connecting a fixed external anchor element (AE) with a suspension element
(SE) of a movable element (ME).
14. MEMS device comprising a rectangular shaped movable element (ME) being flexibly suspended
between 2 fixed external anchor elements (AE) by means of 4 resilient devices (RD)
as described in claim 13, wherein, on each of two opposing sides of the moveable element
(ME), two of the resilient devices (RD) are connected with one of their distal ends
(DE) to a respective one of two sides of a respective one of the anchor elements (AE)
each, while the respective other distal ends of the resilient devices (RD) are connected
to a suspension element (SE) of the movable element (ME) each.
15. MEMS device comprising a trapezoid shaped movable element (ME) being flexibly connected
to two external anchor elements (AE) by means of two resilient devices (RD) as described
in claim 13, wherein, on each of two opposing non parallel sides of the moveable element
(ME), one of the resilient devices (RD) is connected
- with one of its distal ends (DE) to a suspension element (SE) at the respective
non parallel side of the movable element (ME) while
- the respective other distal end of the respective resilient device (RD) is connected
to a respective one of the anchor elements (AE).
1. Elastische Vorrichtung (RD)
mit einer Länge L, einer variablen Breite w(x) und einer variablen Dicke t(x), die
aufweist
- einen ersten Längsabschnitt (LS1) mit der Länge l1 mit einem Flächenträgheitsmoment
I (0 <= x <= l1) und mit einem ersten distalen Ende (DE) bei x = 0,
- einen zweiten Längsabschnitt (LS2) mit der Länge l2 mit einem konstanten Flächenträgheitsmoment
l (l1 < x <= l1 + l2), der am ersten Längsabschnitt (LS1) befestigt ist,
- einen dritten Längsabschnitt (LS3) mit der Länge l3 mit einem Flächenträgheitsmoment
l (l1 + l2 < x <= l1 + l2 + l3), der am zweiten Längsabschnitt (LS2) befestigt ist
und ein zweites distales Ende (DE) bei x = L aufweist, wobei
- das Flächenträgheitsmoment des ersten Längsabschnitts (LS1) von x = 0 bis x = l1
monoton abnimmt,
- das Flächenträgheitsmoment des dritten Längsabschnitts (LS3) von x = l1 + l2 bis
x = l1 + l2 + l3 monoton zunimmt,
- l1 + l2 + l3 = L und x, l1, l2, l3, L, w und t reelle Zahlen > 0 sind,
dadurch gekennzeichnet, dass die elastische Vorrichtung einem gekrümmten Weg entlang der Länge L folgt und x sich
auf die lineare Position entlang des Weges bezieht.
2. Elastische Vorrichtung nach Anspruch 1, wobei
- das Flächenträgheitsmoment des ersten Längsabschnitts (LS1) von x = 0 bis x = l1
streng monoton abnimmt, oder
- das Flächenträgheitsmoment des dritten Längsabschnitts (LS3) von x = l1 + l2 bis
x = l1 + l2 + l3 streng monoton zunimmt.
3. Elastische Vorrichtung nach einem der Ansprüche 1 oder 2, wobei in jeder Längsposition
x der Querschnitt (CS) eine rechteckige Form mit einer Querschnittsfläche a(x) = w(x)
*t (x) aufweist.
4. Elastische Vorrichtung nach einem der Ansprüche 1 bis 3, wobei die Dicke t(x) über
die ganze Vorrichtung konstant ist.
5. Elastische Vorrichtung nach einem der Ansprüche 1 bis 4, wobei das Flächenträgheitsmoment
I(x) mit zunehmendem x im ersten Längsabschnitt (LS1) linear abnimmt und im dritten
Längsabschnitt (LS3) linear zunimmt.
6. Elastische Vorrichtung nach einem der Ansprüche 1 bis 5 mit einem distalen Ende (DE),
das mit einem Verankerungselement (AE) steif verbunden ist.
7. Elastische Vorrichtung nach einem der Ansprüche 1 bis 6, wobei die Vorrichtung ein
Teil einer MEMS-Vorrichtung (MD) ist.
8. Elastische Vorrichtung nach Anspruch 7 mit einem distalen Ende (DE), das mit einem
beweglichen Element (ME) der MEMS-Vorrichtung (MD) verbunden ist.
9. Elastische Vorrichtung nach einem der Ansprüche 1 bis 8, deren Breite w(x) von 15
µm bis 60 µm im ersten (LS1) und im dritten (LS3) Längsabschnitt variiert.
10. Elastische Vorrichtung nach einem der Ansprüche 1 bis 9, wobei der zweite Längsabschnitt
eine Länge l2 (LS2) aufweist, die gleich null ist.
11. Elastische Vorrichtung nach einem der Ansprüche 1 bis 10, deren Breite w(x) zwischen
0, 4*wmax und 1,0*wmax im Intervall 0 <= x <= L variiert, wobei wmax der maximale Wert der Breite w(x) ist.
12. Elastische Vorrichtung nach einem der Ansprüche 1 bis 11, deren Längsabschnitte (LS1,
LS2, LS3) eines von einem Metall, einem anorganischen Dielektrikum, einer Keramik,
einer Al enthaltenden Legierung und einem Kunststoff aufweisen.
13. Elastische Vorrichtung nach einem der Ansprüche 1 bis 12 zur Verwendung in einer MEMS-Vorrichtung
(MD), wobei die elastische Vorrichtung (RD) ein festes äußeres Verankerungselement
(AE) mit einem Aufhängungselement (SE) eines beweglichen Elements (ME) verbindet.
14. MEMS-Vorrichtung mit einem rechteckförmigen beweglichen Element (ME), das zwischen
2 festen äußeren Verankerungselementen (AE) mittels 4 elastischer Vorrichtungen (RD),
wie in Anspruch 13 beschrieben, flexibel aufgehängt ist, wobei auf jeder von zwei
entgegengesetzten Seiten des beweglichen Elements (ME) zwei der elastischen Vorrichtungen
(RD) mit einem ihrer distalen Enden (DE) jeweils mit einer jeweiligen von zwei Seiten
eines jeweiligen der Verankerungselemente (AE) verbunden sind, während die jeweiligen
anderen distalen Enden der elastischen Vorrichtungen (RD) jeweils mit einem Aufhängungselement
(SE) des beweglichen Elements (ME) verbunden sind.
15. MEMS-Vorrichtung mit einem trapezförmigen beweglichen Element (ME), das mit zwei äußeren
Verankerungselementen (AE) mittels zwei elastischer Vorrichtungen (RD), wie in Anspruch
13 beschrieben, flexibel verbunden ist, wobei auf jeder von zwei entgegengesetzten
nicht parallelen Seiten des beweglichen Elements (ME) eine der elastischen Vorrichtungen
(RD)
- mit einem ihrer distalen Enden (DE) mit einem Aufhängungselement (SE) an der jeweiligen
nicht parallelen Seite des beweglichen Elements (ME) verbunden ist, während
- das jeweilige andere distale Ende der jeweiligen elastischen Vorrichtung (RD) mit
einem jeweiligen der Verankerungselemente (AE) verbunden ist.
1. Dispositif élastique (RD)
ayant une longueur L, une largeur variable w(x) et une épaisseur variable t(x), comprenant
- une première section longitudinale (LS1) de longueur l1 ayant un moment quadratique
I (0<= x <= l1) et ayant une première extrémité distale (DE) à x = 0,
- une deuxième section longitudinale (LS2) de longueur l2 ayant un moment quadratique
constant I (l1 < x <= l1 + l2) et attachée à la première section longitudinale (LS1),
- une troisième section longitudinale (LS3) de longueur l3 ayant un moment quadratique
I (l1 + l2 < x <= l1 + l2 + l3) et attachée à la deuxième section longitudinale (LS2)
et ayant une deuxième extrémité distale (DE) à x = L,
- le moment quadratique de la première section longitudinale (LS1) diminuant de manière
monotone à partir de x = 0 jusqu'à x = l1,
- le moment quadratique de la troisième section longitudinale (LS3) augmentant de
manière monotone à partir de x = l1 + l2 jusqu'à x = l1 + l2 + l3,
- l1 + l2 + l3 = L et x, l1, l2, l3, L, w et t étant des nombres réels > 0,
caractérisé en ce que le dispositif élastique suit un trajet incurvé le long de la longueur L et x désigne
la position linéaire le long du trajet.
2. Dispositif élastique selon la revendication 1, dans lequel
- le moment quadratique de la première section longitudinale (LS1) diminue de manière
strictement monotone à partir de x = 0 jusqu'à x = l1 ou
- le moment quadratique de la troisième section longitudinale (LS3) augmente de manière
strictement monotone à partir de x = l1 + l2 jusqu'à x = l1 + l2 + l3.
3. Dispositif élastique selon l'une des revendications 1 et 2, dans lequel, à chaque
position longitudinale x, la section transversale (CS) présente une forme rectangulaire
d'aire en section transversale a(x) = w(x)*t(x).
4. Dispositif élastique selon l'une des revendications 1 à 3, dans lequel l'épaisseur
t(x) est constante sur l'ensemble du dispositif.
5. Dispositif élastique selon l'une des revendications 1 à 4, dans lequel le moment quadratique
I(x) diminue de manière linéaire lorsque x augmente dans la première section longitudinale
(LS1) et augmente de manière linéaire dans la troisième section longitudinale (LS3).
6. Dispositif élastique selon l'une des revendications 1 à 5, ayant une extrémité distale
(DE) reliée rigidement à un élément d'ancrage (AE).
7. Dispositif élastique selon l'une des revendications 1 à 6, le dispositif faisant partie
d'un dispositif MEMS (MD).
8. Dispositif élastique selon la revendication 7, ayant une extrémité distale (DE) reliée
à un élément mobile (ME) du dispositif MEMS (MD).
9. Dispositif élastique selon l'une des revendications 1 à 8, dont la largeur w(x) varie
de 15 µm à 60 µm dans la première (LS1) et la troisième (LS3) section longitudinale.
10. Dispositif élastique selon l'une des revendications 1 à 9, dans lequel la deuxième
section longitudinale a une longueur l2 (LS2) égale à zéro.
11. Dispositif élastique selon l'une des revendications 1 à 10, dont la largeur w(x) varie
entre 0 ,4 *wmax et 1,0*wmax dans l'intervalle 0 <= x <= L, wmax étant la valeur maximale de la largeur w(x).
12. Dispositif élastique selon l'une des revendications 1 à 11, dont les sections longitudinales
(LS1, LS2, LS3) comprennent l'un parmi un métal, un diélectrique inorganique, une
céramique, un alliage contenant de l'aluminium, et un plastique.
13. Dispositif élastique selon l'une des revendications 1 à 12, destiné à être utilisé
dans un dispositif MEMS (MD), le dispositif élastique (RD) reliant un élément d'ancrage
externe fixe (AE) à un élément de suspension (SE) d'un élément mobile (ME).
14. Dispositif MEMS comprenant un élément mobile (ME) de forme rectangulaire suspendu
de manière flexible entre 2 éléments d'ancrage externes fixes (AE) au moyen de 4 dispositifs
élastiques (RD) tels que décrits dans la revendication 13, dans lequel, sur chacun
de deux côtés opposés de l'élément mobile (ME), deux des dispositifs élastiques (RD)
sont reliés chacun par l'une de leurs extrémités distales (DE) à un côté respectif
des deux côtés d'un élément d'ancrage respectif parmi les éléments d'ancrage (AE),
tandis que les autres extrémités distales respectives des dispositifs élastiques (RD)
sont reliées chacune à un élément de suspension (SE) de l'élément mobile (ME).
15. Dispositif MEMS comprenant un élément mobile (ME) de forme trapézoïdale relié de manière
flexible à deux éléments d'ancrage externes (AE) au moyen de deux dispositifs élastiques
(RD) tels que décrits dans la revendication 13, dans lequel, sur chacun de deux côtés
opposés non parallèles de l'élément mobile (ME), l'un des dispositifs élastiques (RD)
est relié
- par l'une de ses extrémités distales (DE) à un élément de suspension (SE) au niveau
du côté non parallèle respectif de l'élément mobile (ME) tandis que
- l'autre extrémité distale respective du dispositif élastique (RD) respectif est
reliée à un élément d'ancrage respectif parmi les éléments d'ancrage (AE).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description