US 10,757,510 B2Granted

High performance sealed-gap capacitive microphone with various gap geometries

OwnerHayrettin Koymen, Abdullah Atalar +3inventors

InventorsHayrettin Koymen, Abdullah Atalar, Akif Sinan Tasdelen, Mehmet Yilmaz, Itir Koymen

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Abstract

Some preferred embodiments include a microphone system for receiving sound waves, the microphone including a back plate, a radiation plate, first and second electrodes, first and second insulator layers, a power source and a microphone controller. The radiation plate is clamped to the back plate so that there is a hermetically sealed regular convex polygon-, ellipse-, or regular convex elliptic polygon-shaped gap between the radiation plate and the back plate. The first electrode is fixedly attached to a side of the back plate proximate to the gap. The second electrode is fixedly attached to a side of the radiation plate. The insulator layers are attached to the back plate and/or the radiation plate, on respective gap sides thereof, so that the insulator layers are between the electrodes. The microphone controller is configured to use the power source to drive the microphone at a selected operating point comprising normalized static mechanical force, bias voltage, and relative bias voltage level. Relevant dimensions of the gap, and a thickness of the radiation plate, are determined using the selected operating point so that a sensitivity of the microphone at the selected operating point is an optimum sensitivity for the selected operating point.

Claims40

Dependent claims

A microphone system for receiving sound waves, the microphone system comprising:

a back plate;
a radiation plate having a thickness tm, the radiation plate clamped to the back plate so that there is a sealed gap between the radiation plate and the back plate such that passage of gas into or out of the gap is prevented, the gap having a regular convex polygon shape and a gap height tg;
the gap having a regular convex polygon shape with a number n≥4 sides, the gap having an apothem of length rn;
a first electrode, either the first electrode being fixedly coupled to a side of the back plate proximate to the gap, or the first electrode comprising or contained within the back plate;
a second electrode, either the second electrode being fixedly coupled to a side of the radiation plate, or the first electrode comprising or contained within the radiation plate;
a first insulator layer of thickness ti1 and relative permittivity εr_i1, and a second insulator layer of thickness ti2 and relative permittivity εr_i2, the first and second insulator layers being disposed between the first and second electrodes, and the first and second insulator layers being disposed between the back plate and the radiation plate;
a power source;
and
a microphone controller configured to use the power source to drive the microphone at an operating point, wherein FPeb is a net static force exerted on the radiation plate due to an ambient static pressure, FPeg is a uniformly distributed force required to displace a center of the radiation plate by an effective gap height tge, and VC is a limit to bias voltage VDC for uncollapsed operation of the microphone system, the operating point comprising:
a normalized static mechanical force FPeb/FPeg, a bias voltage of the first and second electrodes VDC, and a relative bias voltage level of the first and second electrodes VDC/VC;
wherein
t
ge
=
t
g
+
t
i
⁢
⁢
1
ɛ
r
⁢
⁢
_
⁢
⁢
i
⁢
⁢
1
+
t
i
⁢
⁢
2
ɛ
r
⁢
⁢
_
⁢
⁢
i
⁢
⁢
2
;
wherein the apothem length rn, the gap height tg, and the radiation plate thickness tm are determined using the selected operating point so that an OCRV sensitivity of the microphone at the selected operating point is an optimum OCRV sensitivity for the selected operating point;
and
wherein the equivalent disc gap radius aeq is related to a minimum equivalent disc gap radius aeq_min corresponding to the optimum sensitivity at the operating point, and the radiation plate thickness tm is related to a minimum radiation plate thickness tm_min corresponding to the optimum sensitivity at the operating point, by a selected scaling constant K, such that aeq(K3)aeq_min, and tm=(K4)tm_min.

51 more elements

A microphone system for receiving sound waves, the microphone system comprising:

a back plate;
a radiation plate having a thickness tm, the radiation plate clamped to the back plate so that there is a sealed gap between the radiation plate and the back plate such that passage of gas into or out of the gap is prevented, the gap having an elliptic shape with minor radius a1 and major radius a2 and a gap height tg;
a first electrode, either the first electrode being fixedly coupled to a side of the back plate proximate to the gap, or the first electrode comprising or contained within the back plate;
a second electrode, either the second electrode being fixedly coupled to a side of the radiation plate, or the first electrode comprising or contained within the radiation plate;
a first insulator layer of thickness ti1 and relative permittivity εr_i1, and a second insulator layer of thickness ti2 and relative permittivity εr_i2, the first and second insulator layers being disposed between the first and second electrodes, and the first and second insulator layers being disposed between the back plate and the radiation plate;
a power source;
and
a microphone controller configured to use the power source to drive the microphone at an operating point, wherein FPeb is a net static force exerted on the radiation plate due to an ambient static pressure, FPeg is a uniformly distributed force required to displace a center of the radiation plate by an effective gap height tge, and VC is a limit to bias voltage VDC for uncollapsed operation of the microphone system, the operating point comprising:
a normalized static mechanical force FPeb/FPeg, a bias voltage of the first and second electrodes VDC, and a relative bias voltage level of the first and second electrodes VDC/VC;
wherein
t
ge
=
t
g
+
t
i
⁢
⁢
1
ɛ
r
⁢
⁢
_
⁢
⁢
i
⁢
⁢
1
+
t
i
⁢
⁢
2
ɛ
r
⁢
⁢
_
⁢
⁢
i
⁢
⁢
2
;
wherein the pair elliptic gap minor radius a1 and elliptic gap major radius a2, the gap height tg, and the radiation plate thickness tm are determined using the selected operating point so that an OCRV sensitivity of the microphone at the selected operating point is an optimum OCRV sensitivity for the selected operating point;
and
wherein a is a radius of a seed circle of the elliptic shaped gap, and ρe is an aspect ratio of the elliptic shaped gap, and the seed circle radius a is related to a minimum gap radius amin corresponding to the optimum sensitivity at the operating point, and the radiation plate thickness tin is related to a minimum radiation plate thickness tm_min corresponding to the optimum sensitivity at the operating point, by a selected scaling constant K, such that a=(K3)amin, and tm=(K4)tm_min,
where
a
2
=
a
⁡
(
1
8
⁢
(
3
⁢
ρ
e
4
+
2
⁢
⁢
ρ
e
2
+
3
)
4
)
⁢
and
a
1
=
a
⁡
(
1
ρ
e
⁢
1
8
⁢
(
3
⁢
⁢
ρ
e
4
+
2
⁢
⁢
ρ
e
2
+
3
)
4
)
.

113 more elements

A microphone system for receiving sound waves, the microphone system comprising:

a back plate;
a radiation plate having a thickness tm, the radiation plate clamped to the back plate so that there is a sealed gap between the radiation plate and the back plate such that passage of gas into or out of the gap is prevented;
the gap having an elliptic polygon shape with a number n≥4 sides and a gap height tg, the elliptic polygon shaped gap having a minor apothem of length rn1 and a major apothem of length rn2, an equivalent ellipse of the elliptic polygon shaped gap having a minor radius ae1 and a major radius ae2 such that:
a
eq
⁢
⁢
1
=
r
n
⁢
⁢
1
⁢
n
π
⁢
tan
⁢
⁢
(
π
n
)
4
,
and
a
eq
⁢
⁢
2
=
r
n
⁢
⁢
2
⁢
n
π
⁢
tan
⁢
⁢
(
π
n
)
4
;
a first electrode, either the first electrode being fixedly coupled to a side of the back plate proximate to the gap, or the first electrode comprising or contained within the back plate;
a second electrode, either the second electrode being fixedly coupled to a side of the radiation plate, or the first electrode comprising or contained within the radiation plate;
a first insulator layer of thickness ti1 and relative permittivity εr_i1, and a second insulator layer of thickness ti2 and relative permittivity εr_i2, the first and second insulator layers being disposed between the first and second electrodes, and the first and second insulator layers being disposed between the back plate and the radiation plate;
a power source;
and
a microphone controller configured to use the power source to drive the microphone at an operating point, wherein FPeb is a net static force exerted on the radiation plate due to an ambient static pressure, FPeg is a uniformly distributed force required to displace a center of the radiation plate by an effective gap height tge, and VC is a limit to bias voltage VDC for uncollapsed operation of the microphone system, the operating point comprising:
a normalized static mechanical force FPeb/FPeg, a bias voltage of the first and second electrodes VDC, and a relative bias voltage level of the first and second electrodes VDC/VC;
wherein
t
ge
=
t
g
+
t
i
⁢
⁢
1
ɛ
r
⁢
_
⁢
i
⁢
⁢
1
+
t
i
⁢
⁢
2
ɛ
r
⁢
_
⁢
i
⁢
⁢
2
;
wherein the minor apothem length rn1 and the major apothem length rn2, the gap height tg, and the radiation plate thickness tm are determined using the selected operating point so that an OCRV sensitivity of the microphone at the selected operating point is an optimum OCRV sensitivity for the selected operating point
wherein a is a radius of a seed circle of the equivalent ellipse, and ρe is the aspect ratio of said ellipse, and the seed circle radius a is related to a minimum gap radius amin corresponding to the optimum sensitivity at the operating point, and the radiation plate thickness tm is related to a minimum radiation plate thickness tm_min corresponding to the optimum sensitivity at the operating point, by a selected scaling constant K, such that a=(K3)amin, and tm=(K4)tm_min
where
a
eq
⁢
⁢
2
=
a
⁢
⁢
(
1
8
⁢
(
3
⁢
ρ
e
4
+
2
⁢
ρ
e
2
+
3
)
4
)
and
a
eq
⁢
⁢
1
=
a
⁢
⁢
(
1
ρ
e
⁢
1
8
⁢
(
3
⁢
ρ
e
4
+
2
⁢
ρ
e
2
+
3
)
4
)
.

162 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/241,164Filed 7 Jan 2019 · us provisional application
Priority: 8 Jan 2018
Published: US 2020/0007992 A12 Jan 2020
Granted: 25 Aug 2020
Term ends: Not estimatedThe source records don’t support an estimate.