Electroactive sound transducer foil having a structured surface

Patent metadata

Field	Value
Publication number	US-9832572-B2
Application number	US-201414553489-A
Country	US
Kind code	B2
Filing date	Nov 25, 2014
Priority date	Nov 25, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

An electroactive sound transducer foil includes a composite foil made up of at least one carrier foil, at least one first and one second electrode, and at least one piezoelectric layer including an electroactive polymer, the surface of the sound transducer foil including a structuring having different slopes, and the slope of the sound transducer foil surface changing the sign at least twice.

First claim

What is claimed is:

1. An electroactive sound transducer foil, comprising:
a composite foil having:
a carrier foil;
a first electrode;
a second electrode; and
a piezoelectric layer including an electroactive polymer;

a vibration-soft bed to which the composite foil is applied; and
vibration-hard spacers crisscrossing the vibration-soft bed, thereby dividing a surface of the transducer foil into a plurality of areas having different natural frequencies;
wherein:
a modulus of elasticity of material of which the vibration-hard spacers are made is greater than a modulus of elasticity of material of which the vibration-soft bed is made;
the transducer foil includes at least one surface, a slope of which changes sign at least twice; and
at least one of:
(a) one of the at least one surface is a surface of the piezoelectric layer;
(b) one of the at least one surface is a surface of the first electrode;
(c) one of the at least one surface is a surface of the second electrode; and
(d) when viewed in a direction that is perpendicular to the at least one surface, the at least one surface forms a two-dimensional plane that is perpendicular to a stacking direction in which the first electrode, second electrode, and piezoelectric layer are stacked over each other.

2. The sound transducer foil as recited in claim 1 , wherein the electroactive polymer includes PVDF.

3. The sound transducer foil as recited in claim 1 , wherein elasticity of the composite foil varies along the slope.

4. The sound transducer foil as recited in claim 1 , further comprising a third electrode, wherein electrode edges of the first, second, and third electrodes extend in parallel to areas having a constant surface slope.

5. The sound transducer foil as recited in claim 1 , further comprising an additional protective or cover layer applied at least partially to an outer side of the composite foil.

6. A method for manufacturing an electroactive sound transducer having a structured sound transducer foil, the method comprising: producing a sound transducer foil from a carrier layer, a first electrode layer, a second electrode layer, and a piezoelectric layer including an electroactive polymer, wherein: the carrier layer, first electrode layer, second electrode layer, and piezoelectric layer form a composite foil; the composite foil is applied to a vibration-soft bed, and vibration-hard spacers crisscross the vibration-soft bed, thereby dividing a surface of the transducer foil into a plurality of areas having different natural frequencies; and a modulus of elasticity of material of which the vibration-hard spacers are made is greater than a modulus of elasticity of material of which the vibration-soft bed is made; one of mechanically and chemically structuring the sound transducer foil to include at least one surface, a slope of which changes sign at least twice, wherein at least one of: (a) one of the at least one surface is a surface of the piezoelectric layer; (b) one of the at least one surface is a surface of the first electrode; (c) one of the at least one surface is a surface of the second electrode; and (d) when viewed in a direction that is perpendicular to the at least one surface, the at least one surface forms a two-dimensional plane that is perpendicular to a stacking direction in which the first electrode, second electrode, and piezoelectric layer are stacked over each other; and joining the structured sound transducer foil to one of a frame and a surface.

7. The method as recited in claim 6 , further comprising attaching vibration-hard spacers at least in subareas of a rear side of the structured sound transducer foil prior to the joining step.

8. The method as recited in claim 6 , further comprising contacting at least subareas of a rear side of the structured sound transducer foil with a vibration-soft bed prior to the joining step.

9. An electroactive sound transducer, producible using a method for manufacturing an electroactive sound transducer having a structured sound transducer foil, the method comprising: producing a sound transducer foil from a carrier layer, a first electrode layer, a second electrode layer, and a piezoelectric layer including an electroactive polymer, wherein: the carrier layer, first electrode layer, second electrode layer, and piezoelectric layer form a composite foil; the composite foil is applied to a vibration-soft bed, and vibration-hard spacers crisscross the vibration-soft bed, thereby dividing a surface of the transducer foil into a plurality of areas having different natural frequencies; and a modulus of elasticity of material of which the vibration-hard spacers are made is greater than a modulus of elasticity of material of which the vibration-soft bed is made; one of mechanically and chemically structuring the sound transducer foil to include at least one surface, a slope of which changes sign at least twice, wherein at least one of: (a) one of the at least one surface is a surface of the piezoelectric layer; (b) one of the at least one surface is a surface of the first electrode; (c) one of the at least one surface is a surface of the second electrode; and (d) when viewed in a direction that is perpendicular to the at least one surface, the at least one surface forms a two-dimensional plane that is perpendicular to a stacking direction in which the first electrode, second electrode, and piezoelectric layer are stacked over each other; and joining the structured sound transducer foil to one of a frame and a surface.

10. A method comprising using an electroactive sound transducer as one of a microphone, a loudspeaker, a human machine interface (HMI), and a sensor, wherein:
the electroactive sound transducer includes:
a composite sound transducer foil that includes a carrier layer, a first electrode layer, a second electrode layer, and a piezoelectric layer including an electroactive polymer;
a vibration-soft bed to which the composite foil is applied; and
vibration-hard spacers crisscrossing the vibration-soft bed, thereby dividing a surface of the transducer foil into a plurality of areas having different natural frequencies;

a modulus of elasticity of material of which the vibration-hard spacers are made is greater than a modulus of elasticity of material of which the vibration-soft bed is made;
the composite foil includes at least one a surface, a slope of which changes sign at least twice; and
at least one of:
(a) one of the at least one surface is a surface of the piezoelectric layer;
(b) one of the at least one surface is a surface of the first electrode;
(c) one of the at least one surface is a surface of the second electrode; and
(d) when viewed in a direction that is perpendicular to the surface, the at least one surface forms a two-dimensional plane that is perpendicular to a stacking direction in which the first electrode, second electrode, and piezoelectric layer are stacked over each other.

11. The sound transducer foil as recited in claim 1 , wherein the first and second electrodes are arranged along only a portion of the piezoelectric layer.

12. The sound transducer foil as recited in claim 1 , wherein the modulus of elasticity of the vibration-hard spacers is greater than or equal to 5,000 N/mm 2 and the modulus of elasticity of the vibration-soft bed is less than or equal to 5,000 N/mm 2 .

13. The sound transducer foil as recited in claim 1 , wherein the modulus of elasticity of the vibration-hard spacers is greater than or equal to 10,000 N/mm 2 and the modulus of elasticity of the vibration-soft bed is less than or equal to 1,000 N/mm 2 .

14. The sound transducer foil as recited in c

Assignees

• Bosch Gmbh Robert

Inventors

• Gerlach Andre

Classifications

• H04R17/00 Primary

  Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) · CPC title

• H04R17/005

  using a piezoelectric polymer · CPC title