DIELECTRIC COMPOSITE AND A METHOD OF MANUFACTURING A DIELECTRIC COMPOSITE

• US 20090072658A1
• Filed: 11/03/2006
• Published: 03/19/2009
• Est. Priority Date: 11/02/2000
• Status: Active Grant

• Current Assignee: Danfoss A/S
• Original Assignee: Danfoss A/S
• Inventors: Benslimane, Mohamed Yahia, Gravesen, Peter
• Granted Patent: US 7,518,284 B2
• Time in Patent Office: Days
• US Class Current: 310/300
• CPC Class Codes: B81B 2201/038 Microengines and actuators not provided for in B81B2201/031 - B81B2201/037
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• CPC Class Codes: H02N 1/006 of the gap-closing type H02N1/004 takes precedence
• CPC Class Codes: H04R 23/00 Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/084 by moulding or extrusion
• CPC Class Codes: H10N 30/098 Forming organic materials
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/506 of cylindrical shape with stacking in radial direction, e.g. coaxial or spiral type rolls
• CPC Class Codes: H10N 30/871 Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF
• CPC Class Codes: Y10T 428/24612 Composite web or sheet

Abstract

A composite for a transducer facilitates an increased actuation force as compared to similar prior art composites for transducers. In accordance with the present invention, the composite also facilitates increased compliance of the transducer in one direction and an improved reaction time as compared to similar prior art composites for transducers, as well as provides an increased lifetime of the transducer in which it is applied.

Claims

1. A composite comprising:

a film made of a dielectric material and having a first surface and second surface, at least the first surface comprising a surface pattern of raised and depressed surface portions, and

a first electrically conductive layer being deposited onto the surface pattern, the electrically conductive layer having a corrugated shape which is formed by the surface pattern of the film;

wherein the second surface is substantially flat.

2. The composite according to claim 1, wherein the electrically conductive layer has a modulus of elasticity being higher than a modulus of elasticity of the film.

3. The composite according to claim 1, provided as a web of potentially unlimited length.

4. The composite according to claim 1, wherein the dielectric material is a polymer material.

5. The composite according to claim 1, wherein the dielectric material has properties similar to an elastomer.

6. The composite according to claim 1, wherein the film has a largest thickness which is less than 110 percent of an average thickness of the film.

7. The composite according to claim 1, wherein the film has a smallest thickness which is at least 90 percent of an average thickness of the film.

8. The composite according to claim 1, wherein the first electrically conductive layer has a largest thickness which is less than 110 percent of an average thickness of the first electrically conductive layer.

9. The composite according to claim 1, wherein the first electrically conductive layer has a smallest thickness which is at least 90 percent of an average thickness of the first electrically conductive layer.

10. The composite according to claim 1, wherein the surface pattern comprises waves forming troughs and crests extending in essentially one common direction, each wave defining a height being a shortest distance between a crest and neighbouring troughs.

11. The composite according to claim 10, wherein the waves have a shape which is periodically repeated.

12. The composite according to claim 10, wherein an average height of the waves is between 1/3 and 20 μ

m.

13. The composite according to claim 12, wherein each wave defines, a largest wave having a height of at most 110 percent of the average wave height.

14. The composite according claim 12, wherein each wave defines a smallest wave having a height of at least 90 percent of the average wave height.

15. The composite according to claim 10, wherein the film has an average thickness being between 10 and 200 μ

m.

16. The composite according to claim 10, wherein a ratio between an average height of the waves and an average thickness of the film is between 1/50 and 1/2.

17. The composite according to claim 10, wherein the waves have a wavelength defined as the shortest distance between two crests, and wherein a ratio between an average height of the waves and an average wavelength is between 1/30 and 2.

18. The composite according to claim 10, wherein a ratio between an average thickness of the first electrically conductive layer and an average height of the waves is between 1/1000 and 1/50.

19. The composite according to claim 1, wherein the first electrically conductive layer has a thickness in the range of 0.01-0.1 μ

m.

20. The composite according to claim 1 and being substantially (i.e. at least 10 times) longer in a lengthwise direction than in a perpendicular crosswise direction.

21. The composite according to claim 20, wherein the surface pattern defines a compliance direction in which the composite is mostly compliant, wherein the compliance direction forms an angle between 0 and 90 degrees to the lengthwise direction.

22. The composite according to claim 21, wherein the composite has a compliance in the compliance direction which is at least 50 times larger than its compliance in a direction being at least substantially perpendicular to the compliance direction.

23. The composite according to claim 20, wherein the surface pattern forms wave crests and troughs extending essentially in the lengthwise direction.

24. The composite according to claim 20, wherein the surface pattern forms wave crests and troughs extending essentially in the crosswise direction.

25. The composite according to claim 1, wherein the surface pattern comprises a plurality of identical sub patterns.

26. The composite according to claim 1, wherein the film has a surface with a shape which is essentially unaffected by its contact with the first electrically conductive layer.

27. The composite according to claim 26, wherein the composite has a shape which is essentially unaffected by an elastic modulus of the first electrically conductive layer.

28. The composite according to claim 26, wherein the film has a surface with a shape which is essentially unaffected by the thickness of the first electrically conductive layer.

29. The composite according to claim 1, wherein the film has a surface with a shape which is essentially unaffected by an elastic modulus of the film.

30. The composite according to claim 29, wherein the film has a surface with a shape which is essentially unaffected by the thickness of the film.

31. The composite according to claim 1, comprising a second electrically conductive layer arranged on an opposite surface of the film relative to the first electrically conductive layer to form an electroactive composite.

34. The composite according to claim 1, wherein a resistivity of the dielectric material is larger than 10¹⁰ Ω

·

cm.

35. The composite according to claim 1, wherein a resistivity of the electrically conductive material is less than 10⁴ Ω

·

cm.

32. (canceled)

33. (canceled)

36. A composite comprising:

a film made of a dielectric material and having a first surface and second surface, at least the first surface comprising a surface pattern of raised and depressed surface portions; and

a first electrically conductive layer being deposited onto the surface pattern, the electrically conductive layer having a corrugated shape which is formed by the surface pattern of the film;

wherein the surface pattern forms wave crests and troughs extending essentially in the lengthwise direction and wherein the composite is substantially (i.e. at least 10 times) longer in a lengthwise direction than in a perpendicular crosswise direction.