ELECTROACTIVE POLYMER TRANSDUCERS BIASED FOR INCREASED OUTPUT

• US 20080157631A1
• Filed: 12/29/2006
• Published: 07/03/2008
• Est. Priority Date: 12/29/2006
• Status: Active Grant

• Current Assignee: Parker-Hannifin Corporation
• Original Assignee: Artificial Muscle, Inc. (Covestro AG)
• Inventors: Zarrabi, Alireza, Hui, Otto, Polyakov, Ilya, HEIM, Jonathan R.
• Granted Patent: US 7,492,076 B2
• Time in Patent Office: Days
• US Class Current: 310/330
• CPC Class Codes: B06B 1/02 making use of electrical energy B06B1/18, B06B1/20 take precedence
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: F04B 19/006 Micropumps F04B43/043 and F04B43/095 take precedence
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: H10N 30/886 Mechanical prestressing means, e.g. springs springs in general F16F1/00
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

Electroactive polymer transducers are disclosed. They are biased in a manner that provides for increased force and/or stroke output, thereby offering improved work potential and power output capacity. The biasing may offer additional or alternate functional advantage in terms of matching transducer performance with a given application such as a normally-closed valve. The improved biasing (including increased output biasing) may utilize negative spring rate biasing and/or a combination of negative or zero-rate biasing with positive rate biasing to achieve the desired ends.

Claims

1. A transducer assembly comprising an electroactive polymer and at least one biasing element, the improvement consisting of at least one biasing element set to provide a negative spring rate within the transducer assembly.

2. The transducer assembly of claim 1, wherein the at least one other biasing element is set to provide a positive spring rate.

3. The transducer assembly of claim 1, wherein the at least one biasing element comprises any of a coil spring, leaf spring, air pressure, fluid pressure or a combination thereof.

4. The transducer assembly of claim 1, comprising a plurality of biasing elements in the form of leaf springs arranged in a clover configuration.

9. The transducer assembly of claim 1, wherein the transducer assembly forms part of a lens positioner, a valve mechanism, a pump, a light reflector, a speaker, a vibrator, a haptic feedback device or a force feedback device.

5. A transducer assembly comprising electroactive polymer and a positive rate biasing element, the improvement consisting of at least one biasing element set to provide a negative or substantially zero spring rate.

6. A diaphragm transducer assembly comprising electroactive polymer and at least one biasing element, the improvement consisting the at least one biasing element having a bistable configuration to allow the transducer to actuate in opposite directions without further biasing.

7. The transducer assembly of claim 6, wherein the diaphragm includes a cap to form a frustum-style assembly.

8. (canceled)

10. A negative spring rate assembly comprising:

a compressible member configured to be in a most compressed condition when the assembly is in a neutral position and in a least compressed condition when the assembly is in an extended position; and

an output member associated with the compressible member, wherein the output member is leveraged most when the assembly is in the neutral position and is leveraged least when the assembly is in the extended position.

11. The assembly of claim 10, further comprising a frame associated with the compressible member wherein output force of the output member is substantially perpendicular to the frame.

12. The assembly of claim 10, further comprising a frame associated with the compressible member wherein output force is along a line parallel to the frame.

13. The assembly of claim 10, the compressible member comprises a C or S shaped section of material.

14. The assembly of claim 13, wherein the compressible member comprises a buckled elongate form.

15. The assembly of claim 10, wherein the compressible member comprises a plurality of coil spring and the coil springs are each mounted on a linkage arm, the linkage arms rotatably connected a central hub, the hub providing the output interface.

20. The assembly of claim 10, wherein the compressible member comprises a spring element.

21. The assembly of claim 10, wherein the output member comprises one of a frame, cap structure, linkage and a shaft.

16. A transducer assembly comprising:

a molded negative rate spring diaphragm and electroactive polymer, each coupled to a frame, wherein the electroactive polymer is configured in a frustum shape and wherein the negative rate spring diaphragm is operatively coupled to the electroactive polymer to provide biasing.

17. The transducer assembly of claim 16, further comprising a lens located substantially at a center of the electroactive polymer frustum.

18. The transducer assembly of claim 16, further comprising valve poppet located opposite a valve inlet or outlet conduit in a valve body, wherein the spring diaphragm defines a portion of a valve chamber.

19. The transducer assembly of claim 16, further comprising a piston region substantially at a center of the electroactive polymer frustum, and check valves for inlet and outlet conduits in a pump body, wherein the spring diaphragm defines a portion of a valve chamber.