Electromechanical transducer

• US 6,946,779 B2
• Filed: 05/16/2001
• Issued: 09/20/2005
• Est. Priority Date: 06/07/2000
• Status: Expired due to Fees

• Current Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Original Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Inventors: Birgel, Dietmar
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US10/296,248
• Publication Number:
  US 20030168945A1
• Time in Patent Office: 1,588 Days
• Field of Search: 310/328, 310/366
• US Class Current: 310/366
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H10N 30/101 with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• CPC Class Codes: H10N 30/1071 with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• CPC Class Codes: H10N 30/503 having a non-rectangular cross-section in a plane orthogonal to the stacking direction, e.g. polygonal or circular in top view
• CPC Class Codes: H10N 30/871 Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes
• CPC Class Codes: H10N 30/872 Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices
• CPC Class Codes: H10N 30/875 Further connection or lead arrangements, e.g. flexible wiring boards, terminal pins

Abstract

The invention relates to an electromechanical transducer that is easy and inexpensive to produce. The inventive transducer comprises stacked piezoelectric elements between which contact electrodes (G, S, E) are interposed via which the piezoelectric elements are electrically connected. The contact electrodes (G, S, E) are configured as planar terminal lugs that are connected to the outside from a flexible printed board.

Claims

1. An electromechanical transducer, comprising:

a plurality of piezoelectric elements disposed in a stack;

a plurality of electrically connected contact electrodes each disposed between adjacent ones of said piezoelectric elements; and

a flexible printed circuit board to which said plurality of electrically connected contact electrodes are connected and from which they extend, wherein said plurality of electrically connected contact electrodes comprise planar terminal lugs.

2. The electromechanical transducer as defined in claim 1, wherein said flexible printed circuit board has one portion embodied in steplike fashion comprising a plurality of steps, from each of which a respective one of said planar terminal lugs extends to the outside, and wherein the height of each of said steps is equal to the thickness of one of said plurality of piezoelectric elements adjoining said respective step.

3. The electromechanical transducer as defined in claim 1, wherein said stack comprises two partial stacks disposed one on the other, and wherein said plurality of piezoelectric elements associated with each partial stack are connected by means of respective ones of said plurality of planar terminal lugs, which are disposed around a bottom face associated with said partial stack.

4. The electromechanical transducer as defined in claim 1, wherein said flexible printed circuit board has one portion having a plurality of conductor tracks which extend one above the other, wherein each conductor track ends in a terminal lug extending perpendicular to said conductor track, and wherein the individual terminal lugs are disposed parallel to one another and serve to connect piezoelectric elements adjoining them.

5. The electromechanical transducer as defined in claim 1, wherein electronic components are disposed on said flexible printed circuit board.

6. The electromechanical transducer as defined in claim 5, wherein the electronic components include SMDs.

7. A method for producing a electromechanical transducer, having a plurality of piezoelectric elements, a plurality of electrically connected contact electrodes comprising planar terminal lugs, and a flexible printed circuit board, the method comprising the steps of:

stacking the plurality of piezoelectric elements, said stacking being compact;

equipping the flexible printed circuit board with components; and

disposing the planar terminal lugs parallel to one another and one above the other by deformation of the flexible printed circuit board, as a result of which the piezoelectric elements are stacked on one another.

8. The method as defined in claim 7, wherein the components are one of:

piezoelectric elements and SMDs.

9. The method as defined in claim 7, wherein the steps are done automatically.

10. A device for ascertaining and/or monitoring a predetermined fill level in a container, comprising:

a mechanical oscillation structure mounted at the height of the predetermined fill level; and

an electromechanical transducer, comprising;

a plurality of piezoelectric elements disposed in a stack;

a plurality of electrically connected contact electrodes each disposed between adjacent ones of said piezoelectric elements, and a flexible printed circuit board to which said plurality of electrically connected contact electrodes are connected and from which they extend, wherein said electromechanical transducer in operation serves to set said mechanical oscillation structure into oscillation and pick up its oscillations that are dependent on an instantaneous fill level and make them accessible for further processing and/or evaluation.

11. The electromechanical transducer as defined in claim 10, wherein said flexible printed circuit board has one portion embodied in steplike fashion comprising a plurality of steps, from each of which a respective one of said planar terminal lugs extends to the outside, and wherein the height of each of said steps is equal to the thickness of one of said plurality of piezoelectric elements adjoining said respective step.

12. The electromechanical transducer as defined in claim 10, wherein said stack comprises two partial stacks disposed one on the other, and wherein said plurality of piezoelectric elements associated with each partial stack are connected by means of respective ones of said plurality of planar terminal lugs, which are disposed around a bottom face associated with said partial stack.

13. The electromechanical transducer as defined in claim 10, wherein said flexible printed circuit board has one portion having a plurality of conductor tracks which extend one above the other, wherein each conductor track ends in a terminal lug extending perpendicular to said conductor track, and wherein the individual terminal lugs are disposed parallel to one another and serve to connect piezoelectric elements adjoining them.

14. The electromechanical transducer as defined in claim 10, wherein electronic components are disposed on said flexible printed circuit board.

15. The electromechanical transducer as defined in claim 14, wherein the electronic components include SMDs.