Electroacoustic transducer

• US 4,492,825 A
• Filed: 07/28/1982
• Issued: 01/08/1985
• Est. Priority Date: 07/28/1982
• Status: Expired due to Fees

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Brzezinski, Alex M., Hershey, Harold J., Whitesell, Stephen R.
• Primary Examiner(s): Rubinson, Gene Z.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/402,613
• Time in Patent Office: 895 Days
• Field of Search: 179/111 R, 179/111 E, 179/110 A, 179/146 R, 29/592 E, 29/594, 29/25.35, 307/400, 367/173, 367/188, 361/397, 310/322, 310/324
• US Class Current: 381/113
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer
• CPC Class Codes: H04R 19/01 characterised by the use of electrets
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A transducer embodying the present invention is assembled on a discrete electrically conductive frame (100) that has been formed to provide both leads (120-140) and a backplate (110). An integrated circuit chip (200) is bonded to one of the leads, and a dielectric inner housing member (300) is molded about the backplate and the portion of the leads adjacent to it. The inner housing member encapsulates the chip, embraces the perimeter of the backplate, and provides a cylindrical opening (310) that extends on each side of the backplate. A conductive outer housing member (400) is subsequently molded about the perimeter of the inner housing member, and a spacer (500), electret diaphragm assembly (600), and conductive gasket (700) are sequentially positioned in the opening on one side of the backplate. Conductive front and back covers (800,900) are thereafter bonded to the outer housing to close the opening and to complete a conductive enclosure that provides electrostatic shielding for the transducer. In addition, electrical continuity is provided between a metalized surface on the electret diaphragm and the conductive enclosure by means of the gasket.

Claims

1. An electroacoustic transducer comprising:

a unitary discrete electrically conductive member from which both a plurality of leads and a backplate are formed;

a diaphragm positioned adjacent to the backplate; and

means for providing electrical interconnection between the backplate and at least one of the leads.

2. An electroacoustic transducer as in claim 1 wherein the electrical interconnection means comprises an integrated circuit and a connecting wire extending between the circuit and the backplate and between the circuit and at least one of the leads.

3. An electroacoustic transducer as in claim 2 wherein the integrated circuit is supported on one of the leads and a dielectric housing is molded about the perimeter of the backplate and the portion of the leads adjacent to the backplate, the dielectric housing encapsulating the integrated circuit and the connecting wires and including an opening on one side of the backplate within which the diaphragm is positioned.

4. An electroacoustic transducer as in claim 3 wherein capacitors are supported on and electrically connected to the leads, and the dielectric housing encapsulates the capacitors.

5. An electroacoustic transducer as in claim 1 further including a dielectric housing molded about the perimeter of the backplate and the portion of the leads adjacent to the backplate, the dielectric housing including an opening on one side of the backplate within which the diaphragm is positioned.

6. An electroacoustic transducer as in claim 3 wherein the dielectric housing is an inner housing member and an electrically conductive outer housing member is molded about the inner housing member and engages one of the leads.

7. An electroacoustic transducer as in claim 6 wherein the diaphragm comprises an electret, the surface of the diaphragm remote to the backplate is electrically conductive, the diaphragm is joined to an electrically conductive annular support member that maintains the diaphragm under tension, and an electrically conductive annular gasket engages the support member and provides an electrical connection to the same lead engaged by the outer housing member.

8. An electroacoustic transducer as in claim 7 further including an electrically conductive cover that is positioned over the opening in the inner housing member in engagement with the conductive gasket and joined to the outer housing member.

9. An electroacoustic transducer comprising:

a conductive member;

a dielectric housing molded about the perimeter of the conductive member, the housing including an opening on at least one side of the conductive member; and

a diaphragm positioned within the opening adjacent to the conductive member.

10. An electroacoustic transducer as in claim 9 wherein the dielectric housing is an inner housing member and an electrically conductive outer housing member is molded about the inner housing member.

11. An electroacoustic transducer as in claim 10 further including an electrically conductive cover that is positioned over the opening in the inner housing member and joined to the outer housing member.

12. An electroacoustic transducer comprising:

a plurality of leads separated from one another;

a dielectric member molded about the leads;

an electrically conductive member supported by the dielectric member;

a diaphragm positioned adjacent to the conductive member; and

a conductive housing molded about the dielectric member.

13. An electroacoustic transducer as in claim 12 wherein the conductive member is a backplate, the diaphragm has a conductive surface remote to the backplate, and the transducer further includes means for providing electrical continuity between the conductive surface of the diaphragm and the conductive housing.

14. An electroacoustic transducer as in claim 12 wherein the conductive housing includes an opening in registration with the conductive member and an electrically conductive closure member is positioned within the opening and joined to the housing.

15. An electret transducer comprising:

a rigid electrically conductive frame member;

a dielectric member molded about the frame member, the dielectric member including an opening on at least one side of the frame member;

a backplate supported within the opening; and

an electret diaphragm positioned within the opening adjacent to the backplate.

16. An electret transducer as in claim 15 wherein the frame member includes a plurality of leads and the backplate.

17. An electret transducer as in claim 15 further including an electrically conductive housing molded about the dielectric member.

18. An electroacoustic transducer comprising:

an electrically conductive frame member;

a dielectric inner housing member molded about the frame member, the inner housing member including at least one acoustic chamber; and

an electrically conductive outer housing member molded about the dielectric inner housing member.

19. An electroacoustic transducer comprising:

a unitary electrically conductive frame member from which both a plurality of leads and a backplate are formed;

a dielectric inner housing member molded about the perimeter of the backplate and the portions of the leads adjacent to the backplate, the inner housing member having an opening extending on each side of the backplate;

a conductive outer housing member molded about the inner housing member, the outer housing member engaging one of the leads and including openings in registration with the openings in the inner housing member;

an electret diaphragm positioned within the opening in the inner housing member on one side of the backplate, the diaphragm having a conductive surface remote to the backplate;

an annular rigid conductive support member joined to the conductive surface of the diaphragm, the support member maintaining the diaphragm under tension;

a compressible electrically conductive annular member positioned in engagement with the support member, the compressible member making electrical connection with the same lead engaged by the outer housing; and

front and back electrically conductive cover members positioned within the openings of the outer housing member and joined to the outer housing member, the front cover member engaging the compressible member.

20. An electroacoustic transducer as in claim 19 wherein the cover member compresses the compressible member whereby the compressible member biases the support member and diaphragm into position with respect to the backplate.

21. An electroacoustic transducer as in claim 19 wherein joining of the cover members to the outer housing member provides front and back acoustic chambers, and the cover members have protrusions that extend into the respective chambers, the protrusions serving to adjust the front and back acoustic chamber volumes.

22. An electroacoustic transducer comprising:

a unitary discrete electrically conductive member from which both a plurality of leads and a backplate are formed;

a dielectric inner housing member molded about the perimeter of the backplate and the portion of the leads adjacent to the backplate, the inner housing member including an opening on one side of the backplate;

a diaphragm positioned within the opening in the inner housing member adjacent to the backplate; and

an electrically conductive outer housing member molded about the inner housing member, the outer housing member engaging one of the leads.

23. An electroacoustic transducer as in claim 22 wherein the diaphragm comprises an electret, the surface of the diaphragm remote to the backplate is electrically conductive, the diaphragm is joined to an electrically conductive annular support member that maintains the diaphragm under tension, and an electrically conductive annular gasket engages the support member and provides an electrical connection to the same lead engaged by the outer housing member.

24. An electroacoustic transducer as in claim 23 further including an electrically conductive cover that is positioned over the opening in the inner housing member in engagement with the conductive gasket and joined to the outer housing member.

25. An electroacoustic transducer comprising:

a conductive member;

a dielectric inner housing member molded about the perimeter of the conductive member, the inner housing member including an opening on at least one side of the conductive member;

an electrically conductive outer housing member molded about the inner housing member; and

a diaphragm positioned within the opening adjacent to the conductive member, the diaphragm comprising a piezoelectric polymer that has a conductive surface both adjacent to and remote to the conductive member, the conductive surface adjacent to the conductive member being in electrical continuity with the conductive member, and the conductive surface remote to the conductive member being in electrical conductivity with the outer housing member.

26. An electroacoustic transducer comprising:

a plurality of leads separated from one another;

a dielectric member molded about the leads;

an electrically conductive backplate supported by the dielectric member;

a diaphragm positioned adjacent to the backplate, the diaphragm having a conductive surface remote to the backplate;

a conductive housing molding about the dielectric member; and

means for providing electrical continuity between the conductive surface of the diaphragm and the conductive housing, the continuity means including a rigid electrically conductive member in engagement with the conductive surface of the diaphragm and a compressible electrically conductive member in engagement with the rigid member.

27. An electroacoustic transducer comprising:

a plurality of leads separated from one another;

a dielectric member molded about the leads;

an electrically conductive member supported by the dielectric member;

a diaphragm positioned adjacent to the conductive member; and

a conductive housing molded about the dielectric member, the conductive housing engaging one of the leads.