Process for variable inductor using nickel titanium and placement

• US 6,275,131 B1
• Filed: 12/06/1999
• Issued: 08/14/2001
• Est. Priority Date: 12/06/1999
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Liebman, Henry F., Swope, Charles B., Koskan, Patrick D.
• Primary Examiner(s): Donovan, Lincoln
• Assistant Examiner(s): NGUYEN, TUYEN T
• Application Number:
  US09/454,967
• Time in Patent Office: 617 Days
• Field of Search: 336/222, 336/20, 336/10, 336/192, 336/107, 336/223
• US Class Current: 336/20
• CPC Class Codes: H01F 21/04 by relative movement of turns or parts of windings

Abstract

A variable inductor is made from two elements separated by an insulating layer. The first element is elastic and serves as a coil shaped support for the inductive element. This elastic element is made with a memory and can be made to change its size by the application of heat. The inductive element is formed over the coil shaped support by layering a thin layer of a highly conductive material such as gold over the insulator layered on the elastic element. As heat is applied to the coil or as an electric current is applied to the elastic element, the size of the coil shaped support is changed which changes the inductive value of the inductive element formed by the conductive layer.

Claims

1. An inductive system comprising:

an elastic element made from an elastic material with a memory state, and formed in the shape of a coil for supporting an conductive element;

an insulating coating on said elastic element; and

a conductive coating formed on said insulative coating forming an inductive element;

said insulating coating extending over said elastic element with ends of said elastic element exposed for making electrical connections; and

wherein

said elastic element is responsive to heat for altering its shape and the inductive value of said inductive element.

2. The inductive system of claim 1, wherein, said elastic element is responsive to heat for changing its length and the length of said inductive system.

3. The inductive system of claim 1, wherein said elastic element is responsive to a current applied to said exposed ends, for heating said elastic element and altering its shape.

4. The inductive system of claim 2, wherein said elastic element changes in length in said response to said heat and said inductive value of said inductive element changes in response to said elastic element changing its length.

5. The system of claim 1, wherein said elastic element is made from nickel titanium.

6. The inductive system of claim 1, wherein said insulating coating extends over said elastic element and between said exposed ends and said inductive element is a coating applied over said insulating coating.

7. The inductive system of claim 1, wherein said insulating coating is a polyurethane.

8. The inductive system of claim 1, wherein said conductive coating is made from gold.

9. The inductive system of claim 1, wherein the material of said elastic element is NiTi and the resistance of said conductive element is substantially the same under said heat applied to said elastic element.

10. An inductive system used in a tuned circuit comprising:

an elastic material having a memory state, made in the shape of an inductive coil having two ends;

an insulating coating applied over said elastic material;

with said two ends of said elastic material exposed for making an electrical connection;

a conductive material applied over said insulating material for forming an inductor;

said elastic material made from a conductive material for carrying a current between said two ends for heating said elastic material and for changing its shape and the inductive value of said conductive material; and

said conductive material being made of a material having a greater conductivity then the elastic material which maintains its internal resistance and the Q of the tuned circuit, substantially the same in response to said heating of said elastic material.

11. The system of claim 10, where said inductor has connectors at said ends for an electrical connection.

12. The system of claim 10, wherein said elastic material has connectors at said ends for connection to a source of current for heating said elastic material.

13. The system of claim 10, wherein said conductive material is coated over said insulating material.

14. The system of claim 10, wherein said insulating material is coated over said elastic material.