Variable inductor

• US 20060220775A1
• Filed: 03/20/2006
• Published: 10/05/2006
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ishikawa, Hiroshi
• Granted Patent: US 7,138,898 B2
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 21/02 continuously variable, e.g. variometers
• CPC Class Codes: H01F 21/10 by means of a movable shield
• CPC Class Codes: H01F 5/003 Printed circuit coils

Abstract

A variable inductor includes a conductor and an electroconductive member. The conductor has a coil and a pair of terminals electrically connected with the coil. The electroconductive member is movable closer to and farther away from the coil. The inductance between the terminals becomes smaller as the distance between the coil and the electroconductive member becomes shorter. Conversely, the inductance between the terminals becomes larger as the distance between the coil and the electroconductive member becomes longer.

Claims

1. A variable inductor comprising:

a conductor including a coil and a pair of terminals electrically connected with the coil; and

an electroconductive member movable closer to and farther away from the coil;

wherein an inductance between the terminals becomes smaller as a distance between the coil and the electroconductive member becomes shorter, and wherein the inductance between the terminals becomes larger as the distance between the coil and the electroconductive member becomes longer.

2. The variable inductor according to claim 1, wherein the coil is provided by a flat spiral coil, the electroconductive member being provided by an electroconductive film or an electroconductive plate that is spaced from the flat spiral coil in a thickness direction of the flat spiral coil but arranged to face the flat spiral coil.

3. The variable inductor according to claim 2, wherein the electroconductive member extends in an in-plane direction of the flat spiral coil and beyond the flat spiral coil.

4. The variable inductor according to claim 2, wherein the flat spiral coil includes a center opening, the electroconductive member including an opening at a place corresponding to the center opening.

5. The variable inductor according to claim 4, wherein the opening in the electroconductive member is within the center opening of the flat spiral coil as in an in-plane direction of the flat spiral coil.

6. The variable inductor according to one of claim 1, wherein the flat spiral coil includes a center opening, the electroconductive member including a region corresponding to the center opening and provided with a projection.

7. The variable inductor according to claim 6, wherein the projection is made of an electroconductive material or a dielectric material.

8. The variable inductor according to one of claim 1, wherein the electroconductive member is thicker than a skin depth of an induced current generated in the electroconductive member at the lowest frequency of a frequency range utilized.

9. The variable inductor according to one of claim 1, wherein the coil is made of one of Au, Cu, Al and Ni.