ANTENNA COIL

• US 20090243952A1
• Filed: 06/10/2009
• Published: 10/01/2009
• Est. Priority Date: 12/14/2006
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: SAKO, Yoshihiro, NAITO, Kenji, OOI, Takaaki
• Granted Patent: US 8,358,250 B2
• Time in Patent Office: Days
• US Class Current: 343/788
• CPC Class Codes: H01Q 1/3241 particular used in keyless entry systems
• CPC Class Codes: H01Q 1/40 Radiating elements coated with or embedded in protective material
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core

Abstract

An antenna coil includes a wound body including a magnetic core, a bobbin surrounding the magnetic core, and a coil wound around the bobbin, a case in which the wound body is placed, and a foam disposed in a gap between the wound body and the case. The foam is compressed at a rate of about 45% to about 65% on the basis of a thickness of the foam in a non-load state. The antenna coil prevents breakage of the magnetic core and is suitable for use in a short-distance communication system in an LF-band.

Claims

1. An antenna coil comprising:

a wound body including a magnetic core, a bobbin surrounding the magnetic core, and a coil wound around the bobbin;

a case in which the wound body is disposed; and

a foam disposed in a gap between the wound body and the case;

wherein

the foam is compressed at a rate of about 45% to about 65% on the basis of a thickness of the foam in a non-load state.

2. The antenna coil according to claim 1, wherein the foam is compressed at a rate of about 57% to about 64% on the basis of the thickness of the foam in the non-load state.

3. The antenna coil according to claim 2, wherein the foam is compressed at a rate of about 59% to about 62% on the basis of the thickness of the foam in the non-load state.

4. The antenna coil according to claim 1, further comprising a cap fitted to the case and supporting a first end of the wound body.

5. The antenna coil according to claim 4, wherein the foam is disposed on a second end side of the wound body.

6. The antenna coil according to claim 1, further comprising a gel disposed between the foam and the case.