NEAR FIELD COMMUNICATION ANTENNA AND MOBILE DEVICE

• US 20080238799A1
• Filed: 02/25/2008
• Published: 10/02/2008
• Est. Priority Date: 03/26/2007
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications Japan Incorporated (Sony Group Corp.)
• Inventors: TSUSHIMA, Takaaki
• Granted Patent: US 7,688,270 B2
• Time in Patent Office: Days
• US Class Current: 343/788
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 19/10 using reflecting surfaces
• CPC Class Codes: H01Q 7/06 with core of ferromagnetic material H01Q7/02 takes precedence
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core
• CPC Class Codes: H04B 5/0075 using inductive coupling transformers or inductances adapted for inductive coupling H01F38/14
• CPC Class Codes: H04B 5/24 Inductive coupling

Abstract

An NFC antenna (“NFC” stands for “near field communication”) includes a ferrite antenna including a primary antenna coil wound on a ferrite core of the ferrite antenna; a loop coil provided in a position where components of a magnetic flux on a non-communication direction side interlink, the magnetic flux being generated by the ferrite antenna; and a loop coil switching unit for switching between a mode for forming a loop of the loop coil and a mode for disconnecting the loop.

Claims

1. An NFC antenna (“

NFC”

stands for “

near field communication”

), comprising;

a ferrite antenna including a primary antenna coil wound on a ferrite core of the ferrite antenna;

a loop coil provided in a position where components of a magnetic flux on a non-communication direction side interlink, the magnetic flux being generated by the ferrite antenna; and

loop coil switching means for switching between a mode for forming a loop of the loop coil and a mode for disconnecting the loop.

2. An NFC antenna as claimed in claim 1, wherein

the ferrite core includes a correction coil wound thereon, wherein the correction coil is used to correct for a resonant frequency varying depending on the mode for forming the loop of the loop coil and the mode for disconnecting the loop, the modes being set by the loop coil switching means;

and

the NFC antenna further comprises correction coil switching means for switching between a mode for closing the correction coil and a mode for not closing the correction coil in operative association with switching by the loop coil switching means between the mode for forming the loop of the loop coil and the mode for disconnecting the loop.

3. An NFC antenna as claimed in claim 1, wherein the loop coil switching means is a manual switch.

4. An NFC antenna as claimed in claim 2, wherein the loop coil switching means and the correction coil switching means are configured from a double pole switch.

5. An NFC antenna as claimed in claim 1, wherein the loop coil switching means is an electronic switch.

6. An NFC antenna as claimed in claim 2, wherein the loop coil switching means and the correction coil switching means are each configured from an electronic switch.

7. A mobile device comprising an NFC communication portion, wherein an NFC antenna of the NFC communication portion includes:

a ferrite antenna including a primary antenna coil wound on a ferrite core of the ferrite antenna;

a loop coil provided in a position where components of a magnetic flux on a non-communication direction side interlink, the magnetic flux being generated by the ferrite antenna; and

loop coil switching means for switching between a mode for forming a loop of the loop coil and a mode for disconnecting the loop.

8. A mobile device as claimed in claim 7, wherein the NFC antenna includes:

the ferrite core including a correction coil wound thereon, wherein the correction coil is used to correct for a resonant frequency varying depending on the mode for forming the loop of the loop coil and the mode for disconnecting the loop, the modes being set by the loop coil switching means; and

the NFC antenna further includes a correction coil switching means for switching between a mode for closing the correction coil and a mode for not closing the correction coil in operative association with switching by the loop coil switching means between the mode for forming the loop of the loop coil and the mode for disconnecting the loop.

9. A mobile device as claimed in claim 7, wherein

the loop coil switching means is an electronic switch;

and

control means for performing control such that, when a function using the NFC communication portion is activated, the loop coil switching means is set to a mode for disconnecting the loop of the loop coil.

10. A mobile device as claimed in claim 7, wherein:

the loop coil switching means is an electronic switch; and

the mobile device further comprises

detector means for detecting a state where a reception level of the NFC antenna is higher than a predetermined level; and

control means for controlling the loop coil switching means to switch to a mode for disconnecting the loop of the loop coil when the detector means has detected a state where the reception level of the NFC antenna is higher than a predetermined level.