Wireless IC device

• US 8,757,500 B2
• Filed: 10/22/2009
• Issued: 06/24/2014
• Est. Priority Date: 05/11/2007
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Kato, Noboru, Dokai, Yuya
• Primary Examiner(s): HESS, DANIEL A
• Application Number:
  US12/603,608
• Publication Number:
  US 20100038437A1
• Time in Patent Office: 1,706 Days
• Field of Search: 235/492, 340/572.1
• US Class Current: 235/492
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil
• CPC Class Codes: G06K 19/07783 the coil being planar
• CPC Class Codes: G06K 19/07784 the inductive antenna consisting of a plurality of coils stacked on top of one another
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/40 Radiating elements coated with or embedded in protective material
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A wireless IC device has a structure such that the size of a radiation plate and a radiation characteristic may be determined irrespective of an impedance of a wireless IC chip. The wireless IC device includes a wireless IC chip that is arranged to process transmission and reception signals, a spiral matching inductance element and a plane electrode that are located on a surface of a feeder circuit substrate, and a coil-shaped radiation plate located on a radiation substrate. Plane electrodes connected to both ends of the radiation plate are electromagnetically coupled respectively to the inductance element and the plane electrode. The wireless IC chip is operated by a signal received by the radiation plate, and a response signal from the wireless IC chip is radiated outside from the radiation plate.

Claims

1. A wireless IC device comprising:

a wireless IC arranged to process transmission and reception signals;

a feeder circuit including an inductance electrode and a plane electrode; and

a radiation member including a first end portion and a second end portion;

wherein

the wireless IC is connected to the feeder circuit;

the first end portion of the radiation member is magnetically coupled to the inductance electrode of the feeder circuit, and the second end portion of the radiation member is capacitively coupled to the plane electrode of the feeder circuit;

the wireless IC is mainly magnetically coupled to the first end portion of the radiation member via a first connection electrode connected to the inductance electrode of the feeder circuit;

the wireless IC is mainly capacitively coupled to the second end portion of the radiation member via a second connection electrode connected to the plane electrode;

the wireless IC is arranged to be operated by a signal received by the radiation member, and a response signal from the wireless IC is radiated outside from the radiation member; and

the first end portion of the radiation member is defined by a first plane electrode that is arranged to face the inductance electrode.

2. The wireless IC device according to claim 1, wherein both of the first and second end portions of the radiation member are arranged adjacent to each other.

3. The wireless IC device according to claim 1, wherein the radiation member has a belt-shaped configuration.

4. The wireless IC device according to claim 1, wherein the first plane electrode of the radiation member is arranged between the inductance electrode and one end of the radiation member, and is electrically continuous with the radiation member via a connecting portion.

5. The wireless IC device according to claim 1, wherein the first plane electrode of the radiation member has an area that is larger than an area occupied by the inductance electrode.

6. The wireless IC device according to claim 1, wherein the plane electrode of the feeder circuit is arranged between the wireless IC and the radiation member.

7. The wireless IC device according to claim 1, wherein the plane electrode of the feeder circuit is arranged between the wireless IC and the second end portion of the radiation member, and the wireless IC device is arranged so that the first end portion of the radiation member faces the inductance electrode and the second end portion of the radiation member faces the plane electrode of the feeder circuit.

8. The wireless IC device according to claim 7, further comprising a feeder circuit substrate including the feeder circuit, and the plane electrode of the feeder circuit is arranged inside or on a surface of the feeder circuit substrate.

9. The wireless IC device according to claim 1, wherein a resonant frequency of a signal from the radiation member is higher than a resonant frequency of the inductance electrode and a frequency used in the wireless IC device.

10. The wireless IC device according to claim 1, wherein the radiation member has a loop shape.

11. The wireless IC device according to claim 1, wherein the radiation member has a spiral shape.

12. The wireless IC device according to claim 1, further comprising a feeder circuit substrate including the feeder circuit, wherein the feeder circuit substrate is a multilayer substrate in which the inductance electrode is embedded.

13. The wireless IC device according to claim 1, further comprising a feeder circuit substrate including the feeder circuit, wherein the feeder circuit substrate is a flexible substrate.

14. The wireless IC device according to claim 1, wherein the radiation substrate is a multilayer substrate and the radiation member is a coil-shaped radiation member that is embedded in the multilayer substrate.

15. The wireless IC device according to claim 1, wherein the radiation substrate is a flexible substrate.

16. The wireless IC device according to claim 1, wherein the radiation member is a radiation plate.