IC tag and method for fabricating the same

• US 7,701,350 B2
• Filed: 04/27/2007
• Issued: 04/20/2010
• Est. Priority Date: 11/06/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sakama, Isao, Ashizawa, Minoru
• Primary Examiner(s): Goins; Davetta W
• Assistant Examiner(s): LAU, HOI CHING
• Application Number:
  US11/741,012
• Publication Number:
  US 20080106412A1
• Time in Patent Office: 1,089 Days
• Field of Search: 3405721-5729, 340/568.2, 342/51, 235/492, 235/491, 235/380, 343/702, 343/700.MS, 343/795, 343/793, 343/873, 257/678, 438/106, 296/00, 295/921, 296/01
• US Class Current: 340/572.7
• 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 19/07756 the connection being non-galvanic, e.g. capacitive
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• CPC Class Codes: G06K 19/07796 arrangements on the record carrier to allow stacking of a plurality of similar record carriers, e.g. to avoid interference between the non-contact communication of the plurality of record carriers
• 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 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration

Abstract

The RFID tag is composed of the first antenna of metal film layer on which the IC chip is mounted and at least one second antenna of metal film layer on which the IC chip is not mounted The metal film layer is formed on the base, and the metal film layer is formed on the base. The metal film layer partially overlaps the metal film layer with the base interposed between them, so that the first antenna and the second antenna are capacitively coupled to each other.

Claims

1. An IC tag comprising

an IC chip operable with radio waves;

a first antenna electrically connected to the IC chip; and

at least one second antenna capacitively coupled with the first antenna via an insulating material,

the IC chip being connected to the first antenna over a slit formed in the first antenna used for impedance matching,

the at least one second antenna being connected with the first antenna to avoid overlapping with the slit of the first antenna.

2. The IC tag as claimed in claim 1, wherein the first antenna and the at least one second antenna have their own overlapping area wherein the first antenna and the at least one second antenna overlap each other via the insulating material.

3. The IC tag as claimed in claim 1, wherein

the insulating material has a belt-like shape;

two second antennas are formed on the insulating material along a lengthwise direction of the insulating material;

the first antenna is formed between the two second antennas; and

the insulating material is folded toward the first antenna and folded toward the two second antennas, so that the first antenna overlaps partially with the two second antennas via the insulating material.

4. The IC tag as claimed in claim 1, wherein

the insulating material has a belt-like shape;

the first antenna is formed on one surface of the insulating material;

two second antennas are formed on another surface of the insulating material along the lengthwise direction of the insulating material; and

a positional relationship along the lengthwise direction of the insulating material between the first antenna and the two second antennas is such that lengthwise ends of the first antenna overlap with opposite ends of the two second antennas via the insulating material.

5. The IC tag as claimed in claim 1, wherein

the first antenna and the at least one second antenna are formed on a same surface of the insulating material;

and

the first antenna and the at least one second antenna are separated from each other and opposed to each other via a fine gap between them.

7. The IC tag as claimed in claim 1, wherein a length of the first antenna is shorter than a wave length of the radio waves.

6. A method for fabricating an IC tag comprising the steps of

forming a first antenna and at least one second antenna on a base of insulating flexible material;

electrically connecting an IC chip operable with radio waves to the first antenna via a slit;

providing capacitive coupling between the first antenna and the at least one second antenna without overlapping with the slit at end portion of the first antenna and the at least one second antenna, and

folding the base at a predetermined space by bending the at least one second antenna toward the first antenna and then bending back the at least one second antenna so that the end portion of the first antenna and the end portion of the at least one second antenna overlap each other with the base interposed between them so that the capacitive coupling is formed between the first antenna and the at least one second antenna and the at least one second antenna is arranged at a side of the end portion of the first antenna.

8. The method as claimed in claim 6, wherein a length of the first antenna is shorter than a wave length of the radio waves.