Magnetic antenna, and RF tag and board mounted with the RF tag

Patent metadata

Field	Value
Publication number	US-9634735-B2
Application number	US-201013146276-A
Country	US
Kind code	B2
Filing date	Jan 28, 2010
Priority date	Jan 30, 2009
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

The present invention relates to an RF tag comprising a magnetic antenna for transmitting and receiving information using an electromagnetic induction method, and an IC mounted to the magnetic antenna, wherein the magnetic antenna comprises a magnetic core and a plurality of coils formed on the magnetic core; the coils each have an inductance L 1 satisfying the specific relational formula, and are connected in parallel to each other in an electric circuit and disposed in series on the magnetic core; and a combined inductance L 0 of the magnetic antenna satisfies the specific relational formula. The RF tag of the present invention is used as a magnetic antenna for information communication using a magnetic field component which is capable of satisfying both reduction in size and improvement in communication sensitivity.

First claim

The invention claimed is:

1. An RF tag comprising a magnetic antenna for transmitting and receiving information using an electromagnetic induction method, and an IC mounted to the magnetic antenna, which magnetic antenna comprises a magnetic core and a plurality of coils formed on the magnetic core, which coils each have an inductance L 1 satisfying the following relational formula (1) such that the inductances L 1 of the coils are identical to each other, and are connected in parallel to each other in an electric circuit and disposed in series on the same, common magnetic core,
a combined inductance L 0 of the magnetic antenna satisfying the following relational formula (2):
L 1 ≧1/(4π 2 ×(operating frequency) 2 ×(capacitance of IC +parasitic capacitance of antenna))  <Relational formula (1)>

wherein L 1 is an inductance per one coil;
L 0 ≦1/(4π 2 ×(operating frequency) 2 ×(capacitance of IC +parasitic capacitance of antenna))  <Relational formula (2)>

wherein L 0 is a combined inductance of the magnetic antenna.

2. An RF tag according to claim 1 , wherein the RF tag is coated with a resin.

3. An RF tag according to claim 1 , wherein L 1 is not less than 3 times L 0 .

Assignees

• Koujima Jun
• Ohmae Satoshi
• Kimura Tetsuya
• Sato Yoshiro
• Toda Kogyo Corp

Inventors

• Koujima Jun
• Ohmae Satoshi
• Kimura Tetsuya
• Sato Yoshiro

Classifications

• H05K2203/162

  Testing a finished product, e.g. heat cycle testing of solder joints · CPC title

• H05K1/165

  incorporating printed inductors · CPC title

• H01Q7/08

  Ferrite rod or like elongated core · CPC title

• H04B5/0087 Primary

  Electricity · mapped topic

• H01Q1/2225 Primary

  used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal · CPC title