Detecting device having spaced transmitting and receiving coils for detecting a metal strip embedded in paper money

Patent 4536709 Issued on August 20, 1985. Estimated Expiration Date:

August 29, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

2217843

2513745

2711510

3020472

3286168

3422346

Balanced field theft detection system Patent #: 4063230
Issued on: 12/13/1977
Inventor: Purinton , et al.

Inventor

Ishida, Tsuyoshi

Assignee

Tokyo Shibaura Denki Kabushiki Kaisha

Application

No. 06/645533 filed on 08/29/1984

US Classes:

324/239, Induced voltage-type sensor194/206, By pliant currency (e.g., dollar bill, etc.)194/213, Test electrical or magnetic property235/449, Magnetic340/675, Web, film, or strip902/22TERMINAL* REGISTERS TRANSACTION* (E.G., POINT OF SALE TERMINAL*)

Examiners

Primary: Strecker, Gerard R.

Attorney, Agent or Firm

Banner, Birch, McKie & Beckett

International Classes

G07D 7/00 (20060101)
G07D 7/04 (20060101)
H03K 17/95 (20060101)
H03K 17/94 (20060101)

Foreign Application Priority Data

1981-01-12 JP

Abstract

The metal detecting device includes first and second coils provided on both sides of a passageway for paper money. This metal detecting device is designed for use in detecting a metal strip embedded in the paper money in order to determine whether the paper money is genuine or counterfeit. The first coil is connected to a high frequency AC source to generate an AC magnetic field. The second coil is connected to a capacitor to form a resonance circuit which resonates at the same frequency as the AC current. The variation of the Q factor of the resonance circuit due to eddy-current losses produced in the metal strip of the paper money is used by a detecting circuit to determine whether the paper money passing through the space between the first and second coils is genuine.