The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 25, 2003
Filed:
Feb. 15, 2000
Applicant:
Inventors:
Assignee:
Fijitsu Limited, Kawasaki, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06K 1/906 ; G06K 5/00 ;
U.S. Cl.
CPC ...
G06K 1/906 ; G06K 5/00 ;
Abstract
A circuit, of a simple structure, for detecting the presence or absence of a proximity IC card (PICC) in a proximity coupling device (PCD) which transmits data to and receives data from the PICC. This circuit includes an antenna for receiving a carrier signal outputted to a proximity IC card, a D.C. detecting device for rectifying a carrier signal received from the antenna and for detecting a D.C. component of the received carrier signal, and a level judgment device for determining the level of the D.C. component detected by the D.C. detecting device and for judging, when the level of the direct component is within a predetermined range that a proximity IC card is present in an RF field.