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:
May. 04, 2004
Filed:
Jul. 26, 1999
Takashi Ueda, Kyoto, JP;
Rohm Co., Ltd., Kyoto, JP;
Abstract
In a non-contact communication system, when an interrogator is attempting to detect that a responder is present in a range communicable therewith, the interrogator transmits a weak radio wave from its tuning circuit. The responder receives this radio wave and acquires electric power by rectifying it, but, because the electric power thus obtained is insufficient, the responder is turned on and off repeatedly at regular intervals. This causes variation in the impedance with which the tuning circuit is loaded. The interrogator, by detecting this variation in the impedance occurring at regular intervals, recognizes that the responder is present within the range communicable therewith. Only then, the interrogator transmits a radio wave strong enough to permit the responder to acquire sufficient electric power.