Patent Number: 7,710,242

Title: Information access system and active-type contactless information storage device

Abstract: A contactless information storage device for use in an information access system includes a receiver unit and a transmitter unit. The receiver unit is operable to sense a carrier at a first frequency in a slave mode and be continuously ready to receive an RF signal at a second frequency different from the first frequency in a master mode. In the slave mode, the transmitter unit transmits a response signal at the second frequency in response to reception of an information request signal. In the master mode, the transmitter unit cyclically transmits an information request signal at the first frequency in a transmission period and goes into an inactive state in a sleep period. In the slave mode, the transmitter unit and the receiver unit are caused to go into the master mode, when the receiver unit receives no information request signal in a time period longer than given periods.

Inventors: Yamada; Isamu (Kawasaki, JP), Shiotsu; Shinichi (Kawasaki, JP), Inano; Satoshi (Kawasaki, JP), Itasaki; Akira (Kawasaki, JP)

Assignee: Fujitsu Limited

International Classification: H04Q 5/22 (20060101); G08B 13/14 (20060101)

Expiration Date: 5/04/12018