Patent ID: 7175082

Claim:
A contactless data communication system, comprising: a contactless identification tag having tag identification information inherent to the contactless identification tag and comprising: a drive power generation means to generate drive power from an electromagnetic wave used for a power supply sent from a data communication system; an acquisition request receiving means to receive an acquisition request of the tag identification information from the data communication system; and an identification information sending means to send the tag identification information to the data communication system in response to the acquisition request of the tag identification information received by the acquisition request receiving means; the data communication system having a data communication system information inherent to the data communication system, the data communication system further comprising: an electromagnetic wave sending means for supplying power, which sends the electromagnetic wave used for the power supply to the contactless identification tag; an identification information acquisition means to acquire the tag identification information from the contactless identification tag existing within an area where communication is made; an information sending means to send the data communication system information inherent to the data communication system and the tag identification information acquired by the identification information acquisition means to other data communication systems; an information acquisition means to acquire the data communication system information inherent to the other data communication systems and the tag identification information acquired in the other data communication systems from the other data communication systems; and a position information computation means to compute position information of the contactless identification tag based on the data communication system information and the tag identification information acquired from the other data communication systems, and not acquired from the data communication system being used to compute position information of the contactless tag.