Patent ID: 7135975

Claim:
A contactless data communication system, comprising: a reader-writer device; and a contactless identification tag, the reader-writer device including: a data communication means that is capable of data communications with the contactless identification tag; and an electromagnetic wave transmission means for supplying power that transmits an electromagnetic wave for supplying power to the contactless identification tag at the time of data communications by the data communication means; and the contactless identification tag including: a driving electric power generation means that generates driving electric power from the electromagnetic wave for supplying power transmitted from the reader-writer device; an attachment means that attaches the contactless identification tag to a given object; a detachment detection means that detects whether the contactless identification tag attached to the given object by the attachment means is detached from the given object; and a specific information display means which displays specific information based on a detection result obtained by the detachment detection means.