Patent ID: 7920051

Claim:
An information providing system comprising: a wireless sheet attached to an article; and an information notifying apparatus that sends a first request signal and a second request signal having a different frequency from the first request signal, the second request signal being sent based on a response signal sent from the wireless sheet in response to the first request signal, wherein, the wireless sheet comprises a wireless measuring unit which, when receiving the request signal, generates and sends the response signal by using the received request signal as an energy source, the response signal including identification data when the request signal is the second request signal and data of physical quantity measured in the wireless sheet when the request signal is the first request signal, the wireless measuring unit comprising: an exciter that receives the request signal and generates a mechanical vibration; a vibration medium on which a surface acoustic wave is generated by a mechanical vibration that is generated by the exciter, and on which an attribute of the surface acoustic wave changes due to a distortion of the vibration medium by a physical quantity; and a transmitter that converts a surface acoustic wave generated on the vibration medium to an electrical signal and sends the electrical signal as the response signal; and the information notifying apparatus comprises: a radio unit that exchanges request and response signals with the wireless sheet and that transmits the first request signal to the wireless sheet; a storage unit that stores the identification data and the article information in association with each other; a notifying unit that extracts from the response signal at least one of the identification data and the measured data of physical quantity data, and under the condition that the measured data is extracted and the extracted measured data indicates that the physical quantity is being applied, the radio unit transmits the second request to the wireless sheet, and under the condition that the identification information is extracted, the notifying unit reads the article information stored in association with the identification data in the storage unit, and notifies the article information and the measured data of physical quantity; and a distance calculation unit that calculates a distance between the information notifying apparatus and the wireless sheet on the basis of the response signal, wherein the physical quantity is pressure.