Patent ID: 7248166

Claim:
An imaging device for receiving a radio signal output from an RF tag attached to a subject to acquire identification information of said subject, comprising: an imaging unit operable to continuously image a plurality of subjects to acquire a moving image; a radio receiver operable to receive a plurality of radio signals respectively output from RF tags attached to said plurality of subjects to acquire a plurality of units of subject identification information respectively indicated by said plurality of radio signals, said subject identification information being information for identifying a corresponding one of said subjects, said radio receiver moving together with said imaging unit and having directivity in a direction approximately the same as an imaging direction of said imaging unit; a moving amount calculation unit operable to calculate a moving amount of said radio receiver based on said moving image acquired by said imaging unit; and a subject direction specifying unit operable to specify directions of said plurality of subjects that are identified by said plurality of units of subject identification information acquired by said radio receiver based on changes in field intensities of said plurality of radio signals received by said radio receiver, respectively, said changes corresponding to said moving amount of said radio receiver calculated by said moving amount calculation unit.