Patent ID: 7786936

Claim:
A position information detection system comprising: a first RF chip; a second RF chip; and a reader/writer which transmits and receives data by transmission and reception of a radio signal to/from the first RF chip and the second RF chip, wherein the first RF chip has a function to detect a first signal intensity of a radio signal transmitted from the reader/writer, a function to calculate a first calculated distance from the first signal intensity, and a function to transmit data on the first calculated distance to the reader/writer; wherein the second RF chip has a function to detect a second signal intensity of a radio signal transmitted from the reader/writer, a function to calculate a second calculated distance from the second signal intensity, and a function to transmit data on the second calculated distance to the reader/writer; and wherein the reader/writer has a function to calculate a position of the second RF chip from the first calculated distance, the second calculated distance, a position of the first RF chip, and a position of the reader/writer.