Patent ID: 6885293

Claim:
A tire air pressure monitoring system comprising: a plurality of sensor units each provided in each of tires of a vehicle for measuring an air pressure of the corresponding tire and for transmitting a transmission signal including the air pressure measurement value; and a monitoring unit for receiving said transmission signal from each of said plurality of sensor units to monitor an air pressure state of each of said tires on the basis of the air pressure measurement value included in said transmission signal, wherein said monitoring unit includes a plurality of transmitting means provided in a state associated with said plurality of sensor units, respectively, and each of said transmitting means transmits an instruction signal calling for the transmission of said transmission signal and has a transmission zone so that said instruction signal reaches only the corresponding sensor unit, and each of said plurality of sensor units includes receiving means for receiving said instruction signal and, when receiving said instruction signal, said receiving means transmits said transmission signal in response to said instruction signal.