Tire condition monitoring apparatus

摘要

A tire monitoring apparatus includes transponders and a transmitter-receiver. Each transponder is provided in one of the tires of a vehicle, and the transmitter-receiver is mounted on the body frame of the vehicle. In response to a predetermined interrogating radio wave, each transponder detects a condition of the corresponding tire and wirelessly transmits data representing the detected condition of the tire. The transmitter-receiver transmits the interrogating radio wave and receives data wirelessly transmitted by each transponder. In a part of a period during which the corresponding tire rotates through one revolution, each transponder passes through a communication range. The transmitter-receiver changes the time interval at which the interrogating radio wave is transmitted such that the interrogating radio wave is transmitted while the transponder is in the communication zone. As a result, the conditions of the tires are always monitored in a reliable manner.