Patent ID: 6922142

Claim:
A tire air pressure monitoring system comprising: a sensor unit mounted on a tire of a vehicle for measuring an air pressure of said tire and for transmitting a signal including an air pressure measurement value intermittently; and a monitoring unit mounted on a body of said vehicle for receiving the transmitted signal from said sensor unit to monitor an air pressure state of said tire on the basis of said air pressure measurement value included in the transmitted signal, said monitoring unit includes: timing acquiring means for acquiring a transmission timing at which a signal is transmitted from said sensor unit; and mode switching means for, in synchronism with said signal transmission timing acquired by said timing acquiring means, setting said monitoring unit in a monitoring processing mode to receive the transmitted signal and monitor said tire air pressure state and for setting said monitoring unit in a sleep mode to rest its monitoring processing function for a period of time from when monitoring processing in said monitoring processing mode reaches completion until the next signal transmission timing.