Patent ID: 7137296

Claim:
A tire air pressure monitoring system comprising: a tire air pressure detecting device coupled to each tire of a vehicle including a pressure detecting section configured and arranged to detect a tire air pressure, a transmitting section configured and arranged to transmit a wireless signal indicative of at least the tire air pressure detected by the pressure detecting section, and a transmission control section operatively coupled to the pressure detecting section and the transmitting section, and configured to selectively control transmission of the wireless signal from the transmitting section to selectively operate a rest mode, a normal mode in which the wireless signal is transmitted in at least a first prescribed interval, and a generally continuous transmission mode in which the wireless signal is transmitted in a continuous transmission interval that is shorter than the first prescribed interval; and a tire air pressure alarm control device coupled to the vehicle including a receiving section configured and arranged to receive the wireless signal from the transmitting section of the tire air pressure detecting device, and an alarm control section configured to issue an alarm when the tire air pressure is equal to or less than a prescribed pressure, the transmission control section of the tire air pressure detecting device being further configured to shift from the rest mode to the generally continuous transmission mode upon determination of decrease in the tire air pressure by an amount equal to or greater than a prescribed amount within a prescribed period of time, and to shift from the generally continuous transmission mode to the normal mode upon determination of a continuous transmission termination condition that indicates the receiving section of the tire air pressure alarm control device can receive the wireless signal.