Tire condition monitoring apparatus

A transmitter, which is located in a tire of a vehicle and activated by a battery, the transmitter comprising:

• a tire condition sensor for detecting the condition of the tire;
• a transmission circuit for wirelessly transmitting data representing the tire condition;
• a voltage sensor, which detects a voltage of the battery;
• and
• an electricity control circuit, wherein, during a period from when the tire condition sensor detects the condition of the tire to when the transmission circuit starts transmitting the data, the electricity control circuit performs a transmission preparation process to gradually increase electricity supplied to the transmission circuit from the battery, thereby gradually increasing a radio wave output of the transmission circuit, and wherein, if the value of the voltage detected by the voltage sensor is lowered to a lowest operation voltage of the transmitter during the transmission preparation process, the electricity control circuit limits the supply of electricity to the transmission circuit from the battery.

A transmitter, which is located in a tire of a vehicle and activated by a battery, the transmitter comprising:

• a tire condition sensor for detecting the condition of the tire;
• a transmission circuit for wirelessly transmitting data representing the tire condition;
• a voltage sensor, which detects a voltage of the battery;
• and
• an electricity control circuit, wherein, after the tire condition sensor detects the condition of the tire, the electricity control circuit gradually increases electricity supplied to the transmission circuit from the battery, thereby gradually increasing a radio wave output of the transmission circuit, and wherein, if the value of the voltage detected by the voltage sensor reaches a lowest operation voltage before the value of the radio wave output reaches a predetermined value, the electricity control circuit limits the supply of electricity to the transmission circuit from the battery, such that the transmission circuit performs transmission at a radio wave output that is less than the predetermined value.