Patent ID: 7705719

Claim:
A detecting apparatus for detecting an air-pressure of a tire fitted around each of a plurality of wheels provided on a body of a vehicle, said detecting apparatus comprising: a triggering device provided on the body; a plurality of transmitters, one transmitter being provided on each of the plurality of wheels; and a receiver provided on the body; the triggering device sending a trigger signal to the plurality of transmitters so that the trigger signal reaches the plurality of transmitters; each of the plurality of transmitters comprising: a sensing unit sensing a datum representing the air-pressure of tire; a first receiving unit receiving the trigger signal from the triggering device; a first control unit getting the datum from the sensing unit, embedding the datum into a frame, and outputting the frame to when receiving the trigger signal; and a transmitting unit receiving the frame output from the first control unit and transmitting the frame at a timing; and the receiver comprising: a second receiving unit receiving the frame sent by each of the plurality of transmitters; a second control unit comprising: a calculating unit calculating the air-pressure of a tire fitted around each of the plurality of wheels based on the datum embedded in the frame; a judging unit judging whether or not the second receiving unit receives the frame at the timing of sending a frame by the transmitting unit; and a retrying unit commanding the triggering device to resend the trigger signal at a different timing from the timing of a transmitting frame by the transmitting unit of the transmitter when the judging unit judges that the second receiving unit fails to receive the frame.