Patent ID: 7113083

Claim:
A passive keyless entry device for monitoring a tire pneumatic pressure by bidirectional communication comprises: a car mounting device mounted to an automobile; a keyless entry portable device; and a transmitter-receiver for monitoring the tire pneumatic pressure, wherein said car mounting device comprises a low frequency signal transmitting section for transmitting a request signal of a low frequency to said keyless entry portable device and said transmitter-receiver for monitoring the tire pneumatic pressure, a receiving section for a keyless entry for receiving an answer signal of a high frequency responsive to said request signal from said keyless entry portable device, a receiving section for monitoring the tire pneumatic pressure for receiving the answer signal of the high frequency responsive to said request signal from said transmitter-receiver for monitoring the tire pneumatic pressure, and a controller for forming said request signal and controlling operation of a door lock mechanism in response to said answer signal and obtaining tire pneumatic pressure information.