Christensen O'Connor Johnson & Kindness PLLC
Apparatus for detecting pressure condition in a pneumatic tire
 In an apparatus for detecting the pressure condition in a pneumatic tire on a vehicle body, a pressure-responsive resonant switching device is mounted on the pneumatic tire and is switchable between a first impedance state, where pressure in the pneumatic tire is within a predetermined normal operating pressure range, and a second impedance state, where the pressure in the pneumatic tire is not within the predetermined normal operating pressure range. An excitation unit is mounted on the vehicle body adjacent to the pneumatic tire. A controller supplies an excitation signal to the excitation unit in order to enable the latter to co-act with the resonant switching device by virtue of mutual induction according to the impedance state of the resonant switching device for inducing current in the resonant switching device as the resonant switching device is moved so as to be proximate with the excitation unit due to rotation of the pneumatic tire relative to the vehicle body. The controller monitors an output signal from the excitation unit and detects the presence of a change in the output signal of the excitation unit due to inducing of the current in the resonant switching device during a complete cycle of rotation of the pneumatic tire to enable the controller to determine the pressure condition in the pneumatic tire. 
B
B60C
inventional
Tien-Tsai
Huang