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Interrogating system for remotely monitoring tire air pressure

  • US 4,363,020 A
  • Filed: 12/22/1980
  • Issued: 12/07/1982
  • Est. Priority Date: 12/22/1980
  • Status: Expired due to Fees
First Claim
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1. An interrogating system for remotely monitoring the air pressure in a tire mounted on a wheel of a vehicle, comprising:

  • a passive transponder attached to the wheel and including a semiconductor diode having anode and cathode elements;

    a relatively rigid, self-supporting metallic conductor directly connected to and extending from one of the diode'"'"'s elements to provide an antenna for the diode;

    sensing means for sensing the air pressure within the tire;

    a movable electromagnetic shield for the antenna; and

    means controlled by said sensing means for positioning said shield, with respect to the antenna and in response to the sensed tire air pressure, so that the shield surrounds the antenna when the tire air pressure is within a predetermined desired normal range thereby shielding the antenna from radiation, and so that the antenna extends out of the shield and is exposed to radiation when the sensed tire air pressure is either above or below the desired normal range;

    transmitting means in the vehicle for transmitting electromagnetic radiation to said passive transponder to effectively interrogate said transponder, said diode responding to the received radiation, when said antenna is exposed, and generating a response signal which is retransmitted from said antenna;

    and receiving means in the vehicle for receiving said response signal and for producing therefrom an output for controlling an indicator to provide an indication to the driver of the vehicle that the tire air pressure is outside of the desired normal range.

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