Tire pressure sensor system with improved sensitivity and power saving
First Claim
1. In a tire pressure sensor system having a variable resistance displacement sensor for providing resistance values indicative of internal tire pressure when coupled to a pneumatic tire;
- a processor coupled to said displacement sensor element for converting resistance values corresponding to inadequate internal tire pressure to r.f. generator activation signals; and
an r.f. generator circuit for transmitting an unsafe tire pressure warning signal when activated by said processor;
the improvement wherein said variable resistance displacement sensor comprises a variable resistance sensor assembly having first and second individual stretch sensors, each said stretch sensor having a first flexible layer containing a variable resistance element and a second flexible support layer, said individual stretch sensors being arranged with said first flexible layer of said first stretch sensor in facing relation with said first flexible layer of said second stretch sensor.
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Accused Products
Abstract
A battery powered tire pressure sensor system with a high sensitivity stretch sensor assembly having a variable resistance longitudinal displacement characteristic. The stretch sensor assembly has at least two juxtaposed stretch sensors, each with a first layer bearing the variable resistance element and a second support layer. The sensor assembly is mounted on or in the side wall of a pneumatic tire so that the assembly is displaced by the tire side wall and the resistance is a function of internal tire pressure. The assembly is coupled to a processor which samples the resistance of the stretch sensor assembly periodically. When the processor determines that the pressure is outside a safe range, an r.f. generator is activated by the processor to generate an unsafe tire pressure signal. This signal is converted by a receiver to a warning for the driver. A power saving unit controls application of electrical power to the system as a function of tire speed to prolong battery life.
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Citations
11 Claims
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1. In a tire pressure sensor system having a variable resistance displacement sensor for providing resistance values indicative of internal tire pressure when coupled to a pneumatic tire;
- a processor coupled to said displacement sensor element for converting resistance values corresponding to inadequate internal tire pressure to r.f. generator activation signals; and
an r.f. generator circuit for transmitting an unsafe tire pressure warning signal when activated by said processor;
the improvement wherein said variable resistance displacement sensor comprises a variable resistance sensor assembly having first and second individual stretch sensors, each said stretch sensor having a first flexible layer containing a variable resistance element and a second flexible support layer, said individual stretch sensors being arranged with said first flexible layer of said first stretch sensor in facing relation with said first flexible layer of said second stretch sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- a processor coupled to said displacement sensor element for converting resistance values corresponding to inadequate internal tire pressure to r.f. generator activation signals; and
Specification