Tire pressure sensor system with improved power saving
First Claim
1. For use in a tire pressure sensor system having a variable resistance sensor for providing resistance values indicative of internal tire pressure when coupled to a pneumatic tire;
- a processor coupled to said sensor 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;
a power saving unit for limiting the application of electrical power to said variable resistance sensor, said power saving unit including an input terminal adapted to be coupled to a source of electrical power, an output terminal for supplying electrical power to said variable resistance sensor, and a vehicle speed sensitive switch for connecting said input terminal to said output terminal when said tire attains a first predetermined speed and for disconnecting said input terminal from said output terminal when the speed of said tire drops below said first predetermined speed.
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Accused Products
Abstract
A battery powered vehicle tire pressure sensor system has a power saving unit which controls the application of electrical power to the system as a function of tire speed to prolong battery life. The power saving unit has a power control switch which is responsive to tire angular speed. Each sensor assembly of the system is mounted on or in the side wall of a pneumatic tire to generate signals representative of tire pressure whenever power is applied. A processor periodically samples the signals. When the processor determines that the tire 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.
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Citations
20 Claims
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1. For use in a tire pressure sensor system having a variable resistance sensor for providing resistance values indicative of internal tire pressure when coupled to a pneumatic tire;
- a processor coupled to said sensor 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;
a power saving unit for limiting the application of electrical power to said variable resistance sensor, said power saving unit including an input terminal adapted to be coupled to a source of electrical power, an output terminal for supplying electrical power to said variable resistance sensor, and a vehicle speed sensitive switch for connecting said input terminal to said output terminal when said tire attains a first predetermined speed and for disconnecting said input terminal from said output terminal when the speed of said tire drops below said first predetermined speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- a processor coupled to said sensor for converting resistance values corresponding to inadequate internal tire pressure to r.f. generator activation signals; and
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17. A method of reducing power consumption in an electrically powered tire pressure sensor system having a variable resistance sensor for providing resistance values indicative of internal tire pressure when coupled to a pneumatic tire, a processor coupled to the sensor for converting resistance values corresponding to inadequate 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 the processor, said method comprising the steps of:
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(a) providing a source of electrical power; and (b) applying the electrical power to the variable resistance sensor for a tire pressure measurement period whose duration is related to tire speed. - View Dependent Claims (18, 19, 20)
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Specification