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Quick registering thermometer

  • US 6,059,452 A
  • Filed: 03/09/1998
  • Issued: 05/09/2000
  • Est. Priority Date: 12/23/1994
  • Status: Expired due to Fees
First Claim
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1. A quick registering thermometer for displaying the core body temperature of a mammal, the thermometer comprising:

  • a housing having a probe adapted to contact the skin of the mammal, the probe at least partially comprised of a heat insulating material;

    temperature responsive means having electrical resistance varying with temperature, the temperature responsive means mounted on the periphery of the heat insulated portion of the probe to contact the skin when the probe is applied thereto, wherein the temperature responsive means contact the skin'"'"'s surface in the concha when the probe is inserted into the ear;

    means for detecting the changes in the resistance of the temperature responsive means;

    means for converting the detected changes in resistance of the temperature responsive means to signals representative of core body temperature;

    means for displaying the core body temperature;

    wherein the means for detecting the changes in the resistance of the temperature responsive means comprises;

    a reference resistor coupled to one end of said temperature responsive means to form a series electrical circuit;

    a constant current source coupled to said series electrical circuit for providing a constant current thereto;

    a first amplifier coupled to said series circuit at said one end of said temperature responsive means between said responsive means and said reference resistor for providing an output that is the amplified analog voltage drop across said reference resistor;

    a second amplifier coupled to said series electrical circuit at the other end of said responsive means for providing an output that is the amplified analog voltage drop across said series circuit; and

    an analog-to-digital converter having first and second input terminals respectively coupled to said first and second amplifier outputs for converting the difference in said amplifier analog voltages to a digital signal;

    wherein said series electrical circuit further comprises a microprocessor; and

    ,wherein said microprocessor calculates the temperature at which the temperature responsive means would move to thermal equilibrium, Tf, wherein
    
    
    space="preserve" listing-type="equation">T.sub.f =Tn-1-Tn 1-e.sup.-1k +TnwhereinTn-1=the temperature at time, N+1,Tn=the temperature at time, N,T=the time since the last measurement and is a constant; and

    k=the coefficient of heat transfer determined experimentally.

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