Quick registering thermometer
First Claim
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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Accused Products
Abstract
A quick registering thermometer utilizing a sensor that has electrical resistance varying with temperature located at the tip of a probe, the sensor having relatively small thermal mass and short thermal time constant. Within seconds of contact with the patient, the circuitry communicating with the sensor determines the rate of change in resistance of the sensor and, in turn, the temperature that the sensor would reach if allowed the length of time it would need to reach equilibrium with the contact surface of the patient. Based on the equilibrium temperature determined for the surface of the patient, the circuitry calculates and registers the core body temperature.
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Citations
17 Claims
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1. A quick registering thermometer for displaying the core body temperature of a mammal, the thermometer comprising:
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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 +Tnwherein Tn-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. - View Dependent Claims (2, 3, 4, 5)
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6. A quick registering thermometer comprising:
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a housing having a probe, the probe at least partially comprised of a heat insulating material; temperature responsive means having electrical resistance properties that vary with temperature, the responsive means mounted on the periphery of the heat insulated portion of the probe; means communicating with the temperature responsive means for detecting the changes in the resistance of the responsive means; means communicating with the detecting means for converting the detected changes in resistance of the temperature responsive means to electrical signals representing a calculated temperature; means communicating with the converting means for displaying the calculated 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; a noise filter including a capacitor coupled from each end of the responsive means to ground for high frequency noise filtering; and a paralleled set of capacitors coupled across said responsive means for providing high frequency and low frequency noise filtering. - View Dependent Claims (7, 8)
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9. A quick registering thermometer comprising:
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a housing having a probe, the probe at least partially comprised of a heat insulating material; temperature responsive means having electrical resistance properties that change with temperature, the responsive means mounted on the periphery of the heat insulated portion of the probe; 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, the converter converting said amplifier analog voltages to a digital signal; means communicating with the temperature responsive means for converting changes in resistance of the temperature responsive means to electrical signals representing a calculated temperature; and
,means communicating with the converting means for displaying the calculated temperature; wherein a microprocessor samples said digital signal from the analog-to-digital converter representing the instantaneous voltage across said temperature responsive means at four equally spaced time intervals during one cycle; and said microprocessor averages said four samples to substantially cancel 60-cycle noise. - View Dependent Claims (10, 11, 12, 13, 14)
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12. A thermometer as in claim 11 wherein:
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said microprocessor has first and second data storage registers; and said microprocessor averages the digital signal samples in groups that are factors of two to allow each sample to be shifted in said first register.
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13. The thermometer of claim 9, further comprising error adjustment means to adjust upward the displayed temperature an amount determined from an initial resistance of the temperature responsive means.
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14. The thermometer of claim 9 further comprising error adjustment means to adjust the displayed temperature an amount determined from the number of readings the temperature had been displayed in a preceding period of time.
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15. A quick registering thermometer comprising:
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a housing having a probe, the probe at least partially comprised of a heat insulating material; temperature responsive means having electrical resistance properties that vary with temperature, the responsive means mounted on the periphery of the heat insulated portion of the probe; 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; 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; means communicating with the detecting means for converting the detected changes in resistance of the temperature responsive means to electrical signals representing a calculated temperature; and
,means communicating with the converting means for displaying the calculated temperature. - View Dependent Claims (16, 17)
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Specification