High resolution digital thermometer
AssigneeThe United States of America, as represented by the Secretary, Department of Health and Human Services
InventorsWalter S. Friauf, Thomas R. Clem, Sr., Robert L. Berger
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Abstract
A high resolution digital thermometer capable of measuring temperature differences on the order of several micro-degrees centigrade. The device includes a bridge circuit having two thermistors in series. An output of the bridge circuit feeds a signal to an analog-to-digital convertor via a high gain amplifier. A computer maintains the balance of the bridge circuit to avoid a situation wherein the range of the analog-to-digital convertor would be exceeded.
Claims13
A high resolution digital thermometer which comprises:
- a bridge circuit;
- first and second thermistors arranged in series in said bridge circuit;
- a high gain amplifier connected to an output of said bridge circuit;
- an analog-to-digital converter connected to an output of said high gain amplifier;
- and
- a computer means for initiating and maintaining said bridge circuit in a balanced state.
In a device for measuring temperature differences between two thermistors in a bridge circuit, the improvement comprising a computer means for initiating and maintaining said bridge circuit in a balanced state, wherein said computer means includes a means for supplying control signals to said bridge circuit, means for receiving output signals from said bridge circuit and means for calculating temperature differences between said thermistors.
A method of measuring temperature differences which comprises:
- providing a bridge circuit containing first and second thermistors, wherein an output of said bridge circuit is connected to a high gain amplifier and an output of said high gain amplifier is connected to an analog-to-digital converter;
- balancing said bridge circuit with a computer means;
- exposing said second thermistor to a thermal environment different from that of said first thermistor;
- and
- determining temperature differences between the first and second thermistors from the output of said analog-to-digital converter.
Dependencies are inferred from the claim text.