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US 5,842,788 AGranted
Differential scanning calorimeter
AssigneeTA Instruments, Inc.
InventorsRobert L. Danley, John R. Reader, Jr., John W. Schaefer
Life of this patent
Estimating the term…
Abstract
A Differential Scanning Calorimeter (DSC) which has constant calorimetric sensitivity over its entire range of operating temperatures from -200.degree. C. to 540.degree. C. The DSC sensor consists of a pair of thin-film Resistance Temperature Detectors (RTDs) which are used to sense the temperature of a sample and the temperature difference between the sample and an inert reference. The RTDs are supplied with an excitation current which varies according to the temperature of the reference to achieve constant calorimetric sensitivity, independent of the operating temperature.
Claims26
A sensing system for a differential scanning calorimeter comprising:
- (a) an electrically insulating substrate;
- (b) a sample thin-film resistance temperature detector sensor having a sample output and mounted in a sample region on the electrically insulating substrate;
- (c) a reference thin-film resistance temperature detector sensor having a reference output and mounted in a reference region on the electrically insulating substrate;
- (d) sample current means for providing a sample current to the sample temperature detector sensor for producing a sample output voltage across the sample resistance temperature detector sensor and reference current means for providing a reference current to the reference current detector sensor for producing a reference output voltage across the reference resistance temperature detector sensor;
- (e) a sample temperature amplifier amplifying the sample output voltage and a reference temperature amplifier amplifying the reference output voltage;
- (f) a sample temperature calculation function calculating a temperature for the sample region;
- (g) a reference temperature calculation function calculating a temperature for the reference region;
- (h) means for determining the amplitude of the sample current and means for determining the amplitude of the reference current;
- (i) means for amplifying the difference between the temperature of the sample region and the temperature of the reference region;
- and
- (j) means for calculating a differential heat flow to the sample with respect to the reference from the amplified difference between the temperature of the sample region and the temperature of the reference region,
- wherein the determined amplitude of the sample current and the determined amplitude of the reference current are modified so as to obtain an amplitude for said currents such that the calorimeter has constant calorimetric sensitivity over a desired temperature range.
9 more elements
A method for measuring the differential heat flow to a sample with respect to a reference comprising:
- (a) providing a sample thin-film resistance temperature detector sensor deposited on a sample region on a first surface of an electrically insulating substrate and a reference thin-film resistance temperature detector sensor deposited on a reference region on the first surface of the electrically insulating substrate;
- (b) placing a sample in a sample pan and a reference pan on a surface of the electrically insulating substrate opposite to the first surface of the electrically insulating substrate;
- (c) providing a sample sensing current to the sample thin-film resistance temperature detector, said sample sensing current producing a sample output voltage across the sample resistance detector, and providing a reference sensing current to the reference thin-film temperature detector, said reference sensing current producing a reference output voltage across the reference resistance detector;
- (d) measuring the amplitude of the sample output voltage and measuring the amplitude of the reference output voltage;
- (e) determining the amplitude of the sample sensing current and the amplitude of the reference sensing current, and modifying the determined amplitudes of said sample and reference sensing currents so as to obtain amplitudes for said sensing currents such that the calorimeter provides constant calorimetric sensitivity over a desired temperature range;
- (f) calculating the temperature of the sample region and the temperature of the reference region from the amplitude of the sample output voltage and the amplitude of the reference output voltage;
- (g) amplifying the difference between the temperature of the sample region and the temperature of the reference region;
- and
- (h) calculating a differential heat flow to the sample with respect to the reference from the amplified difference between the temperature of the sample region and the temperature of the reference region.
6 more elements
A differential scanning calorimeter comprising:
- (a) an electrically insulating ceramic substrate having a top surface and a bottom surface;
- (b) a sample thin-film resistance temperature detector sensor deposited on the bottom surface of the electrically insulating ceramic substrate;
- (c) a reference thin-film resistance temperature detector sensor deposited on the bottom surface of the electrically insulating ceramic substrate;
- (d) a protective layer of dielectric covering the sample thin-film resistance temperature detector sensor and a protective layer of dielectric covering the reference thin-film resistance temperature detector sensor;
- (e) a sample in a sample pan placed on the top surface of the ceramic substrate opposite to the sample thin-film resistance temperature detector sensor, and a reference pan placed on the top surface of the ceramic substrate opposite to the reference thin-film resistance temperature detector sensor;
- (f) means for applying a sample sensing current to the sample thin-film resistance temperature detector and means for applying a reference sensing current to the reference thin film temperature detector;
- (g) means for measuring a sample output voltage across the sample thin-film resistance temperature detector sensor and means for measuring a reference output voltage across the reference thin-film resistance temperature detector sensor;
- and
- (h) means for calculating the temperature of the sample pan from the sample output voltage, and means for calculating the temperature of the reference pan from the reference output voltage;
- (i) means for determining and amplifying the difference between the temperature of the sample pan and the temperature of the reference pan;
- and
- (j) means for calculating the differential heat flow to the sample from the amplified difference between the temperature of the sample pan and the temperature of the reference pan,
- wherein the amplitudes of the sample sensing current and the reference sensing current are determined and modified so as to obtain amplitudes for said sensing currents so as to provide constant calorimetric sensitivity for the calorimeter over a desired temperature range.
10 more elements
A sensing system for a differential scanning calorimeter comprising:
- (a) a metallic disk;
- (b) a sample thin-film resistance temperature detector sensor mounted in a sample region of the metallic disk;
- (c) a reference thin-film resistance temperature detector sensor mounted in a reference region of the metallic disk;
- (d) sample current means for producing a sample sensing current for the sample sensor and reference current means for producing a sensing current for the reference sensor, said sample current means producing a sample output voltage and said reference current means producing a reference output voltage;
- (e) a sample temperature amplifier amplifying the sample output voltage and a reference temperature amplifier amplifying the reference output voltage;
- (f) a sample temperature calculation function calculating a temperature for the sample region:
- (g) a reference temperature calculation function calculating a temperature for the reference region;
- (h) means for determining the amplitude of the sample sensing current and the amplitude of the reference sensing current and for modifying the determined amplitudes of said sensing currents so as to obtain amplitudes for said sensing currents such that the calorimeter provides constant calorimetric sensitivity over a desired temperature range;
- (i) means for determining and amplifying the difference between the temperature of the sample region and the temperature of the reference region;
- and
- (j) means for calculating the amplitude of the differential heat flow to the sample with respect to the reference from the amplified difference between the temperature of the sample region and the temperature of the reference region.
8 more elements
Dependencies are inferred from the claim text.