Thermal measuring and testing – Differential thermal analysis
Reexamination Certificate
1998-01-16
2001-12-18
Barlow, John (Department: 2859)
Thermal measuring and testing
Differential thermal analysis
C374S031000, C219S209000
Reexamination Certificate
active
06331074
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermal analyzer used for examination of physical and chemical states in relation to heat of substance as well as to a method of measuring with the same, and more specifically to a thermal analyzer which can obtain information such as a melting point of an extremely minute quantity of substance, a transmit temperature, change in mass of the substance, a boiling point, specific heat types and quantities of contained substances, thermal change or change in mass associated with a chemical reaction, and a method of measuring with the same.
BACKGROUND OF THE INVENTION
As a thermal analyzer based on the conventional technology, there is, for instance, a differential thermal analyzer, or a differential scan calorimeter (DSC) based on the compensation system. The differential thermal analyzer is an apparatus which measures and records temperature difference as a function of time or temperature between a substance as an object for thermal analysis and a reference substance both put under conditions for heating or cooling the samples at an adjusted rate.
The differential scan calorimeter based on the compensation system compensates for a temperature difference between a sample to be measured and a reference substance with a heater of a compensating circuit, and records the compensation rate (difference in an energy supply rate).
Further as a thermal analyzer based on the conventional technology, there is an apparatus which uses a magnetic balance and detects changes in magnetized rate based on transmit temperature such as the Curie temperature, when scanning temperature of a magnetic body, by detecting a force in and inhomogeneous magnetic field; or an apparatus like vibrating sample type of magnetometer (VSM) which vibrates a sample magnetized with a magnet at a low frequency and detects changes of a magnetic field caused by change of a space with a magnetism sensor such as a coil to detect change of change in magnetized rate at transmit temperature such as Curie temperature when scanning temperature.
However, with the thermal analyzers based on the conventional technology as described above, efforts for size reduction can be recognized in each of the apparatus, but the apparatuses have the configuration in which heaters each manufactured independently are arrayed, so that the total quantity of heat generated by these heaters is large with the response rather dull and for this reason there is no way but to increase a quantity of sample to be measured, and in addition each heater requires a large power, and when high temperature such as several hundred degrees is required, it is difficult to shield the generated heat, and because of this problem, the size of each apparatus inevitably becomes larger, and further it is disadvantageously difficult to achieve homogeneity in temperature, and also it is difficult to equalize characteristics of a heater for a sample to be measured to those of a heater for a standard sample.
Also as for a thermocouple or a thermopile as a temperature sensor for detecting temperature, those independently manufactured are inserted and contacted to each other, and size of each apparatus based on the conventional technology inevitably becomes larger for considerations to a problem of thermal contact, the problems concerning size of each component, and the necessity for a wiring space, and as a result the cost of each apparatus becomes very expensive.
Also the conventional type of thermal analyzers each based on a magnetic body such as a magnetic balance or a VSM have problems such as that the size is large, or that a magnet having a large size is required for raising the detection sensitivity as amplitude of a magnetic field becomes abruptly smaller when it gets away from a magnetic pole.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thermal analyzer which enables measurement with an extremely small quantity of sample by heating the sample with a heater having an extremely small heat capacity and can heat the sample with a minute current up to high temperature with a high response speed, and further which can be produced in mass with the unified specifications.
It is another object of the present invention to provide a thermal analyzer which enables a high speed response with a minute current.
The thermal analyzer according to the present invention scans temperature by thermally altering a sample and measuring a thermal change based on physical and chemical changes of the sample as a function of time and/or temperature. The thermal analyzer includes a heat-generating section for heating a sample. The heat-generating section includes a first semiconductor substrate of a first conductivity type forming a thin-film heater with a cavity section in a lower section thereof and a second semiconductor substrate of a second conductivity type connected to the first substrate. The cavity section forms a sample holding section for holding the sample. The thermal analyzer further includes a temperature detecting section for detecting a temperature of the sample holding section. The sample holding section and the temperature detecting section are monolithically formed on the thin-film heater or an area proximate the thin-film heater in a thin-film supporting section for supporting the thin-film heater.
In the measuring method with a thermal analyzer according to the present invention, when temperature scanning is executed with the thermal analyzer by letting a current flow through a thin-film heater, a current component for heating or cooling a sample at a constant rate is superimposed over an AC current component for minutely changing temperature, and a temperature change component corresponding to the AC current component is taken out as a signal from the temperature detecting unit; and the signal is subjected to a prespecified processing, and for that purpose the thermal analyzer according to the above invention has a high responsibility, so that a current component for heating or cooling a sample at a constant rate can be superimposed over an AC current component for minutely changing temperature. In other words, the measuring method with a thermal analyzer having a high responsibility even at a minute power can be provided.
Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.
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Barlow John
Fernandez Maria
Olbon, Spivak, McClelland, Maier & Neustadt, P.C.
Ricoh & Company, Ltd.
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