JP4135181B2 - Thermocouple system for heating measurement - Google Patents

Description

  The present invention relates to a thermocouple system for heating measurement in which a thermocouple method having a sample holding function, a heater function, and a temperature detection function is improved with respect to a temperature control function, sample observation and data recording. is there.

Technical background

  In conventional high-temperature science research, as a device for directly observing the molten state and the reaction between the melt and the solid, as the heating power source, the filament with the thermocouple formed at half the commercial frequency is heated and the remaining half cycle In this case, there is a method in which the heating current flowing in the filament is interrupted by a silicon rectifier, connected to a temperature measuring circuit by a high-speed relay, and the thermoelectromotive force is detected and recorded by a DC voltage measuring device. In the hot thermocouple method described in thermal measurement 13 (2) 1986, a heat-resistant and corrosion-resistant R thermocouple is used as a heating filament and temperature measuring element, and the thermocouple is attached to a sample container made of hard glass and equipped with cooling means. The sample to be observed is held on the surface and observed with a stereomicroscope while heating and cooling the sample. For example, the melting and solidification process of the mineral sample can be directly observed and recorded along with the temperature, or the liquid phase in the glass forming system. The line temperature can be determined.

  Although no method corresponding to the hot thermocouple method is found in the patent publication, Japanese Patent Application Laid-Open No. 2002-107317 discloses a high-temperature observation apparatus that observes changes in the appearance of a sample while heating and cooling the sample and detecting the temperature. As described above, a high-temperature observation apparatus for observing a change due to a heating temperature of a sample, which is a high-temperature chamber having an airtight structure, a sample stage disposed in the center of the high-temperature chamber and mounting a sample, and a sample on the sample stage Heating means and cooling means for heating and cooling, temperature detection means for detecting the temperature of the sample heated and cooled by these heating means and cooling means, and heating means and cooling based on the detection result of this temperature detection means Control means for controlling the means, at least one image pickup means for picking up an image of the sample temperature-controlled by the control means through an observation window provided in the high temperature chamber, and the image pickup means There is high temperature observation apparatus provided with a monitor displaying an image video.

  Further, the sample stage includes a substrate on which the sample is placed and a support body connected to the substrate via a heat insulating member, and the heating means sandwiches the sample stage diagonally above both sides of the sample stage. Two upper heaters arranged side by side in this manner, and two lower heaters arranged side by side at a position sandwiching the sample table diagonally below both sides of the sample table and arranged narrower than the distance between the upper heaters The temperature detecting means has a thermocouple, and the thermocouple is inserted into a recessed portion formed on the back surface of the substrate.

Reference 1

Kenji Morinaga, Kunihiko Nakajima, Norio Ota, Thermal Measurement 13 (2) 1986
JP 2002-107317 A

  The hot thermocouple method described in the above document has a small sample amount and a small heat capacity of a thermocouple as a heating means, so it can be rapidly heated and cooled, and can be measured up to a high temperature of 1900K. Although recording is possible, manual control, such as temperature control such as temperature rise and temperature drop, observation recording, etc. requires technique and patience, long measurement time, heavy burden on the measurer, and heat cycle is heat Since the electromotive force cannot be captured, a sag (voltage drop) occurs in the measurement voltage due to the measurement circuit time constant, resulting in an error in the direct reading value. Therefore, it is necessary to correct the measurement value with a standard sample (NaCl) or the like. There was a drawback.

  In addition, the high-temperature observation apparatus described in Japanese Patent Application Laid-Open No. 2002-107317 performs temperature detection using a thermocouple, but is provided with a heater and a sample stand separately from the thermocouple. Since the function, heater function and sample holding function are not provided, the heat capacity of the sample stage is large, and the sample cannot be heated or cooled rapidly. Also, there is a difference between the sample temperature and the detected temperature. It tends to occur, and the configuration and contents are different from those of the present invention. In a conventional thermal analyzer such as a differential thermal analyzer, visible data on the melting point, freezing point, and transformation point of a sample cannot be obtained, and further, the operation is not easy. Further, since the temperature detection is a mechanism for detecting the external temperature of the sample pan, there is a drawback that it is not sensitive to subtle temperature changes.

  An object of the present invention is to improve a temperature control function, sample observation, data recording, and the like in a thermocouple having a temperature detection, a heater function, and a sample holding function.

In order to solve the above problem, a thermocouple holding the sample to be observed is switched at a predetermined frequency using a variable direct current, and a voltage is applied to the thermocouple with a half-cycle rectangular wave to generate a heating current. The thermocouple and the sample are heated to flow, the heating current flowing through the thermocouple is shut off in the remaining half cycle, the thermoelectromotive force of the thermocouple is detected by the temperature measurement signal at the temperature measurement timing, the temperature is measured, and the sample is determined A heating measurement unit for observing temperature, an automatic temperature increase for automatically increasing the temperature according to a preset temperature increase gradient, an automatic temperature decrease for automatically decreasing according to a preset temperature decrease gradient, a predetermined value A setting operation unit that can perform setting operations such as maintenance of observation temperature, temperature recording at a predetermined point, and data recording at start and end , and heating the heating measurement unit by energizing the thermocouple Power supply and A measurement unit that measures the thermoelectromotive force of the thermocouple, a heating measurement switching unit that switches between the heating power supply unit and the measurement unit by switching at a predetermined frequency, and an analog temperature signal based on the thermoelectromotive force measured by the measurement unit is converted to digital An A / D converter, a controller that receives and controls the converted digital temperature signal, a D / A converter that analog-converts the digital temperature signal of the controller, and a temperature that receives this analog value and adjusts the temperature Consists of a control unit.

With the above configuration, the thermocouple has a heater function, a temperature detection function, and a sample holding function. Both the sample and the thermocouple have a small heat capacity, so that the sample can be rapidly heated and cooled, and the accuracy and follow-up of the temperature measurement can be achieved. Since it is improved and various settings are facilitated, it is possible to easily and directly observe the molten state of the sample at the predetermined observation temperature and the reaction between the melt and the solid.
Further , based on the setting by the setting operation unit, the control unit alternately heats the thermocouple with the heating power supply unit and heats the thermocouple while switching the heating power supply unit and the measurement unit alternately with the heating measurement switching unit. The analog thermoelectric signal for the temperature from the thermocouple is digitally converted by the A / D converter via the measuring unit, and is output as temperature data to the personal computer. The D / A converter converts the temperature data to analog and sends it to the temperature controller. The temperature controller adjusts the setting by the setting operation unit and the temperature data of this digital value to perform temperature adjustment and PID control. If the control unit can perform heating measurement control, data processing, and condition setting, the use of a square wave for the heating facilitates the interface with the control unit and simplifies the circuit. In addition, as a merit of digitizing the thermoelectromotive force signal by the A / D converter, even if the thermoelectromotive force cannot be captured in the heating cycle, the measured voltage is sag by holding the measured value until the next measurement cycle. (Voltage drop) does not occur, and accurate measurement is possible. By digitalization, a voltage equivalent to the thermoelectromotive force is input from the tip of the thermocouple holder without generating a heating output instead of the electromotive force generated by the thermocouple. The system can be easily calibrated and guaranteed, and heating measurement control, data processing, and condition setting can be performed according to the settings.

Since the present invention has the above configuration, the heater function to the thermocouple, to have a temperature detecting function and the sample holding function, the sample and the thermocouple both heat capacity can rapid heating and rapid cooling of the sample becomes very small, the temperature The accuracy and follow-up of the measurement is improved, and various settings such as automatic temperature rise, automatic temperature drop, temperature maintenance, temperature recording and data recording are facilitated. It is possible to provide a thermocouple system for heating measurement that can easily and directly observe the reaction of the above.

By using a square wave for heating, the interface with the control unit becomes easy, the circuit is simplified, and the thermoelectromotive force signal is digitized by the A / D conversion unit so that the thermoelectromotive force can be captured in the heating cycle. Even if it is not, the measurement value is held until the next measurement cycle, and the measurement voltage does not sag, and accurate measurement is possible. Digitization does not generate heating output instead of electromotive force generated by thermocouple. It is possible to provide a thermocouple system for heating measurement in which a voltage equivalent to a thermoelectromotive force can be input and calibration and guarantee of the system can be easily performed, and heating measurement control, data processing, and condition setting can be performed according to settings.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a heating measurement thermocouple system according to an embodiment of the present invention, FIG. 2 is a block configuration diagram of a heating measurement unit of the heating measurement thermocouple system, and FIG. It is a timing diagram which shows the heating measurement principle of the thermocouple system for an industrial use.

  In FIG. 1, a heating measurement unit 1 of the thermocouple system for heating measurement according to the present invention includes a setting operation unit 2 for setting operations such as various heating controls and temperature measurements, and a thermocouple 3 made of heat-resistant and corrosion-resistant, for example, R thermocouple. It is connected to the. The thermocouple 3 is mounted in an observation chamber 5 made of hard glass and equipped with a cooling means while being attached to a thermocouple holder 4, and holds a minute sample 6 to be observed. The observation chamber 5 is provided with an observation window through which the internal thermocouple 3 and the sample 6 can be observed. A stereomicroscope 7 for observing the state of the thermocouple 3 and the sample 6 is provided opposite to the observation window. It has been. In order to display and record the observation video through the stereomicroscope 7, a CCD camera 8, a telop device 9, a video system 10, and a display 11 are connected in order. Further, in order to control these and record data, a personal computer 12 is connected to the heating measurement unit 1, the telop device 9 and the video system 10, and a printer 13 is connected to the personal computer 12 for printing the recording.

  Next, in the setting operation unit 2, the temperature is raised (for example, three kinds of temperatures of 10 ° C./min, 100 ° C./min, 500 ° C./min are automatically raised according to a preset temperature rise gradient), and the temperature is lowered ( For example, 3 types of 10 ° C./min, 100 ° C./min, 500 ° C./min, temperature is automatically decreased according to a preset temperature decrease gradient), temperature maintenance, temperature recording (for example, 5 points), data recording (for example, start, Setting operations such as 2 points at the end) can be performed. Based on these settings, the heating measurement unit 1 holds the sample 6 in the observation chamber 5 by the thermocouple 3, measures the temperature while heating or cooling, and controls the PID temperature of the sample 6. Therefore, the thermocouple 3 has a sample holding function, a heater function, and a temperature detection function.

  In addition, a predetermined portion of the sample 6 in the observation chamber 5 is magnified and observed in detail with the stereomicroscope 7, and the image is taken at a high speed with the CCD camera 8, and the sample 6 and temperature are monitored with the telop device 9. A predetermined telop is added, video data with a telop is recorded in the video system 10, and this video data can be observed on the display 11.

  The personal computer 12 controls the telop device 9 and the video system 10, and as a data recording system, captures temperature data such as video data and PID temperature control status, set temperature, and measured temperature of the heating measurement unit 1 as trend data, The observation record can be recorded and saved. Further, the personal computer 12 can print the observation record by the printer 13.

  As shown in FIG. 2, the heating measurement unit 1 includes a heating power source unit 23 that energizes and heats the thermocouple 3, a measurement unit 24 that measures the thermoelectromotive force of the thermocouple, and performs switching at a predetermined frequency. A heating measurement switching unit 22 that switches between the power supply unit 23 and the measurement unit 24, an A / D conversion unit 25 that digitally converts an analog temperature signal based on the thermoelectromotive force measured by the measurement unit 23, and the converted digital temperature signal. A control unit 21 comprising, for example, a microcomputer for controlling them, a D / A conversion unit 26 for converting the digital temperature signal of the control unit 21 into analog, a temperature adjustment unit 27 for adjusting the temperature by receiving the analog value, and a control unit 21 and a serial communication unit 28 to which the temperature adjustment unit 27 is connected.

  Hereinafter, the operation of the heating measurement unit 1 will be described. Based on the setting by the setting operation unit 2, the control unit 21 energizes the thermocouple 3 by the heating power supply unit 23 while alternately switching the heating power supply unit 23 and the measurement unit 24 by the heating measurement switching unit 22. Then, the analog temperature signal based on the thermoelectromotive force from the thermocouple 3 is digitally converted via the A / D conversion unit 25 during the next half cycle by the measuring unit 24 and received as temperature data to the personal computer 12. Control output. Subsequently, the digital temperature signal is analog-converted by the D / A conversion unit 26 from the control unit 21 and sent to the temperature adjustment unit 27. The temperature adjustment unit 27 calculates the set temperature by the setting operation unit 2 and the analog temperature signal. Temperature control and PID control. As described above, the control unit 21 can perform heating measurement control, data processing, and condition setting, and can send data to the personal computer 12.

  The heating measurement in the present invention uses 0-12 V variable direct current from the heating power supply unit 23 while the heating measurement switching unit 22 alternately switches the heating power supply unit 23 and the measurement unit 24 at the heating / measurement timing shown in FIG. Then, switching is performed at 300 Hz, and a voltage is applied to the thermocouple 3 with a half-cycle rectangular wave to heat the thermocouple 3 with a heating current. Next, the heating current flowing through the thermocouple 3 in the remaining half cycle is cut off by a rectifier (not shown), and the measuring unit 24 is connected to a temperature measuring circuit (not shown) by a high-speed relay to generate a temperature measurement signal at the temperature measurement timing. The thermoelectromotive force of the thermocouple is detected by a DC voltage measuring device (not shown).

  By using a rectangular wave for heating the thermocouple 3, the interface with the controller 21 is facilitated, and the circuit is simple. Further, there are the following two effects as the merit of digitizing the thermoelectromotive force signal by the A / D conversion unit 25. 1. In the conventional hot thermocouple method, the thermoelectromotive force cannot be captured in the heating cycle, so a sag (voltage drop) occurs in the measurement voltage due to the measurement circuit time constant, and an error occurs in the direct reading value. Accurate measurement is possible by holding the measured value until the measurement cycle. 2. Digitization makes it easy to calibrate and guarantee the system by inputting a voltage corresponding to the thermoelectromotive force from the tip of the thermocouple holder without generating a heating output instead of the electromotive force generated by the thermocouple. (In the past, it was necessary to correct the measured value with a standard sample (NaCl), etc.)

  The heating measurement unit 1 measures the temperature of the changing sample 6 with the thermocouple 3 while giving the temperature change to the sample 6 to be observed with the thermocouple 3, and the temperature characteristics of the sample based on the temperature change are described above. If the thermal analysis is carried out by observing with the stereomicroscope 7 and taking in the data obtained by measurement and observation, the endothermic and exothermic reaction of the sample 6 that occurs during the process of automatic temperature rise, automatic temperature drop, or constant temperature heating Draws a unique curve on the trend recording data, which makes it possible to detect the thermal transformation point of the sample and to visually observe its state, and to absorb the endotherm of the sample 6, exothermic reaction, etc. However, in this method, the thermocouple 3 which is a temperature detection unit is in direct contact with the sample 6 and can be detected very sensitively.

  In the present embodiment, the setting operation unit 2 performs various setting operations. However, the setting operation unit 2 may not be provided, and the same setting operation may be performed by the personal computer 12. In addition, the heating measurement unit 1 and the personal computer 12 are connected by a communication cable, and the melting process and the solidification process of the sample 6 are directly observed with the stereo microscope 7 while the remote operation of the entire system and the measurement / setting temperature are recorded. It is good also as what can be recorded with it.

  It is a block diagram of the thermocouple system for heating measurement which concerns on one Embodiment of this invention.   It is a block block diagram of the heating measurement unit of the thermocouple system for heating measurement.   It is a timing diagram which shows the heating measurement principle of the thermocouple system for the heating measurement. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating measurement unit 2 Setting operation part 3 Thermocouple 6 Sample 7 Stereomicroscope 8 CCD camera 9 Telop apparatus 10 Video system 11 Display 12 Personal computer 13 Printer 21 Control part 22 Heating measurement switching part 23 Heating power supply part 24 Measuring part 25 A / D Conversion unit 26 D / A conversion unit 27 Temperature control unit

Claims (1)

The thermocouple holding the sample to be observed is switched at a predetermined frequency using variable direct current, and a voltage is applied to the thermocouple with a half-cycle rectangular wave to flow a heating current to heat the thermocouple and sample. The heating measurement unit that cuts off the heating current flowing in the thermocouple in the remaining half cycle, detects the thermoelectromotive force of the thermocouple with the temperature measurement signal at the temperature measurement timing, measures the temperature, and brings the sample to the predetermined observation temperature For this heating measurement unit, automatic temperature increase that automatically increases temperature according to a preset temperature increase gradient, automatic temperature decrease that automatically decreases temperature according to a preset temperature decrease gradient, maintenance of a predetermined observation temperature, at a predetermined point and a setting operation unit setting operation, such as temperature recording and the start and end of data recording can be provided, and shall forth used in the molten state or melt and solid sample at a predetermined observation temperature can be observed easily directly, the heating Total A heating power supply unit that heats the thermocouple by energizing the thermocouple, a measurement unit that measures the thermoelectromotive force of the thermocouple, a heating measurement switching unit that switches between the heating power supply unit and the measurement unit by switching at a predetermined frequency, An A / D converter that digitally converts an analog temperature signal based on the thermoelectromotive force measured by the measurement unit, a control unit that receives and controls the converted digital temperature signal, and an analog conversion of the digital temperature signal of the control unit A D / A converter that performs this operation and a temperature controller that adjusts the temperature by receiving the analog value. Based on the setting by the setting operation unit, the controller switches the heating power supply unit and the measuring unit at the heating measurement switching unit. While switching alternately, a half-cycle rectangular wave is energized and heated by the heating power supply unit, and an analog thermoelectromotive force signal with respect to the temperature from the thermocouple is A / D via the measurement unit. The converter converts the digital data and receives it as temperature data and outputs it to a personal computer. Subsequently, the digital temperature data is converted into analog data by the D / A converter and sent to the temperature controller. It is possible to calculate the setting by the setting operation unit and the temperature data of this digital value to perform temperature adjustment and PID control, and that the control unit can perform heating measurement control, data processing, and condition setting. A thermocouple system for heating measurement.

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