JP4737605B2 - Thermal analysis method - Google Patents

Description

The present invention relates to a thermal analysis method for measuring a change in weight of a sample when the temperature of the sample changes.

  2. Description of the Related Art Conventionally, thermal analyzers that measure changes in the weight of a sample when the temperature of the sample changes are widely known. For example, a TG (Thermogravimetry) apparatus is known as such a thermal analysis apparatus (see, for example, Patent Document 1). There is also known a thermal analyzer that performs measurement while automatically exchanging a plurality of samples (see, for example, Patent Document 1). A technique for calibrating a measurement system in a thermal analyzer is known (see, for example, Patent Document 2).

JP-A-5-052732 (pages 2 and 3, FIG. 1) JP 2002-055066 A (Page 4, FIG. 1)

  In a thermal analyzer as disclosed in Patent Document 1, generally, a built-in measurement system sometimes deteriorates or changes over time. Therefore, in order to maintain accurate measurement results, the measurement system has been calibrated regularly. For example, calibration is performed once every few days or once every several months. Further, in the calibration apparatus disclosed in Patent Document 2, calibration processing is executed after the measurement of all standard samples is completed.

  However, when calibration is performed periodically as described above, or when calibration is performed after all standard samples have been measured as described above, when there are multiple samples to be measured, On the other hand, it was not possible to carry out the measurement after appropriate calibration.

  The present invention has been made to solve the above-described problems, and is intended to enable appropriate calibration for individual samples when performing thermal analysis on a plurality of samples. Objective.

The thermal analysis method according to the present invention includes (1) a weight measuring means for performing weight measurement on a sample placed at a sample measuring position, (2) a sample standby section on which a plurality of samples are placed, and the sample measuring position. And (3) the plurality of samples are placed at the sample measurement position while being transferred one by one to the sample measurement position by the sample transfer means. Weighing operation means for measuring the weight of the sample by the weight measurement means with respect to the sample, and realizing a function for obtaining a true weight value by calculation from the measured weight value; and (4) the true weight from the measured weight value. And (5) a calibration calculation means for performing a calibration process for adjusting the calculation based on a weight whose weight is known, which is placed in the sample standby section. The weight is already And (6) the weighing calculation means for the sample sequentially placed at the sample measurement position following the weight detected by the weight detection means. A thermal analysis method using a thermal analyzer that obtains a true weight value in accordance with the calibration process performed corresponding to a weight, wherein a plurality of weights having different weights are placed at different sequential positions of the sample standby unit. A sample having a weight in the vicinity of the weight of the weight is placed in the sequential position following the order corresponding to each weight .

  In the above configuration, the “weight measuring unit” is configured by a mechanism including a balance beam, for example. In addition, the “sample transport unit” is configured by a mechanism including, for example, a gripping member that grips a sample and a device that moves the gripping member. The “weighing calculation means” and the “calibration calculation means” are configured by function realization means including, for example, a CPU (Central Processing Unit), a memory, program software, and the like.

According to the thermal analysis method of the present invention, calibration is performed prior to at least one of the weight measurements performed alternately on a plurality of samples. This calibration can be performed prior to the desired weight measurement for which an accurate weight measurement is desired. If calibration is performed periodically as in the past or if calibration is performed after all standard samples have been measured, calibration cannot be performed immediately before the measurement for the sample for which accurate measurement is desired. In addition, when there are a plurality of samples for which accurate measurement is desired, it is impossible to calibrate each of them.

  On the other hand, when the plurality of samples are sequentially measured by the weighing calculation means as in the present invention, the calibration calculation means automatically calibrates at least one of the individual measurements. If set so as to realize, it is possible to individually perform calibration processing on a sample for which accurate measurement is desired, and therefore it is possible to improve the reliability of weight measurement. Further, even when there are a plurality of samples for which accurate measurement is desired, the calibration processing unit can automatically and individually perform calibration processing on these samples, so that the reliability of weight measurement can be improved.

Next, in the thermal analysis method according to the present invention, when the calibration calculation means performs weight measurement by the weight measurement means in a state in which a weight having a known weight is placed at the sample measurement position, a result of the measurement is obtained. It is desirable to perform the calibration by adjusting the calculation by the weighing calculation means so that becomes the known weight. According to this configuration, accurate calibration processing can be performed by a simple operation. In this case, it is desirable that the weight of the weight is the same as or close to the weight of the sample used for the weight measurement performed immediately after the calibration process.

Next, in the thermal analysis method according to the present invention, the weight measuring means detects a balance mechanism provided with a balance beam, and shake of the balance beam when a sample is placed on a sample measurement position of the balance mechanism. A shake detecting means for outputting a signal; a force generating means for generating a force according to the supplied power; and a power control means for supplying power to the force generating means based on an output signal of the shake detecting means. It is desirable. In this case, it is preferable that the weight measurement is a process for obtaining the weight of the sample by comparing the power supplied to the force generation unit by the power control unit with predetermined reference calibration curve data. Further, it is desirable that the calibration calculation means realize calibration by adjusting the reference calibration curve data.

  According to this configuration, the weight change of the sample can be accurately measured, the measurement system can be accurately calibrated, and the timing for performing calibration can be freely set.

  In the present invention, there is provided a weight detecting means for detecting a weight having a known weight placed in the sample standby section, and the weighing calculation means is for the samples in the order after the order of the weights detected by the weight detecting means. Therefore, the analyst, that is, the operator, puts the weight in the sample standby part before placing the sample to be calibrated in the sample standby part. By simply performing a simple operation of placing the sample, the measurement of the sample can be performed by an appropriate measurement system in a calibrated state.

Hereinafter, a case where the thermal analysis apparatus capable of performing the thermal analysis method according to the present invention is applied to a TG-DTA apparatus having an automatic sample exchange function will be described as an example. Of course, the present invention is not limited to this embodiment.

FIG. 1 shows an embodiment of a thermal analysis apparatus capable of performing the thermal analysis method according to the present invention. The thermal analysis apparatus 1 includes a TG-DTA apparatus 2 that performs measurement using an appropriate substance as a sample, a sample changer 3 that automatically replaces a sample that is measured by the TG-DTA apparatus 2, and an input as input means. Device 4, image display device 6 as display means, printer 7 as printing means, CPU (Central Processing Unit) 8, RAM (Random Access Memory) 9, ROM (Read Only Memory) 10, external And a hard disk 11 as a storage medium. The operation of the sample changer 3 is controlled by a sample change control circuit 5. The above elements are connected to each other by a bus 12.

  The input device 4 includes, for example, a button switch, a keyboard, a mouse, and the like. The input device 4 includes a calibration button, a non-calibration button, and a clear button. The calibration button is a button operated when a calibration process is instructed. The button without calibration is a button operated when performing measurement without performing calibration processing. The clear button is operated when returning the calibration curve data used in the calibration process to the initial value (that is, the default value).

  The image display device 6 is configured by an image display device such as a CRT display or a liquid crystal display. The image display device 6 inputs image data generated by arithmetic processing and control processing by the CPU 8 and displays an image corresponding to the data on the screen. As the printer 7, an ink plotter, a dot printer, an ink jet printer, an electrostatic transfer printer, or any other printing apparatus having an arbitrary structure can be used. The hard disk 11 can also be configured by a magneto-optical disk, a semiconductor memory, or any other storage medium having an arbitrary structure.

  In the hard disk 11, a TG measurement program 16 for performing TG (thermogravimetric) measurement by the TG-DTA apparatus 2 and DTA (Differential Scanning Calorimetry) measurement by the TG-DTA apparatus 2 are performed. Various programs such as a DTA measurement program 17 for calibration and a calibration program 18 for executing calibration processing are stored. These programs, for example, implement predetermined functions after being read from the hard disk 11 and transferred to the RAM 8 as necessary. Further, inside the hard disk 11, a file 21 storing calibration curve data used in the calibration process executed by the calibration program 18 and a measurement for storing data measured by the TG-DTA apparatus 2 are stored. A data file 22 is provided.

  In the calibration curve data file 21, at least two types of calibration curve data are stored. One is calibration curve data used in the calibration process actually performed, and the other is calibration curve data as an initial value (that is, a default value). The calibration curve data used in the calibration process may be (1) one predetermined value, (2) a plurality of predetermined data, or (3) calculated each time the calibration process is performed. There may be one case determined by (4), or (4) a plurality of cases determined by calculation each time calibration processing is performed.

  The calibration curve data is data corresponding to, for example, lines (usually straight lines) indicated by symbols L0 and L1 in FIG. In the graph shown in FIG. 5, the horizontal axis indicates the current value supplied to the electromagnetic coil or the like for compensation. The current value for compensation will be clarified in the later description. The vertical axis represents the weight measured by the measuring device. If the calibration curve L0 is the default calibration curve, and the TG measurement is performed using the default calibration curve L0, the weight of the sample is weighed as Wm when the compensation current is im. Further, when TG measurement is performed using the calibration curve L1, the weight of the sample is weighed as Wm 'when the compensation current is im.

  Next, the TG-DTA apparatus 2 of FIG. 1 has a pair of balance units 26a and 26b, as shown in FIG. Each balance unit has balance beams 28a and 28b rotatably supported by torsion bands 27a and 27b constituting fulcrums, and an electric furnace 29 for changing the temperature of the sample and the standard material.

  At the tips of the balance beams 28a and 28b, thermal plates 31a and 31b are provided as sample mounting portions. The heat sensitive plate 31b constitutes the sample measurement position in the present invention. A sample container 32 containing a sample to be measured is placed on one heat sensitive plate 31b and used for measurement. A standard material 33 is placed on the other heat sensitive plate 31a. The standard material 33 is a material whose physical properties do not change even when the temperature changes.

  An electromagnetic compensator 34 is provided in the vicinity of the fulcrums 27a and 27b of the balance beams 28a and 28b. Further, a shake detection device 36 is provided at the rear end of each of the balance beams 28a and 28b. The electric furnace 29 incorporates a heater that generates heat when energized, and has a space R having a volume that can accommodate the heat sensitive plates 31a and 31b. In addition, a furnace moving device 37 is attached to the electric furnace 29. The furnace moving device 37 includes a position where the electric furnace 29 covers the heat sensitive plates 31a and 31b (position indicated by broken lines in FIG. 3) and a position where the heat sensitive plates 31a and 31b are opened to the outside (position indicated by solid lines in FIG. 3). ). FIG. 2 shows a state where the electric furnace 29 is placed at a position where the heat sensitive plates 31a and 31b are opened to the outside.

  The furnace moving device 37 can be configured by any conventionally known parallel moving device. For example, the electric furnace 29 is supported by a guide element such as a rail so as to be linearly movable, and the electric furnace 29 is linearly driven by a linear drive device. It is possible to adopt a configuration such as reciprocating. In this case, the linear drive device is, for example, a linear drive device in which a slider is screw-fitted on a feed screw shaft, and the slider is linearly moved by rotating the feed screw shaft, or a rectilinear drive device using a wire that moves around. A driving device or the like is conceivable.

  As shown in FIG. 3, the electromagnetic compensator 34 is disposed in a permanent magnet 38 fixed to a portion near the fulcrums 27 a and 27 b of the balance beams 28 a and 28 b, and in a magnetic field region of the permanent magnet 38. A coil 39 and a voltage detection resistor 41 are provided. One end of the resistor 41 is taken out as a TG output signal Stg. The TG output signal Stg is a signal corresponding to the current supplied to the coil 39, that is, power.

  When a current is supplied to the coil 39, a magnetic field is generated and a force is generated in the magnet 38. This force is transmitted to the balance beams 28a and 28b, and functions as a force for holding the balance beams in an equilibrium state, in this embodiment, a horizontal state. The TG signal Stg is temporarily stored, for example, in a predetermined storage area in the RAM 9 in FIG. 1 and used as data in a calculation performed by the TG measurement program 16.

  As shown in FIG. 3, the shake detection device 36 of FIG. 2 includes a light shielding plate 44 fixed to the rear ends of the balance beams 28a and 28b, a light source 46 that emits light toward the light shielding plate 44, And a light receiving element 47 disposed on the opposite side of the light source 46 with the light shielding plate 44 interposed therebetween. An output terminal of the light receiving element 47 is connected to an input terminal of a PID (proportional, integral, derivative) regulator 48 as a power control means. The output terminal of the PID adjuster 48 is connected to the input terminal of the coil 39 via the power amplifier 49.

  The sample S in the sample container 32 is heated by the electric furnace 29, and further changes in temperature when the heating is released. During this temperature change, the sample S changes its weight according to its own thermal properties. When the weight change occurs in the sample S, the balance beam 28b swings around the fulcrum 27b, that is, tilts and the rear end thereof swings. When the balance beam 28b is shaken in this way, the amount of light received by the light receiving element 47 is changed in the shake detecting device 36, the output signal of the light receiving element 47 is changed, and the change is applied to the output terminal of the PID adjuster 48. A signal corresponding to is output. The output signal is supplied to the coil 39 in the electromagnetic compensator 34, whereby a force is applied to the balance beam 28b, and as a result, the balance beam 28b is maintained in an equilibrium state.

  In FIG. 3, a temperature detecting element 51a (for example, a temperature measuring terminal of a thermocouple) is fixed to the bottom surface of a heat sensitive plate 31a supporting the standard material 33 by an appropriate fixing method, for example, spot welding. A similar temperature detecting element 51b is also fixed to the bottom surface of the heat sensitive plate 31b that supports the sample S. In FIG. 3, the two temperature detection elements 51 a and 51 b are shown as being fixed to different places on the bottom surfaces of the heat sensitive plates 31 a and 31 b, respectively, but this is a measure for facilitating the explanation. Actually, the temperature detecting elements 51a and 51b are fixed to the same position on the bottom surfaces of the heat sensitive plates 31a and 31b.

  The temperature detection element 51a detects the temperature of the standard substance 33 and outputs a temperature signal Sdta1. The temperature detecting element 51b detects the temperature of the sample S and outputs a temperature signal Sdta2. These temperature signals Sdta1 and Sdta2 are temporarily stored, for example, in a predetermined storage area in the RAM 9 of FIG. 1 and used as data in the calculation performed by the DTA measurement program 17.

  Next, as shown in FIG. 2, the sample changer 3 in FIG. 1 includes a turntable 52 that constitutes a sample standby portion where a plurality of sample containers 32 are placed, a transport arm 53 that transports the sample containers 32, and Have An appropriate amount of the sample to be measured is accommodated in the sample container 32. A table rotating device 54 is attached to the turntable 52. The table rotating device 54 is a device for intermittently rotating the turntable 52 around its central axis X0. This intermittent rotation is an operation for sequentially carrying different sample containers 32 to the removal position P0.

  The table rotating device 54 can be configured by any conventionally known rotary driving device. For example, a structure in which the rotation of a rotating device such as a motor is transmitted to the turntable 52 by a power transmission element such as a gear can be adopted. In this case, in order to realize intermittent rotation of the turntable 52, it is desirable to use a stepping motor or a servo motor as a motor that is a power source. Further, in order to measure the rotation angle of the turntable 52, it is desirable to attach a pulse generator to the rotation axis of the turntable 52 or arrange a photo sensor around the rotation axis of the turntable 52. .

  The transfer arm 53 is supported by a support shaft 56. Further, an arm rotating device 57 and an arm lifting device 58 are attached to the support shaft 56. The arm rotation device 57 is a device for rotating the transport arm 53 around the support shaft 56 as indicated by an arrow A. The arm lifting device 58 is a device for moving the transport arm 53 up and down as indicated by an arrow B.

  FIG. 4 shows the support shaft 56 and the configuration around it. In the drawing, the support shaft 56 is included in a turning / lifting device 59. The turning / lifting device 59 has a casing 63 that is rotatably supported by the machine frame 62 by a shaft member 61. Inside the casing 63 are a DC (ie, direct current) motor 64, a gear train 66 connected to the output shaft of the DC motor 64, and a feed screw shaft 67 connected to the output shaft of the gear train 66. A slide base 68 is provided to be fitted to the feed screw shaft 67. The support shaft 56 is fixed to the slide base 68 and passes through the upper portion of the casing 63.

  The shaft member 61 fixed to the bottom of the casing 63 is connected to the output shaft of the stepping motor 69 inside the machine frame 62. When the stepping motor 69 operates and the output shaft rotates, the shaft member 61 rotates and the casing 63 rotates accordingly. By the rotation of the casing 63, the transfer arm 53 moves around between the standby unit Pw and the measurement unit Pm in FIG.

  In FIG. 4, when the DC motor 64 operates to rotate its output shaft, the rotation is transmitted to the feed screw shaft 67 via the gear train in the gear train 66, and the feed screw shaft 67 rotates. When the feed screw shaft 67 rotates, the slide base 68 fitted to the feed screw shaft 67 translates in the axial direction of the feed screw shaft 67, that is, in the vertical direction in FIG. At the time of this parallel movement, the support shaft 56 fixed to the slide base 68 is moved in parallel in the vertical direction, whereby the transfer arm 53 fixed to the support shaft 56 moves up and down, that is, moves up and down.

  The transfer arm 53 includes an elevating base 71 fixed to the support shaft 56, a linear stepping actuator 72 fixed on the elevating base 71, and an opening / closing mechanism connected to the output shaft of the linear stepping actuator 72. 73 and a cover 74 covering each of the above elements. The linear stepping actuator 72 is an operating device that operates so that its output shaft 72a moves forward and backward as indicated by an arrow C. Such a structure can be achieved, for example, by converting the rotational output of the rotating device into linear movement by screw fitting.

  As shown in FIG. 4A, a pair of opening / closing members 76 facing each other are provided at the tip of the opening / closing mechanism 73. The opening / closing mechanism 73 functions to move the opening / closing member 76 in parallel as indicated by arrow E when the output shaft 72a of the linear stepping actuator 72 moves forward and backward as indicated by arrow C. Since this function can be achieved by various known mechanisms, detailed description thereof is omitted.

  A support member 77 is fixed to the tip of each of the pair of opening / closing members 76. These support members 77 extend downward as shown in FIG. And the finger 78 as a holding member is attached to the lower end of each of these support members 77 with a screw and other fasteners. Thus, the finger 78 has a structure that can be attached to and detached from the support member 77.

  Although detailed illustration is omitted, a position sensor for detecting the height position of the finger 78 and a detection that the transfer arm 53 is in the standby portion Pw in FIG. 2 are detected at appropriate positions around the support shaft 56 and the casing 63. And a position sensor for detecting that the transfer arm 53 is in the measurement unit Pm. These position sensors can be constituted by sensors having an arbitrary structure, but can be constituted by, for example, a micro switch, a photo sensor, or the like.

  The arm rotation device 57 in FIG. 2 is configured by a drive system including the stepping motor 69 in FIG. 4 and a casing 63 that is rotationally driven by the motor 69. 2 is constituted by a drive system including the DC motor 64, the gear train 66, the feed screw shaft 67, and the slide base 68 shown in FIG.

  The “weight measuring means” of the present invention is realized by the TG-DTA measuring device 2. Further, the “sample transport means” is realized by the sample changer 3. Further, the “weighing calculation means” and the “calibration calculation means” are realized by a computer including the CPU 8 and the hard disk 11.

  The operation of the thermal analyzer having the above configuration will be described below. Since this thermal analyzer has a TG measurement function, a DTA measurement function, an automatic sample exchange function, and a calibration function, they will be described individually.

(TG measurement function)
When performing TG measurement, the TG measurement program 16 of FIG. The operation for TG measurement described below is executed according to the TG measurement program 16. When performing TG measurement, in FIG. 2, the balance beams 28a and 28b supported with the torsion bands 27a and 27b as fulcrums freely rotate and tilt in the direction of the arrow FF ′ around the torsion bands 27a and 27b. Set to moveable. A standard sample 33 is placed on the heat sensitive plate 31a at the tip of the balance beam 28a. A sample container 32 containing a sample to be measured is placed on the heat sensitive plate 31b at the tip of the balance beam 28b. When performing the TG measurement, the electric furnace 29 is placed at a measurement position indicated by a broken line in FIG. 3, whereby the sample container 32 containing the sample S and the sample container 32 containing the standard substance 33 are both in the electric furnace 29. Be placed.

  In FIG. 3, a light shielding plate 44 provided at the rear ends of the balance beams 28 a and 28 b blocks the optical path from the light source 46 to the light receiving element 47. When the balance beams 28a and 28b are tilted from the horizontal position, that is, from the equilibrium position, the output signal of the light receiving element 47 changes from the reference signal. By detecting this signal change, the positions of the balance beams 28a and 28b can be detected. The output signal of the light receiving element 47 is applied as a control signal to the coil 39 of the electromagnetic compensator 34 through the PID adjuster 48 and the power amplifier 49. The coil current i is converted into a voltage by the detection resistor 41, and the voltage is output as a TG output signal Stg.

  The temperature of the electric furnace 29 changes according to a predetermined temperature control program, and the temperature of the sample S and the standard material 33 in the sample container 32 changes accordingly. During this temperature change, the standard substance 33 is a thermally stable substance and therefore does not usually change in weight. However, the sample S changes in weight according to its physical properties. When the weight change occurs in the sample S, the balance beam 28b swings in the D direction or the D 'direction. This shake is detected as a change in the amount of received light by the light receiving element 47, and the PID adjuster 48 and the power amplifier 49 cause the coil 39 to pass a current for returning the shake of the balance beam 28b. When a current flows through the coil 39, an electromagnetic force is generated in the magnet 38, and the magnet 38 is moved to the original reference position by this electromagnetic force, thereby compensating for the shake of the balance beam 28b.

  Since the standard material 33 is a material that does not change in weight with respect to temperature change, the balance beam 28a supporting the standard material 33 always maintains an equilibrium state. Since the reference material 33 is placed in the same environment as the sample S, the weight change of the sample S can be accurately measured by measuring the behavior of the balance beam 28b supporting the sample S with respect to the balance beam 28a supporting the reference material 33. .

  In the above-described shake compensation operation for the balance beam 28b, the current i supplied to the coil 39 corresponds to the return moment acting on the balance beam 28b, and the return moment corresponds to the increase / decrease amount of the weight of the sample S. . Therefore, by measuring the TG output voltage Stg corresponding to the current i, the weight change of the sample S is measured, that is, weighed. Specifically, the weight change of the sample S follows the TG measurement program 16 based on the calibration curve data indicated by the symbol L0 or L1 in FIG. 5 and stored in the calibration curve data file 21 of FIG. Calculated by calculation. The change in the weight of the sample S thus obtained is displayed, for example, as a TG curve shown in FIG. 6 in the screen of the display device 6 in FIG. In the display example of FIG. 6, the result of the TG measurement is displayed in the form of a graph in which the horizontal axis represents the temperature change and the vertical axis represents the weight change.

  In the present embodiment, the TG measurement is performed while calibrating the mechanism relating to the balance beam 28b that supports the sample in FIG. 2 in a timely manner. This calibration process will be described in detail later.

(DTA measurement function)
When performing DTA measurement, the DTA measurement program 17 of FIG. In the case of performing DTA measurement, in FIG. 2, the standard material 33 is placed on the heat sensitive plate 31a at the tip of the balance beam 28a. A sample container 32 containing a sample to be measured is placed on the heat sensitive plate 31b at the tip of the balance beam 28b. When performing DTA measurement, the electric furnace 29 is placed at a measurement position indicated by a broken line in FIG. 3, whereby both the sample container 32 containing the sample S and the sample container 32 containing the standard substance 33 are placed in the electric furnace 29. Be placed.

  When the DTA measurement program 17 is started, the temperature of the electric furnace 29 changes in accordance with a predetermined temperature control program in FIG. 3, and the temperatures of the sample S and the standard substance 33 in the sample container 32 change accordingly. At the time of this temperature change, the temperature of the standard substance 33 is detected by the temperature detecting element 51a and stored in the RAM 9 of FIG. 1 or other appropriate memory as the temperature signal Sdta1. Further, the temperature of the sample S is detected by the temperature detecting element 51b and stored as the temperature signal Sdta2 in the RAM 9 of FIG. 1 or other appropriate memory.

  At the time of the above temperature change, the standard substance 33 is a thermally stable substance and therefore usually does not change in temperature. However, the sample S changes in temperature according to its physical properties. For example, the temperature changes according to changes in physical properties such as melting and evaporation. The DTA measurement program 17 obtains the temperature difference between the standard substance 33 and the sample S when the temperature changes. If necessary, the result is displayed on the screen of the display device 6 of FIG. 1 as a DTA curve shown in FIG. In the display example of FIG. 6, the result of DTA measurement is displayed in the form of a graph in which the horizontal axis represents the temperature change and the vertical axis represents the temperature difference. As shown in FIG. 6, if the TG curve and the DTA curve are simultaneously displayed on one screen, the characteristics of the sample can be analyzed accurately and quickly.

(Automatic sample exchange function)
When TG-DTA measurement is completed for one sample, TG-DTA measurement is then performed for a different sample. In this case, it is necessary to replace the sample on the heat sensitive plate 31b of FIG. In this embodiment, the replacement can be performed automatically and continuously. Such a sample exchange operation is executed by sending a sample exchange signal to the sample change control circuit 5 of FIG.

  The sample change control circuit 5 that has received the sample exchange signal first places the transfer arm 53 of FIG. 2 at the home position. Although this home position can be set to an appropriate position as required, in this embodiment, the standby unit Pw in FIG. 2 is set as the home position. This process is performed by appropriately operating the arm rotation device 57 and the arm lifting device 58. Note that when the transfer arm 53 is already at the home position, the operation of moving the transfer arm 53 to the home position is not performed.

  When the transfer arm 53 is placed at the home position, it is checked whether or not the sample container 32 is on the heat sensitive plate 31b in the TG-DTA apparatus 2 of FIG. This can be executed by checking the current flowing through the electromagnetic compensator 34 of FIG. 3 or by providing a dedicated sensor in the vicinity of the thermal plate 31b. If there is a container 32 on the heat sensitive plate 31b, a process for collecting the container 32 is performed. On the other hand, if there is no container 32 on the heat sensitive plate 31b, the process which takes out the next sample container 32 from the turntable 52 of FIG. 2 is performed.

  When removing the container 32 from the turntable 52, the transfer arm 53 is lowered to lower the tip of the finger 78 to the side of the container 32. Next, the finger 78 is closed and moved in the direction of arrow C to grip the container 32 from both sides. Next, the transfer arm 53 is raised to lift the container 32 from the turntable 52. Next, the transfer arm 53 is swung from the standby part Pw to the measurement part Pm, and the container 32 held by the finger 78 is set above the heat sensitive plate 31b.

  Next, the transfer arm 53 is lowered and the tip of the finger 78 is lowered to the vicinity of the heat sensitive plate 31b. At this time, the container 32 held by the finger 78 does not contact the heat sensitive plate 31b, but is lowered to a position in the vicinity thereof. When the container 32 is set in the vicinity of the heat sensitive plate 31b, the finger 78 moves in the direction of the arrow C and the container 32 falls from the finger 78, whereby the container 32 is placed on the heat sensitive plate 31b.

  Thereafter, the transfer arm 53 moves up and stops at a predetermined height position, and further turns as shown by an arrow A from the measurement unit Pm to the standby unit Pw, and is set to the standby unit Pw, that is, the home position. As described above, a new sample is placed on the heat sensitive plate 31b, and then the above-described TG measurement and DTA measurement are performed on the sample.

  When measuring a new sample, if it is determined that there is an old container on the thermal plate 31b, the old container on the thermal plate 31b is removed before placing the new sample on the thermal plate 31b. Must be collected. In that case, first, in order to collect the container 32 on the heat sensitive plate 31 b, the finger 78 is transported from the home position to the container 32, and the container 32 is gripped by these fingers 78. Then, the finger 78 holding the container 32 on the heat sensitive plate 31b is lifted to a predetermined height position above the heat sensitive plate 31b. The finger 78 thus lifted is transported by the transport arm 53 from the measurement unit Pm to the standby unit Pw as indicated by the arrow A, and the finger 78 is lowered to return the container 32 onto the turntable 52. As a result, the sample container 32 is collected on the turntable 52.

(Calibration processing function)
When the TG-DTA apparatus 2 of the present embodiment is used for a long period of time, there may be a difference in measurement results even when the same sample is measured. That is, a change with time may occur in the TG-DTA apparatus 2. This change with time is considered to occur when the characteristics of a plurality of components constituting the TG-DTA apparatus 2 change with time. For example, if the characteristics of the torsion bands 27a and 27b, the electromagnetic compensator 34, the shake detector 36, and the like change with time, it is conceivable that the weighing results will differ. If such a change with time is left unattended, highly reliable measurement cannot be performed.

  The thermal analysis apparatus of the present embodiment can perform calibration processing on the TG-DTA apparatus 2 so that accurate measurement, for example, accurate weighing can be performed even when such a change with time occurs. It has become. In particular, in this embodiment, the calibration process is automatically performed by the CPU 8 in FIG. 1 using a weight whose weight is known, as shown in the flowchart in FIG.

  When the calibration process is performed, the operator places the calibration weight 81 at a desired position on the turntable 52 in FIG. 2, and places the container 32 containing the measurement sample at other positions. In the present embodiment, No. is provided at a portion near the periphery of the turntable 52. 1-No. 24 sample mounting positions of 24 are set at equal intervals.

  Next, the operator operates the calibration button in the input device 4 in FIG. 1 to instruct the CPU 8 that calibration should be performed. The CPU 8 determines whether or not the calibration button has been operated in step S1 of FIG. 7. If it is determined that it has been operated (YES in step S1), the CPU 8 starts the calibration program 18 of FIG. Proceed to measurement step S2. If it is determined in step S1 that the calibration button is not operated (NO in step S1), it is determined whether or not the button is operated without calibration in the input device 4 of FIG. The button without calibration is a button operated when the operator wants to perform TG-DTA measurement without performing calibration processing. If the button is operated without calibration by the operator (YES in step S3), the process proceeds to step S4, and the above-described TG measurement and DTA measurement are performed without performing calibration processing.

When the calibration / measurement routine of step S2 is entered, in step S51 of FIG. 9 , an input screen 82D as shown in FIG. 10A is displayed in the screen of the display device 6 of FIG . In the input screen 82D, the column “Sample No.” at the left end indicates No. on the turntable 52 of FIG. 1-No. The sample mounting position numbered 24 is shown.

In FIG. 10A, the column “exchange temperature” is used to instruct how many times the temperature of the sample heated by the electric furnace 29 in FIG. It is a column. The column “condition file” is a column for instructing the conditions of measurement performed on the sample. The conditions for the measurement performed on the sample are, for example, conditions such as the sample name, sample weight, type of container used, and the like. For example, these conditions are stored in an appropriate storage area in the hard disk 11 of FIG. Stored as a file. Further, Retsuran of "temperature program" in FIG. 10 (a) is a field for indicating how to change the temperature by an electric furnace 29 of Figure 2. This temperature control condition is also stored as a file in an appropriate storage area in the hard disk 11 of FIG. 1, for example.

Before or after the input screen 82D of FIG. 10A is displayed, the operator places the calibration weight 81 at a desired position on the turntable 52 of FIG. A container 32 containing various samples to be measured is placed at the position. The weight of the weight 81 is known, for example, 100 mg. Next, the operator selects each NO. In the input screen 82D shown in FIG . The desired condition for the sample is input into the corresponding blank via the input device 4 of FIG. FIG. 10B shows a display state after conditions are input for each sample. For example, no. If the sample 2 is seen, “30 ° C.” is set as the exchange temperature, “condition 1” is set as the condition file, and “temperature 1” is specified as the temperature program. “Condition 1”, “Temperature 1”,... Indicate the file names of files stored in the hard disk 11 of FIG.

When conditions are set for all the samples as shown in FIG. 10B , YES is determined in step S52 of FIG. 9 , and a weight or sample replacement operation is executed in step S54 or step S56. Specifically, when an old container is left on the heat sensitive plate 31b of FIG. 2, the container is collected and the weight 81 or the next container is placed on the heat sensitive plate 31b. On the other hand, when an old container is not left on the heat sensitive plate 31b, the weight 81 or the next container is immediately placed on the heat sensitive plate 31b. When the weight 81 is placed on the heat sensitive plate 31b, a calibration processing routine is executed in step S55.

In the calibration processing routine S55, first, in step S21 of FIG. 8 , the weight of the weight is weighed, and the weighing result is displayed numerically on the display device 6 of FIG. This weighing result may be displayed on a dedicated display device (not shown) installed in the vicinity of the TG-DTA device 2 in FIG. 2 instead of the display device 6. Further, the CPU 8 in FIG. 1 calculates the difference between the weighed weight and the actual weight weight (ie, the weight error) according to the calibration program 18, and further, the ratio of the weight difference to the actual weight weight (ie, the error). Ratio) is calculated according to the calibration program 18, and it is further determined whether or not the error ratio falls within 10%. Here, the determination criterion of the error ratio is set to 10% or less is an example, and the value of this determination criterion is set to an appropriate value according to the type of apparatus.

  As a result of the determination, if it is determined that the error ratio is 10% or more (NO in step S21), an error display is performed in step S23. For example, an appropriate error display is performed on the screen of the display device 6 of FIG. 1, or an error is displayed by lighting a dedicated warning lamp (not shown). This error display indicates that the TG-DTA apparatus 2 or the like needs to be fundamentally repaired because the error range exceeds the calibration range.

  If it is determined in step S21 that the error ratio is within 10% (YES in step S21), calibration processing is executed on the balance beam 28b in the TG-DTA apparatus 2 in FIG. 2 in step S22. At this time, the display device 6 of FIG. 1 or a dedicated display device (not shown) displays that the calibration process is being performed. For example, the characters “CALB” are displayed. The specific calibration processing can adopt an appropriate method as necessary, but in the present embodiment, the following method is adopted.

For example, in the calibration curve data shown in FIG. 5, the calibration curve L0 is the default (that is, initial value) data, and measurement is performed using this default data L0 . In step S21 in FIG. It is assumed that the calibration process is started in step S22. For example, in FIG. 5, it is assumed that a compensation current of “i100” flows and 99 mg is weighed by the calibration curve L0. Since the actual weight of the weight is 100 mg, this weighing has an error of 1 mg.

  When the calibration process is started, the CPU 8 in FIG. 1 performs weighing by changing the calibration curve data from the data L0 in FIG. And the calibration curve L1 which displays 100 mg which is the actual weight weight is searched for, and it determines as a calibration curve which uses this calibration curve L1. Thereby, the TG-DTA apparatus 2 is calibrated. When the calibration is completed in this way, the calibrated weight of 100 mg is displayed on an appropriate display device in step S24.

When the calibration process is completed as described above, sample exchange is performed in step S56 of FIG. 9 , and the weight 81 is collected from the heat sensitive plate 31b of FIG. 2 to the turntable 52, and instead, the next on the turntable 52 is displayed. The sample container 32 is placed on the heat sensitive plate 31b. In step S57, TG measurement and DTA measurement are executed. The measurement at this time is performed according to the conditions specified by the operator in FIG . This TG measurement and DTA measurement are sequentially repeated for all the sample containers 32 on the turntable 52 (steps S53 to S58). When the measurement for all the samples is completed, the measurement data temporarily stored in the RAM 9 of FIG. 1 is transferred to the measurement data file 22 in the hard disk 11 and stored therein in step S59.

  Since the measurement data stored in this way is measurement data after performing calibration processing, it is highly reliable data after appropriate calibration is performed on a plurality of samples. In addition, according to the present embodiment, the calibration process is always performed prior to performing the measurement on the sample placed on one turntable 52. Therefore, once every few days or once every several months. Compared to the case where calibration is performed in the case where the calibration is performed, or the case where calibration is performed after the measurement of all the samples is completed, highly reliable and accurate measurement data can be obtained. In addition, since the calibration process is automatically performed according to the program software, the operation is easy for the operator.

  As described above, in the present embodiment, by performing steps S1 and S2 in FIG. 7, it is possible to perform TG measurement and DTA measurement after performing calibration processing. However, in the field of thermal analysis, there are times when it is desired to know the measurement result after performing a calibration process of returning the calibration curve to the default state. Assuming such a case, in this embodiment, a clear button is provided in the input device 4 of FIG.

  If the operator operates this clear button, YES is determined in step S5 in FIG. 7 and the control proceeds to step S6. The CPU 8 in FIG. 1 returns the calibration curve L1 in FIG. 5 to the calibration curve L0 of the initial value. Calculate the measurement results. During this calculation process, the CPU 8 displays on the screen of the display device 6 that the measurement result in the default state is being calculated, for example, “CLEAR”. After completion of the calculation, the weight based on the default calibration curve L0 is displayed in step S7.

  In this embodiment, No. 2 on the turntable 52 in FIG. 1-No. The calibration process is automatically performed on the sample position where the weight is placed among the 24 sample positions. That is, the operator can perform the calibration process on the desired sample by simply placing the weight at the desired sample position on the turntable 52 without performing an input operation on the display screen.

  In the present embodiment, in FIG. 1-No. It is necessary to provide a weight detection device for detecting which of 24 sample positions the weight is placed on. This weight detection device can use a detection device having an arbitrary structure that has been conventionally known. For example, a weight sensor is provided in the vicinity of the take-out position P0 of the turntable 52 or the tip of the finger 78, and then a weight is provided. For example, a configuration may be adopted in which a mark is provided on the weight that is detected but not detected by the sample container.

In this embodiment, if it is determined that the calibration process is instructed in step S1 of FIG. 7 (YES in step S1), the calibration / measurement routine of step S2 is entered. Then, in step S51 of FIG . 9 , the input screen 82D of FIG. 10A is displayed. In this input screen 82D, the row columns for all “sample Nos.” Are blank, and the operator can input them. The operator inputs the desired measurement conditions in the blanks on the input screen 82D of FIG. 10A in the order of placement on the turntable 52 of FIG . FIG. 10B shows an example of a screen display after the operator performs such an input operation.

In this embodiment, weights are placed on some of the sample positions on the turntable 52 in FIG. 2 by the operator, but no calibration processing instruction is given on the input screen 82D in FIG. 10B . Therefore, at the time when the operator's input operation is performed, the “sample No.” on the turntable does not exactly correspond to the “sample No.” on the input screen 82D.

Now, suppose that the operator sets the No. of the turntable 52 in FIG. 1-No. In the process of sequentially placing the sample containers at the 24 sample positions, no. 1 and no. Assume that a calibration weight is placed at 10 sample positions. That is, no. 1及 beauty No. It is assumed that 10 substances are set to be calibrated. Then, immediately after the input operation by the operator, the calibration process is not displayed on the input screen 82D as shown in FIG . 1 and no. When the calibration process is executed corresponding to the sample position of No. 10 , as shown in FIG. 1 and no. The display of the calibration process for 10 is displayed in an interrupted state.

In the present embodiment, when the input operation by the operator as shown in FIG. 10 (b) is completed, it is determined YES in step S52 of FIG. 9. In step S53, it is determined whether or not a weight is placed on each “sample No.” on the turntable 52 of FIG. If it is determined that a weight is placed (YES in step S53), it is determined that calibration processing is instructed, and calibration processing is executed in steps S54 to S55. On the other hand, if it is determined that the weight is not loaded, that is, it is determined that the container containing the sample is loaded (NO in step S53), TG measurement and DTA measurement are performed in steps S56 to S57.

  According to the present embodiment, since the operator can instruct the calibration process with only a simple operation of placing the weight on the desired sample position on the turntable 52 in FIG. 2, the operation for the calibration process can be performed. It will be very easy.

In the embodiment described with reference to FIGS . 5 and 8 , one weight of 100 mg is used as a calibration weight, but a plurality of calibration weights can be used. For example, if it is assumed that three types of 1 mg, 50 mg, and 100 mg are automatically recognized in FIG. 5 and calibration weights of these three types of weights are prepared, calibration can be performed based on these three types of weights.

  In general, when calibration is performed using a weight that is close to the measured weight, the error is smaller than when a weight that is far from the measured weight is used. Therefore, it is desirable to prepare a plurality of types of calibration weights having different weights and select one of them according to the measured weight to perform calibration.

As shown in FIG. 8 , when the error ratio judgment standard is within ± 10%, if two weights, for example, 95 mg and 100 mg are selected, the difference in weight between the two weights is small. After that, it becomes impossible to judge which weight should be used. Accordingly, when a plurality of types of weights are prepared, it is desirable to select a weight having a sufficient weight difference in relation to the value of the error ratio determination criterion.

  As a specific example of measurement using a plurality of types of weights, No. 1 on the turntable 52 in FIG. Place a 100 mg weight on the sample mounting position. 2-No. 5 Place a sample in the vicinity of 100 mg at the sample placement position. 6 Place a 50 mg weight on the sample mounting position. 7-No. Place a sample in the vicinity of 50 mg at the 10 sample placement position. 11 Place a 1 mg weight on the sample placement position. 12-No. If a sample in the vicinity of 1 mg is placed at the 15 sample placement position, an appropriate calibration value can be selected corresponding to each of the three types of measured weights.

(Other embodiments)
The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the embodiments, and various modifications can be made within the scope of the invention described in the claims. For example, in the above embodiment, the case where DTA measurement is performed using two balance beams is exemplified, but the case where only one balance beam is used and only TG measurement is performed is also included in the present invention.

It is a block diagram showing one embodiment of a thermal analysis device concerning the present invention. It is a perspective view which shows the principal part of the mechanical structure of the thermal analyzer which concerns on this invention. It is a figure which shows the balance mechanism which is the principal part of FIG. It is sectional drawing which shows the drive mechanism of the arm which is the principal part of FIG. It is a graph for demonstrating a calibration process concretely. It is a graph which shows the TG-DTA curve which is an example of a measurement result. It is a flowchart which shows the flow of the calculation and control which are performed by CPU of FIG. 10 is a flowchart illustrating an example of a calibration routine that is a main part of the flowchart of FIG. 9 . It is a flowchart which shows an example of the calibration / measurement routine which is the principal part of the flowchart of FIG. It is a figure which shows the input screen displayed on a screen at the time of control of FIG.

1. 1. Thermal analysis device 2. TG-DTA device (weight measuring means) 3. Sample changer (sample transport means) 4. input device; Sample change control circuit, 6. 6. image display device; Printer, 11. Hard disk, 12. Buses 26a, 26b. Balance unit, 27a, 27b. Torsion band, 28a, 28b. Balance beam,
29. Electric furnace, 31a, 31b. Heat sensitive plate, 32. Sample container, 33. Reference material,
34. Electromagnetic compensator, 36. Shake detection device 37. Furnace transfer device, 38. permanent magnet,
39. Coil, 41. Voltage detection resistor 44. Light shielding plate, 46. Light source, 47. Light receiving element, 48. PID adjuster, 49. Power amplifiers 51a, 51b. Temperature sensing element, 52. Turntable, 53. Transport arm, 56. Spindle, 59. Turning / lifting device, 61. Shaft member, 62. Machine frame, 63. Casing, 64. Motor, 66. Gear train, 67. Feed screw shaft, 68. Slide base, 69. Stepping motor, 71. Lifting base, 72. Linear stepping actuator 73. Opening and closing mechanism, 74. Cover, 76. Opening and closing member, 77. Support member, 78. Fingers, 81. Weight, 82A, 82B, 82C, 82D. Input screen, L0, L1. Calibration curve, P0. Removal position, Pw. Standby unit, Pm: measuring unit, R.I. Space, S. sample

Claims (5)

A weight measuring means for measuring the weight of the sample placed at the sample measuring position;
A sample transport means for transporting a sample between a sample standby section where a plurality of samples are placed and the sample measurement position;
While the plurality of samples are transferred one by one to the sample measurement position by the sample transfer means and sequentially transferred, the weight of the sample is measured by the weight measurement means with respect to the sample placed at the sample measurement position, and measured. A weighing calculation means for realizing a function of calculating a true weight value by calculation from the weight value obtained,
Calibration calculation means for performing a calibration process for adjusting the calculation for obtaining the true weight value from the measured weight value based on a weight having a known weight placed in the sample standby unit;
A weight detecting means for detecting a weight having a known weight placed in the sample standby section,
The weighing calculation means calculates a true weight value in accordance with the calibration process performed corresponding to the weight for a sample placed in sequence at the sample measurement position following the weight detected by the weight detection means. a thermal analysis method using the thermal analyzer Ru determined,
A plurality of weights having different weights are placed in different order positions of the sample standby part,
Place a sample with a weight in the vicinity of the weight of the weight in the sequential position following the order corresponding to each weight.
The thermal analysis method characterized by this. 2. The thermal analysis method according to claim 1, wherein when the weight measurement unit performs weight measurement in a state in which a weight having a known weight is placed at the sample measurement position, the measurement result is the measurement result. A thermal analysis method characterized in that the calibration process is performed by adjusting the calculation by the weighing calculation means so as to obtain a known weight. The thermal analysis method according to claim 1 or 2, wherein the weighing calculation means calculates the true weight using a calibration curve, and the calibration process is to change the calibration curve. Analysis method . In the thermal analysis method according to any one of claims 1 to 3,
The weight measuring means includes
A balance mechanism with a balance beam;
A shake detection means for detecting a shake of the balance beam when a sample is placed on a sample measurement position of the balance mechanism and outputting a signal;
Force generating means for generating a force according to the supplied power;
Power control means for supplying power to the force generation means based on an output signal of the shake detection means,
The weight measurement is to determine the weight of the sample by comparing the power supplied to the force generation means by the power control means with a predetermined reference calibration curve data.
The thermal analysis method characterized in that the calibration calculation means realizes calibration by adjusting the reference calibration curve data. In the thermal analysis method according to any one of claims 1 to 4,
The weighing calculation means includes:
In addition to the function of obtaining a true weight value according to the calibration process performed corresponding to the weight for the sample placed in order at the sample measurement position following the weight detected by the weight detecting means. ,
A function for obtaining a true weight value without performing a calibration process on a sample placed in sequence at the sample measurement position following the weight detected by the weight detecting means,
A function for obtaining a true weight value after performing a calibration process for returning a calculation condition to a default state with respect to a sample sequentially placed at the sample measurement position following the weight detected by the weight detecting means,
A thermal analysis method comprising selectively having at least one of the following.

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