JP2724986B2 - Differential thermobalance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential thermobalance provided with a feedback control system for balancing a beam between a sample-side balance beam and a reference material-side balance beam.

[0002]

2. Description of the Related Art A differential thermobalance provided with a sample-side balance beam and a reference material-side balance beam is disclosed, for example, in Japanese Patent Laid-Open No. 58-72.
As disclosed in Japanese Patent No. 033, this differential thermobalance has a feedback control system for each of the two beams, and calculates the reference material side balance beam based on the output value of the sample side balance beam feedback control system. By subtracting the output value of the feedback control system, the influence (for example, the influence of buoyancy and convection) due to factors other than the weight change of the sample is offset. However, when subtracting the output values of both, instead of simply subtracting, the difference between the two balance beams is compensated by multiplying by a correction coefficient and then subtracting.

[0003] Further, after devising that the current flowing through the feedback coil of one balance beam also flows through the feedback coil of the other balance beam, the outputs of the two feedback control systems are calculated to calculate the weight change of the sample. Japanese Patent Laid-Open Publication No.
No. 251753.

[0004]

In the conventional examples described in the above two publications, when two beams are tilted due to a factor other than a change in the weight of the sample, a transient until the output of the feedback control system becomes stable. An error signal may appear in the TG output during a specific period. The reason is that, in these conventional examples, the output values of the two feedback control systems are finally subtracted to obtain the TG output. If the two feedback control systems have different time constants (in general, the time constants cannot be completely the same), when the outputs of the two feedback control systems during the transition period are calculated, the resulting values are meaningless. Error signal. Also, if an arithmetic circuit is used in the final stage for obtaining the TG output, the drift and gain error of the arithmetic circuit directly affect the measurement result.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object the purpose of making a transient beam immediately after two balance beams are affected by factors other than a change in the weight of a sample. An object of the present invention is to provide a differential thermobalance in which an error does not occur in the TG output even in a simple control state.

[0006]

A differential thermobalance according to the present invention has a reference material-side balance beam on which a reference material can be placed at one end and which is rotatably supported by a fulcrum;
A sample-side balance beam capable of mounting a sample on one end and rotatably supported by a fulcrum, a first tilt detection device for detecting a tilt of the reference material-side balance beam from a predetermined balance state, A second tilt detector for detecting the tilt of the side balance beam from a predetermined balance state, and a reference by applying a first rotational moment to the reference material side balance beam according to the output of the first tilt detector. A reference material-side feedback control system for returning the material-side balance beam to a predetermined balance state; and a reference material-side balance by applying a second rotational moment to the sample-side balance beam according to the output of the first tilt detector. An interlocking control system that applies a rotational moment corresponding to the unbalance generated by the beam to the sample-side balance beam, and a sample-side balance beam in accordance with the output of the second tilt detector. A sample-side feedback control system that returns the sample-side balance beam to a predetermined balance state by applying a third rotational moment to the system, and measures the weight change of the sample based only on the output of the sample-side feedback control system. It is characterized by doing.

To explain the operation of the present invention, when the balance between the two balance beams is lost, the reference material side feedback control system returns the reference material side balance beam to a predetermined balance state. The interlocking control system also applies a rotational moment corresponding to the unbalance generated in the reference material-side balance beam to the sample-side balance beam, and cancels out factors other than a change in the weight of the sample by the two balance beams. further,
The sample side feedback control system returns the sample side balance beam to a predetermined balance state. The output of the sample-side feedback control system corresponds to the change in the weight of the sample, and it is sufficient to measure only this. In the present invention, when a rotational moment for returning to the balance state is applied to the reference material-side balance beam, an equivalent rotational moment is also applied to the sample-side balance beam, and thereby, except for a change in weight of the sample. To offset the effects. However, instead of applying exactly the same rotational moment, if there is no change in the weight of the sample, adjust the gain appropriately so that the sample-side balance beam returns to a completely balanced state only by the operation of the interlocking control system. ing.

In the present invention, it is preferable that the time constant of the reference material-side feedback control system be smaller than the time constant of the sample-side feedback control system. In this case, regarding the influence other than the change in the weight of the sample, the sample-side balance beam moves (ie, follows) almost simultaneously and in the same direction as the reference material-side balance beam, so that meaningless noise hardly appears in the TG output. .

Each of the three control systems, ie, the reference material side feedback control system, the interlocking control system, and the sample side feedback control system, has a control coil through which a control current flows. Since both the second control coil of the interlocking control system and the third control coil of the sample-side feedback control system impart a rotational moment to the sample-side balance beam, the second control coil is wound. It is convenient to manufacture by winding the wire and the winding of the third control coil around a common bobbin. By doing so, the control coil is lighter and the installation space is smaller than when a winding is wound around a separate bobbin. Furthermore, the effect of the spatial non-uniformity of the permanent magnet arranged adjacent to the control coil is reduced between the second control coil and the third control coil.

[0010]

FIG. 1 is a block diagram of an embodiment of a differential thermobalance according to the present invention. The thermobalance includes a reference material-side balance beam 10 and a sample-side balance beam 12. The two balance beams 10 and 12 are respectively connected to the fulcrum 1
It is rotatably supported by 4 and 16. A reference material container 18 is provided at one end of the reference material-side balance beam 10, and a shutter 20 having a slit is fixed at the other end. A sample container 22 is installed at one end of the sample-side balance beam 12, and a shutter 24 having a slit is fixed at the other end. The reference material container 18 contains a material that is thermally stable in the temperature range to be measured.
A sample to be measured is placed in the sample container 22. Movable weights 26 and 28 are attached to the middle of the two balance beams 18 and 20 so that the imbalance of the initial state of the beams can be corrected.

The tilt of the reference material-side balance beam 10 from the horizontal state is detected by the first tilt detecting device 30. The first tilt detecting device 30 includes a light source 32, a shutter 20, and a first light receiving device 34. Shutter 20 is light source 3
Of the light emitted from the light source 32 and disposed between the second light-receiving device 34 and the first light-receiving device 34, only the light that has passed through the slit of the shutter 20 reaches the first light-receiving device 34.

FIG. 2A is a front view of the first light receiving device 34, and FIG. 2B is an electric circuit diagram of the first light receiving device 34. As shown in FIG. 2, an optically symmetric 1
A pair of photodiodes 54 and 56 are arranged side by side in the vertical direction, and are connected to have opposite polarities. When the light that has passed through the slit of the shutter 20 (see FIG. 1) hits the first light receiving device 34, a signal proportional to the difference between the irradiation area 55 on the photodiode 54 and the irradiation area 57 on the photodiode 56 is output from the first light receiving device. Are output from the light-receiving device 34 of FIG. That is, a signal corresponding to the inclination of the balance beam on the reference material side is output. When the reference material side balance beam 10 of FIG.
The positional relationship between the light source 32, the shutter 20, and the first light receiving device 34 is adjusted so that the output of the light receiving device 34 becomes zero. Note that a solar cell or a phototransistor may be used instead of the photodiode.

FIG. 2C is a front view of a modified example of the first light receiving device 34. In this example, the vicinity of the center in the vertical direction of the first light receiving device 34 is blocked by the shutter 59,
Light is applied to the photodiodes 54 and 56 at the upper and lower portions. Also in this case, the photodiode 54
A signal proportional to the difference between the upper irradiation area 55a and the irradiation area 57a on the photodiode 56 is transmitted to the first light receiving device 34.
Is output from However, the relationship between the sign of the difference in irradiation area and the moving direction of the balance beam is opposite to that in the case of FIG. In the case of this modification, there is no need to form a slit in the shutter.
Alternatively, the end of the balance beam on the reference material side can be used as it is.

The tilt of the sample-side balance beam 12 from the horizontal state is detected by a second tilt detecting device 36. The configuration of the second tilt detecting device 36 includes a light source 38, a shutter 24, and a second light receiving device 40, similarly to the first tilt detecting device 30 described above. The configuration 40 of the second light receiving device is the same as that of the first light receiving device 34 described above. The light source 38 and the shutter 24 are arranged such that the output of the second light receiving device 40 becomes zero when the sample-side balance beam 12 is in the horizontal state.
And the first light receiving device 40 is adjusted in positional relationship.

In the middle of the balance beam 10 on the reference material side, the first
Is fixed, and the permanent magnet 42 is
Of the control coil 44 in the vertical direction. Thereby, the reference material side balance beam 10 is
Of the rotating moment. The sample-side balance beam 1
2 are fixed with a second permanent magnet 46 and a third permanent magnet 48, which are respectively connected to the second control coil 5.
0 and a current flowing through the third control coil 52 receive a vertical force. That is, the sample-side balance beam 12 receives the second rotational moment by the operation of the second control coil 50, and receives the third rotational moment by the operation of the third control coil 52.

Next, the configuration of the control system of the differential type thermobalance will be described. The output of the first light receiving device 34 is input to the reference material side control circuit 58. The reference material side control circuit 58 is constituted by a PID circuit, and outputs a control signal for returning the reference material side balance beam 10 to the horizontal state by the two drive circuits 60 and 6.
Output to 2. The first drive circuit 60 includes a power amplification circuit 66
Consists of The second drive circuit 62 includes a gain setter 68 and a second power amplifier circuit 70. First drive circuit 60
Outputs a first control current 67 for returning the inclination of the reference material-side balance beam 10 to a horizontal state, and this is the first control current 67.
Flow through the control coil 44. Also, the second drive circuit 62
Outputs a second control current 71 corresponding to the above-described first control current 67, which flows through the second control coil 50. The important point here is that the second control current 71
Is the current corresponding to the imbalance of the reference material-side balance beam 10, which is the sample-side balance beam 12.
Is input to the second control coil 50 on the side of.

On the other hand, the output of the second light receiving device 40 on the side of the sample-side balance beam 12 is input to the sample-side control circuit 72. The sample-side control circuit 72 includes a PID circuit and a power amplifier circuit. This sample side control circuit 72
A third control current 73 for returning the sample-side balance beam 12 to a horizontal state is output, and flows through the third control coil 52. The third control current 73 is detected by the current detection circuit 74 and sent to the TG measurement circuit 76. The TG measurement circuit 76 includes a scaling circuit, a smoothing circuit, a differentiation circuit, a zero shift circuit, and a% (percent) calculation circuit. The output of the TG measurement circuit 76 is sent to a data processing computer, a recorder, a display panel device, a temperature control circuit, an atmosphere controller, and the like, and is used for data analysis, recording, temperature control, atmosphere gas control, and the like. You.

The control system described above is roughly divided into a reference material side feedback control system, an interlocking control system, and a sample side feedback control system. The reference material side feedback control system is configured to reach the first control coil 44 from the first light receiving device 34 via the reference material side control circuit 58 and the first power amplifier circuit 66. It plays a role of returning the balance beam 10 to a predetermined balance state (horizontal state in this embodiment). The interlocking control system includes the first light receiving device 34, the reference substance side control circuit 58, the gain setting device 6
8, through the second power amplifier circuit 70, to the second control coil 50, the reference material side balance beam 10
A role of imparting a rotational moment corresponding to the unbalance generated in the above to the sample-side balance beam 12 as well. The sample-side feedback control system is configured to reach the third control coil 52 from the second light receiving device 40 via the sample-side control circuit 72, and to adjust the sample-side balance beam 12 to a predetermined balance state (this embodiment). In the horizontal state).
The control output (third control current 73 in this embodiment) of the sample-side feedback control system indicates a change in the weight of the sample.

Next, adjustment of the beam balance by the movable weights 26 and 28 will be described. With the reference material in the reference material container 18 of the balance beam 10 on the reference material side, the movable weight 2
6 is moved so that the reference material-side balance beam 10 is in a horizontal state with almost no current flowing through the first control coil 44. Similarly, while the sample to be measured is placed in the sample container 22 of the sample-side balance beam 12, the movable weight 28 is moved, and the second control coil 50 and the third control coil 52 are moved.
The sample-side balance beam 12 is set to be in a horizontal state even when almost no current flows. By adjusting in this manner, the driving force burden on the control coils 44, 50, and 52 can be reduced, and the coils can be reduced in size and weight.

Next, the principle of the differential thermobalance will be described. This differential-type thermobalance cancels out the effects of factors other than the weight change of the sample with the two balance beams so that only the unbalance amount of the sample-side balance beam caused by the weight change of the sample can be measured. It is. Since the reference material-side balance beam 10 and the sample-side balance beam 12 are basically made to have the same structure, the unbalance amount other than the change in the weight of the sample can be measured not only by the sample-side balance beam 12 but also by the reference. It will appear in the material-side balance beam 10 as well.
Therefore, if the unbalance amount of the reference material-side balance beam 10 is subtracted from the entire unbalance amount of the sample-side balance beam 12, only the unbalance amount due to a change in the weight of the sample should be measured. In this thermobalance, the same rotational moment as the rotational moment for maintaining the reference material-side balance beam 10 horizontal is also applied to the sample-side balance beam 12 so that influences other than a change in the weight of the sample are affected. They try to offset each other. Since the sample-side balance beam also has an unbalance amount due to a change in the weight of the sample, in order to keep the sample-side balance beam “actually” horizontal, a third rotation separate from the above-described rotation moment is required. You need a moment. And this third
Is the change in weight of the sample.

It is not actually appropriate to apply a rotational moment having exactly the same value as the rotational moment for maintaining the reference-material-side balance beam 10 horizontal to the sample-side balance beam 12. This is because the two balance beams 10, 12 cannot be under exactly the same conditions. When the same reference material is placed on the two balance beams 10 and 12 and the temperature is changed in the heating furnace, the unbalance amounts of the two balance beams are not always the same. Therefore, it is necessary to compensate for such an error. That is, a rotation moment for maintaining the reference material-side balance beam 10 horizontal is multiplied by a predetermined correction coefficient to calculate a correction rotation moment (second rotation moment). What is necessary is just to give. In this way, when there is no change in the weight of the sample, the sample-side balance beam is also kept horizontal.
In other words, if the sample-side balance beam can be finally maintained horizontal by applying a third rotational moment, the third rotational moment alone indicates a change in the weight of the sample. Since the third rotational moment applied to the sample-side balance beam 12 is proportional to the current 73 flowing through the third control coil 52, a change in the weight of the sample can be known by measuring the current 73.

In the thermobalance shown in FIG.
Is provided for correctly compensating the relationship between the first rotational moment and the second rotational moment. That is, the gain setting unit 68 corrects the difference between the load moments received by these two beams when a common imbalance occurs between the reference material-side balance beam and the sample-side balance beam due to an effect other than a change in the weight of the sample. Is what you do. The set gain can be obtained experimentally by performing a TG measurement using two balance beams 10 and 12 without using a sample.

Next, the operation of the differential thermobalance will be described. The reference substance is placed in the reference substance
A sample to be measured is placed in the heating furnace, and the tips of the two balances are inserted into a heating furnace (not shown) to heat the sample and the reference substance by a predetermined temperature raising program. When the balance of the reference material-side balance beam 10 is lost due to the imbalance, the first light-receiving device 34 detects this and the control circuit 58 outputs a control signal for returning the reference material-side balance beam 10 to the horizontal state. Is output. This control signal passes through the first power amplifier circuit 66 to become a first control current 67, which flows through the first control coil 44. Thereby, the permanent magnet 42 receives the driving force, and the reference material-side balance beam 10 receives the first rotational moment, and is returned to the horizontal state. The control circuit 5
The control signal output from the gain setting device 68 and the second
, A second control current 71 flows through the second control coil 50. Accordingly, the permanent magnet 46 receives the driving force, and the sample-side balance beam 12 also receives the second rotational moment in the same direction as the reference material-side balance beam 10. At that time, the gain setting device 6
By virtue of 8, the sample-side balance beam 12 receives a rotational moment such that if there is no change in the weight of the sample, it will be kept horizontal.

When there is a change in the weight of the sample, the sample-side balance beam 12 is tilted from the horizontal state even if it receives the second rotational moment by the second control coil 50. This tilted state is detected by the second light receiving device 40 and input to the sample-side control circuit 72. In the sample side control circuit 72, a third direction of returning the sample side balance beam 12 to the horizontal state is set.
Of the third control coil 52
Flows through. By such feedback control, the sample-side balance beam 12 is finally brought into a horizontal state. At this time, the third control current 73 flowing through the third control coil 52 is detected by the current detection circuit 74. This third control current 7
3 represents the weight change of the sample. Then, the third control current 73 is sent to the TG measurement circuit 76, and the weight change of the sample is obtained.

This differential thermobalance is excellent in measurement accuracy in a transient period when compensating for imbalance when an influence other than a change in weight of a sample is received. This point will be described by comparing a conventional example with the present embodiment. FIG. 3A is a graph schematically showing the transient response of a conventional differential thermal balance having two balance beams. The horizontal axis is time. This graph shows a case where the sample was affected by a change other than the change in weight of the sample. The effects other than the weight change of the sample include, for example, thermal expansion of the beam, buoyancy and convection,
Transmission of vibration from the outside can be considered. In the conventional differential-type thermobalance, the imbalance generated in the reference material-side balance beam is eliminated by a feedback control system dedicated to this beam, and the control output at that time is represented by curve 8 in FIG.
It will be like 0. On the other hand, the imbalance generated in the sample-side balance beam is eliminated by a feedback control system dedicated to this beam, and the control output at that time is as shown by a curve 82. Then, a difference between the curves 80 and 82 is obtained to obtain a TG output as shown by a curve 84. In fact, since the above-mentioned effects do not act exactly on the two beams, the difference is obtained by multiplying one of the control outputs by a predetermined correction coefficient without taking the difference, and taking the difference as the TG output. I have. By the way, if the above-mentioned correction coefficient is set correctly, if there is no change in the weight of the sample, the TG output certainly returns to zero after the elapse of the predetermined time. However, in a transient state up to that point, an error signal as shown by a curve 84 appears in the TG output even though there is no change in the weight of the sample. This is because the two balance beams each have an independent feedback control system and their time constants are different from each other. The signal appearing at the TG output in this transient state is physically meaningless noise.

On the other hand, in the differential thermobalance according to the present embodiment, as shown in FIG. 3B, when there is no change in the weight of the sample, the TG output remains almost zero even in the transient state. It is. A first control current for compensating for the imbalance of the reference-side balance beam is shown by curve 86. on the other hand,
The second control coil of the sample-side balance beam includes the first control coil described above.
, A second control current corresponding to the control current of FIG. Since the first control current is an output of the reference material-side feedback control system, it changes with its own time constant, but the second control current is obtained by simply multiplying the first control current by a predetermined correction coefficient. The second control current also changes with the same time constant as the first control current. Therefore, the first control current and the second control current show similar transient changes.

On the other hand, the control output of the feedback control system for maintaining the sample-side balance beam horizontal is a third control current, but the sample-side balance beam is maintained horizontal by the second control current. (Assuming that there is no change in the weight of the sample), the third control current (ie, T
G output) remains substantially zero, as shown by curve 90.

However, in order for the present embodiment to show such a transient change, the following conditions must be satisfied. That is, the time constant of the reference material-side feedback control system is set to be smaller than the time constant of the sample-side feedback control system. By doing so, when an effect other than a change in the weight of the sample simultaneously acts on both the reference material-side balance beam and the sample-side balance beam, first, the feedback control system of the reference material-side balance beam quickly responds, The tilt of the reference-material-side balance beam is returned to the horizontal state, and at the same time, the sample-side balance beam also attempts to return to the horizontal state at the same speed via the second control current. Thereafter, the feedback control system of the sample-side balance beam responds, and if there is a change in the weight of the sample, a third control current is output to compensate for the inclination of the sample-side balance beam caused by the change. This is the TG output. As described above, the sample-side balance beam is first given a rotational moment so as to perform the same operation as the unbalance compensation operation of the reference material-side balance beam, and thereafter, the unbalance compensation due to the change in the weight of the sample is performed. Work. Therefore,
Even in a transient state, an irrelevant noise signal hardly occurs in the TG output.

The transient time until the balance beam is unbalanced is typically on the order of a few seconds, after which the TG output of a conventional differential thermobalance also has an error. Does not occur. However, even during transitional periods,
If noise of unknown meaning occurs in the TG output, it will affect the measurement result. The present embodiment is superior to the conventional example in that such noise can be avoided.

FIG. 4 is a side view schematically showing an example of arrangement of control coils. Sample side balance beam 12, Sample container 22
Is divided into a beam portion 12a on the side on which is mounted and a beam portion 12b on the side provided with the shutter 24. And
These are fixed to the bobbin 92 of the control coil. The bobbin 92 is wound with the winding 50c of the second control coil and the winding 52c of the third control coil together. An arc-shaped permanent magnet 94 penetrates a central through hole of the bobbin 92. The permanent magnet 94 is fixed to a support 96. When current flows through the windings 50c and 52c of the control coil, the bobbin 92 around which these windings receive a force due to the interaction with the permanent magnet 94, and the sample-side balance beam 12 rotates around the fulcrum 16. Receive the moment.

The control coil of the reference material side balance beam 10 has the same structure as the sample side balance beam 12. However, only the winding of the first control coil 44 is wound around the bobbin.

In the embodiment shown in FIG. 4 described above, the control coil is fixed to the balance beam so as to be movable, and the permanent magnet is fixed to the support and is stationary. Therefore, the movable side and the stationary side are opposite to the embodiment shown in FIG. 1 (the movable side is a permanent magnet and the stationary side is a control coil). Thus, either the permanent magnet or the control coil may be on the movable side. Therefore, in FIG. 4, a structure in which the permanent magnet 94 is fixed to the balance beam 12 may be employed.

FIG. 5 is a perspective view of the bobbin 92 fixed to the sample-side balance beam. At both ends of the bobbin 92, there are flanges 98, 100, between which the winding 50c,
52c is wound. In the center of bobbin 92, through hole 1
The arc-shaped permanent magnet 94 penetrates the through hole 102. Second control coil winding 5
Oc is wound at the upper half position of the bobbin 92 and is connected to the terminals 50a and 50b. The winding 52c of the third control coil is wound at the lower half position of the bobbin 92 and is connected to the terminals 52a and 52b. Thus, the two control coil windings 50c, 52c
Are wound around a common bobbin 92.

FIG. 6 shows an example in which the winding method is changed. In this example, first, over the entire bobbin 92,
Winding the winding 50c of the second control coil, on which
The winding 52c of the third control coil is wound. The winding 50c is connected to the terminals 50a and 50b,
2c is connected to terminals 52a and 52b.

As still another winding method, in FIG.
A method in which two windings 50c of the second control coil and 52c of the third control coil are wound around the bobbin 92 at the same time may be adopted.

[0036]

According to the differential thermobalance of the present invention, the balance beam of the reference material side is controlled by the reference material side feedback control system, and the balance of the sample side balance beam is controlled by the interlocking control system and the sample side feedback control system. Therefore, since the measurement result is obtained based only on the output of the sample-side feedback control system, when the two balance beams are affected by other than the change in the weight of the sample, the TG can be obtained even in the transient control state immediately after. There is no error in the output. Further, since it is not necessary to obtain the measurement result by subtracting the output values of the two feedback control systems, a drift error and a gain error due to the arithmetic circuit in the final stage do not occur. Furthermore, if the time constant of the reference-material-side feedback control system is set smaller than the time constant of the sample-side feedback control system, the sample-side balance beam is almost the same as the reference-material-side balance beam with respect to effects other than changes in the weight of the sample. Simultaneously and in the same direction (that is, following), meaningless noise is less likely to appear on the TG output in the transient state. Furthermore, if the windings of the two control coils related to the sample-side balance beam are wound around a common bobbin, the structure of the control coil can be simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a differential thermobalance according to the present invention.

FIG. 2 shows two front views and an electric circuit diagram of a first light receiving device.

FIG. 3 is a graph showing a comparison between a conventional example and an embodiment of the present invention with respect to a transient output change of a differential thermobalance.

FIG. 4 is a side view schematically showing an example of arrangement of control coils.

FIG. 5 is a perspective view of a bobbin fixed to a sample-side balance beam.

FIG. 6 is a perspective view of a bobbin in which a winding method is changed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 reference material-side balance beam 12 sample-side balance beam 14, 16 fulcrum 30 first tilt detector 36 second tilt detector 44 first control coil 50 second control coil 52 third control coil 58 reference material Side control circuit 60 first drive circuit 62 second drive circuit 66 first power amplifier circuit 67 first control current 68 gain setter 70 second power amplifier circuit 71 second control current 72 sample side Control circuit 73 Third control current 74 Current detection circuit 76 TG measurement circuit

Continued on the front page (72) Inventor Kasumi Sugiura 3-9-12 Matsubara-cho, Akishima-shi, Tokyo Inside Rigaku Electric Co., Ltd. (72) Inventor Nobuhiro Tanaka 3-9-1-12 Matsubara-cho, Akishima-shi, Tokyo Rigaku Electric stock In-house (56) References JP-A-3-251735 (JP, A) JP-A-5-80005 (JP, A)

Claims (3)

(57) [Claims] 1. A reference material-side balance beam capable of mounting a reference material at one end and rotatably supported by a fulcrum, and a sample capable of mounting a sample at one end and rotatably supported by a fulcrum. A first method for detecting an inclination of the sample-side balance beam and the reference material-side balance beam from a predetermined balance state.
A second tilt detector that detects the tilt of the sample-side balance beam from a predetermined balance state, and a first reference-balance-balance beam according to the output of the first tilt detector. A reference material-side feedback control system that returns the reference material-side balance beam to a predetermined balance state by applying a rotation moment; and a second rotation moment to the sample-side balance beam according to the output of the first tilt detection device. An interlocking control system that also applies a rotational moment corresponding to an imbalance generated by the reference material-side balance beam to the sample-side balance beam; and a sample-side balance beam according to the output of the second tilt detection device. A sample-side feedback control system that returns the sample-side balance beam to a predetermined balance state by applying a third rotational moment to the sample-side balance. Differential thermobalance, characterized by measuring the weight change of the sample on the basis of only the output of the readback control system. 2. The differential thermobalance according to claim 1, wherein the time constant of the reference material-side feedback control system is smaller than the time constant of the sample-side feedback control system. 3. The reference-material-side feedback control system includes a first control coil through which a current flows according to an output of the first tilt detection device, and the interlocking control system includes the first tilt detection device. A second control coil through which a current flows according to the output of the sample side feedback control system,
A third control coil through which a current flows according to an output of the second tilt detection device, wherein a winding of the second control coil and a winding of the third control coil are wound around a common bobbin; 2. The differential thermobalance according to claim 1, wherein