JP3647022B2 - Rotation amount detection device for thermobalance device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermobalance device used for thermal analysis such as thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), and the like. The present invention relates to a rotation amount detection device for detecting a rotation amount around the center.
[0002]
[Prior art]
Examples of thermal analysis of substances include thermogravimetry (TG) and differential thermal analysis (DTA). Here, in thermogravimetry (hereinafter referred to as “TG”), a weight change of a substance is measured with respect to temperature (or time) while the substance is heated, cooled, or held at a constant temperature. In differential thermal analysis (hereinafter referred to as “DTA”), a sample and a reference material are heated symmetrically in a furnace, and the temperature difference between the two is measured with respect to time (or temperature). .
[0003]
A conventional thermobalance device used for thermal analysis of these TG, DTA, etc. is shown in FIG. The thermobalance device shown in FIG. 1 is called a vertical differential thermobalance device, and has a pair of support rods called a sample side beam 1 and a reference side beam 2, and a sample holder 3 at the tip of these beams. , 4 are held.
In the sample holder 4 held by the reference side beam 2, a thermally stable substance is stored as a reference substance in a sample container 6 disposed at the tip thereof, while the sample holder 3 held by the sample side beam 1 is stored in the sample holder 3. The sample to be measured is stored in the sample container 5 arranged at the tip thereof.
[0004]
The beams 1 and 2 are connected to the drive coil 11 via the auxiliary fulcrums 7 and 8 and the connecting rods 9 and 10 and are rotatably supported by a torsion band 12 serving as a rotation fulcrum. The torsion band 12 is made of a long and thin metal wire, and maintains a straight line by applying a certain tension. Further, the bases of the beams 1 and 2 are coupled to each other by a pulling wire 13, so that the beams 1 and 2 rotate around the auxiliary fulcrums 7 and 8 with respect to environmental changes in the heating furnace 14. ing.
[0005]
Now, when the reference substance and the sample stored in the sample containers 6 and 5 are heated in the heating furnace 14 under the same conditions, the weight of the sample changes according to the change in physical properties. On the other hand, since the reference substance is thermally stable, there is almost no change in weight due to changes in physical properties. The sample holders 3 and 4 held by the beams 1 and 2 rotate integrally around the torsion band 12 as the weight of the sample changes due to heating. The sample holders 3 and 4 are also rotated due to the environment in the heating furnace 14, but this rotation is absorbed by the rotation around the sub-fulcrums 7 and 8 as described above.
[0006]
A rotation amount around the torsion band 12 of each of the sample holders 3 and 4 due to a change in the weight of the sample is detected by a rotation amount detection device 15 and driven from the TG measurement control circuit 16 to the drive coil 11 based on the detected value. A signal is output, and the sample holders 3 and 4 are returned to their original positions. And TG is implement | achieved by detecting the weight change of a sample based on the electric current value of the drive coil 11 required at this time.
[0007]
[Problems to be solved by the invention]
In the conventional thermobalance device described above, the rotation amount detection device 15 for detecting the rotation amount of each sample holder 3, 4 according to the change in the weight of the sample includes the light source 17 and the optical sensor 18 facing each other, and the drive coil 11. And a shielding plate 19 that rotates together with the sample holders 3 and 4. The shielding plate 19 shields a part of the light beam applied to the optical sensor 18 from the light source 17 and changes the shielding amount according to the rotation position.
[0008]
The change in the light shielding amount accompanying the rotation of the shielding plate 19 is taken out as a change in the output of the optical sensor 18 (specifically, a solar cell). Generally, each change associated with a change in the weight of the sample in the thermobalance device is taken out. Since the rotation amount of the sample holders 3 and 4 is very small, when the light shielding position is close to the rotation fulcrum (torsion band 12), the change in the light shielding amount accompanying the rotation is small. The change in the output becomes small, and sufficient resolution cannot be obtained.
[0009]
Therefore, conventionally, the shielding plate 19 is formed long and the light shielding position is separated from the rotation fulcrum to amplify the change in the light shielding amount with respect to the minute rotation. There is a limit to the range in which the shielding plate 19 can be made long due to the technical restrictions, and further improvement in resolution has been desired. Further, when the shielding plate 19 is long, expansion and contraction due to a temperature change of the shielding plate 19 are included in the change of the light shielding amount, and the rotation amount of the sample holders 3 and 4 may not be detected with high accuracy. was there.
[0010]
Further, when the torsion band 12 is bent due to the influence of external vibration or impact, fatigue, or the like, the shielding plate 19 is displaced along with the bending, so that the output of the optical sensor 18 fluctuates and the weight of the sample changes. There was also a risk of false detection.
[0011]
[Means for Solving the Problems]
The present invention has been made in view of the above circumstances, and is a rotation amount detection device for detecting a rotation amount around a rotation fulcrum of a sample holder accompanying a change in the weight of a sample in a thermobalance device, And an optical sensor disposed opposite to the light source, a slit means disposed on the light receiving surface of the optical sensor or on the front surface thereof, and a light shielding means which is disposed at an intermediate position between the light source and the slit means and rotates together with the sample holder. The slit means has a plurality of light receiving side slits arranged in parallel, and the light shielding means has a plurality of light emitting side slits arranged in parallel.
[0012]
With such a configuration, the amount of light shielding can be greatly changed with a slight rotation of the light shielding means by the interaction of the plurality of light receiving side slits and the light emitting side slits, and the sample has a high resolution. The amount of rotation about the rotation fulcrum of the sample holder accompanying the change in weight can be detected. Therefore, it is not necessary to largely separate the light shielding position by the light shielding means from the rotation fulcrum, and it is possible to perform highly accurate detection that is not easily affected by external influences.
[0013]
Here, the light receiving side slit is preferably formed narrower than the light emitting side slit. Further, if at least one pair of light shielding means is provided with the rotation fulcrum interposed therebetween, and a light source, a light sensor, and a slit means are provided corresponding to each light shielding means, the amount of light received by each light sensor is reduced. Depending on the rate of change, it is possible to detect the amount of rotation of the sample holder with respect to rotation in both directions.
[0014]
Furthermore, a pair of light shielding means is provided at a horizontally symmetrical position about the rotation fulcrum, and a relative difference in the output from the optical sensor provided corresponding to each light shielding means, the sample holder of the sample holder accompanying a change in the weight of the sample. If it is configured to detect the amount of rotation about the rotation fulcrum, even if a displacement such as bending occurs at the rotation fulcrum, the displacement of each light shielding means due to the bending is equal to each other. The relative difference in the output from the sensor does not change, and therefore the rotation amount of the sample holder can be detected with high accuracy without being affected by the displacement of the rotation fulcrum.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments in which the present invention is applied to a vertical differential thermobalance apparatus will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram showing an embodiment in which a rotation amount detection device of the present invention is applied to a vertical differential thermobalance device. In addition, the whole structure of the vertical differential thermobalance apparatus to be applied is as described above with reference to FIG.
[0016]
The rotation amount detection device according to the present embodiment includes a light source 30, an optical sensor 31, a slit plate 32 (slit means), and a light shielding plate 33 (light shielding means), and the torsion band 12 as a rotation fulcrum. Are provided at symmetrical positions around the center. In the present embodiment, an infrared lamp is used for the light source 30 and a solar cell is used for the optical sensor 31. As shown in FIG. 2, the light source 30 and the light receiving surface 31a of the optical sensor 31 are arranged to face each other. A light beam (infrared light) emitted from the light source 30 is received by the optical sensor 31.
[0017]
The slit plate 32 is formed with a plurality of narrow light receiving side slits 34 extending in the horizontal direction and arranged in the vertical direction. The slit plate 32 is affixed to the light receiving surface 31 a of the optical sensor 31, and only the light beam that has passed through the light receiving side slit 34 enters the optical sensor 31. Note that the slit plate 32 can also be disposed at a position intermediate between the light source 30 and the optical sensor 31 and separated from the optical sensor 31. Further, the light receiving side slit 34 may be formed directly on the light receiving surface 31a of the optical sensor 31 by coating or the like.
[0018]
The light shielding plate 33 is fixed to the drive coil 11 via the support arm 36 and rotates together with the sample holders 3 and 4 around the torsion band 12 as a rotation fulcrum. As described above, the light shielding plates 33 are provided at symmetrical positions around the torsion band 12 serving as a pivot point. A light source 30, an optical sensor 31, and a slit plate 32 are provided corresponding to each of the light shielding plates 33 (see FIG. 1). As shown in FIG. 2, the light shielding plate 33 is disposed at an intermediate position between the light source 30 and the optical sensor 31 and closer to the light source 30 than the slit plate 32. The light shielding plate 33 is also formed with a plurality of narrow light emitting side slits 35 extending in the horizontal direction and arranged in the vertical direction. The formation intervals of these light emitting side slits 35 are matched with the formation intervals of the light receiving side slits 34.
[0019]
FIG. 3 is a front view showing the relative positional relationship between the light receiving side slit formed in the slit plate and the light emitting side slit formed in the light shielding plate. The width d of the light receiving side slit 34 is formed narrower than the width e of the light emitting side slit 35. The slits 34 and 35 are preferably adjusted before the start of measurement, with the position where the edges (upper edge in the figure) coincide with each other as viewed from the light source 30 side as the reference position. At such a reference position, the entire light receiving side slit 34 is opened as viewed from the light source 30 side. Therefore, the light from the light source 30 passes through the light emitting side slit 35 and further passes through the entire light receiving side slit 34. The light passes through and enters the light receiving surface 31 a of the optical sensor 31.
[0020]
Now, together with the sample holders 3 and 4, when the light shielding plate 33 rotates about the torsion band 12 in the clockwise direction in FIG. 3 (arrow a direction), a part of the light beam transmitted through the light receiving side slit 34 is light shielded. The amount of light rays that are blocked by the plate 33 and incident on the optical sensor 31 decreases. Even if the light reduction amount is small for one light receiving side slit 34, the amount of light transmitted through the light receiving side slits 34 is similarly reduced. . Therefore, even if the light shielding plate 33 is slightly rotated, a decrease in the amount of light transmitted to the plurality of light receiving side slits 34 is added. As a result, the amount of light incident on the light receiving surface 31a of the optical sensor 31 is greatly reduced. Accordingly, the detection signal (voltage) output from the optical sensor 31 changes greatly.
[0021]
From the above, in this embodiment, the amount of light shielding can be greatly changed with respect to slight rotation of the light shielding plate 33 by the interaction of the plurality of light receiving side slits 34 and the light emitting side slits 35. The amount of rotation about the torsion band 12 of the sample holders 3 and 4 accompanying the change in the weight of the sample can be detected with high resolution.
[0022]
Furthermore, since it is not necessary to increase the rotation range of the light shielding plate 33 by increasing the distance from the torsion band 12, the support arm 36 can be shortened. There is almost no bending, and a reduction in detection accuracy due to these can be prevented.
[0023]
The light receiving side slit 34 preferably has an arbitrary area opened through the light emitting side slit 35 even when the light shielding plate 33 is most rotated. That is, when the entire light receiving side slit 34 is shielded when viewed from the light source 30 side during the rotation of the light shielding plate 33, the amount of light incident on the light receiving surface 31a of the optical sensor 31 becomes zero. This is because the output from the optical sensor 31 does not change even when the shielding plate 33 rotates, and the amount of rotation of the sample holders 3 and 4 cannot be detected. The width d of the light receiving side slit 34 and the width e of the light emitting side slit 35 are preferably set in consideration of such points.
[0024]
Further, when the sample holders 3 and 4 are rotated counterclockwise (arrow b direction) from the reference position shown in FIG. 3, the lower end edge of the light receiving side slit 34 and the light emitting side slit 35 are viewed from the light source 30 side. Since there is a distance from the lower edge, the opening area of the light receiving side slit 34 does not change, and therefore the amount of light incident on the light receiving surface 31a of the optical sensor 31 through the light receiving side slit 34 does not change. However, the light-receiving side slit 34 of the slit plate 32 provided at a symmetrical position about the torsion band 12 serving as a pivotal fulcrum is shielded in response to the counterclockwise (arrow b direction) rotation of the light shielding plate 33. Thus, the amount of rotation of the sample holders 3 and 4 can be detected from the output of the optical sensor 31. Thus, in this embodiment, even if the sample holders 3 and 4 are rotated in any direction, the rotation amount can be detected.
[0025]
In addition, if the amount of rotation of the sample holders 3 and 4 is detected based on the relative difference between the outputs from the optical sensors 31 provided symmetrically about the torsion band 12 serving as a rotation fulcrum, the sample holders 3 and 4 are bent. Even if this occurs, the displacement of each light shielding plate 33 due to the bending is equal, so the relative difference in output from the optical sensor 31 at the reference position does not change. Therefore, the amount of rotation of the sample holders 3 and 4 can be detected with high accuracy without being affected by the bending of the torsion band 12.
[0026]
In addition, this invention is not limited to embodiment mentioned above.
For example, not only the vertical differential thermobalance device but also various thermobalance devices such as a single beam thermobalance device and a horizontal differential thermobalance device can be used.
[0027]
Further, as shown in FIG. 4, the vertical type difference is such that the sample holders 3 and 4 are rotated with the sub-fulcrum being omitted and the rod-shaped support shaft 21 supported by the bearing 20 instead of the torsion band being used as the rotation fulcrum. When the rotation amount detection device of the present invention is applied to the dynamic thermobalance device, the light shielding plate 33 may be attached to the support shaft 21 via the support arm 36. Also in this case, the light shielding plate 33 is provided at a bilaterally symmetrical position around the support shaft 21 serving as a rotation fulcrum, and the light source 30, the optical sensor 31, and the slit correspond to each of the light shielding plates 33. A plate 32 is preferably provided.
[0028]
【The invention's effect】
As described above, according to the present invention, the amount of light shielding can be greatly changed with respect to slight rotation of the light shielding means by the interaction of the plurality of light receiving side slits and the light emitting side slits. The amount of rotation around the rotation fulcrum of the sample holder can be detected with resolution.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment in which a rotation amount detection device of the present invention is applied to a vertical differential thermobalance device.
FIG. 2 is a perspective view showing a rotation amount detection device according to an embodiment of the present invention.
FIG. 3 is a front view showing a relative positional relationship between a light receiving side slit formed in the slit plate and a light emitting side slit formed in the light shielding plate.
FIG. 4 is a configuration diagram showing an application example of the present invention.
FIG. 5 is a configuration diagram showing a conventional vertical differential thermal balance apparatus.
[Explanation of symbols]
1: Sample side beam 2: Reference side beam 3, 4: Sample holder 5, 6: Sample container 7, 8: Sub fulcrum 11: Drive coil 12: Torsion band (rotation fulcrum)
14: heating furnace 15: rotation amount detection device 16: TG measurement control circuit 17: light source 18: light sensor 19: shielding plate 30: light source 31: light sensor 31a: light receiving surface 32: slit plate 33: light shielding plate 34: light reception Side slit 35: Light emission side slit 36: Support arm

Claims (4)

A rotation amount detection device for detecting a rotation amount around a rotation fulcrum of the sample holder accompanying a change in the weight of the sample in the thermobalance device,
A light source and a photosensor arranged opposite to the light source, slit means arranged on the light receiving surface of the photosensor or in front of the light sensor, and light rotating with the sample holder arranged at an intermediate position between the light source and the slit means Shielding means,
The slit means has a plurality of light receiving side slits arranged in parallel,
The light shielding means includes a plurality of light emitting side slits arranged in parallel, and a rotation amount detecting device. In the rotation amount detection device of the thermobalance device according to claim 1,
The rotation amount detecting device, wherein the light receiving side slit is formed narrower than the light emitting side slit. In the rotation amount detection device of the thermobalance device according to claim 1 or 2,
While providing at least one pair of the light shielding means with a rotation fulcrum in between,
A rotation amount detection device comprising the light source, the optical sensor, and the slit means corresponding to each of the light shielding means. In the rotation amount detection device of the thermobalance device according to claim 3,
A pair of the light shielding means is provided at a horizontally symmetrical position around the rotation fulcrum,
With a relative difference between the output from the optical sensor provided in correspondence with the light shielding means, the rotation amount detecting unit and detects the amount of rotation around the pivot point of the sample holder with the weight change of the sample .

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