JPS645244Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a moisture content measuring device that measures the moisture content of a subject such as a fiber bundle by holding it between probes.

Generally, when an object with a certain dielectric constant is inserted between closely spaced electrodes and a high-frequency voltage is applied, a high-frequency current proportional to the dielectric constant flows between the electrodes as shown in equation (1).

i = ωεS / 4πdυ ...(1) υ: Applied high-frequency voltage d: Inter-electrode distance S: Electrode area ε: Permittivity ω: 2π Since the dielectric constant of water is very large compared to other substances, the above-mentioned high-frequency current is approximately proportional to the moisture content in the object, and therefore, by measuring this current, the moisture content in the object can be determined.

Several measuring devices are already known that measure the moisture content of objects based on this principle, but when a subject is held between electrodes, the electrode bed, that is, the surface on which the subject is held, is made of metal or has a high surface. Since it is made of a rigid object such as a molecular material, there is a problem in that the accuracy decreases as described below.

That is, as shown in FIG. 1, the clamping surfaces 2a, 2b of the rigid clamping arms 1a, 1b, respectively.
Hot electrodes 3a, 3b and ground electrodes 4a, 4b
When the fiber bundle 5 is sandwiched between the clamping arms 1a and 1b, the fiber bundle tends to protrude from the clamping surface at both ends of the clamping surface, so that the clamping density tends to decrease. Therefore, the density of the fiber bundle within the clamping surface shows a distribution such that it is high in the central portion 5a and decreases toward both sides 5b, and the porosity is extremely high at both ends of the electrode bed. may become high. The presence of air layers at both ends of the electrode bed is a factor in reducing the accuracy of moisture content measurement.

Furthermore, variations in the density distribution due to differences in the frictional resistance of the specimen and differences in the clamping method are also causes of reduced reproducibility of measurements.

The present invention is configured so that the specimen held between the electrode beds exhibits a uniform density distribution, and prevents a decrease in measurement accuracy and reproducibility due to variations in the density distribution of the specimen. It is characterized by this.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, the moisture content measuring device of the present invention includes a probe 10 equipped with a sensor electrode consisting of a hot electrode and a ground electrode, a control circuit connected to the sensor electrode in the probe 10, and a control circuit connected to the sensor electrode of the probe 10. comprising an arithmetic circuit and a display unit connected to the
It is also equipped with a high frequency oscillation circuit.

The probe 10 has a pair of clamping arms 12a and 12b made of an insulator attached to the tip of a handle 11 so as to be openable and closable, and these arms 12a and 12b can be opened and closed by operating means 13 such as push buttons. As is clear from FIGS. 3 and 4A and 4B, hot electrodes 14a and 14 are provided on the clamping surfaces of each arm for applying a high frequency voltage, respectively.
4b, and annular ground electrodes 15a and 15b concentrically surrounding the hot electrode. Preferably, these electrodes are offset from each other as shown. An elastic body 17 is provided on the clamping surface of each arm to make the density distribution of the subject 16 uniform.
a, 17b are attached. This elastic body 17a,
17b elastically clamps the subject 16 so that it can be reliably clamped on the entire clamping surface even if there is a partial difference in the amount of clamping, so that the specimen 16 at both ends of the clamping surface can be clamped reliably. It prevents the body from protruding and makes its density distribution uniform, and is made of not only natural rubber but also synthetic rubber such as silicone rubber, butadiene rubber, isoprene rubber, and polymeric materials with a sponge-like or mesh structure. In addition, since the density is high in the central part of the clamping surface of the subject, and the density tends to decrease toward both sides, the central part of the elastic body is formed in a concave shape, and the pair of elastic bodies Subject 1 between 17a and 17b
6 may be configured so that the density of the subject can be easily made uniform when sandwiching the sample.

Note that 18a and 18b are reliefs for arms 12a and 12b for applying clamping pressure only to the subject.

When measuring moisture content using the above-mentioned measuring device, a test object 16 such as hair, fibers, thread, etc. is held between the elastic bodies 17a and 17b of the arms 12a and 12b, and a high frequency voltage is applied to the hot electrode. . Then, a high-frequency current proportional to the dielectric constant of the test object flows between the hot electrode and the ground electrode, and this is detected by the control circuit, amplified to a certain level, and then input to the calculation circuit, where the moisture content is determined. It is converted into a proportional signal and displayed as moisture percentage on the display.

In this case, shifting the positions of both hot electrodes is extremely effective in reducing the mutual influence of the lines of electric force from the hot electrodes 14a, 14b toward the ground electrodes 15a, 15b of the own arm. This improves the accuracy of moisture content measurement. That is, the electric lines of force have a shielding effect that shields each other's electric lines of force, and the degree of this effect changes depending on the distance between the arms, and the depth to which the electric lines of force reach changes. Although the measured value of moisture content changes depending on the clamping interval of 16, by shifting the position of the hot electrode as described above, the influence of the electric lines of force described above can be reduced, and measurement accuracy can be improved. Also, from this, when the clamping interval is relatively large,
It can be seen that there is no need to shift the position of the hot electrode.

In such measurements, the subject 16, such as oriented hair or objects with uneven surfaces, tends to have higher density in the center as shown in FIG. By being elastically clamped by the elastic bodies 17a and 17b on the clamping surfaces, the subject 16 is reliably clamped over the entire clamping surface, and almost no protrusion of the subject 16 occurs at both ends of the clamping surfaces. Therefore, the density in the central part of the test object 16 and the parts on both sides thereof appear to be approximately the same, and the porosity in both parts decreases, making it possible to significantly improve the accuracy and reproducibility of moisture content measurement. Become.

As described above, according to the moisture content measuring device of the present invention, since the elastic body capable of elastically clamping the subject is attached to the clamping surface, the specimen can be securely clamped on the entire clamping surface by the elastic body. , it is possible to prevent the specimen from protruding at both ends of the clamping surface, thereby keeping the density distribution of the clamped specimen substantially constant, and measuring the moisture content with high accuracy and reproducibility. I can do it.

[Brief explanation of drawings]

Figure 1 is a sectional view of the main parts showing the usage state of the previously proposed moisture content measuring device, Figure 2 is a configuration diagram of the embodiment of the present invention, and Figures 3 and 4 A and B are enlarged cross-sections of the same main parts. FIG. 10... Probe, 12a, 12b... Clamping arm, 14a, 14b... Hot electrode, 15a,
15b... Earth electrode, 16... Subject, 17
a, 17b...Elastic body.

Claims (1)

[Scope of utility model registration request] A high-frequency voltage is applied to an electrode attached to the probe, and the moisture content in the subject is measured from the high-frequency current flowing in accordance with the dielectric constant of the subject. The clamping method uses a clamping method in which the subject is clamped between the clamping arms, and each of the clamping arms is provided with a hot electrode to which a high-frequency voltage is applied and a ground electrode, and the subject can be elastically clamped on the clamping surface provided with these electrodes. A moisture content measuring device characterized by being equipped with an elastic body.