JPS6319021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moisture measuring device for measuring the moisture contained in an object, and more specifically, the present invention relates to a moisture measuring device for measuring moisture contained in an object. The present invention relates to a moisture measuring device using a clamping method.

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 / 4πdν ... (1) ν: Applied high frequency voltage d: Distance between electrodes S: Electrode area, ε: Dielectric constant ω: 2π Since the dielectric constant of water is very large compared to other substances, the above high frequency The 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.

Although some measuring devices for measuring the moisture content of objects based on such a principle are already known, no device has been proposed that employs a clamping method in which a subject is clamped between electrodes. This is based on the conventional wisdom that moisture cannot be measured accurately using the clamping method, where fluctuations in d are unavoidable, since the high-frequency current i and the inter-electrode distance d are inversely proportional in equation (1). This is for the sake of

The present invention has the advantage that if a hot electrode for applying a high-frequency voltage and a corresponding ground electrode are attached to each of a pair of clamping arms, the distance between these electrodes becomes constant regardless of the clamping interval of the arms. From this point of view, the present invention aims to provide a moisture measuring device that uses a clamping method and is capable of performing highly accurate measurements.

That is, as shown in FIG. 1A, the clamping arm 1
If hot electrodes 2a, 2b and ground electrodes 3a, 3b are attached to arms 1a, 1b, respectively, the distance d between the electrodes will be constant regardless of the clamping interval l, and theoretically an arbitrary amount of distance can be formed between arms 1a and 1b. It should be possible to measure by holding the subject in place. However, in reality, as shown in FIG. 1B, even if d is constant, the measured value of moisture content changes depending on l. This is because the lines of electric force from the hot electrodes 2a, 2b toward the ground electrodes 3a, 3b of the own arm influence each other, producing a shielding effect in which each other shields the lines of electric force of the other, and the degree of this effect varies depending on the arm. It is assumed that this is because the depth at which the electric lines of force reach changes depending on the distance between the two. Then,
As can be seen from FIG. 1B, the moisture content at this time changes almost proportionally to the sandwiching interval l, and this relationship is opposite to the relationship between i and d in equation (1).

The present invention is particularly characterized in that the influence of such electric lines of force on each other is reduced to improve measurement accuracy.

Hereinafter, the present invention will be described in more detail with reference to the drawings. As shown in FIG. 10
The device includes a control circuit connected to the sensor electrode, an arithmetic circuit and a display section connected to the control circuit, and further includes a high frequency oscillation circuit.

As is clear from FIG. 3, 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 are operated by operating means such as push buttons. 13 so that it can be opened and closed.
Small-diameter hot electrodes 14a, 14b for applying a high-frequency voltage, and long-diameter rod-shaped earth electrodes 15a, 15b facing each other with the hot electrodes sandwiched therebetween are attached to the clamping surfaces of each arm. Hot electrodes 14a, 14
b are disposed at positions not facing each other by shifting their mounting positions along the clamping surface.

Note that 16a and 16b are reliefs for arms 12a and 12b for applying clamping pressure only to the subject.

Shifting the positions of the two hot electrodes is extremely effective in reducing the influence of the electric lines of force on each other as described above.
It is possible to prevent the high frequency current i from changing with the clamping interval l between a and 12b. That is, the fourth
As shown in the figure, by shifting the positions, the proportion of the lines of electric force in the hot electrodes 14a and 14b that directly influence each other is reduced, and as a result, the lines of electric force directed toward the ground electrode on the other arm increase, and this This is because the reach depth of the electric lines of force is less affected by the interval l.

The direction in which the hot electrodes 14a, 14b are shifted is the x-axis direction of the clamping surfaces of the arms 12a, 12b, that is, the direction of the earth electrodes 15a, 15b, as shown in FIG. 5A, which is a developed view of the clamping surfaces. It may be moved in a direction perpendicular to the axis of the earth electrode, or in the y-axis direction, that is, a direction parallel to the axis of the ground electrode, or in both directions.

When the position of the hot electrode is shifted as described above, a relationship as shown in FIG. 6A is obtained between the high frequency current i, that is, the moisture content, and the clamping distance l between the arms. This is the case when the hot electrodes 14a and 14b are shifted by the width t in the x-axis direction (P=t) and a high frequency voltage of 20 KHz is applied. From this characteristic curve, the clamping interval l is 0.4 to 1.8 mm. It can be seen that the indicated value is approximately constant within the range of , and the clamping interval has no effect on the measured value. On the other hand, in Figure 6B,
This figure shows the distribution of the clamping distance when hair is arbitrarily clamped between the two arms 12a and 12b, and most cases fall within the range of 0.4 to 1.8 mm. Therefore, from these data, in normal measurements, even if there is slight variation in the pinching interval depending on the amount of hair sandwiched between the arms 12a and 12b, accurate measurements can be made regardless of the pinching interval. It is understood that this can be done.

Furthermore, it has been experimentally confirmed that the characteristic curve shown in FIG. 6A shifts left and right depending on the amount of positional deviation P, and the interval between the inflection points m and n also changes. That is,
FIG. 6C shows a characteristic curve when the displacement amount P of the hot electrodes 14a and 14b in the x-axis direction is P=2t, and in this case, the clamping interval l is 0.8
The indicated value is approximately constant within the range of ~2.0 mm. Therefore, measurement accuracy can be maintained by performing measurements such that the clamping interval falls within this range.

The displacement amount and direction of the hot electrodes 14a and 14b are optimally set depending on the subject, the structure of the probe, the frequency of the applied voltage, and the like.

7 and 8 show different configuration examples of the clamping surfaces of the arms 12a and 12b. FIG. 7 shows a case where one hot electrode 17 and one rod-shaped ground electrode 18 are attached, and FIG. In FIG. 8, a hot electrode 20 is attached to the inside of a ring-shaped earth electrode 19.

These electrodes are not limited to the structure shown, but can be formed in any shape and size, and at least one of these electrodes may be attached to the same arm in an appropriate arrangement. In this case, the clamping surfaces of the pair of arms do not need to have the same structure.

Furthermore, although each of the above embodiments is a case in which an independent ground electrode is provided on the insulating arm, the arm itself can also be used as the ground electrode. FIG. 9 shows an example of the structure of such a probe, in which the arms 12a, 12b are made of a conductive material such as aluminum, iron, or steel, and insulating parts are placed in recesses 21a, 21b provided on the clamping surface. Hot electrodes 24a, 24b are attached via members 22a, 22b and 23a, 23b, and ring-shaped ground electrodes 25a, 25b surrounding the hot electrodes are directly formed on arms 12a, 12b. In this case, the hot electric wires 26a and 26b are also connected to the insulating member 27 as shown in FIGS. 10 and 11.
Wiring is done via a and 27b. Note that there is no particular need to provide the insulating members 23a and 23b on the hot electrodes.

In the above probe, the hot electrode 24a,
Electric lines of force from 24b connect to the surrounding earth electrode 25
a, 25b and hardly fly out to the outside, therefore the shielding effect is improved, and the measurement of moisture content is not affected by the test object or other objects protruding from the clamping surface.

In addition, in FIG. 1, the control circuit connected to the probe 10 connects the hot electrode to a high-frequency oscillation circuit, detects the high-frequency current flowing between the electrodes, amplifies it to a necessary level, and performs subsequent calculations. It is input to the circuit.

Further, the arithmetic circuit converts the output signal from the control circuit into a signal corresponding to the moisture content of the subject, and the output signal from this arithmetic circuit is input to the display unit and displayed as the moisture content.

When measuring the moisture content using the above-mentioned measuring device, the subject is held between 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.

According to the moisture measuring device of the present invention described in detail above, the following effects can be expected.

(1) Measurement can be performed very easily by using the clamping method.

(2) Since the hot electrodes attached to the pair of clamping arms are placed at positions not facing each other,
It is possible to eliminate variations in the measured moisture content due to changes in the clamping interval, thereby allowing highly accurate measurements to be made regardless of the clamping interval.

(3) Moisture content can be measured regardless of the clamping interval, so it can be measured not only for hair and fibrous materials whose density and thickness tend to be approximately constant depending on clamping, but also for paper, cloth, plastic, etc. be able to.

(4) Since the holding arm itself is configured as a ground electrode, there is no need to attach a separate ground electrode, and not only is the structure simple and easy to manufacture, but it also ensures the capture of electric lines of force from the hot electrode. This can enhance the sealing effect and make it less susceptible to the effects of the subject or other objects protruding from the clamping surface.

[Brief explanation of the drawing]

Fig. 1A is a partial sectional view of a probe to which the present invention is applied, Fig. 1B is a characteristic diagram thereof, Fig. 2 is a configuration diagram showing an embodiment of the present invention, and Fig. 3 is an enlarged view of the main parts of the probe. A cross-sectional view, Figure 4 is an explanatory diagram of the action of electric lines of force,
Figures 5A and B are front views of the clamping surfaces for explaining how to shift the positions of the hot electrodes for a pair of arms, Figures 6A and C are characteristic diagrams when the positions of the hot electrodes are shifted, and Figure 6B 7 and 8 are front views showing different embodiments of the probe, and FIG. 9 is a schematic diagram showing still another embodiment of the probe. The partial sectional views, FIGS. 10 and 11, are sectional views taken along the line AA in FIG. 9, and show different embodiments. 10... Probe, 12a, 12b... Clamping arm, 14a, 14b, 17, 20, 24a, 2
4b...Hot electrode, 15a, 15b, 18, 1
9, 25a, 25b... Earth electrode.

Claims (1)

[Claims] 1. A high-frequency current is applied to an electrode attached to a probe, and the moisture content in the subject is measured from the high-frequency current flowing according to the dielectric constant of the subject, in which the probe is opened and closed. A clamping method is adopted in which the subject is clamped between a pair of flexible 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 two hot electrodes in both arms are arranged so as not to face each other. A moisture measuring device characterized by being placed at a certain position. 2. In a device that applies a high frequency current to an electrode attached to the probe and measures the moisture content in the subject from the high frequency current that flows according to the dielectric constant of the subject, a pair of clamping arms that can freely open and close the probe. A clamping method is adopted in which the subject is clamped between them, and hot electrodes to which a high-frequency voltage is applied are provided to each of the clamping arms formed of a conductive material in a non-opposed state, and each clamping arm itself is configured as a ground electrode. A moisture measuring device featuring: