JPH08136452A - Moisture meter - Google Patents

Abstract

PURPOSE: To accurately measure moisture regardless of change in material and the like for an object and the like to be measured. CONSTITUTION: The light of a light source 1 is projected to a measured object 3 through a projecting lens 2, transmitted light or reflected light is injected to a detection element 6 by a condensing lens 4 through filters 51 and 52 provided for a rotating sector 5, which have the comparison wave lengths of λ1 and λ3 free from moisture and the like, and the measuring wave length of λ2, its output signal is amplified by an amplifier 7, it is then transformed into signals R1, S and R2 corresponding to the respective wave lengths by a signal separation and rectifier 8 so as to be separately taken out by a synchronous signal generator 9, and its moisture percentage is then operated by an operating means 10 through an integrated analytical curve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture meter for measuring the moisture content of an object to be measured using infrared rays.

[0002]

2. Description of the Related Art Conventionally, in order to measure the moisture content by using infrared rays, the measurement signal of the reflected light or transmitted light from the object to be measured in the absorption wavelength band of moisture and the reflected light in the non-absorption band of moisture or There is known a two-color or three-color infrared moisture meter that obtains the moisture content of an object to be measured from a ratio signal of transmitted light to one or two comparison signals.

[0003]

However, there is a problem that the output characteristic changes when the kind of the object to be measured such as paper is different. It is considered that one of the causes for this is that the spectral characteristics and the output characteristics change due to changes in the materials and the like. To eliminate this effect, the applicant has disclosed in Japanese Patent Publication No. 61-61623. We have proposed a correction method, but there were aspects that were not sufficient.

In view of the above points, an object of the present invention is to provide a moisture meter capable of highly accurate measurement even if the material or the like of the object to be measured changes.

[0005]

According to the present invention, a measurement wavelength band is provided in an absorption wavelength band of moisture, and transmitted light or reflected light from an object to be measured in this wavelength band is used as a first signal, and the absorption wavelength of the moisture is At least one wavelength band other than the band is provided, and the transmitted light or the reflected light from the measurement target in this wavelength band is used as the second signal, and the moisture content is calculated from the ratio signal of the first signal and at least one second signal. In a moisture meter that requires
A moisture content is obtained by obtaining a calibration curve in which the ratio signal output when measuring two reference moisture contents for each of a plurality of types of objects to be measured matches the two reference moisture contents, and calculating the moisture content from the calibration curve. Total.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a structural explanatory view showing an embodiment in which the present invention is applied to a transmission type infrared moisture meter. Reference numeral 1 denotes a light source for projecting light, and the light from this light source 1 is projected onto an object 3 to be measured by a projecting lens 2, and its transmitted light or reflected light is provided on a rotating sector 5 by a condenser lens 4, respectively. PbS, PbSe, Ge, thermistor bolometer, S through filters 51, 52, 53 having transmission wavelengths λ1, λ2, λ3.
The light enters the detection element 6 made of i, InGaAs or the like.
The detection signal of the detection element 6 is amplified by the amplifier 7,
In the signal separation / rectifier 8, the signals R1, S, R2 for the wavelengths λ1, λ2, λ3 of the filters 51, 52, 53 of the rotating sector 5 are separated by the synchronizing signal of the synchronizing signal generator 9 provided in the rotating sector 5. Then, rectify and take out. The signals R1, S, R2 are calculated from a ratio signal of the first signal S and at least one second signal R1, R2, etc., by a calculation means 10 such as a microcomputer, and the moisture content is calculated from an output terminal 11. The moisture signal can be retrieved.

FIG. 2 shows an embodiment of a reflection type infrared moisture meter, in which the light from the light source 1 is transmitted through the filters 51, 52 and 53 of the rotating sector 5 by the condenser lens 2 and the wavelength λ1, by the mirror M1. Lights λ2 and λ3 are projected onto the object 3 to be measured, and reflected light is incident on the detection element 6 by the concave mirror M2. The output signal of the detecting element 6 is amplified by the amplifier 7, the signals R1, S and R2 are taken out from the signal separating / rectifying device 8, the calculating means 10 performs the calculation, and the output terminal 11
More moisture signal can be taken out.

That is, as shown in FIG. 3, the constituent portion before the arithmetic means 10 of FIGS. 1 and 2 is used as the detection unit A, and various kinds of samples of the object 3 to be measured are preliminarily measured to obtain a calibration curve. Ask for. For example, for a certain first type, from the ratio signal output y when measuring the reference bodies 31 and 32 having two reference moisture contents such as X1 (= 0%) and X2 (= 10%), FIG. A calibration curve a shown by is created. Next, calibration curves b and c shown in FIG. 4A are created from the above outputs when two reference moisture contents are measured for each of the other second and third plural types of samples. Then, the outputs y of these three calibration curves a, b, and c are standardized so as to match each of the two reference points x1 and x2, and one calibration curve d shown in FIG. Ask.

This makes it possible to measure the water content of the above type based on this one calibration curve d. In addition, it is possible to perform measurement for other types as well, so that it is possible to measure with one calibration curve. The larger the number of these types, the better. The reference points x1 and x2 (zero point, span point) are 0% H ₂ O in the absolutely dry state, and any 2 points other than the specified 10% H ₂ O. But it's okay. Further, the correction may be performed so that the points are not equal to two points, but more points.

For example, assume that three calibration curves a, b, and c are expressed by the following equation.

Y = a1x + b1 (1) y = a2x + b2 (2) y = a3x + b3 (3) To match equations (1) and (3) with equation (2), b2-b
1 or b2-b3, then the coefficients a2 / a1,
It is preferable to perform arithmetic processing such as multiplication by a2 / a3. In this way, if the calibration curve is unified by using the signals for which the zero point and the span point are corrected, it is possible to measure various types with a sufficient accuracy with one calibration curve. Note that these calculations are carried out by the calculation means 10.

[0012]

As described above, according to the present invention, a calibration curve in which the ratio signal output when two reference moisture percentages are measured for each of a plurality of types of objects to be measured is the same for the two reference moisture percentages is obtained. This is a moisture meter that is used to measure the moisture content of the measurement target from this calibration curve.

Therefore, even if the material such as the grammage of the object to be measured such as paper is changed, even if the kind is changed by the above correction, high accuracy can be obtained by the optimum integrated calibration curve obtained in advance. A correct moisture measurement signal can always be obtained, and it can automatically respond to changes in paper and other product types, and can significantly reduce man-hours. Also, by utilizing this, in a high-mix low-volume production process, nearly complete automation can be achieved, and high quality products can always be produced, and the practical effect is extremely large.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is a structural explanatory view showing an embodiment of the present invention.

FIG. 3 is a structural explanatory view showing an embodiment of the present invention.

FIG. 4 is an operation explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 3 object to be measured 5 rotating sector 51, 52, 53 filter 6 detection element 7 amplifier 8 signal / separation rectifier 9 synchronization signal generator 10 computing means

Claims (1)

[Claims] 1. A measurement wavelength band is provided in a water absorption wavelength band, and transmitted light or reflected light from an object to be measured in this wavelength band is used as a first signal, and at least one wavelength band other than the water absorption wavelength band. In the moisture meter for measuring moisture content from the ratio signal of the first signal and at least one second signal, the reflected light from the object to be measured in this wavelength band is used as the second signal. A moisture content is characterized in that a calibration curve is obtained in which the ratio signal outputs when two reference moisture contents are measured for each of a plurality of target types are matched for the two reference moisture contents, and the moisture content is calculated from this calibration curve. Total.