JPS59120940A - Infrared ray type moisture measuring apparatus - Google Patents

Abstract

PURPOSE:To always measure highly precisely an average moisture quantity of an object to be measured having necessary thickness without being influenced by a moisture quantity at a surface part of the object layer to be measured by measuring light transmitted through the object layer to be measured. CONSTITUTION:The light reflected and condensed at a concave mirror 20 is transmitted through a light transmittable supporter 30, made incident to a powder sample layer 26, and is emitted as the transmitted light to oposite side of the layer 26 while reflecting among the powder particles. This transmitted light is converted to an electrical signal at a photodetector 34 through an infrared transmission filter 32. In this case, the moisture quantity of the powder sample layer cn be measured by measuring Imes (signal of the detector 34 due to the light of the wavelength of the peak of a water absorption band), Iref (signal of the detector 34 due to the light of the wavelength of the valley deviated from the water absorption band) and Io (incident intensity of the light of reference wavelength to the layer 26).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an infrared moisture measuring device for measuring the total amount of moisture contained in food powders such as powdered milk and starch.

Conventionally, apparatuses have been known that measure moisture by measuring the absorption '1'A of infrared radiation with respect to moisture. Generally, as a sub-means of this kind of optical moisture meter using the red IA line, a method is adopted in which the reflected light from the object to be measured is measured to determine the moisture content. However, according to this method, aU 1711 + the irregularities of the surface of the target object, for example, the powder J on the conveyor when the powder is transported by the conveyor.
Due to unevenness of C'+, ff111 accuracy has decreased, or the average water content h)- across the womb cannot be measured if the moisture content is different between the upper and lower parts of the powder layer. , many drawbacks have been pointed out in the solid line powder drying process of 70 steps.

For example, a reflection type moisture analyzer as shown in FIG. 1 is known as a conventional optical powder moisture measuring device that is generally used. Jin's reflective moisture meter is
Optical lens io, condensing lens 1.2, and rotating chopper/l:
, an optical bandpass filter /2, a reflecting mirror /r, a concave mirror -0, an infrared transmission filter λλ, and a photodetector 2hiro. Next, the function of this moisture meter will be explained. First, light (the light emitted from jL410 is
The light is condensed by condenser lens /2 and enters the rotating chopper puffer fish. Rotating chopper l≠.

It is formed as a disc-shaped rotating body and is configured to rotate at a constant period by driving a motor, and at least two optical bandpass filters/l are installed at the negative position through which the light passes. In this case, when setting the wavelength of the optical bandpass filter/B, it is necessary to consider the absorption band inertia of water in a predetermined optical wavelength region. For example, the Mud λ diagram shows the absorption spectrum of water in the /~Vμm wavelength range.
In this case, the absorption band of water is /9.211m,
/, 4'J' l1m, /, Fj Ilm and, 2. Each has a peak at F j ltm. Therefore, as light for redundantly measuring the moisture content in the powder, one luminous flux is sent to the optical bandpass filter/object.
When using light that includes only one of the three wavelengths (for example, 23 μm), 7 is effective from the standpoint of Oki Jashi sensitivity. However, as another luminous flux, a wavelength unrelated to the absorption band of water (for example, 7.70-μm or ≠O
ttm) to include the light of
The moisture content is determined by calculating the signal obtained from the light beam passing through this optical band-pass filter /l' and the light beam including the measurement wavelength passing through the optical band-pass filter /2. In addition, when measuring the crystal sheath degree, light of two wavelengths unrelated to the absorption band of water before and after the absorption band of water (for example, 7.70 μnt and λ, ≠ μm) is used as a comparison wavelength. It is preferable to measure using an optical bandpass filter 16''.

In this way, the wavelength of the light beam passing through it is set by the light band pass filter /A, /lr' and if necessary at 1mm~/4'', the light beam passes through it and becomes intermittent. It is reflected 8 by the successive reflecting mirror 1g and reaches the tough body sample layer 2B.

The light is reflected by the surface of the powder h (material) (>4.21°), but among this reflected light, the primary reflected light is optically simple on the surface of the sample layer-2. Since the light is reflected by
It is hardly absorbed by moisture, and when this light is detected, the sensitivity decreases significantly. Therefore, this primary reflecting beam f is blocked by a reflecting mirror 7g, etc., so that it does not enter the detector 2 by devising a uniform arrangement.

On the other hand, in order to measure moisture, it is effective and necessary to collect the reflected light that is diffusely reflected on the surface of the sample layer 2 and repeatedly reflected between powder particles. Therefore, these diffusely reflected lights are condensed by the concave mirror 2Q, passed through the infrared kilometer filter 22, and are incident on the photodetector, where they can be extracted as electric light.

In this way, according to the existing conventional moisture measurement method, the primary reflected light reflected from the surface of the powder sample layer 2B is mixed up and is not allowed to enter the detector 21/-. However, in the case of a powder sample, it is difficult and difficult to remove the above-mentioned reflected light at the tip because the sample surface is not microscopically flat. The normally reflected light occupies a larger proportion of the total reflected light than the diffusely reflected light, and therefore the intensity of the primary reflected light incident on the detector changes due to slight changes in the surface condition of the powder sample. , the signal changes regardless of the moisture content. Regarding the scattered and diffusely reflected light, a large proportion is due to the diffusely reflected light from the powder particles located very close to the surface of the powder sample layer 2B.
If the moisture content differs between the upper layer and the center or lower layer, for example, if the upper layer is gradually drying out, there is a problem in that the average moisture content of the layer cannot be measured.

Therefore, in order to overcome the problems of the conventional moisture measuring device mentioned above, the present invention was developed by the Kogane side, which transparently penetrates the target layer of personal finance. In addition, by fixing the thickness of the 1 can of elongated fish and the back of the can, it is possible to eliminate the loss of both foot axis caused by the unevenness of the damaged 1" rectangular object. The problem mentioned above can be solved by defining the equation of the average water content as "b", which is the equation of the water content divided by 2 in "eζ board carrier i", and eliminating the shadow of "b". I have found something to pray for.

Therefore, the purpose of the present invention is *:4! By measuring the element + C that passes through the water to be measured, it is possible to determine the change in water content on the surface of the contrast object. Without having to worry about it, we can provide an infrared shaft type moisture meter with a fixed price by adding the average moisture content of the two-legged grass to the high bk.

In order to achieve the above object, the present invention includes an infrared light source and a radiation light selection means that selectively extracts light of a specific wavelength from the source and interrogates the object to be measured. and a light detection hand plate that receives the light whose intensity changes from the target object and converts it into the ME light.
The Jk synchrotron radiation tracer stage is configured to emit a light beam corresponding to the growth of water absorption characteristics and at least one light beam including all of the growth sources near the water absorption band and outside the water absorption characteristic. Furthermore, the above-mentioned filter detection means is arranged so that the light emitted from the radiation light selection means is handled and transmitted through a constant object and the light obtained is determined to be 9kt. do.

In the above-mentioned infrared Lummet type moisture supplementary iron, one light beam having a growth that deviates from the absorption band characteristics of moisture emitted from the synchrotron radiation selection means is exposed to the surface of a fixed object. A light Yokota + stage is provided to measure the amount of reflected light, and from the reflected light beam and transmitted light sound, it is possible to detect the thickness of the object to be measured and severe defects.
- It is preferable to configure the device so that a signal related to the moisture content is output.

Next, an embodiment of the infrared moisture measuring device according to the present invention will be described in detail with reference to the drawings of the remote village.

Figure 3 shows a diagram of the external fat type moisture measuring device according to the present invention.
The principle showing an example of biu (h is the bottom surface. For convenience of explanation, the same reference number is used for the same configuration as the conventional extra wire type moisture measuring device, which is not shown in the figure. In other words, in FIG. 3, the light emitted from the light source /θ is passed through the condensing lens /, 2 to the rotating chopper /4 and the original band-pass filters /A, /l, '
The structure is the same as that of a conventional infrared moisture measuring device in that it is configured to pass light with a wavelength corresponding to the peak position of the absorption band of water. In addition, in this example, 1
The rotary chopper/lt has a disc-shaped rotary plate that is moved by the same J motor, and at least two optical band-pass filters with different wavelengths of transmitted light are installed at positions corresponding to the light path. , it' can be preferably used. In addition, in order to improve measurement accuracy as an optical bandpass filter, it is also possible to use one or both of the conventional light and the light of the wavelength after RfJ of the absorption band peak of I'ifJ-like pregnant water as a comparison light flux. .

In this way, the light obtained after passing through the optical bandpass filter/6°/6' is reflected and focused via the concave mirror 20, and the light transmitting support supporting the powder sample layer 2B. It is formed so as to be incident on the body 30. Therefore, in the present invention, 1 the original permeable support 30 1 powder test + F layer,
Infrared transmission filter 3 for detecting light transmitted through 24
−2 and photodetector 3≠ are provided. On the other hand, the light incident on the light transmitting 1Tet support 30 through the concave blunt surface 2Of is reflected and reflected from the powder sample layer 2O! L
What is the incident intensity of light at the source or comparison wavelength? A photodetector 3B for detection is provided.

Next, the operation of the infrared moisture measuring device according to the present invention configured as described above will be explained.

As mentioned above, the light reflected by the concave mirror 20 is transmitted through the transparent support 30 and the powder sample %, 2
A, and while reflecting between the powder particles, the sample layer, 200
It is emitted to the opposite side as transmitted light.

This transmitted light passes through an infrared transmission filter 32 and is converted into an electrical signal by a photodetector 3'l. In this case, the moisture content of the powder sample layer is determined by the following formula.

However, l1neS'No. 16 of the photodetector 3hiro due to light at the wavelength of the peak of the absorption band of water'Rcf: Signal α of the photodetector 34' due to light at the wavelength of the valley outside the absorption band of water: Constant cl120: Average moisture content of powder sample layer negative d-1! ! Bulk density of powder sample layer x thickness of layer) In the above formula (1), dJ is related to IR,ef according to the following formula.

I Ref = ■(' IOeXP (-(β・d
−z) ) −−−−−−(2) In the above formula (2), ■o is the incident intensity of light of the comparison wavelength to the powder sample layer 2B, which is detected by the photodetector 3t. is converted into an electrical signal.

Further, β is a constant.

Based on the above equations (1) and (2), a linear relationship is obtained.

Therefore, from Mt+ expression (3), by measuring "[1+"Ref and tmes, CH2O, that is, the water content can be measured.

As is clear from the above-mentioned coil, according to the present invention,
Since the light incident on the powder sample layer 2& passes through the sample layer 2&, the average moisture content can be reliably measured.

In addition, the reflected light at the powder sample layer 2B is measured as the primary reflected light as IO, and is not directly involved in the signal 11neS related to the moisture content, so it is different from the conventional method. There are no carvings, and 61-point precision is possible. In the embodiment shown in FIG. 3, the measurement light is incident on the powder sample layer 2 from the light-transmitting support 30 side, but the incident direction of the measurement light and the photodetector 31I are Of course, even if the positions are reversed, the same results as in the previous hc embodiment can be obtained.

Figures 1 and 5 show the infrared moisture treatment system of the present invention having the above-mentioned configuration. llI] This shows a specific example of how the fixed device is attached to the powder sample layer.

In Fig. 3, the powder falling from the hopper outlet 3g is continuously deposited on the light-transmitting support 30 by placing a light-transmitting support 30 in the middle of the powder. A set of moisture metering devices 1.10. similar to the embodiment shown in FIG. This is an arrangement in which the HiroI are facing each other.

FIG. 5 shows a structure in which the powder falling from the hopper outlet 3g is deposited on a conveyor belt made of a light-transmitting support 30 and transported, and the powder formed on the belt made of the light-transparent support 30 is A set of moisture measuring devices G0. The goo is placed facing each other. In this example, if a squeegee 4t is placed for the powder sample layer 2 in front of the moisture measuring device Hiro O, g λ, the state of the surface will always be flat and the sample The thickness of the layers 2 and 2 can be made substantially constant, improving the accuracy of correction of d and J layers, and making it possible to measure moisture with a high degree of oxidation.

Fig. 6 shows a modification of the expression state for the powder sample layer of the infrared moisture measuring device of the present invention. In order to measure moisture while fixing the thickness of the powder sample surface formed on the light-transmitting support 30, the moisture measuring device is equipped with hi θ and 4Lλ.
I made a decision as to how many. In other words, in this actual case, one of the water mounts 141.2, which stores the photodetector 3g, has a condensing lens <zg (=
The powder sample layer 2 is placed facing the light-transmitting support 30 at a predetermined distance from the side.

With this configuration, it is possible to easily transfer the sample layer without the need for a powder transport means such as a conveyor! /- keep the value constant,
It is possible to improve the correction accuracy of t'h and easily realize highly accurate moisture measurement.

The preferred embodiments of the present invention have been described above. However, according to the present invention, the average water content of the powder sample layer is determined by the light transmission method.
Since it can be measured with high accuracy, it can be effectively applied as a moisture 6111 determination device in powder drying processes, etc. It is not a simple device, and it can be used in other ways without departing from the characteristics of the present invention. It goes without saying that the country is in disarray.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the basic structure of a conventional reflection-type infrared moisture measuring device, Figure 2 is a characteristic diagram showing the absorption spectrum of water in the infrared region with a wavelength of /~≠μm, and Figure 3 is a diagram of the present invention. 1 is a diagram illustrating the principle configuration of an infrared moisture measuring device according to the present invention. FIG. 5 is an explanatory diagram showing another embodiment of the infrared moisture measuring device according to the present invention in a state shown in FIG. It is an explanatory diagram. IO...Light source /2.・、Condensing lens/Za...Reflector 、2Q...Concave mirror、26・
Powder sample layer 30... Photosensitive support 32°°° Infrared transmission filter 31/L... Photodetector 36...
Photodetector 3g...Hopper exit Hiro 0. I1.2
・・Moisture measuring device lI−≠・・Ski lag t・・・・
Condensing lens FIG, I Fl (3,2 wavelength knowledge m) FIG, 3 4 FIG, 4 FIG, 5 8 FIG, 6

Claims (1)

[Claims] (1) An infrared light source, a synchrotron radiation selection means for selectively extracting light with a constant wavelength of 114 from the light emitted from the light source and directing it to the object to be measured, and Stronger than normal f8: Equipped with a photodetection means for receiving changed light and converting it into an electrical signal, and a front H-ray radiation selection means for detecting a luminous flux corresponding to the wavelength of the absorption band characteristic of moisture and absorption of moisture. The light detection means is configured to emit at least one light beam including growth light outside the moisture absorption band in the vicinity of the water absorption band, and further includes the light detection means,
An infrared moisture measuring device, characterized in that the infrared moisture measuring device is positioned so as to detect the amount of light obtained by transmitting the light emitted from the emitted light selection means through the object to be measured. f2) '1. ! 1' In the infrared moisture measuring device as set forth in claim 1, one luminous flux containing light with a wavelength outside the absorption band characteristics of moisture emitted from the radiation selection means six times on the provisional measurement target. A light detecting means for measuring the reflected light on the surface is provided, and the product of the layer thickness and density of the object to be measured is determined from the reflecting member and the transmitted light R1-, and the signal related to the water content is corrected. An infrared moisture measuring device configured to perform