JP6875639B2 - Moisture content measuring device and moisture content measuring method - Google Patents

Description

The present invention relates to a technique for measuring the amount of water in a container.

Various precision devices such as electronic devices and communication devices are placed in containers such as plastic and metal to prevent the adverse effects of light, heat and moisture. In order to prevent photodegradation of parts inside the container due to ultraviolet rays, visible light, and near infrared rays, the container of general-purpose precision equipment has a structure in which the inside of the container cannot be seen, such as using black or other colored resin as a raw material. It is often the case. As the material of the container, for example, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAc), polyurethane (PUR), teflon (polytetrafluoroethylene). , PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin, acrylic resin (PMMA), polyamide (PA, nylon), polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polyester (PEs), polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), polybutylene terephthalate (PBT), cyclic polyolefin (COP), polyphenylensulfide (PPS), polysulfone (PSF), Polyetheralphone (PES, Polyethersulfone), Acrylic Polyarylate (PAR), Liquid Crystal Polymer (LCP), Polyetheretherketone (PEEK), Thermoplastic Polyethylene (PI), Polyamideimide (PAI, Polyamide-imide), Glass Examples thereof include fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP). Of these materials, transparent ones are colored to prevent photodegradation.

"Utilization of IoT and ICT technology in manufacturing process" (Chapter 3, Section 4, Identification of molecular species and crystal species in tablets by continuous wave terahertz spectroscopy), Technical Information Association, April 2017, pp. 180-190

Deterioration of the container of precision equipment causes water to enter the inside of the container, which causes hydrolysis of the resin product inside the container, elution of the plasticizer, and swelling of the resin, which causes deformation, deterioration of strength, deterioration of the adhesive, etc. , There is a possibility that the performance of the electronic circuit may deteriorate due to the oxidation of iron and semiconductors.

The container of precision equipment has a structure in which the inside of the container cannot be seen in order to prevent photodegradation of the parts inside the container, and the water content is measured from the outside of the container as a non-destructive inspection with ultraviolet light, visible light, and near infrared light. There was a problem that it could not be done.

If it is possible to search for an electromagnetic wave other than light that sees through the container, it may be possible to measure the amount of water using the absorption peak due to the vibration or relaxation of water vapor molecules. However, since a container made of resin such as plastic often has anisotropy at the stage of molding the material, it may have low transparency with a general light source.

The present invention has been made in view of the above, and an object of the present invention is to measure the amount of water inside a container in a non-destructive manner.

The water content measuring device according to the present invention is a water content measuring device that measures the water content in the container by measuring the absorption peak of electromagnetic waves due to water vapor in the resin container, and has a frequency within a desired range. A polarization light source that is variable and generates a linearly polarized electromagnetic wave, a first wavelength plate that incidents the electromagnetic wave output by the polarization light source and emits the electromagnetic wave in a different direction, and the first wavelength plate. A second wavelength plate in which the electromagnetic wave emitted from the wavelength plate is incident and emitted by changing the direction of polarization of the electromagnetic wave, and a state in which the container is not arranged between the first wavelength plate and the second wavelength plate. In each of the states in which the container is arranged , the detector that detects the electromagnetic wave emitted from the second wavelength plate and the state in which the container is not arranged between the first wavelength plate and the second wavelength plate, the said. At least one of the first wavelength plate and the second wavelength plate is rotated so that the intensity of the electromagnetic wave detected by the detector is maximized, and the container is placed between the first wavelength plate and the second wavelength plate. A wavelength plate control unit that rotates the first wavelength plate and the second wavelength plate in synchronization or rotates the container so that the intensity of the electromagnetic wave detected by the detector is maximized. It is characterized by having.

The water content measuring method according to the present invention is a water content measuring method for measuring the water content in the container by measuring the absorption peak of electromagnetic waves due to water vapor in the resin container, and the frequency is within a desired range. A step of generating a linearly polarized electromagnetic wave using a variable polarized light source, and a step of incident the electromagnetic wave output by the polarized wave light source on a first wavelength plate and emitting the electromagnetic wave by changing the direction of polarization of the electromagnetic wave. The step of incident the electromagnetic wave emitted from the first wavelength plate on the second wavelength plate to change the direction of polarization of the electromagnetic wave and emit the electromagnetic wave, and the container between the first wavelength plate and the second wavelength plate. Each of the state in which the container is not arranged and the state in which the container is arranged has a step of detecting the electromagnetic wave emitted from the second wavelength plate, and the container is arranged between the first wavelength plate and the second wavelength plate. In this state, at least one of the first wavelength plate and the second wavelength plate is rotated so that the intensity of the electromagnetic wave to be detected is maximized, and between the first wavelength plate and the second wavelength plate. The first wavelength plate and the second wavelength plate are synchronously rotated or the container is rotated so that the intensity of the electromagnetic wave to be detected is maximized in the state where the container is arranged. ..

According to the present invention, the amount of water inside the container can be measured non-destructively.

It is a functional block diagram which shows the structure of the moisture content measuring apparatus of this embodiment. It is a figure which shows the state which arranged the container on the optical path of the electromagnetic wave of the moisture content measuring apparatus of FIG. It is a flowchart which shows the flow of the measurement process of the moisture content in a container using the moisture content measuring apparatus of this embodiment. It is a graph which shows the transmittance of the electromagnetic wave of the container for each frequency in each polarization direction when the polarization direction is changed. It is a graph which shows the optical density for each frequency obtained by measuring the electromagnetic wave which transmitted through a container. It is a functional block diagram which shows the structure of another moisture content measuring apparatus of this embodiment.

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

1 and 2 are functional block diagrams showing the configuration of the water content measuring device 1 of the present embodiment. The water content measuring device 1 shown in the figure includes a polarization light source 11, a detector 12, 1/2 wavelength plates 13A and 13B, a wave plate control unit 14, a wave plate rotating unit 15A and 15B, a dry air chamber 16, and a moving unit. The stage 17 is provided.

The water content measuring device 1 measures the absorption peak of electromagnetic waves due to water vapor in the container 100 of a precision instrument by irradiating the resin container 100 as a sample with electromagnetic waves and detecting the electromagnetic waves transmitted through the container 100. This is a device for measuring the amount of water in the container 100. Each part will be described below.

The polarized light source 11 is a light source whose frequency is variable in the range of 1 GHz to 10 THz and outputs linearly polarized electromagnetic waves. Since water vapor has a plurality of absorption peaks due to vibration and relaxation in the above range, it is sufficient if it can be varied in the range of 1 GHz to 10 GHz, 10 GHz to 100 GHz, 100 GHz to 1 THz, or 1 THz to 10 THz. As the polarization light source 11, for example, a single cycle source used for terahertz time region spectroscopy can be used. Alternatively, a gyrotron, a reverse wave tube, a far-infrared laser, a quantum cascade laser, a free electron laser, a synchrotron emission, a photomixing source, a tannet / gun diode, an HBT / HEMT, a Josephson element, a gallium nitride semiconductor element, and a resonance. A tunnel diode, a DAST organic nonlinear optical crystal, or the like may be used.

The detector 12 measures the spectrum of the electromagnetic wave transmitted through the container 100. As the detector 12, for example, a light conduction antenna used for terahertz time region spectroscopy can be used. The detector 12 may be able to detect the electromagnetic wave output by the polarization light source 11.

The 1/2 wave plates 13A and 13B emit the incident linearly polarized electromagnetic waves in different directions. The electromagnetic wave output from the polarization light source 11 passes through the 1/2 wavelength plate 13A, further passes through the 1/2 wavelength plate 13B, and is input to the detector 12. The container 100 is arranged between the two 1/2 wave plates 13A and 13B.

The wave plate control unit 14 controls the wave plate rotating units 15A and 15B to rotate the 1/2 wave plate 13A and 13B. Before the spectrum measurement, the wave plate control unit 14 maximizes the electromagnetic wave intensity detected by the detector 12 in the state where the container 100 is not arranged in the optical path and in the state where the container 100 is arranged in the optical path. The 1/2 wave plates 13A and 13B are rotated.

As shown in FIG. 1, when the container 100 is not arranged in the optical path, the wave plate control unit 14 of the 1/2 wave plates 13A and 13B so as to maximize the electromagnetic wave intensity detected by the detector 12. Rotate one or both. Since the sensitivity of the detector 12 may have anisotropy with respect to the polarization of the electromagnetic wave, the polarization anisotropy of the detector 12 is removed in synchronization with the direction of polarization of the polarization light source 11.

As shown in FIG. 2, when the container 100 is arranged in the optical path, the wave plate control unit 14 uses both the 1/2 wave plates 13A and 13B so as to maximize the electromagnetic wave intensity detected by the detector 12. Synchronize and rotate. Since containers such as plastic often have anisotropy at the stage of molding the material, the direction of polarization of electromagnetic waves is rotated so as to be parallel to the direction of anisotropy of the container 100. The container 100 may be rotated so that the direction of polarization of the electromagnetic wave is parallel to the direction of anisotropy of the container 100.

The dry air chamber 16 is arranged on the optical path of the electromagnetic wave.

The moving stage 17 moves the container 100 to the optical path of the electromagnetic wave.

Next, a process for measuring the amount of water in the container 100 using the water content measuring device 1 of the present embodiment will be described.

FIG. 3 is a flowchart showing the flow of the water content measurement process in the container 100 using the water content measuring device 1 of the present embodiment.

A THz pulse wave having an output of 150 nW and a pulse width of 0.5 picoseconds is generated in the polarization light source 11, is transmitted through the 1/2 wave plate 13A and the 1/2 wave plate 13B, and is guided to the detector 12.

The wave plate control unit 14 rotates the 1/2 wave plates 13A and 13B so that the electromagnetic wave intensity at the detector 12 is maximized in a state where the container 100 is not arranged in the optical path (step S11). After completing the step S11, the two 1/2 wave plates 13A and 13B are set to rotate in synchronization.

The container 100 is arranged on the optical path of the electromagnetic wave by using the moving stage 17 (step S12). Since some parts of the precision instrument in the container 100 do not transmit electromagnetic waves, the container 100 is arranged so that there are no parts that do not transmit electromagnetic waves on the optical path.

The wave plate control unit 14 rotates the 1/2 wave plates 13A and 13B in synchronization with each other so that the electromagnetic wave intensity at the detector 12 is maximized while the container 100 is arranged in the optical path (step S13).

FIG. 4 shows the transmittance of electromagnetic waves of the container 100 for each frequency in each polarization direction when the polarization directions are changed to 0 degrees, 45 degrees, and 90 degrees. In FIG. 4, the horizontal axis represents the frequency and the vertical axis represents the transmittance of the electromagnetic wave of the container. As shown in FIG. 4, it was confirmed that the angle at which the container 100 easily transmits electromagnetic waves is when the polarization direction is 0 degrees (the left-right direction when the container 100 is viewed from above). Further, it was confirmed that the container 100 easily transmits electromagnetic waves having a frequency around 0.5 THz. The wave plate control unit 14 fixes the 1/2 wave plates 13A and 13B at an angle at which the container 100 easily transmits electromagnetic waves.

The detector 12 integrates the spectrum of the electromagnetic wave transmitted through the container 100 several times to several tens of times at an angle at which the container 100 obtained in step S13 easily transmits the electromagnetic wave (step S14). Further, the container 100 may be moved on the moving stage 17 to measure several points through which electromagnetic waves are transmitted. The measurement may be performed in a frequency range in which the container 100 easily transmits electromagnetic waves.

FIG. 5 shows the optical density for each frequency obtained by measuring the electromagnetic wave transmitted through the container 100. In FIG. 5, the horizontal axis represents the frequency and the vertical axis represents the optical density. FIG. 5 shows the results of a plurality of measurements. From FIG. 5, it can be seen that the absorption peaks of water vapor exist at 0.56 THz and 0.75 THz.

A calibration curve was created from the relationship between the humidity in the laboratory and the absorption peak of water vapor when the container 100 was not placed in the optical path, and it was found that the humidity inside the container 100 was 70% at the maximum.

Next, another water content measuring device of this embodiment will be described.

FIG. 6 is a functional block diagram showing the configuration of another water content measuring device 1 of the present embodiment.

It differs from the water content measuring device 1 shown in FIGS. 1 and 2 in that the 1/2 wave plate 13B close to the detector 12 is changed to the 1/4 wave plate 18. The 1/4 wave plate 18 changes the electromagnetic wave incident on the detector 12 from linearly polarized light to circularly polarized light, and removes the polarization dependence of the detector 12. Since the wave plate control unit 14 controls the wave plate rotating unit 15 and only needs to rotate one 1/2 wave plate 13, the number of parts that control the wave plate can be reduced. Further, it is not necessary to perform the step S11 of the measurement process shown in FIG.

As a result of measuring the container 100 of the same precision instrument using the water content measuring device 1 of FIG. 6, it was found that the maximum humidity was 70%.

As described above, according to the present embodiment, the polarization light source 11 that generates a linearly polarized electromagnetic wave having a variable frequency in a desired range and the container that changes the polarization direction of the incident linearly polarized electromagnetic wave. It has a 1/2 wavelength plate 13A that irradiates 100 and a detector 12 that detects electromagnetic waves that have passed through the container 100, and the 1/2 wavelength plate 13A is provided so that the electromagnetic wave intensity detected by the detector 12 is maximized. By rotating, it becomes possible to nondestructively measure the amount of water inside the container 100 by utilizing the absorption peak of electromagnetic waves for water vapor.

According to the present embodiment, by having the 1/2 wave plate 13B that changes the direction of polarization of the electromagnetic wave transmitted through the container 100, or the 1/4 wave plate 18 that changes the electromagnetic wave transmitted through the container 100 into circularly polarized light. The polarization anisotropy of the detector 12 can be removed.

1 ... Moisture content measuring device 11 ... Polarized light source 12 ... Detector 13, 13A, 13B ... 1/2 Wave plate 14 ... Wave plate control unit 15, 15A, 15B ... Wave plate rotating unit 16 ... Dry air chamber 17 ... Moving Stage 18 ... 1/4 wave plate 100 ... Container

Claims (2)

A water content measuring device that measures the amount of water in the container by measuring the absorption peak of electromagnetic waves due to water vapor in the resin container.
A polarized light source that has a variable frequency in a desired range and generates linearly polarized electromagnetic waves,
A first wave plate that incidents the electromagnetic wave output by the polarization light source and emits the electromagnetic wave by changing the direction of polarization of the electromagnetic wave.
A second wave plate that incidents the electromagnetic wave emitted from the first wave plate and emits the electromagnetic wave by changing the direction of polarization of the electromagnetic wave.
A detector that detects the electromagnetic wave emitted from the second wave plate in each of the state where the container is not arranged and the state where the container is arranged between the first wave plate and the second wave plate.
In a state where the container is not arranged between the first wave plate and the second wave plate, the first wave plate or the second wave plate is used so that the intensity of the electromagnetic wave detected by the detector is maximized. In a state where at least one of the above is rotated and the container is arranged between the first wave plate and the second wave plate, the first wavelength is maximized so that the intensity of the electromagnetic wave detected by the detector is maximized. A water content measuring device comprising a wave plate control unit that rotates the plate and the second wave plate in synchronization with each other or rotates the container. It is a water content measuring method for measuring the water content in the container by measuring the absorption peak of electromagnetic waves due to water vapor in the resin container.
A process of generating linearly polarized electromagnetic waves using a polarized light source with a variable frequency within a desired range,
A step of incident the electromagnetic wave output by the polarization light source on the first wave plate and emitting the electromagnetic wave by changing the direction of polarization of the electromagnetic wave.
A step of incidenting the electromagnetic wave emitted from the first wave plate on the second wave plate and emitting the electromagnetic wave by changing the direction of polarization of the electromagnetic wave.
It has a step of detecting the electromagnetic wave emitted from the second wave plate in each of the state where the container is not arranged and the state where the container is arranged between the first wave plate and the second wave plate.
At least one of the first wave plate and the second wave plate so that the intensity of the electromagnetic wave to be detected is maximized in a state where the container is not arranged between the first wave plate and the second wave plate. Rotate one and
With the container arranged between the first wavelength plate and the second wavelength plate, the first wavelength plate and the second wavelength plate are rotated in synchronization so that the intensity of the electromagnetic wave to be detected is maximized. A method for measuring the amount of water, which comprises rotating the container.

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