JPS6120808B2 - - Google Patents
Info
- Publication number
- JPS6120808B2 JPS6120808B2 JP53132287A JP13228778A JPS6120808B2 JP S6120808 B2 JPS6120808 B2 JP S6120808B2 JP 53132287 A JP53132287 A JP 53132287A JP 13228778 A JP13228778 A JP 13228778A JP S6120808 B2 JPS6120808 B2 JP S6120808B2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- infrared
- detector
- background object
- measured
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000001514 detection method Methods 0.000 claims description 20
- 238000010521 absorption reaction Methods 0.000 claims description 8
- 238000005259 measurement Methods 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 239000007789 gas Substances 0.000 description 33
- 230000005855 radiation Effects 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 description 2
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3577—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing liquids, e.g. polluted water
Description
【発明の詳細な説明】
本発明は、例えば建物壁や各種プラント配管に
おける管壁など温度をもつ背景物体から放射され
る赤外線領域での放射エネルギーを利用して、該
物体と検出器の間に存在する測定対象ガスの濃度
測定を行なうようにすることにより、赤外線照射
用光源、サンプリング装置、試料セルなどを省略
した簡単な構成であり、それでいて、前記物体の
温度変動に影響を受けることなく正確な測定が行
なえ、もつて、ガス漏れ警報器として好適に使用
できる赤外線濃度測定装置を提供するものであ
る。DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes radiant energy in the infrared region emitted from a background object having a temperature, such as a building wall or a pipe wall in various plant piping, to create a space between the object and a detector. By measuring the concentration of the existing gas to be measured, it has a simple configuration that does not require an infrared irradiation light source, a sampling device, a sample cell, etc., and yet is accurate without being affected by temperature fluctuations of the object. An object of the present invention is to provide an infrared concentration measuring device that can perform accurate measurements and can be suitably used as a gas leak alarm.
近年、ガス漏れによる中毒、爆発等の事故が増
加し、石油プラント、製鉄所、燃料貯蔵庫等には
ガス漏れ警報器の設置が義務づけられるに至つて
いる。 In recent years, accidents such as poisoning and explosions due to gas leaks have increased, and it has become mandatory to install gas leak alarms in oil plants, steel mills, fuel storage facilities, etc.
従来、これらのガス漏れ警報器おけるガス検出
手段としては、接触燃焼式または金属酸化物等の
所謂半導体ガス検出素子を使つたものと、非分散
型赤外線ガス分析計を使つたものとがある。しか
し乍ら、前記ガス検出素子は、検出感度が低く、
かつ、選択性に欠け、特に塩化ビニール、ホスゲ
ン等の所謂有害ガスの検知警報器としては不適当
である。また、非分散型赤外線ガス分析計は、高
換度で選択性も高いといつた長所を有する反面、
赤外線照射用光源、サンプリング装置、試料セル
等々多くの構成部材よりなる複雑な構成で非常に
高価であり、保守も面倒であるところから、一般
には使用されていないのが現状である。 Conventionally, gas detection means in these gas leak alarms include those using a so-called semiconductor gas detection element such as a catalytic combustion type or a metal oxide, and those using a non-dispersive infrared gas analyzer. However, the gas detection element has low detection sensitivity;
In addition, it lacks selectivity and is particularly inappropriate as a detection alarm for so-called harmful gases such as vinyl chloride and phosgene. In addition, while non-dispersive infrared gas analyzers have the advantages of high conversion and high selectivity,
Currently, it is not generally used because it has a complicated structure consisting of many components such as an infrared irradiation light source, a sampling device, a sample cell, etc., is very expensive, and is troublesome to maintain.
これらの検出方式は、いずれも漏れたガスが拡
散して検出素子に到達し、所定濃度に達した時点
ではじめて警報を発するため、被測定物体周囲の
風向き、風速等に大きく左右され、確実なガス漏
れ検出ができない欠点を有している。 In all of these detection methods, an alarm is issued only when the leaked gas diffuses and reaches the detection element and reaches a predetermined concentration. It has the disadvantage of not being able to detect gas leaks.
本発明は、このような現状に鑑みて開発された
ものであつて、プラント配管の管壁、タンク壁、
建物壁等の背景物体から放射される赤外線を集光
する光学系と、この赤外線のうち、大気の固有吸
収のない波長帯域のみを透過する干渉フイルタな
らびに前記背景物体と検出器との間に存在する測
定対象ガスの固有吸収波長帯域のみを透過する干
渉フイルタと、これら両種の干渉フイルタを透過
した赤外線の放射エネルギー量をそれぞれ検出す
る検出素子と、これら両検出素子からの出力信号
の比を算出する演算器とを備えた点に特徴があ
る。 The present invention was developed in view of the current situation, and is intended for use in plant piping walls, tank walls,
An optical system that condenses infrared rays emitted from a background object such as a building wall, an interference filter that transmits only a wavelength band of this infrared ray that is not uniquely absorbed by the atmosphere, and an interference filter that exists between the background object and the detector. An interference filter that transmits only the characteristic absorption wavelength band of the gas to be measured, a detection element that detects the amount of infrared radiant energy that has passed through both types of interference filters, and a ratio of the output signals from these two detection elements. The feature is that it is equipped with a calculation unit.
以下、本発明の実施例を図面に基づいて説明す
る。 Embodiments of the present invention will be described below based on the drawings.
第１図は本発明に係る赤外線濃度測定装置の使
用状態を略示し、第２図はその回路構成を略示す
る。１は、赤外線輻射源である建物壁、管壁、タ
ンク壁等の背景物体、２は、前記物体１から放射
される赤外線輻射源を集光するレンズ群よりなる
集光系３と、集光された赤外線輻射源のうち、相
異なる特定の波長帯域のみを透過する二種類の多
層膜赤外線輻射源干渉フイルタFa，Fbと、これ
ら両種の干渉フイルタFa，Fbを透過した赤外線
輻射源の放射エネルギー量を検出してその検出結
果を電圧に変換して出力する検出素子４ａ，４ｂ
とを備えた検出器である。前記干渉フイルタ
Fa，Fbの一方Faは、大気中の水分や炭酸ガスに
よる大気の固有吸収のない波長帯域（所謂大気の
窓なる波長帯域）のみを透過するように構成さ
れ、他方Fbは、塩化ビニール、ホスゲンなど前
記背景物体１と検出器２との間に存在する測定対
象ガス５の固有吸収波長帯域のみを透過するよう
に構成されている。第２図中、６ａ，６ｂは検出
素子４ａ，４ｂからの出力信号を増幅する前置増
幅器、７ａ，７ｂは増幅された各出力信号のリニ
アライザー、８はリニアライザー７ａ，７ｂで直
線化された出力信号の比を算出する演算器であ
り、該演算器８の出力側には、濃度表示計、濃度
記録計又は警報器９が接続されるように構成され
ている。 FIG. 1 schematically shows how an infrared concentration measuring device according to the present invention is used, and FIG. 2 schematically shows its circuit configuration. 1 is a background object that is an infrared radiation source such as a building wall, a pipe wall, a tank wall, etc.; 2 is a condensing system 3 consisting of a group of lenses that condenses the infrared radiation source emitted from the object 1; Two types of multilayer infrared radiation source interference filters Fa and Fb that transmit only different specific wavelength bands among the infrared radiation sources that have been detected, and the radiation of the infrared radiation source that has passed through both of these types of interference filters Fa and Fb. Detection elements 4a and 4b that detect the amount of energy, convert the detection result into voltage, and output it.
The detector is equipped with: The interference filter
One of Fa and Fb is configured to transmit only a wavelength band in which there is no inherent atmospheric absorption due to moisture or carbon dioxide in the atmosphere (the so-called atmospheric window wavelength band), and the other Fb is configured to transmit only a wavelength band in which there is no inherent atmospheric absorption due to moisture or carbon dioxide in the atmosphere. It is configured to transmit only the characteristic absorption wavelength band of the gas to be measured 5 existing between the background object 1 and the detector 2 . In Fig. 2, 6a and 6b are preamplifiers that amplify the output signals from the detection elements 4a and 4b, 7a and 7b are linearizers for each amplified output signal, and 8 is a linearizer for each amplified output signal. The calculation unit 8 is configured to be connected to an output side of the calculation unit 8 to a concentration display meter, a concentration recorder, or an alarm device 9.
次に、上記構成による作用を説明すると、物体
１から放射された赤外線は、前記物体１とこれに
対向配置した検出器２との間の空間を経て集光さ
れ、特性（透過帯域）の異なる二種の干渉フイル
タFa，Fbを透過する。これら両干渉フイルタ
Fa，Fbを透過した赤外線輻射源の放射エネルギ
ー量はそれぞれ検出素子４ａ，４ｂにより検出さ
れる。各検出素子４ａ，４ｂからの出力信号は、
それぞれ前置増幅器６ａ，６ｂで増幅され、さら
に、前記物体１の温度とこれに対して一定の相
関々係にある各出力信号とが直線性をもつように
リニアライザー７ａ，７ｂにより処理される。リ
ニアライザー７ａ，７ｂにて直線化された出力信
号Va，Vbに基づき演算器８でVb／Vaなる比が算
出される。 Next, to explain the effect of the above configuration, the infrared rays emitted from the object 1 are condensed through the space between the object 1 and the detector 2 placed opposite to it, and the infrared rays have different characteristics (transmission bands). It passes through two types of interference filters Fa and Fb. These two interference filters
The amount of radiant energy of the infrared radiation source transmitted through Fa and Fb is detected by detection elements 4a and 4b, respectively. The output signal from each detection element 4a, 4b is
They are amplified by preamplifiers 6a and 6b, respectively, and further processed by linearizers 7a and 7b so that the temperature of the object 1 and each output signal, which has a certain correlation with respect to this, have linearity. . Based on the output signals Va and Vb linearized by the linearizers 7a and 7b, a calculator 8 calculates the ratio Vb/Va.
今、物体１と検出器２との間の空間に、検出す
べき測定対象ガス５が存在しないとすると、
Vb／Vaなる比は、物体１の温度、光学系３の汚
れ等に関係なく一定の値になる。両者１，２間の
空間に、測定対象ガス５が存在する場合には、物
体１より放射される赤外線輻射源のうち、該測定
対象ガス５の固有吸収波長帯域の赤外線は、測定
対象ガス５に吸収されるため、一方の干渉フイル
タFbを透過するエネルギー量が減じ、一方の出
力信号Vbのみが減少し、Vb／Vaなる比が小さく
なる。 Now, assuming that the gas to be measured 5 to be detected does not exist in the space between the object 1 and the detector 2,
The ratio Vb/Va is a constant value regardless of the temperature of the object 1, dirt on the optical system 3, etc. When the gas to be measured 5 exists in the space between the two 1 and 2, among the infrared radiation sources emitted from the object 1, the infrared rays in the characteristic absorption wavelength band of the gas to be measured 5 are absorbed by the gas to be measured 5. Therefore, the amount of energy transmitted through one interference filter Fb decreases, and only one output signal Vb decreases, and the ratio Vb/Va becomes smaller.
従つて、物体１と検出器２との距離を予め求め
ておけば、Vb／Vaなる比から測定対象ガス５の
平均濃度を測定でき、演算器８の出力側に警報器
９を接続し、Vb／Vaなる比が予め設定した値以
下になると警報を発するように構成しておけば、
測定対象ガス５が物体１と検出器２との間の空間
に漏れ出たことを検出警報することが可能であ
る。この場合、前記物体１が有害ガスを収容する
タンク壁、管壁である場合、これらより漏出した
有害ガスは、漏出と同時に、つまり、従来のよう
に、分散により検出素子に接触するに至る時間や
サンプリングして非分散型赤外線ガス分析計の試
料セルに導入するまでの時間を費やすことなく直
ちに検知され警報を発することになる。 Therefore, if the distance between the object 1 and the detector 2 is determined in advance, the average concentration of the gas to be measured 5 can be measured from the ratio Vb/Va, and the alarm 9 is connected to the output side of the calculator 8. If you configure it to issue an alarm when the Vb/Va ratio falls below a preset value,
It is possible to detect and alarm that the gas to be measured 5 has leaked into the space between the object 1 and the detector 2. In this case, if the object 1 is a tank wall or a pipe wall that contains a harmful gas, the harmful gas leaking from these will be released at the same time as the leakage, that is, as in the conventional case, it will take some time for it to come into contact with the detection element due to dispersion. It is possible to detect the gas immediately and issue an alarm without having to spend time sampling it and introducing it into the sample cell of the non-dispersive infrared gas analyzer.
以上のように、本発明によれば、赤外線を放射
する物体を背景とし、この背景物体から放射され
る赤外線輻射源領域での放射エネルギーを利用し
て、該物体と測定装置の間に存在する測定対象ガ
スの濃度を測定するため、赤外線照射用光源、サ
ンプリング装置、試料セル等が省略された極めて
簡単な構成で足り、それでいて、物体を光源とし
て利用するにも拘わらず、物体の温度変動に影響
されることなく正確な濃度測定を行なえるのであ
る。即ち、大気の固有吸収のない波長帯域のみを
透過する干渉フイルタと測定対象ガスの固有吸収
波長帯域のみを透過する干渉フイルタとを用い、
これら干渉フイルタを透過した赤外線の放射エネ
ルギー量の比によつて背景物体と検出器の間に存
在する測定対象ガスの濃度測定を行なうため、物
体の温度変動により該物体より放射される赤外線
の放射エネルギー総量が変動しても、これに影響
されることなく、さらには、測定対象であるガス
とは全く別の物体を背景として、この背景物体と
検出器との間に存在する測定対象ガスの濃度を測
定するものであるから、測定対象ガスのより確実
で精密な濃度測定を行なえるのである。 As described above, according to the present invention, an object that emits infrared rays is used as a background, and the radiant energy in the infrared radiation source region emitted from this background object is used to detect the object that exists between the object and the measuring device. In order to measure the concentration of the gas to be measured, an extremely simple configuration that omits an infrared irradiation light source, a sampling device, a sample cell, etc. is sufficient. Accurate concentration measurements can be made without being affected. That is, by using an interference filter that transmits only the wavelength band in which there is no intrinsic absorption of the atmosphere and an interference filter that transmits only the characteristic absorption wavelength zone of the gas to be measured,
In order to measure the concentration of the target gas existing between the background object and the detector based on the ratio of the amount of radiant energy of the infrared rays transmitted through these interference filters, the infrared rays radiated from the object due to temperature fluctuations of the object are measured. Even if the total amount of energy fluctuates, it will not be affected by this, and furthermore, the measurement target gas that exists between this background object and the detector can be Since it measures the concentration, it is possible to more reliably and precisely measure the concentration of the gas to be measured.
また、実施例のように、演算器の出力側に警報
器を接続して前記比が予め設定した値以下になれ
ば警報を発するように構成することにより、塩化
ビニール、ホスゲンのような有害、ガスの場合で
あつても、これを収容するタンク壁、管壁等の背
景物体から漏れ出た直後に、これを検知警報する
ことができる高感度で選択性が高く、しかも、構
造簡単で安価なガス漏れ警報器を実現し得るもの
である。 In addition, as in the embodiment, by connecting an alarm to the output side of the computing unit and configuring it to issue an alarm when the ratio falls below a preset value, harmful substances such as vinyl chloride and phosgene can be removed. Even in the case of gas, it can detect and alarm immediately after it leaks from background objects such as tank walls and pipe walls that contain it.It is highly sensitive and selective, and has a simple structure and is inexpensive. This makes it possible to realize a gas leak alarm.
尚、実施例は、その技術的思想の範囲内で行な
われる設定変更的事項を含むことはもとよりであ
つて、例えば、図示の実施例のように、同一の検
出器２内に、二種類の干渉フイルタFa，Fb及び
検出素子４ａ，４ｂを設ける他、これら干渉フイ
ルタFa，Fb及び検出素子４ａ，４ｂを各別の検
出器に内装し、ハーフミラーあるいはフイルタチ
ヨツパ等によつて赤外線を二分して各検出器に導
くように構成して実施することも可能である。 Note that the embodiments naturally include settings changes that are made within the scope of the technical idea, and for example, as in the illustrated embodiment, two types of In addition to providing interference filters Fa, Fb and detection elements 4a, 4b, these interference filters Fa, Fb and detection elements 4a, 4b are housed in separate detectors, and the infrared rays are divided into two by a half mirror or a filter splitter. It is also possible to configure and implement it so that it is guided to each detector.
図面は本発明の一実施例を示し、第１図は使用
状態を示す概略断面図、第２図は回路図である。
１……背景物体、２……検出器、３……光学
系、Fa，Fb……干渉フイルタ、４ａ，４ｂ……
検出素子、５……測定対象ガス、８……演算器。
The drawings show one embodiment of the present invention, with FIG. 1 being a schematic sectional view showing the state of use, and FIG. 2 being a circuit diagram. 1...Background object, 2...Detector, 3...Optical system, Fa, Fb...Interference filter, 4a, 4b...
Detection element, 5... gas to be measured, 8... computing unit.
Claims (1)
学系と、この赤外線のうち、大気の固有吸収のな
い波長帯域のみを透過する干渉フイルタならびに
前記背景物体と検出器との間に存在する測定対象
ガスの固有吸収波長帯域のみを透過する干渉フイ
ルタと、これら両種の干渉フイルタを透過した赤
外線の放射エネルギー量をそれぞれ検出する検出
素子と、これら両検出素子からの出力信号の比を
算出する演算器とをそなえ、もつて、背景物体か
ら放射される赤外線のエネルギー量を基準とし
て、この背景物体と検出器との間に存在する測定
対象ガスの濃度を測定するようにしたことを特徴
とする赤外線濃度測定装置。1. An optical system that condenses infrared rays emitted from a background object, an interference filter that transmits only a wavelength band of this infrared ray that is not uniquely absorbed by the atmosphere, and a measurement target that exists between the background object and the detector. An interference filter that transmits only the characteristic absorption wavelength band of the gas, a detection element that detects the amount of infrared radiant energy that has passed through both types of interference filters, and an operation that calculates the ratio of the output signals from both detection elements. The detector is characterized in that the concentration of the gas to be measured existing between the background object and the detector is measured based on the amount of energy of infrared rays emitted from the background object. Infrared concentration measuring device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13228778A JPS5558438A (en) | 1978-10-25 | 1978-10-25 | Device for measuring concentration by infrared ray |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13228778A JPS5558438A (en) | 1978-10-25 | 1978-10-25 | Device for measuring concentration by infrared ray |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5558438A JPS5558438A (en) | 1980-05-01 |
| JPS6120808B2 true JPS6120808B2 (en) | 1986-05-23 |
Family
ID=15077746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13228778A Granted JPS5558438A (en) | 1978-10-25 | 1978-10-25 | Device for measuring concentration by infrared ray |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5558438A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE398360B (en) * | 1975-10-28 | 1977-12-19 | Avtex Fibers Inc | RAYON FIBER CONSISTING OF A CELLULOSA MATERIAL WITH DERIPPERATED POLYVINYL PYRROLIDONE |
| JPS56147045A (en) * | 1980-04-18 | 1981-11-14 | Toshiba Corp | Analytical apparatus for gas component |
| JPS5872037A (en) * | 1981-10-27 | 1983-04-28 | Sanyo Electric Co Ltd | Gas sensor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5290982A (en) * | 1976-01-26 | 1977-07-30 | Hokushin Electric Works | Two color moisture meter |
-
1978
- 1978-10-25 JP JP13228778A patent/JPS5558438A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5290982A (en) * | 1976-01-26 | 1977-07-30 | Hokushin Electric Works | Two color moisture meter |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5558438A (en) | 1980-05-01 |
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