JPH0750079B2 - Moisture sensor - Google Patents
Moisture sensorInfo
- Publication number
- JPH0750079B2 JPH0750079B2 JP2336825A JP33682590A JPH0750079B2 JP H0750079 B2 JPH0750079 B2 JP H0750079B2 JP 2336825 A JP2336825 A JP 2336825A JP 33682590 A JP33682590 A JP 33682590A JP H0750079 B2 JPH0750079 B2 JP H0750079B2
- Authority
- JP
- Japan
- Prior art keywords
- comb
- piezoelectric substrate
- shaped electrodes
- ultrasonic
- standing wave
- 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 - Fee Related
Links
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、木材などの固体、穀物やセメントなどの粉粒
体、および空気などの気体中の水分含有量を検出する水
分検出センサの改良に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is an improvement of a moisture detection sensor for detecting the moisture content in solids such as wood, powders such as grains and cement, and gases such as air. Regarding
（従来の技術） 従来、この種のセンサとしては、検出媒体の電気抵抗が
水分の含有量により変化することを利用し、その電気抵
抗の変化を一対の電極に通電して検出し、水分の含有量
を検出するものが知られている。(Prior Art) Conventionally, as this type of sensor, the fact that the electric resistance of the detection medium changes depending on the content of water is utilized, and the change in the electric resistance is detected by energizing a pair of electrodes to detect the change in water content. It is known to detect the content.
（発明が解決しようとする課題） しかし、従来のセンサでは、検出媒体の電気抵抗が水分
の含有量により変化することを利用しているので、空気
などの気体中の水分含有量を検出するには不向きである
という問題があった。(Problems to be Solved by the Invention) However, since the conventional sensor utilizes the fact that the electric resistance of the detection medium changes depending on the water content, it is necessary to detect the water content in a gas such as air. There was a problem that was not suitable for.
そこで、本発明は、上記の問題点が解消し、検出媒体に
かかわらず水分含有量を検出できるセンサを提供するこ
とを目的とする。Therefore, an object of the present invention is to solve the above problems and provide a sensor capable of detecting the water content regardless of the detection medium.
（課題を解決するための手段） かかる目的を達成するために、本発明は、以下のように
構成した。(Means for Solving the Problem) In order to achieve such an object, the present invention has the following configuration.
すなわち、本発明は、圧電基板の板面の横幅を共振波長
λの1/2の整数倍に形成すると共に、この圧電基板の板
面に２個のくし型電極を向い合わせて形成し、これらの
くし型電極の平行なくし状の電極の間隔をλの等間隔に
し、一方のくし型電極のくし状の電極間に他方のくし型
電極のくし状の電極を配置して、隣接するくし状の電極
の間隔をλ/2にすると共に、これらのくし状の電極のう
ち最外側の電極と圧電基板の側縁との距離をλ/4にした
定在波放射器と、この定在波放射器と同じ構造の超音波
受信器とを有し、 これら定在波放射器と超音波受信器とを、検出空間を挟
んで対向して配置してなる。That is, according to the present invention, the lateral width of the plate surface of the piezoelectric substrate is formed to be an integral multiple of 1/2 of the resonance wavelength λ, and two comb-shaped electrodes are formed facing each other on the plate surface of the piezoelectric substrate. The spacing between the parallel comb-shaped electrodes of the comb-shaped electrodes is made equal to λ, and the comb-shaped electrodes of the other comb-shaped electrode are arranged between the comb-shaped electrodes of one comb-shaped electrode, and the adjacent comb-shaped electrodes are arranged. The spacing between the electrodes of λ / 2 is λ / 2, and the distance between the outermost electrode of these comb-shaped electrodes and the side edge of the piezoelectric substrate is λ / 4. An ultrasonic receiver having the same structure as the radiator is provided, and the standing wave radiator and the ultrasonic receiver are arranged to face each other with a detection space interposed therebetween.
（作用） このように構成する本発明では、定在波放射器の圧電基
板上に形成したくし型電極から位相の揃った超音波が放
射され、粗密波となって検出媒体中を伝搬したのち、超
音波受信器の圧電基板上に形成したくし型電極により超
音波が受信される。(Operation) In the present invention configured as described above, ultrasonic waves in phase are radiated from the comb-shaped electrode formed on the piezoelectric substrate of the standing wave radiator, and propagated in the detection medium after becoming a compressional wave. The ultrasonic waves are received by the comb-shaped electrodes formed on the piezoelectric substrate of the ultrasonic receiver.
検出媒体中を伝搬する超音波は、その検出媒体が同じで
あっても水分の含有量の差異により伝搬速度が変化す
る。従って、超音波の伝搬速度と受波エネルギーを検出
すれば、媒体中の水分の含有率を知ることができる。The ultrasonic wave propagating in the detection medium has a different propagation speed due to the difference in the water content even if the detection medium is the same. Therefore, the content rate of water in the medium can be known by detecting the propagation velocity of the ultrasonic waves and the received energy.
（実施例） 以下、図面を参照して本発明実施例を詳細に説明する。Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.
本発明実施例は、第１図に示すように、定在波放射器１
を凹部２に埋め込み先端を鋭利に形成した垂直部材３
と、超音波受信器４を凹部５に埋め込み先端を鋭利に形
成した垂直部材６とからなり、定在波放射器１と超音波
受信器４とが所定間隔おいて対抗して配置するように、
垂直部材３と垂直部材６とを連結部材７に取り付ける。The embodiment of the present invention, as shown in FIG.
A vertical member 3 having a sharp tip formed by embedding the
And the vertical member 6 in which the ultrasonic receiver 4 is embedded in the recess 5 and the tip is sharply formed, so that the standing wave radiator 1 and the ultrasonic receiver 4 are arranged to face each other at a predetermined interval. ,
The vertical member 3 and the vertical member 6 are attached to the connecting member 7.
定在波放射器１は、第２図に示すように、LiTaO3やLiNb
O3などからなる圧電基板８上に、超音波を放射する定在
波放射体９を形成し、その定在波放射体９の全体を薄い
被覆膜（図示せず）で被覆する。定在波放射体９は、く
し型電極9Aと、くし型電極9Bとを、各くしが交互かつ平
行に配列されるようにアルミニウムの薄膜などで形成す
る。As shown in Fig. 2, the standing wave radiator 1 is composed of LiTaO 3 and LiNb.
A standing wave radiator 9 that radiates ultrasonic waves is formed on a piezoelectric substrate 8 made of O 3 or the like, and the entire standing wave radiator 9 is covered with a thin coating film (not shown). In the standing wave radiator 9, the comb-shaped electrodes 9A and the comb-shaped electrodes 9B are formed of a thin film of aluminum or the like so that the combs are arranged alternately and in parallel.
平行に配列する各くしの中央間の距離は、端子の両端に
供給する入力信号の波長をλとすれば、λ/2である。ま
た、圧電基板８に形成するくし型電極9Bの両端の各くし
の中央と、圧電基板８の端との長さはλ/4とする。The distance between the centers of the combs arranged in parallel is λ / 2, where λ is the wavelength of the input signal supplied to both ends of the terminal. The length between the center of each comb at both ends of the comb-shaped electrode 9B formed on the piezoelectric substrate 8 and the end of the piezoelectric substrate 8 is λ / 4.
超音波受信器４は、第３図に示すように、圧電基板10上
に超音波を受信する超音波受信体11を形成し、その超音
波受信体11の全体を薄い被覆膜（図示せず）で被覆す
る。超音波受信体11は、くし型電極11Aと、くし型電極1
1Bとを、各くしが交互かつ平行に配列されるようにアル
ミニウムの薄膜などで形成する。As shown in FIG. 3, the ultrasonic receiver 4 forms an ultrasonic receiver 11 for receiving ultrasonic waves on a piezoelectric substrate 10, and the entire ultrasonic receiver 11 is covered with a thin coating film (not shown). No.). The ultrasonic wave receiver 11 includes a comb-shaped electrode 11A and a comb-shaped electrode 1
1B and 1B are formed of an aluminum thin film or the like so that the combs are arranged alternately and in parallel.
平行に配列する各くしの中央間の距離は、受信する超音
波の波長をλとすれば、λ/2である。また、圧電基板10
に形成するくし型電極11Bの両端の各くしの中央と、圧
電基板10の端との長さはλ/4とする。The distance between the centers of the combs arranged in parallel is λ / 2, where λ is the wavelength of the received ultrasonic wave. In addition, the piezoelectric substrate 10
The length between the center of each comb at both ends of the comb-shaped electrode 11B formed in and the end of the piezoelectric substrate 10 is λ / 4.
次に、このように構成する実施例を、穀物やセメントな
どの粉粒体を検出媒体とし、その含有水分量を検出する
使用例について説明する。Next, an embodiment configured in this way will be described as a usage example in which a powder or granular material such as grain or cement is used as a detection medium and the water content thereof is detected.
定在波放射器１の圧電基板８上に形成するくし型電極9
A,9Bに、表面弾性波が定在波の形態で生じ（第２図参
照）、これにより超音波が検出媒体である粉粒体中に放
射される。なお、第２図中に示すｎは、ｎ＝1,2,3,・・
・とする。Comb type electrode 9 formed on the piezoelectric substrate 8 of the standing wave radiator 1
Surface acoustic waves are generated in A and 9B in the form of standing waves (see FIG. 2), and as a result, ultrasonic waves are radiated into the granular material that is the detection medium. Note that n shown in FIG. 2 is n = 1,2,3, ...
・ And
このように放射された超音波は、検出媒体中を伝搬した
のち、超音波受信器４の圧電基板10上に形成するくし型
電極11A,11Bにより表面弾性波の形態で受信され（第３
図参照）、電気信号に変換される。The ultrasonic waves thus radiated propagate through the detection medium, and then are received in the form of surface acoustic waves by the comb electrodes 11A and 11B formed on the piezoelectric substrate 10 of the ultrasonic receiver 4 (third part).
(See the figure), and converted into an electric signal.
検出媒体中を伝搬する超音波は、その検出媒体が同じで
あっても水分の含有量の差異により伝搬速度が変化す
る。従って、超音波の伝搬速度と受波エネルギーを検出
すれば、検出媒体中の水分の含有率を知ることができ
る。The ultrasonic wave propagating in the detection medium has a different propagation speed due to the difference in the water content even if the detection medium is the same. Therefore, the content rate of water in the detection medium can be known by detecting the propagation velocity of ultrasonic waves and the received energy.
次に、本発明の他の実施例について、第４図を参照して
説明する。Next, another embodiment of the present invention will be described with reference to FIG.
この実施例は、第１図の定在波放射器１および超音波受
信器４に代えて、定在波放射器１を水晶やLiNbO3などか
らなる圧電基板12とし、超音波受信器４を同様に圧電基
板13とするものである。In this embodiment, instead of the standing wave radiator 1 and the ultrasonic receiver 4 shown in FIG. 1, the standing wave radiator 1 is a piezoelectric substrate 12 made of crystal or LiNbO 3, and the ultrasonic receiver 4 is Similarly, the piezoelectric substrate 13 is used.
圧電基板12,圧電基板13はいずれも、水晶やLiNbO3を薄
くスライス、ポリッシュ後、駆動周波数の波長λの半分
に板の厚さを合わせてダイシングし、両面に金具を蒸着
させる。これにより、第５図（Ａ）〜（Ｃ）に示すよう
な各種のものが構成できる。In both the piezoelectric substrate 12 and the piezoelectric substrate 13, quartz or LiNbO 3 is thinly sliced and polished, and then the thickness of the plate is adjusted to a half of the wavelength λ of the driving frequency and dicing is performed to deposit metal fittings on both surfaces. As a result, various types as shown in FIGS. 5A to 5C can be constructed.
このように構成する各実施例では、定在波放射器である
圧電基板12から超音波が放射され、この放射された超音
波は圧電基板13で受信されるので、上述と同様に検出媒
体中の水分の含有率を知ることができる。In each of the embodiments configured as described above, ultrasonic waves are radiated from the piezoelectric substrate 12 that is a standing wave radiator, and the radiated ultrasonic waves are received by the piezoelectric substrate 13. It is possible to know the water content rate of.
（発明の効果） 以上のように、本発明では、超音波の検出媒体中におけ
る伝搬速度が水分の含有量により変化し、出力電力が増
減することを利用して水分含有量を検出できるので、検
出媒体の形態が固体、粉粒体、気体のいずれであっても
水分含有量を検出でき、汎用性に富む水分センサを提供
できる。(Effect of the invention) As described above, in the present invention, the moisture content can be detected by utilizing the fact that the propagation velocity of ultrasonic waves in the detection medium changes depending on the moisture content, and the output power increases or decreases. It is possible to provide a versatile moisture sensor that can detect the water content regardless of whether the form of the detection medium is solid, powdery or granular, or gas.
第１図は本発明実施例の全体構成を示す斜視図、第２図
は定在波放射器の平面とその振動モードを示す図、第３
図は超音波受信器の平面とその振動モードを示す図、第
４図は本発明の他の実施例の全体構成を示す斜視図、第
５図は圧電基板およびその振動モードを示す図である。 １は定在波放射器、４は超音波受信器、8,10は圧電基
板、９は定在波放射体、9A、9Bはくし型電極、11は超音
波受信体、11A、11Bはくし型電極である。FIG. 1 is a perspective view showing an overall configuration of an embodiment of the present invention, FIG. 2 is a view showing a plane of a standing wave radiator and its vibration mode, and FIG.
FIG. 4 is a diagram showing the plane of the ultrasonic receiver and its vibration mode, FIG. 4 is a perspective view showing the overall structure of another embodiment of the present invention, and FIG. 5 is a diagram showing the piezoelectric substrate and its vibration mode. . 1 is a standing wave radiator, 4 is an ultrasonic receiver, 8 and 10 are piezoelectric substrates, 9 is a standing wave radiator, 9A and 9B comb electrodes, 11 is an ultrasonic receiver, 11A and 11B comb electrodes Is.
Claims (1)
の整数倍に形成すると共に、この圧電基板の板面に２個
のくし型電極を向い合わせて形成し、これらのくし型電
極の平行なくし状の電極の間隔をλの等間隔にし、一方
のくし型電極のくし状の電極間に他方のくし型電極のく
し状の電極を配置して、隣接するくし状の電極の間隔を
λ/2にすると共に、これらのくし状の電極のうち最外側
の電極と圧電基板の側縁との距離をλ/4にした定在波放
射器と、この定在波放射器と同じ構造の超音波受信器と
を有し、 これら定在波放射器と超音波受信器とを、検出空間を挟
んで対向して配置してなる水分検出センサ。1. The horizontal width of the plate surface of the piezoelectric substrate is 1/2 of the resonance wavelength λ.
And the two comb-shaped electrodes are faced to each other on the plate surface of the piezoelectric substrate, and the parallel comb-shaped electrodes of these comb-shaped electrodes are arranged at equal intervals of λ. The comb-shaped electrode of the other comb-shaped electrode is arranged between the comb-shaped electrodes of the comb-shaped electrode so that the distance between the adjacent comb-shaped electrodes is λ / 2. It has a standing wave radiator in which the distance between the outer electrode and the side edge of the piezoelectric substrate is λ / 4, and an ultrasonic receiver having the same structure as this standing wave radiator. A moisture detection sensor in which the ultrasonic wave receiver and the ultrasonic wave receiver are arranged to face each other with a detection space in between.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2336825A JPH0750079B2 (en) | 1990-11-30 | 1990-11-30 | Moisture sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2336825A JPH0750079B2 (en) | 1990-11-30 | 1990-11-30 | Moisture sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04204251A JPH04204251A (en) | 1992-07-24 |
| JPH0750079B2 true JPH0750079B2 (en) | 1995-05-31 |
Family
ID=18303022
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2336825A Expired - Fee Related JPH0750079B2 (en) | 1990-11-30 | 1990-11-30 | Moisture sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0750079B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011112486A (en) * | 2009-11-26 | 2011-06-09 | Nippon Soda Co Ltd | Moisture detector for detecting moisture in liquefied phosgene |
| CN102980941B (en) * | 2012-11-26 | 2015-12-02 | 华南理工大学 | A kind of ultrasonic gas relative humidity detection method and device utilizing sonic velocity change |
| CN113567558B (en) * | 2021-06-30 | 2022-11-22 | 广州大学 | Soil moisture content ultrasonic measuring device and measuring method |
-
1990
- 1990-11-30 JP JP2336825A patent/JPH0750079B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04204251A (en) | 1992-07-24 |
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