【発明の詳細な説明】
〔産業上の利用分野〕
本発明は，水晶振動子湿度センサに関する．更に詳しく
は、感度を向上せしめた水晶振動子湿度センサに関する
．
〔従来の技術〕および〔発明が解決しようとする課題〕
従来から、水晶振動子表面にポリアミド系重合体よりな
る水分吸着膜を形成せしめた水晶振動子湿度センサが用
いられているが、この水分吸着膜はその製膜性、耐久性
および感度の点で問題がみられる。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a quartz crystal humidity sensor. More specifically, it relates to a quartz crystal humidity sensor with improved sensitivity. [Prior art] and [Problem to be solved by the invention]
Conventionally, quartz crystal humidity sensors have been used in which a moisture adsorption film made of a polyamide polymer is formed on the surface of a quartz crystal oscillator, but this moisture adsorption film is inferior in terms of film formability, durability, and sensitivity. I see a problem.
そこで、本出願人は、こうした問題点のない水分吸着膜
として、各種のプラズマ重合膜またはその還元処理膜（
特開昭６２−１１８２３７号公報、同６４−５７１４３
号公報など）あるいは各種の有機化合物塗膜（特開昭６
３−４０８３５号公報，同６３−１７３９３６号公報、
同６３−２４３８３４号公報，同６３−２８２６３１号
公報など）を提案している．
本発明の目的は、プラズマ重合膜の形或に必要なプラズ
マ重合装置などを必要とはせず，また感度の点ですぐれ
た水晶振動子湿度センサを提供することにある．
〔課題を解決するための手段〕
かかる本発明の目的は，水晶振動子表面に粉末状活性炭
分散膜を形成せしめた水晶振動子湿度センサによって達
成される．
水晶振動子としては、ＡＴカット、振動周波数５ Ｍ
Ｈ ｚ以上のものが好んで用いられ，それの使用態様の
一例が第１図に平面図として示されており，例えば表面
積が約０．６４ｃｄの水晶面２１の真中に銀電極２２が
取付けられ，裏面側にも取付けられた銀電極のそれぞれ
から，リード線２３．２３’が引き出されている．
周知の如く，粉末状活性炭は比表面積が大きくかつ物質
を吸着し易い性質を有しており、これを適当な被膜形成
性重合体溶液、例えばボリビニ／Ｌブチラール、ポリス
ルホンなどの有機溶媒溶液ヰやスチルバゾリウム基含有
ポリビニルアルコー／Ｌなどの水溶性光架橋性樹脂の水
溶液中へ、約１〜１０重量算の分散濃度で分散させた分
散液を、スピナ上にクランプした水晶振動子表面に滴下
し，舶１０００〜５０００ｒｐｍの回転数で約ｌ〜６０
秒間回転塗布した後、室温に所定時間放置して乾燥させ
ることにより，また光架橋性樹脂が用いられた場合には
、約１０〜１２０分間放置後更に波長２７００〜４５０
０人，好ましくは３０００〜３７００人の光を約１〜３
００秒間光照劇し、光架橋させることにより，粉末状活
性炭分戯膜の形成が行われる．なお、粉末状活性炭とし
ては，木材，やしがらなど任意の炭素性物質から祷られ
たものが用いられる．
〔作用〕および〔発明の効果〕
水晶振動子は、下記式に示されるように，表面に付着し
た物質の重量変化に対応して、その周波数が変化するの
で，このような原理に基いて湿度を感度良く測定するこ
とができる．
ΔＦ＝Ｋ・Δ一
ΔＦ＝周波数変化量
ΔＩｌ：付着重量変化量
Ｋ：定数
本発明に係る水晶振動子湿度センサは、水晶振動子の表
面に粉末状活性炭分散膜を形成させ，この粉末状活性炭
分散膜は水分吸着膜として有効に作用し，従来の有機物
単独系水分吸着膜と比較して、高感度を示している．
〔実施例〕
次に、実施例について本発明を説明する，実施例
ポリビニルブチラール０．５ｇおよび粉末状活性炭（ｊ
ＩＩ沢薬品製品）ＬＯ２ｇを塩化メチレン５０ｗ ｎ中
に溶解または分散させた分散液を調製し、この分散液２
００μ党を、スビナ上にクランプした第１図に示される
形状の水晶振動子（八雲通信工業製，ＡＴカット，振動
周波数６ＭＨｚ）の電極表面上に滴下し、３００３０秒
間の条件下で回転塗布した後，室温下に２４時間放置し
て乾燥させた．
このようにして表面に粉末状活性炭分散膜（厚さ約ｌＯ
μｍ）を形成させた１個の水晶振動子２５を用いた周波
数測定回路の一例が第２図に示されており、測定された
周波数が周波数カウンタ２６によって計測されるように
した周波数測定装置を２５℃の恒温恒湿槽中に設置し，
相対湿度に対する周波数変化を測定した．
その結果、相対湿度３０〜９郎の範囲内で，相対湿度１
０％当り約−１１０Ｈｚの周波数変化量（ΔＦ）が示さ
れ，相対湿度と周波数変化との間に良好な相関関係が認
められ、この粉末状活性炭分散膜を形成させた水晶振動
子が湿度センサを形成し得ることが確認された．
更に，この水晶振動子湿度センサを、湿度９０％の雰囲
気中に４８時間放置した後，再び湿度に対する感度を測
定したが、その感度に変化はみられなかった．
比較例
実施例において、粉末状活性炭を分散させないポリビニ
ルブチラール膜を表面に形成させた水晶振動子の場合に
は、相対湿度３０〜９０％の範囲内での相対湿度１０当
りの周波数変化量（ΔＦ）は，約−３４Ｈｚであった．Therefore, the present applicant has developed various plasma polymerized membranes or reduction-treated membranes (
JP-A-62-118237, JP-A No. 64-57143
Publications, etc.) or various organic compound coatings (Japanese Unexamined Patent Publication No. 6
Publication No. 3-40835, Publication No. 63-173936,
63-243834, 63-282631, etc.). An object of the present invention is to provide a quartz crystal oscillator humidity sensor that does not require the form of a plasma polymerized film or a necessary plasma polymerization device, and is excellent in sensitivity. [Means for Solving the Problems] The object of the present invention is achieved by a quartz crystal oscillator humidity sensor in which a powdered activated carbon dispersed film is formed on the surface of the quartz crystal oscillator. As a crystal oscillator, AT cut, vibration frequency 5M
Hz or more is preferably used, and an example of its usage is shown in a plan view in FIG. , lead wires 23 and 23' are drawn out from each of the silver electrodes attached to the back side. As is well known, powdered activated carbon has a large specific surface area and has the property of easily adsorbing substances, and it can be mixed with an appropriate film-forming polymer solution, such as an organic solvent solution such as Borivinyl/L-butyral or polysulfone. A dispersion solution prepared by dispersing a water-soluble photocrosslinkable resin such as stilbazolium group-containing polyvinyl alcohol/L at a dispersion concentration of about 1 to 10% by weight is dropped onto the surface of a crystal resonator clamped on a spinner. Approximately 1 to 60 at a rotation speed of 1000 to 5000 rpm
After spin-coating for seconds, leave it at room temperature for a predetermined period of time to dry, or if a photocrosslinkable resin is used, leave it for about 10 to 120 minutes and then further coat it at a wavelength of 2700 to 450.
0 people, preferably 3000-3700 people light about 1-3
By exposing it to light for 00 seconds and photo-crosslinking, a powdery activated carbon film is formed. The powdered activated carbon may be made from any carbonaceous material such as wood or coconut shell. [Operation] and [Effects of the Invention] As shown in the formula below, the frequency of a crystal oscillator changes in response to changes in the weight of substances attached to its surface. can be measured with good sensitivity. ΔF=K・Δ−ΔF=Amount of frequency change ΔIl: Amount of change in attached weight K: Constant The crystal resonator humidity sensor according to the present invention forms a powdery activated carbon dispersed film on the surface of a crystal resonator, and this powdery activated carbon The dispersion membrane acts effectively as a moisture adsorption membrane and exhibits higher sensitivity compared to conventional moisture adsorption membranes based solely on organic matter. [Example] Next, the present invention will be explained with reference to an example, in which 0.5 g of polyvinyl butyral and powdered activated carbon (j
Prepare a dispersion by dissolving or dispersing 2 g of LO (II Sawa Pharmaceutical Products) in 50 w n of methylene chloride, and
00μ was dropped onto the electrode surface of a crystal oscillator (manufactured by Yakumo Tsushin Kogyo, AT cut, vibration frequency 6 MHz) having the shape shown in Fig. 1 that was clamped on a subina, and spin-coated for 30,030 seconds. After that, it was left to dry at room temperature for 24 hours. In this way, the surface is coated with a powdered activated carbon dispersed film (with a thickness of approximately 1O2).
An example of a frequency measuring circuit using a single crystal oscillator 25 formed with micrometers (μm) is shown in FIG. Installed in a constant temperature and humidity chamber at 25℃,
We measured the frequency change with respect to relative humidity. As a result, within the range of relative humidity 30 to 9, relative humidity 1
A frequency change (ΔF) of approximately -110Hz per 0% was shown, indicating a good correlation between relative humidity and frequency change, and the crystal resonator on which this powdered activated carbon dispersed film was formed was used as a humidity sensor. It was confirmed that it is possible to form Furthermore, after this quartz crystal humidity sensor was left in an atmosphere with a humidity of 90% for 48 hours, the sensitivity to humidity was measured again, but no change was observed in the sensitivity. In the comparative example, in the case of a crystal resonator whose surface was formed with a polyvinyl butyral film in which powdered activated carbon was not dispersed, the amount of frequency change (ΔF ) was approximately -34Hz.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は、本発明で用いられる水晶振動子の一態様の平
面図である．また，第２図は、本発明に係る水晶振動子
湿度センサの周波数測定回路の一例である．
（符号の説明）
２ｌ・・・・・水晶面
２２・・・・・銀電極
２４・・・・・水晶振動子
２５・・・・・水晶振動子湿度センサ
２６・・・・・周波数カウンタFIG. 1 is a plan view of one embodiment of a crystal resonator used in the present invention. Moreover, FIG. 2 is an example of a frequency measuring circuit of a crystal resonator humidity sensor according to the present invention. (Explanation of symbols) 2l...Crystal surface 22...Silver electrode 24...Crystal oscillator 25...Crystal oscillator humidity sensor 26...Frequency counter