JP3453962B2 - Capacitive rain sensor - Google Patents
Capacitive rain sensorInfo
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- JP3453962B2 JP3453962B2 JP28304195A JP28304195A JP3453962B2 JP 3453962 B2 JP3453962 B2 JP 3453962B2 JP 28304195 A JP28304195 A JP 28304195A JP 28304195 A JP28304195 A JP 28304195A JP 3453962 B2 JP3453962 B2 JP 3453962B2
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- Prior art keywords
- capacitance
- rain sensor
- detection
- control circuit
- circuit
- Prior art date
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Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、雨の降り始めを正
確に検知する雨センサに関し、更に詳しくは、検知感度
を向上させて、検知面の強度を上げることができる静電
容量型雨センサに関する。
【０００２】
【従来の技術】従来から雨センサは、屋根や窓枠に取り
付けられて、雨滴を検知し窓の開閉制御などのために使
用されている。このような雨センサとしては、空中に露
出させた相対する雨滴検知用電極を設けて、電極間に雨
滴が付着した際に電極間が短絡することを利用して降雨
開始を判断する抵抗型と、絶縁被膜で被覆した相対向す
る雨滴検知用電極を設けて、絶縁被膜表面に雨滴が付着
した際の電極間容量の増加から降雨開始判断を行う静電
容量型が一般的に知られている。
【０００３】後者の静電容量型の雨センサでは、発振回
路を通じて電極間容量の変化を周波数に変換し、所定時
間内に一定値以上の周波数変化が連続してあった際に降
雨開始と判断している。以下に、図７，８を参照しなが
ら、静電容量型の雨センサの動作原理を説明する。
【０００４】図７は、静電容量の変化の有無を判断する
原理を示す図であり、図中の曲線アは、検知面の静電容
量の時間変化を示している。現在時刻をＴ１とすると、
過去Ｔｃ以内すなわち時刻Ｔ０からＴ１の間に所定の閾
値Ｃｔｈ以上の容量変化が生じていれば「容量変化有
り」と判断する。このような判断は所定時間Ｔｃ毎に行
っており、この例では、次の判断時刻Ｔ２では、過去Ｔ
ｃ以内に閾値Ｃｔｈ以上の容量変化が生じていないので
「容量変化無し」と判断している。
【０００５】図８は、降雨開始を判断する原理を示す図
である。図７に示した動作において、「容量変化有り」
という判断をした時刻（図８（ａ）に示す時刻ｔ２）を
基準にして、所定時間Ｔｒ以内に所定回数（Ｎ回）の
「容量変化有り」の判断をした場合には、「降雨開始」
とし降雨検知信号を出力するが、「容量変化有り」の判
断をした時刻（図８（ｂ）に示すｔ２）から時間Ｔｒ以
内に所定回数（Ｎ回）の「容量変化有り」の判断をせ
ず、所定回数以下（Ｍ回）しか判断しなかった場合には
（Ｍ＜Ｎ）、所定時間経過（時刻ｔ２＋Ｔｒ）した後に
初めて「容量変化有り」と判断された時刻（時刻ｔｙ）
を１回目の変化した回数とし、この時刻ｔｙを基準にし
て、再び所定時間Ｔｒ内の容量変化の回数を計数する。
【０００６】このような降雨開始判断方法では、降雨の
場合には、複数の水滴がランダムな時間間隔をおいて継
続的に検知面に付着するため、所定時間Ｔｒ以内に所定
回数以上「容量変化有り」の判断をし、降雨検知信号を
出力する。一方、鳥の糞、ホコリなどの異物が検知面表
面に付着した場合、雨滴のように複数が継続して付着す
ることはないので、所定回数以上「容量変化有り」の判
断をすることはなく降雨検知信号を出力しない。
【０００７】また、結露のように長い時間に渡って徐々
に水滴が検知面に付着する場合や、鳥の糞、ホコリ等の
異物が検知面に残留する場合は、閾値Ｃｔｈ以上の容量
変化が生じる時間が設定値Ｔｃより長いので、降雨検知
信号を出力しない。
【０００８】
【発明が解決しようとする課題】しかしながら、上記従
来の静電容量型の雨センサでは、その取付場所によって
は、鳥の爪、雹、小石等の異物が検知面に接触すること
が多いため、この検知面の絶縁被膜が損傷する場合があ
った。このため、かかる損傷を防止するために検知面の
絶縁層を厚くする必要があるが、これを行うと電極間容
量が変化しにくくなり、雨の検知感度が低下してしま
う。
【０００９】そこで、上記問題を解決するために、本発
明は、検知感度を低下させることなく、検知面の強度を
向上させることができる静電容量型雨センサを提供する
ことを目的とする。
【００１０】
【課題を解決するための手段】以上のような目的を達成
するために本発明の請求項１では、櫛歯電極を対向配置
して形成した検知面と、この検知面に雨滴が付着したと
きに生じる静電容量の変化により降雨検知信号を出力す
る制御回路とを備えた静電容量型雨センサにおいて、前
記検知面を表面に形成した第１の回路基板の下方に、発
振回路を設けた制御回路を実装した第２の回路基板を積
層させた構造としており、上記第１の回路基板の裏側に
は、アース接続された導電シールドパターンを形成し、
上記櫛歯電極および上記導電シールドパターンと上記制
御回路とをスルーホールによって電気接続させた構造と
している。
【００１１】検知面と制御回路間にシールド電極を設け
ることで、電気的ノイズの影響を受けにくするととも
に、検出感度をあげることができる。また、一体化構造
にすることによって、機械的強度を向上させることがで
きるとともに、コンパクトにもできる。ここに制御回路
は、降雨時における静電容量の変化が検知できればよ
く、その構成は限定されない。
【００１２】また、検知面を表面に形成した第１の回路
基板の下方に、発信回路を設けた制御回路を実装した第
２の回路基板を積層させた構造とし、上記第１の回路基
板の裏側には、アース接続されたシールド電極となる導
電シールドパターンを形成する。これによれば、回路基
板が張り合わせれた構造になっているので、一層の小型
化、薄型化が図れる。
【００１３】本発明の雨センサは、次のような原理に基
づいて検出感度を向上させている。図９（ａ）はシール
ド電極を設けた本発明の雨センサ、図９（ｂ）はシール
ド電極のない従来の雨センサの電気力線の比較図であ
り、検知用電極１，２間に生じる電気力線は、上面とな
る検知面では双方の雨センサにおいて変わりはないが、
下面ではシールド電極を設けた面の電気力線は著しく減
少する。
【００１４】このため、雨滴が付着せずに乾燥している
状態における雨センサの等価回路は、図１０（ａ），
（ｂ）に示したようになり、検知面（上面）の静電容量
は両者ともＣｕで変わりはないが、下面の静電容量は従
来のものがＣ１、シールド電極を設けた本発明ではＣ２
となり、全体の静電容量は従来の雨センサではＣｕ＋Ｃ
１、本発明の雨センサではＣｕ＋Ｃ２となる。ここに、
Ｃ１＞Ｃ２であるから、全体の静電容量を比較すれば、
Ｃｕ＋Ｃ１＞Ｃｕ＋Ｃ２となる。
【００１５】また、一方、雨滴が付着した状態における
雨センサの等価回路は、雨滴付着による増加分をＣｒと
すれば、図１１（ａ），（ｂ）に示したようになり、検
知面の静電容量は両者ともＣｕ＋Ｃｒとして変わりはな
いが、下面の静電容量は従来のものがＣ１となり、シー
ルド電極を設けた本発明の雨センサではＣ２となる。し
たがって、雨センサの感度ΔＣ／Ｃは、静電容量の変化
率、つまりセンサの検知面に雨滴が付着することによっ
て増大した静電容量／乾燥時の静電容量で定まるため、
従来の雨センサでは、 ΔＣ１＝Ｃｒ／（Ｃｕ＋Ｃ１）
本発明の雨センサでは、ΔＣ２＝Ｃｒ／（Ｃｕ＋Ｃ２）
となるので、結局、ΔＣ１＜ΔＣ２となり（Ｃｕ＋Ｃ１
＞Ｃｕ＋Ｃ２から）、本発明の雨センサは、従来の雨セ
ンサに比べて静電容量の変化率が増大し、感度が良いこ
とが分かる。
【００１６】
【発明の実施の形態】以下に、本発明の実施の形態の一
例を図面とともに説明する。図１は、本発明に係る静電
容量型雨センサの表面の一例を示す断面図である。図に
おいて、１は雨滴ｕを検知する検知面表面、２は耐薬
品、耐紫外線に優れたフッ素樹脂系塗料等によって好み
の色で塗装されたコーティング面、３，６，９はガラス
エポキシ樹脂、ガラスポリイミド樹脂、ガラスフッ素樹
脂等で形成されたプリント配線基板（上側基板３、中間
基板６、下側基板９）、４，８は絶縁性の接着剤である
ガラスエポキシプリプレグ、５ａ，５ｂは雨滴ｕを検知
するために対向配置して形成された櫛歯電極、７は導電
シールドパターンによって形成されたシールド電極、１
０はソルダーレジスト、１１は制御回路用電極１１ａと
制御回路部品１１ｂとを備えた制御回路である。
【００１７】なお、中間基板６には、上面（表面）に櫛
歯電極５ａ，５ｂ（検知用電極）を設けていることか
ら、雨滴ｕの実際の検知面となる。また、この図では、
検知面となる中間基板６の上方に更に基板３（上側基
板）を設けて、十分な機械的強度を持たせているが、必
ずしもこのような基板３を設けなくてもよい。このよう
に、雨センサは一体化した構造になっており、シールド
電極７を櫛歯電極５ａ，５ｂと制御回路１１の間に設け
ているので、雨滴ｕが付着していないときの櫛歯電極５
ａ，５ｂ間の静電容量は減少するが、雨滴ｕによる静電
容量の増加量は変わらないため、静電容量の変化率、つ
まり、検出感度を増大させることができる（図９〜１１
参照）。
【００１８】制御回路１１では、図２，３に示した内部
構成によって、検知面表面１に雨滴ｕが付着したときに
は、櫛歯電極５ａ，５ｂに生じる静電容量の変化により
発振周期の変化を検知して降雨検知信号を出力する。図
２は、制御回路１１の内部構成を示すブロック図であ
る。図において、２０は発振回路、２１は判定回路、２
２は直流電源端子、２３はアース端子、Ｌは降雨検知信
号を出力する信号線である。
【００１９】また、図３は制御回路１１の要部である発
振回路２０の回路図である。この発振回路２０は、櫛歯
電極５ａ，５ｂ間の静電容量Ｃと、帰還抵抗Ｒ２で決ま
る時定数に基づくパルス信号を出力しており、電極５
ａ，５ｂ間の静電容量Ｃの変化は発振周期に変換されて
判定回路２１へ伝達される。判定回路２１では、発振回
路２０から入力されたパルス信号の時間的な変化の様子
（発振周波数の減少）、すなわち、検知面６の静電容量
Ｃの時間変化の様子（静電容量Ｃの増加）から降雨の開
始を判断し、降雨検知信号を出力する。
【００２０】図４は、静電容量型雨センサの外観構成を
概略的に示す斜視図である。この雨センサは、上述した
ように、櫛歯電極５ａ，５ｂが対向配置して形成されて
おり、検知面表面１に雨滴が付着したときに生じる電極
間の静電容量Ｃの変化により発振回路２０の発振周期の
変化を検知して、制御回路１１は信号線Ｌを介して、降
雨検知信号を窓の開閉制御などを行う外部回路へ出力す
る。なお、Ｗは雨センサの取り付けた窓枠、Ｈは雨セン
サ本体（ハウジング）を示している。
【００２１】次に、図５（ａ）には櫛歯電極５ａ，５ｂ
のパターン図を、（ｂ）には導電シールドパターンによ
って形成されたシールド電極７のパターン図を示し、図
６には、図５の切断線（Ａ−Ａ’）における静電容量型
雨センサの表面の断面部分拡大図を示している。図５
（ａ）に示すように、櫛歯電極５ａ，５ｂは対向配置さ
れており、これらの検知した静電容量Ｃは、２つの検知
電極面用ランド１５ａ，１５ｂから検知電極面用スルー
ホール１６ａ，１６ｂを介して、制御回路１１の発振回
路２０に伝達される。一方、シールド電極７は、シール
ド電極用スルーホール１７を経て、制御回路１１のアー
ス端子２３に接続されているので、常に一定電位に保た
れている（図５（ｂ），図６，図２，図３参照）。
【００２２】このようにして、中間基板６（第１の回路
基板）の表面には、導電パターンをエッチングするなど
して櫛歯電極５ａ，５ｂを対向配置させた検知面を、裏
面には導電シールドパターンを形成し、下側基板９（第
２の回路基板）には、制御回路用電極１１ａを形成しそ
の上に制御回路１１を実装させて、これらを積層し張り
合わせて一体化させることが出来る。
【００２３】
【発明の効果】以上に説明したように、本発明の請求項
１に記載の静電容量型雨センサによれば、検知面と制御
回路間にシールド電極を設けることで、互いの電極及び
外部からの電気的ノイズの影響を受けにくすることがで
きるとともに、検出感度をあげることができる。
【００２４】また、絶縁皮膜表面を厚くできるため、対
候性の向上が図れ、検知面の損傷が内部まで到達しにく
いので、雨検知用の電極の破損を防ぐことが出来る。更
に積層一体化することによって、機械的強度を増加させ
ることができるとともに、装置の小型化が図れる。ま
た、表面に検知面を裏面に導電シールドパターンを形成
した回路基板と、制御回路を実装させた回路基板とを積
層し、かつ櫛歯電極および第１の回路基板の裏側にアー
ス接続された導電シールドパターン、制御回路とをスル
ーホールによって電気接続させているので、製造が簡単
になり、一層の小型化、薄型化が図れる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rain sensor for accurately detecting the start of rain, and more particularly, to improving the detection sensitivity and increasing the strength of a detection surface. The present invention relates to a capacitance type rain sensor that can be raised. Conventionally, a rain sensor is attached to a roof or a window frame, detects raindrops, and is used for controlling opening and closing of windows. As such a rain sensor, there is provided a resistance detection electrode exposed in the air, and a resistance type that determines the start of rain by utilizing a short circuit between the electrodes when raindrops adhere between the electrodes. In general, an electrostatic capacitance type in which opposed raindrop detecting electrodes covered with an insulating film are provided and a rainfall start is determined from an increase in interelectrode capacitance when raindrops adhere to the surface of the insulating film is generally known. . In the latter type of capacitance-type rain sensor, a change in interelectrode capacitance is converted into a frequency through an oscillation circuit, and when a frequency change equal to or more than a certain value continues within a predetermined time, it is determined that rainfall has started. are doing. The operation principle of the capacitance type rain sensor will be described below with reference to FIGS. FIG. 7 is a diagram showing the principle of judging the presence / absence of a change in the capacitance. A curve a in the figure shows a change over time in the capacitance of the detection surface. If the current time is T1,
If a capacity change equal to or greater than a predetermined threshold Cth has occurred within the past Tc, that is, between time T0 and T1, it is determined that "capacity change has occurred". Such a determination is made every predetermined time Tc. In this example, at the next determination time T2, the past T
Since no capacitance change equal to or greater than the threshold value Cth has occurred within c, it is determined that there is no capacitance change. FIG. 8 is a diagram showing the principle of judging the start of rainfall. In the operation shown in FIG. 7, "there is a capacitance change"
Based on the time (time t2 shown in FIG. 8 (a)) as a reference, when a predetermined number of times (N times) of “capacity change” is determined within a predetermined time Tr, “rainfall starts”
A rain detection signal is output, and a predetermined number (N times) of “capacitance change” is determined within a time Tr from the time (t2 shown in FIG. 8B) when the “capacity change” is determined. If the number of determinations is not more than the predetermined number of times (M times) (M <N), the time (time ty) when it is determined that “capacity change has occurred” only after the predetermined time has elapsed (time t2 + Tr)
Is the number of times of the first change, and the number of times of the capacity change within the predetermined time Tr is counted again with reference to the time ty. In such a rain start determination method, in the case of rain, a plurality of water droplets continuously adhere to the detection surface at random time intervals. It judges that there is, and outputs a rainfall detection signal. On the other hand, when foreign matter such as bird droppings or dust adheres to the surface of the detection surface, a plurality of particles do not continuously adhere like raindrops. Does not output rain detection signal. In addition, when water droplets gradually adhere to the detection surface over a long period of time such as dew condensation, or when foreign matter such as bird droppings or dust remains on the detection surface, a change in capacitance greater than the threshold value Cth occurs. Since the generated time is longer than the set value Tc, no rain detection signal is output. [0008] However, in the above-mentioned conventional capacitance-type rain sensor, a foreign matter such as a bird's claw, a hail, or a pebble may contact the detection surface depending on a mounting location. Due to the large number, the insulating film on the detection surface was sometimes damaged. Therefore, in order to prevent such damage, it is necessary to increase the thickness of the insulating layer on the detection surface. However, if this is done, the capacitance between the electrodes will not easily change, and the rain detection sensitivity will decrease. [0009] Therefore, in order to solve the above problem, an object of the present invention is to provide a capacitance type rain sensor capable of improving the strength of the detection surface without lowering the detection sensitivity. [0010] In order to achieve the above object, according to the first aspect of the present invention, a detection surface formed by arranging comb-teeth electrodes to face each other, and raindrops are formed on the detection surface. A control circuit for outputting a rainfall detection signal due to a change in capacitance generated when the sensor is attached, wherein an oscillation circuit is provided below a first circuit board having the detection surface formed on a surface thereof. And a second circuit board on which a control circuit provided with is mounted. The second circuit board has a structure in which a grounded conductive shield pattern is formed on the back side of the first circuit board.
The comb electrode and the conductive shield pattern are electrically connected to the control circuit by through holes. By providing a shield electrode between the detection surface and the control circuit, it is possible to reduce the influence of electric noise and increase the detection sensitivity. In addition, by having an integrated structure, the mechanical strength can be improved and the device can be made compact. The configuration of the control circuit is not limited as long as it can detect a change in capacitance during rainfall. Further, a second circuit board on which a control circuit provided with a transmission circuit is mounted is laminated below the first circuit board having a sensing surface formed on the surface thereof, and On the back side, a conductive shield pattern serving as a grounded shield electrode is formed. According to this, since the circuit board has a structure in which the circuit boards are bonded to each other, further miniaturization and thinning can be achieved. The rain sensor of the present invention has improved detection sensitivity based on the following principle. FIG. 9A is a comparison diagram of electric lines of force of a rain sensor of the present invention provided with a shield electrode, and FIG. 9B is a comparison diagram of electric lines of force of a conventional rain sensor without a shield electrode. The lines of electric force are the same in both rain sensors on the upper detection surface,
On the lower surface, the lines of electric force on the surface provided with the shield electrode are significantly reduced. For this reason, the equivalent circuit of the rain sensor in a state where the raindrops are dry without adhering thereto is shown in FIG.
As shown in (b), the capacitance on the detection surface (upper surface) is the same for both Cu but the capacitance on the lower surface is C1 for the conventional one and C2 for the present invention provided with the shield electrode.
And the total capacitance is Cu + C in the conventional rain sensor.
1. Cu + C2 in the rain sensor of the present invention. here,
Since C1> C2, comparing the total capacitance,
Cu + C1> Cu + C2. On the other hand, the equivalent circuit of the rain sensor in the state where the raindrops are attached is as shown in FIGS. 11A and 11B, where Cr is the increase due to the attachment of the raindrops. Although the capacitance is unchanged as Cu + Cr, the capacitance of the lower surface is C1 in the conventional case, and is C2 in the rain sensor of the present invention provided with the shield electrode. Therefore, the sensitivity ΔC / C of the rain sensor is determined by the rate of change of the capacitance, that is, the capacitance increased by the attachment of raindrops to the detection surface of the sensor / the capacitance during drying.
In the conventional rain sensor, ΔC1 = Cr / (Cu + C1) In the rain sensor of the present invention, ΔC2 = Cr / (Cu + C2)
As a result, ΔC1 <ΔC2 results (Cu + C1
> Cu + C2), it can be seen that the rain sensor of the present invention has a higher capacitance change rate and higher sensitivity than the conventional rain sensor. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the surface of the capacitance type rain sensor according to the present invention. In the figure, 1 is a detection surface surface for detecting raindrop u, 2 is a coating surface painted in a desired color with a fluorine resin paint excellent in chemical resistance and UV resistance, 3, 6, and 9 are glass epoxy resins, Printed wiring boards (upper board 3, intermediate board 6, lower board 9) formed of glass polyimide resin, glass fluorine resin, etc., 4, 8 are glass epoxy prepregs as insulating adhesives, 5a, 5b are raindrops u, 7 are shield electrodes formed by a conductive shield pattern,
Reference numeral 0 denotes a solder resist, and reference numeral 11 denotes a control circuit including a control circuit electrode 11a and a control circuit component 11b. Since the intermediate substrate 6 is provided with the comb-teeth electrodes 5a and 5b (detection electrodes) on the upper surface (front surface), it serves as an actual detection surface of the raindrop u. In this figure,
Although the substrate 3 (upper substrate) is further provided above the intermediate substrate 6 serving as a detection surface to provide sufficient mechanical strength, such a substrate 3 does not necessarily have to be provided. As described above, the rain sensor has an integrated structure, and since the shield electrode 7 is provided between the comb-teeth electrodes 5a and 5b and the control circuit 11, the comb-teeth electrode when the raindrop u is not attached is provided. 5
Although the capacitance between a and 5b decreases, the amount of increase in capacitance due to raindrop u does not change, so that the rate of change in capacitance, that is, the detection sensitivity can be increased (FIGS. 9 to 11).
reference). In the control circuit 11, due to the internal structure shown in FIGS. 2 and 3, when a raindrop u adheres to the detection surface 1, the oscillation cycle changes due to the change in the capacitance generated on the comb-teeth electrodes 5a and 5b. Detect and output rain detection signal. FIG. 2 is a block diagram showing the internal configuration of the control circuit 11. In the figure, 20 is an oscillation circuit, 21 is a judgment circuit, 2
2 is a DC power supply terminal, 23 is a ground terminal, and L is a signal line for outputting a rainfall detection signal. FIG. 3 is a circuit diagram of an oscillation circuit 20 which is a main part of the control circuit 11. The oscillation circuit 20 outputs a pulse signal based on a capacitance C between the comb-tooth electrodes 5a and 5b and a time constant determined by the feedback resistor R2.
The change in the capacitance C between a and 5b is converted into an oscillation cycle and transmitted to the determination circuit 21. In the determination circuit 21, the temporal change of the pulse signal input from the oscillation circuit 20 (decrease of the oscillation frequency), that is, the temporal change of the capacitance C of the detection surface 6 (the increase of the capacitance C) ) To determine the start of rainfall and output a rainfall detection signal. FIG. 4 is a perspective view schematically showing the appearance of the capacitance type rain sensor. As described above, this rain sensor is formed with the comb-teeth electrodes 5a and 5b opposed to each other, and the oscillation circuit is formed by a change in capacitance C between the electrodes that occurs when raindrops adhere to the detection surface surface 1. The control circuit 11 detects a change in the oscillation cycle of 20 and outputs a rainfall detection signal to an external circuit for controlling the opening and closing of windows via a signal line L. W indicates a window frame to which the rain sensor is attached, and H indicates a rain sensor main body (housing). Next, FIG. 5A shows the comb electrodes 5a and 5b.
5B shows a pattern diagram of the shield electrode 7 formed by the conductive shield pattern, and FIG. 6 shows a pattern diagram of the capacitive rain sensor taken along a cutting line (AA ′) in FIG. FIG. 3 shows a partially enlarged cross-sectional view of the surface. FIG.
As shown in (a), the comb-tooth electrodes 5a and 5b are arranged to face each other, and the detected capacitance C is changed from the two detection electrode surface lands 15a and 15b to the detection electrode surface through holes 16a and 15b. The signal is transmitted to the oscillation circuit 20 of the control circuit 11 via 16b. On the other hand, since the shield electrode 7 is connected to the ground terminal 23 of the control circuit 11 through the shield electrode through hole 17, it is always kept at a constant potential (FIGS. 5B, 6, and 2). , FIG. 3). As described above, the sensing surface on which the comb-teeth electrodes 5a and 5b are arranged to face each other by etching the conductive pattern is provided on the surface of the intermediate substrate 6 (first circuit board), and the conductive surface is provided on the back surface. A shield pattern is formed, a control circuit electrode 11a is formed on the lower substrate 9 (second circuit board), and the control circuit 11 is mounted thereon, and these are laminated and laminated to be integrated. I can do it. As described above, according to the capacitive rain sensor according to the first aspect of the present invention, by providing the shield electrode between the detection surface and the control circuit, each other is provided. In addition to being less susceptible to the effects of electrical noise from the electrodes and the outside, the detection sensitivity can be increased. Further, since the surface of the insulating film can be made thicker, the weatherability can be improved, and the damage on the detection surface does not easily reach the inside, so that damage to the electrode for rain detection can be prevented. Further, by laminating and integrating, the mechanical strength can be increased and the size of the device can be reduced. In addition, a circuit board having a sensing surface on the front side and a conductive shield pattern formed on the back side and a circuit board on which a control circuit is mounted are laminated, and a conductive layer grounded to the back side of the comb electrode and the first circuit board. Since the shield pattern and the control circuit are electrically connected to each other through the through holes, the manufacturing is simplified, and the size and thickness can be further reduced.
【図面の簡単な説明】
【図１】本発明に係る静電容量型雨センサの表面の一例
を示す断面図である。
【図２】本発明に係る静電容量型雨センサの制御回路の
内部構成の一例を示すブロック図である。
【図３】制御回路の要部である発振回路の一例を示す回
路図である。
【図４】本発明に係る静電容量型雨センサの外観構成を
概略的に示す斜視図である。
【図５】（ａ）は櫛歯電極のパターン図、（ｂ）はシー
ルド電極のパターン図である。
【図６】図５に示した切断線（Ａ−Ａ’）における静電
容量型雨センサの表面の断面部分拡大図である。
【図７】静電容量型雨センサの静電容量の変化の有無を
判断する原理を示す図である。
【図８】静電容量型雨センサにおいて降雨開始を判断す
る原理を示す図である。
【図９】（ａ），（ｂ）は、本発明の静電容量型雨セン
サの原理を説明するための図である（電気力線図）。
【図１０】（ａ），（ｂ）は、本発明の静電容量型雨セ
ンサの原理を説明するための図である（乾燥状態の等価
回路図）。
【図１１】（ａ），（ｂ）は、本発明の静電容量型雨セ
ンサの原理を説明するための図である（雨滴付着状態の
等価回路図）。
【符号の説明】
１・・・検知面表面
２・・・コーティング面
３，６，９・・・プリント配線基板
５ａ，５ｂ・・・櫛歯電極（検知用電極）
７・・・シールド電極
１１・・・制御回路
１１ａ・・・制御回路用電極
１５ａ，１５ｂ・・・検知電極面用ランド
１６ａ，１６ｂ・・・検知電極面用スルーホール
１７・・・シールド電極用スルーホール
２０・・・発振回路
２１・・・判定回路
２２・・・直流電源端子
２３・・・アース端子
Ｌ・・・信号線
Ｗ・・・窓枠
Ｈ・・・雨センサ本体（ハウジング）
ｕ・・・雨滴
Ｃ・・・静電容量BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of a surface of a capacitive rain sensor according to the present invention. FIG. 2 is a block diagram showing an example of an internal configuration of a control circuit of the capacitive rain sensor according to the present invention. FIG. 3 is a circuit diagram illustrating an example of an oscillation circuit that is a main part of a control circuit. FIG. 4 is a perspective view schematically showing an external configuration of a capacitive rain sensor according to the present invention. 5A is a pattern diagram of a comb electrode, and FIG. 5B is a pattern diagram of a shield electrode. 6 is a partially enlarged cross-sectional view of the surface of the capacitive rain sensor taken along a cutting line (AA ′) shown in FIG. 5; FIG. 7 is a diagram illustrating the principle of determining whether or not the capacitance of the capacitance-type rain sensor has changed. FIG. 8 is a diagram illustrating a principle of determining the start of rainfall in a capacitive rain sensor. FIGS. 9A and 9B are diagrams for explaining the principle of the capacitance-type rain sensor of the present invention (electric force diagram). FIGS. 10A and 10B are diagrams for explaining the principle of the capacitance type rain sensor of the present invention (equivalent circuit diagram in a dry state). FIGS. 11A and 11B are diagrams for explaining the principle of the capacitance-type rain sensor of the present invention (equivalent circuit diagram in a state where a raindrop is attached). [Description of Signs] 1 ... Detection surface 2 ... Coating surfaces 3, 6, 9 ... Printed wiring boards 5a, 5b ... Comb-tooth electrodes (detection electrodes) 7 ... Shield electrode 11 ... Control circuit 11a ... Control circuit electrodes 15a and 15b ... Detection electrode surface lands 16a and 16b ... Detection electrode surface through hole 17 ... Shield electrode through hole 20 ... Oscillation Circuit 21 Judgment circuit 22 DC power supply terminal 23 Earth terminal L Signal line W Window frame H Rain sensor body (housing) u Raindrop C・ Capacitance
フロントページの続き (56)参考文献 特開 平６−58900（ＪＰ，Ａ) 特開 平２−181641（ＪＰ，Ａ) 特開 昭58−92943（ＪＰ，Ａ) 特開 昭61−195341（ＪＰ，Ａ) 実開 平５−62364（ＪＰ，Ｕ) 実開 平５−62365（ＪＰ，Ｕ) 特公 平７−6938（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.7，ＤＢ名) G01W 1/00 - 1/18 G01N 27/00 - 27/24 G01V 3/00 - 3/40 B60S 1/00 - 1/68 ＪＩＣＳＴファイル（ＪＯＩＳ)Continuation of the front page (56) References JP-A-6-58900 (JP, A) JP-A-2-181641 (JP, A) JP-A-58-92943 (JP, A) JP-A-61-195341 (JP) , A) Japanese Utility Model Application Hei 5-62364 (JP, U) Japanese Utility Model Application Hei 5-62365 (JP, U) Japanese Patent Publication No. 7-6938 (JP, B2) (58) Fields surveyed (Int. Cl. 7 , DB G01W 1/00-1/18 G01N 27/00-27/24 G01V 3/00-3/40 B60S 1/00-1/68 JICST file (JOIS)
Claims (1)
と、この検知面に雨滴が付着したときに生じる静電容量
の変化により降雨検知信号を出力する制御回路とを備え
た静電容量型雨センサにおいて、 前記検知面を表面に形成した第１の回路基板の下方に、
発振回路を設けた制御回路を実装した第２の回路基板を
積層させた構造としており、 上記第１の回路基板の裏側には、アース接続された導電
シールドパターンを形成し、 上記櫛歯電極および上記導電シールドパターンと上記制
御回路とをスルーホールによって電気接続させた構造と
している静電容量型雨センサ。(57) [Claim 1] A rainfall detection signal is output by a detection surface formed by arranging comb-tooth electrodes facing each other and a change in capacitance caused when raindrops adhere to the detection surface. A capacitance type rain sensor provided with a control circuit to perform the detection, below the first circuit board having the detection surface formed on the surface thereof,
A second circuit board on which a control circuit provided with an oscillation circuit is mounted is laminated, and a conductive shield pattern connected to ground is formed on the back side of the first circuit board. A capacitance type rain sensor having a structure in which the conductive shield pattern and the control circuit are electrically connected by through holes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28304195A JP3453962B2 (en) | 1995-10-31 | 1995-10-31 | Capacitive rain sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28304195A JP3453962B2 (en) | 1995-10-31 | 1995-10-31 | Capacitive rain sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09127260A JPH09127260A (en) | 1997-05-16 |
| JP3453962B2 true JP3453962B2 (en) | 2003-10-06 |
Family
ID=17660454
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28304195A Expired - Fee Related JP3453962B2 (en) | 1995-10-31 | 1995-10-31 | Capacitive rain sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3453962B2 (en) |
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| JPH09127260A (en) | 1997-05-16 |
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