JP3978097B2 - Tilt detector - Google Patents

Description

式（１）におけるｄは、共通電極１６と対向電極１７，１８との間隔を表す。ε１は、液体１９の誘電率を表し、δ１は、液体１９の比誘電率を表し、δ２は、静電容量検出用粒子２０の比誘電率を表す。本実施の形態では、δ１＜δ２
である。
【００２０】
式（１）は以下のようにして導かれる。
図５（ａ）は、液体１９と静電容量検出用粒子２０とが混在している部分における簡略平断面図を示し、静電容量検出用粒子２０は、液体１９の中で最も密な面心立方構造の集合状態で存在しているものとする。図５（ｂ）は、図５（ａ）をコンデンサ構造と見なして考えた場合の断面図である。即ち、液体１９と静電容量検出用粒子２０とが混在している部分は、静電容量検出用粒子２０と同じ材質の誘電体２０Ａと、液体１９と同じ液体の誘電体１９Ａとが交互に並んだ直列コンデンサと見なすことができる。 図５（ｃ）は、図５（ｂ）における誘電体１９Ａを集めて隣り合わせに並べると共に、図５（ｂ）における誘電体２０Ａを集めて隣り合わせに並べた状態を示す。図５（ｂ）において交互に並んだ誘電体１９Ａの数と誘電体２０Ａの数とを無限大にしたとする。そうした場合、図５（ｃ）における対向電極１７，１８間の誘電体１９Ａの距離ｄ１と、図５（ｃ）における対向電極１７，１８間の誘電体２０Ａの距離ｄ２との比は、図５（ｃ）における誘電体１９Ａの体積と、図５（ｃ）における誘電体２０Ａの体積との比に相当すると考えられる。従って、距離ｄ１と距離ｄ２との比は、０．２６：０．７４となる。つまり、距離ｄ１，ｄ２と距離ｄとの間には次式（２），（３）が成り立つ。
【００２１】
ｄ１＝０．２６ｄ・・・（２）
ｄ２＝０．７４ｄ・・・（３）
共通電極１６の円形状の面積をＳとし、第１の対向電極１７及び第２の対向電極１８の半円形状の面積をそれぞれＳ／２とする。傾斜角度θが０°であるときの図６（ａ）の状態における共通電極１６と第１の対向電極１７との間の静電容量Ｃｏ１は、液体１９と静電容量検出用粒子２０とが混在している部分における静電容量Ｃ１１と、液体１９のみの部分におけるＣ１２との和である。静電容量Ｃ１１は、次式（４）で表され、静電容量Ｃ１２は、次式（５）で表される。
【００２２】
Ｃ１１＝（εｏ×Ｓ／４）／（ｄ１／δ１＋ｄ２／δ２）・・・（４）
Ｃ１２＝（ε１×Ｓ／４）／ｄ ・・・（５）
式（２）におけるεｏは、真空誘電率を表す。図６（ａ）の状態における共通電極１６と第１の対向電極１７との間の静電容量Ｃｏ１は、次式（６）のように静電容量Ｃ１１，Ｃ１２の和で表される。
【００２３】

式（６）は、次式（７）に変形できる。
【００２４】

δ１×εｏ＝ε１であるから、式（７）は、次式（８）に変形できる。
【００２５】

式（２），（３）を式（８）に代入すると、次式（９）が得られる。
【００２６】

傾斜角度θが０°であるときの共通電極１６と第２の対向電極１８との間の静電容量Ｃｏ２は、傾斜角度θが０°であるときの共通電極１６と第１の対向電極１７との間の静電容量Ｃｏ１_と同じ大きさである。
【００２７】
傾斜角度θが０°でないときの図６（ｂ）の状態における共通電極１６と第１の対向電極１７との間の静電容量Ｃｅ１は、液体１９と静電容量検出用粒子２０とが混在している部分における静電容量Ｃｅ11と、液体１９のみの部分におけるＣｅ12との和である。図６（ｂ）において液体１９と静電容量検出用粒子２０とが混在している部分に対応する第１の対向電極１７の面積Ｓ１１は、次式（１０）で表される。
【００２８】
Ｓ１１＝Ｓ／４＋（Ｓ／４）（θ／９０）・・・（１０）
図６（ｂ）において液体１９のみの部分に対応する第１の対向電極１７の面積Ｓ１２は、次式（１１）で表される。
【００２９】
Ｓ１２＝Ｓ／４−（Ｓ／４）（θ／９０）・・・（１１）
静電容量Ｃｅ11は、次式（１２）で表され、静電容量Ｃｅ12は、次式（１３）で表される。
【００３０】
Ｃｅ11＝（ε１×Ｓ１１）／（ｄ１＋ｄ２×δ１／δ２）・・・（１２）
Ｃｅ12＝（ε１×Ｓ１２）／ｄ ・・・（１３）
図６（ｂ）の状態における共通電極１６と第１の対向電極１７との間の静電容量Ｃｅ１は、次式（１４）のように静電容量Ｃｅ11，Ｃｅ12の和で表される。
【００３１】

式（１４）に式（１０），（１１）を代入すると、次式（１５）が得られる。
【００３２】

式（１５）は次式（１６）に変形できる。
【００３３】

式（８）及び式（１６）から次式（１７）が得られる。
【００３４】

式（２），（３）を式（１７）に代入すると、次式（１８）が得られる。
【００３５】

傾斜角度θが０°でないときの図６（ｃ）の状態における共通電極１６と第２の対向電極１８との間の静電容量Ｃｅ２は、液体１９と静電容量検出用粒子２０とが混在している部分における静電容量Ｃｅ21と、液体１９のみの部分におけるＣｅ22との和である。図６（ｂ），（ｃ）の状態における傾斜角度θは、同じ角度である。図６（ｃ）において液体１９と静電容量検出用粒子２０とが混在している部分に対応する第２の対向電極１８の面積Ｓ２１は、次式（１９）で表される。
【００３６】
Ｓ２１＝Ｓ／４−（Ｓ／４）（θ／９０）・・・（１９）
図６（ｃ）において液体１９のみの部分に対応する第２の対向電極１８の面積Ｓ２２は、次式（２０）で表される。
【００３７】
Ｓ２２＝Ｓ／４＋（Ｓ／４）（θ／９０）・・・（２０）
静電容量Ｃｅ21は、次式（２１）で表され、静電容量Ｃｅ22は、次式（２２）で表される。
【００３８】
Ｃｅ21＝（ε１×Ｓ２１）／（ｄ１＋ｄ２×δ１／δ２）・・・（２１）
Ｃｅ12＝（ε１×Ｓ２２）／ｄ ・・・（２２）
図６（ｃ）の状態における共通電極１６と第２の対向電極１８との間の静電容量Ｃｅ２は、次式（２３）のように静電容量Ｃｅ21，Ｃｅ22の和で表される。
【００３９】

式（２３）に式（１９），（２０）を代入すると、次式（２４）が得られる。
【００４０】

式（２４）は次式（２５）に変形できる。
【００４１】

式（８）及び式（２５）から次式（２６）が得られる。
【００４２】

式（２），（３）を式（２６）に代入すると、次式（２７）が得られる。
【００４３】

静電容量Ｃｅ１と静電容量Ｃｅ２との差ΔＣ＝（Ｃｅ１−Ｃｅ２）は、次式（２８）で表される。
【００４４】

面積Ｓ＝πＲ^２を式（２８）に代入すると、式（１）が得られる。傾斜角度θが０°のとき、ΔＣは零となる。つまり、検出された静電容量Ｃｅ１と検出された静電容量Ｃｅ２とが等しいとき（ΔＣが零のとき）には、算出される傾斜角度θは０°となる。傾斜角度θが０°ではないとき、ΔＣは零以外の値をとる。傾斜検出装置１１が図１（ｂ）の状態から図４の状態へと左側に傾いたとき（検出された静電容量Ｃｅ１が検出された静電容量Ｃｅ２よりも大きいとき）には、算出される傾斜角度θは正の値となる。傾斜検出装置１１が図１（ｂ）の状態から右側に傾いたとき（検出された静電容量Ｃｅ１が検出された静電容量Ｃｅ２よりも小さいとき）には、算出される傾斜角度θは負の値となる。
【００４５】
第１の実施の形態では、以下の効果が得られる。
（１）ケース１３内に液体のみを半分ほど入れた従来構成では、液体が表面張力によって液体の液面よりも上位位置における対向電極１７，１８及び共通電極１６の表面に付着する。そのため、ケース１３を小型にするほど、液体の液面よりも上位位置において対向電極１７，１８の表面及び共通電極１６の表面に表面張力によって付着している付着液体の割合（対向電極１７，１８と共通電極１６との間の液体の量に対する前記付着液体の割合）が多くなる。即ち、ケース１３を小型にするほど、ケース内における気体部分が液体の表面張力の影響によって気泡形状に近づいてゆく。前記した付着液体の割合が多くなるほど、対向電極１７，１８と共通電極１６との間の静電容量の検出値と、付着液体がない場合に予想される検出値との差の割合（予想される検出値に対する前記差の割合）が大きくなる。つまり、ケース１３内に液体のみを半分ほど入れた従来構成では、ケース１３を小型にするほど、検出精度が落ちる。これに対し、ケース１３内に液体１９を充填した構成では、ケース１３内に気体部分が存在しない。
【００４６】
液体１９内に静電容量検出用粒子２０を混入した構成では、共通電極１６と第１の対向電極１７との間の静電容量は、傾斜角度θに応じた共通電極１６と第１の対向電極１７との間の静電容量検出用粒子２０の数によって左右される。同様に、共通電極１６と第２の対向電極１８との間の静電容量は、傾斜角度θに応じた共通電極１６と第２の対向電極１８との間の静電容量検出用粒子２０の数によって左右される。ケース１３内に充填された液体１９内に混入している静電容量検出用粒子２０は、共通電極１６の表面や対向電極１７，１８の表面に付着してしまうことはない。つまり、傾斜角度θの変化に応じて静電容量検出用粒子２０の集合上面２０１が水平になるように静電容量検出用粒子２０が動く。
【００４７】
本実施の形態では、ケース１３内に気体部分が存在せず、静電容量検出用粒子２０が傾斜角度θの変化に応じて動く。そのため、ケース１３を従来よりも小型にした場合にも、傾斜角度θのときに検出された対向電極１７，１８と共通電極１６との間の静電容量は、傾斜角度θのときに予想される対向電極１７，１８と共通電極１６との間の静電容量に高い精度で一致する。従って、既存の傾斜検出装置に比べて傾斜検出装置１１の体積を例えば数十分の１から数百分の１の大きさに小さくした場合にも、式（１）を用いて算出される傾斜角度θは、実際の傾斜角度を高い精度で反映する。
【００４８】
（１−２）傾斜角度θが変化した場合、静電容量検出用粒子２０が安定状態（即ち、沈んで集合している静電容量検出用粒子２０の集合上面２０１が水平になっている状態）へ迅速に復帰することは、変化している傾斜角度θを正確に検出する上で重要である。静電容量検出用粒子２０の応答時間Ｔを次式（２９）で定義する。
【００４９】
Ｔ＝Ｒ／ｖ・・・（２９）
式（２９）におけるｖは、液体１９内における静電容量検出用粒子２０の沈降速度を表す。そうすると、応答時間Ｔは、次式（３０）によって算出できる。
【００５０】
Ｔ＝９μＲ／〔２ｒ^２（ｍ２−ｍ１）ｇ〕・・・（３０）
式（３０）におけるｒは、静電容量検出用粒子２０の半径を表し、μは、液体１９の粘性係数を表す。Ｍは、静電容量検出用粒子２０の体積を表し、ｍ１は、液体１９の密度を表し、ｍ２は、静電容量検出用粒子２０の密度を表す。ｇは、重力加速度である。
【００５１】
式（３０）は、次式（３１）の運動方程式から導かれる。
Ｍ×ｍ２×α＝−Ｍ×ｍ２×ｇ＋Ｍ×ｍ１×ｇ＋６πμｖｒ・・・（３１）
αは、静電容量検出用粒子２０の加速度を表す。式（３１）における（−Ｍ×ｍ２×ｇ）は、静電容量検出用粒子２０に作用する重力を表す。（Ｍ×ｍ１×ｇ）は、静電容量検出用粒子２０に作用する浮力を表す。６πμｖｒは、液体１９によって静電容量検出用粒子２０に作用する粘性抗力を表す。沈降速度ｖを一定値と仮定すると、式（３１）における加速度αは０となり、式（３１）は、次式（３２）となる。
【００５２】
０＝−Ｍ×ｍ２×ｇ＋Ｍ×ｍ１×ｇ＋６πμｖｒ・・・（３２）
式（３２）から次式（３３）が導かれる。
ｖ＝Ｍ（ｍ２−ｍ１）ｇ／（６πμｒ）・・・（３３）
球形の静電容量検出用粒子２０の体積Ｍは、４πｒ^３／３であるから、式（３３）は次式（３４）に変形できる。
【００５３】
ｖ＝（４πｒ^３／３）（ｍ２−ｍ１）ｇ／（６πμｒ）・・・（３３）
＝２ｒ^２（ｍ２−ｍ１）ｇ／（９μ）・・・（３４）
式（３４）を式（２９）に代入すると、式（３０）が得られる。応答時間Ｔは、静電容量検出用粒子２０が円形状の共通電極１６の半径Ｒだけ移動するのに要する時間である。つまり、静電容量検出用粒子２０が図７（ａ）の状態から図７（ｂ）の状態へ沈降する際に、速度ｖで移動する静電容量検出用粒子２０が全て沈んで集合するのに要する時間が応答時間Ｔとなる。応答時間Ｔが短いほど、傾斜角度θが変化した場合に静電容量検出用粒子２０が安定状態へ復帰する時間が短くなる。
【００５４】
式（３０）から明らかなように、粘性係数μが小さいほど応答時間Ｔが短くなり、静電容量検出用粒子２０の半径ｒが大きいほど応答時間Ｔが短くなる。又、液体１９の密度ｍ１と静電容量検出用粒子２０の密度ｍ２との差が大きいほど応答時間Ｔが短くなる。そこで、粘性係数μ及び密度ｍ１の小さい絶縁性の液体を適宜に選択すると共に、密度ｍ２の大きい静電容量検出用粒子を用い、静電容量検出用粒子２０の半径ｒを可及的に大きくすることによって応答時間Ｔを短くすることができる。
【００５５】
液体１９の材質がシリコーンオイル、静電容量検出用粒子２０の材質がジルコニアの場合、μ＝９．３５×１０^−３［Ｐａ・sec ］、ｍ１＝９３５［ｋｇ／ｍ^３］、ｍ２＝６５００［ｋｇ／ｍ^３］である。ｒ＝１００［μｍ］、Ｒ＝２［mm］とすると、応答時間Ｔは、０．１５［sec ］となる。この応答時間は、実用的に問題のない値であり、ジルコニアは、傾斜角度θの変化に伴う傾斜検出装置１１の応答性を高める上で、静電容量検出用粒子２０の材質として特に好適である。
【００５６】
（１−３）静電容量検出用粒子２０の形状を球形状とすれば、静電容量検出用粒子２０が液体１９に混入している部分での、静電容量検出用粒子２０の占有空間の大きさと、液体１９の占有空間の大きさとの比が常に一定となる。そのため、静電容量検出用粒子２０が沈んだ安定状態においては、式（１）は、静電容量と傾斜角度θとを常に高い精度で対応付ける。即ち、静電容量検出用粒子２０を球形状にする構成は、傾斜検出装置１１の検出精度を高める上で好適である。
【００５７】
（１−４）式（１）によれば、液体１９の比誘電率δ１と静電容量検出用粒子２０の比誘電率δ２との比が大きいほど、傾斜時に静電容量差ΔＣの変化量が大きくなる。傾斜時に静電容量差ΔＣの変化量が大きいほど、傾斜角度θの検出精度が高くなる。シリコーンオイルの比誘電率は２．２であり、ジルコニアの比誘電率は４６である。シリコーンオイルの比誘電率とジルコニアの比誘電率との比（４６／２．２）は大きいので、ジルコニアは、傾斜角度θの検出精度を高める上で、静電容量検出用粒子２０の材質として特に好適である。
【００５８】
本発明では以下のような実施の形態も可能である。
（１）前記した実施形態において、液体１９よりも密度の小さい静電容量検出用粒子２０を用いること。
【００５９】
この場合、傾斜検出装置１１が静止状態にあるときには、静電容量検出用粒子２０は、浮き上がって集合している。そして、この集合状態のときには、静電容量検出用粒子２０の集合下面が円形状の共通電極１６の円中心を通る直径線と一致するようにすれば、式（１）を用いて傾斜角度θを算出することができ、前記した実施形態と同じ効果が得られる。
【００６０】
（２）前記した実施形態において、第１の対向電極１７と第２の対向電極１８とのうちのいずれか一方のみを前記した実施形態の配置状態で第２の静電容量検出用電極として用いること。
【００６１】
この場合、検出された静電容量が静電容量Ｃｏ１のときには、式（９）を用いて傾斜角度θを算出するようにすればよい。検出された静電容量が静電容量Ｃｏ１よりも大きいときには、式（１８）を用いて傾斜角度θを算出するようにすればよい。検出された静電容量が静電容量Ｃｏ１よりも大きいときには、式（２７）を用いて傾斜角度θを算出するようにすればよい。
【００６２】
（３）前記の実施形態では、式（１）を理論的に導いて、傾斜角度θと静電容量とを対応させたが、傾斜角度θと静電容量との対応付けを実験的に求めてもよい。
【００６３】
一例として、傾斜角度θを例えば１°，２°，３°，４°，５°・・・のように１°間隔で変えて、そのときの傾斜角度θに対応する静電容量（Ｃｅ１，Ｃｅ２に相当）を実験で検出し、この実験で検出した静電容量に１°，２°，３°，４°，５°・・・の傾斜角度θを割り振ること。そして、ｎ°（ｎは、１，２，３，４，５・・・の整数）と（ｎ＋１）°との間の傾斜角度に対しては、例えば線形補間によって算出した静電容量を割り振ること。つまり、ｎ°と（ｎ＋１）°との間の傾斜角度（ｎ＋ρ）°（０＜ρ＜１）には、Ｃ（ｎ）＋〔Ｃ（ｎ＋１）−Ｃ（ｎ）〕×ρの静電容量が割り振られる。Ｃ（ｎ）は、ｎ°に対して割り振られた静電容量であり、Ｃ（ｎ＋１）は、（ｎ＋１）°に対して割り振られた静電容量である。
【００６４】
（４）静電容量検出用粒子の形状は、球形状に限らず、正六面体等の他の形状でもよい。あるいは粉砕して形成した粒子を静電容量検出用粒子として用いてもよい。粉砕粒子の場合には、式（１）に相当するような静電容量と傾斜角度θとを対応付ける理論式を導くことが難しい。前記（３）項のように、傾斜角度θと静電容量との対応付けを実験的に求めるのは、粉砕粒子を静電容量検出用粒子として用いる場合に好適である。
【００６５】
（５）中空の球形状粒子を静電容量検出用粒子として用いること。中空の球形状粒子の密度は、液体の密度よりも大きくても小さくてもよい。中空の球形状粒子の比誘電率は、液体の比誘電率よりも大きくても小さくてもよい。
【００６６】
（６）液体の比誘電率よりも小さい比誘電率を有する静電容量検出用粒子を用いること。
（７）前記した実施形態において、対向電極１７，１８と共通電極１６との間における静電容量検出用粒子の集合体積を対向電極１７，１８と共通電極１６との間の容積の半分よりも多く、あるいは少なくすること。
【００６７】
（８）静電容量検出用粒子２０の材質として、アルミナ（密度４．０［ｇ／cm^３］、比誘電率８．５）、ＳｉＣ（密度３．１６［ｇ／cm^３］、比誘電率９．７），ＳｉＮ（密度３．２［ｇ／cm^３］、比誘電率１１．７）、ＧａＡｓ（（密度５．３２［ｇ／cm^３］、比誘電率１０．９）等を用いること。
【００６８】
前記した実施の形態から把握できる発明について以下に記載する。
〔１〕請求項２において、前記共通電極と第１の対向電極との間における前記静電容量検出用粒子の集合体積と、前記共通電極と第２の対向電極との間における前記静電容量検出用粒子の集合体積との和は、前記共通電極と第１の対向電極の間の容積と、前記共通電極と第２の対向電極の間の容積との和の半分よりも少ない傾斜検出装置。
【００６９】
〔２〕請求項２において、前記共通電極と第１の対向電極との間における前記静電容量検出用粒子の集合体積と、前記共通電極と第２の対向電極との間における前記静電容量検出用粒子の集合体積との和は、前記共通電極と第１の対向電極の間の容積と、前記共通電極と第２の対向電極の間の容積との和の半分よりも多い傾斜検出装置。
【００７０】
〔３〕請求項２及び請求項３のいずれか１項において、前記共通電極と第１の対向電極との間の静電容量を検出する第１の静電容量検出手段と、前記共通電極と第２の対向電極との間の静電容量を検出する第２の静電容量検出手段とを備え、前記第１の静電容量検出手段によって検出された静電容量と、前記第２の静電容量検出手段によって検出された静電容量との差に基づいて傾斜角度を演算する傾斜角度演算手段を備えている傾斜検出装置。
【００７１】
〔４〕前記〔３〕項において、前記傾斜角度演算手段は、式（１）に基づいて傾斜角度を演算する傾斜検出装置。
〔５〕請求項１乃至請求項３、前記〔１〕項乃至〔４〕項のいずれか１項において、静電容量検出用粒子は、球形状である傾斜検出装置。
【００７２】
〔６〕請求項１乃至請求項３、前記〔１〕項乃至〔５〕項のいずれか１項において、前記静電容量検出用粒子の密度は、前記液体の密度よりも大きい傾斜検出装置。
【００７３】
〔７〕請求項１乃至請求項３、前記〔１〕項乃至〔５〕項のいずれか１項において、前記静電容量検出用粒子の密度は、前記液体の密度よりも小さい傾斜検出装置。
【００７４】
〔８〕請求項１乃至請求項３、前記〔１〕項乃至〔７〕項のいずれか１項において、前記静電容量検出用粒子の比誘電率は、前記液体の比誘電率よりも大きい傾斜検出装置。
【００７５】
〔９〕請求項１乃至請求項３、前記〔１〕項乃至〔７〕項のいずれか１項において、前記静電容量検出用粒子の比誘電率は、前記液体の比誘電率よりも小さい傾斜検出装置。
【００７６】
〔１０〕請求項１乃至請求項３、前記〔１〕項乃至〔９〕項のいずれか１項において、第１の静電容量検出用電極と第２の静電容量検出用電極とをケース内に収容し、前記ケース内に前記液体を充填した傾斜検出装置。
【００７７】
【発明の効果】
本発明では、互いに離間して対向する第１の静電容量検出用電極と第２の静電容量検出用電極との間に介在される液体に静電容量検出用粒子を混入したので、検出精度の低下をもたらすことなく傾斜検出装置の小型化を図ることができる。
【図面の簡単な説明】
【図１】一実施形態を示し、（ａ）は一部破断斜視図。（ｂ）は正断面図。
【図２】図１（ｂ）のＡ−Ａ線断面図。
【図３】ブロック図。
【図４】正断面図。
【図５】（ａ）は要部拡大平断面図。（ｂ）は模式図。（ｃ）は模式図。
【図６】（ａ），（ｂ），（ｃ）は、式（１）の導出を説明するための簡略図。
【図７】（ａ），（ｂ）は、応答時間を説明するための簡略図。
【符号の説明】
１１…傾斜検出装置。１３…ケース。１６…第１の静電容量検出用電極としての共通電極。１７…第２の静電容量検出用電極としての第１の対向電極。１８…第２の静電容量検出用電極としての第２の対向電極。１９…液体。２０…静電容量検出用粒子。θ…傾斜角度。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tilt detection apparatus.
[0002]
[Prior art]
As a device for detecting inclination, there is a capacitance detection type device that converts capacitance into an electric signal. As this type of tilt detection device, a device using a mechanical mechanism or a fluid mechanism as disclosed in JP-A-5-172571 is generally used.
[0003]
[Problems to be solved by the invention]
However, the volume of these devices is several cm ³ ~ Hundreds of centimeters ³ Degree. In an inclination detection device using a mechanical mechanism, if it is attempted to reduce the size, the influence of friction and wear increases, and the detection accuracy decreases. Therefore, it is difficult to reduce the size of the tilt detection device using a mechanical mechanism. In an inclination detection device using a fluid mechanism, if it is attempted to reduce the size, the influence of the surface tension of the fluid increases, and the detection accuracy decreases. Therefore, it is difficult to reduce the size of the tilt detection device using the fluid mechanism.
[0004]
It is an object of the present invention to reduce the size of an inclination detection device without causing a decrease in detection accuracy.
[0005]
[Means for Solving the Problems]
Contract In the invention of claim 1, A first capacitance detection electrode and a second capacitance detection electrode facing each other at a distance from each other are accommodated in a case, and are interposed between the pair of capacitance detection electrodes. The case was filled with a liquid, and capacitance detection particles were mixed in the liquid. An inclination detecting device is configured, and the density of the capacitance detection particles and the density of the liquid are made different, and the relative dielectric constant of the capacitance detection particles and the relative dielectric constant of the liquid are made different. The first static electricity depends on the number of the capacitance detection particles between the first capacitance detection electrode and the second capacitance detection electrode according to an inclination angle. The inclination angle is detected based on the capacitance between the capacitance detection electrode and the second capacitance detection electrode. It was.
[0006]
When the density of the capacitance detection particles is larger than the density of the liquid, the capacitance detection particles sink and gather. When the density of the capacitance detection particles is smaller than the density of the liquid, the capacitance detection particles are lifted and gathered. The capacitance between the first capacitance detection electrode and the second capacitance detection electrode is the first capacitance detection electrode and the second capacitance detection according to the inclination angle. Depends on the number of capacitance detection particles between the electrodes. The configuration using the liquid and the capacitance detection particles to detect the capacitance reduces the influence of the surface tension of the liquid accompanying the downsizing and prevents the detection accuracy from being lowered.
[0007]
If the conventional device using only liquid is reduced in size as it is, the capacitance will be reduced, and the detection signal obtained by the tilt detection device will be weakened. Therefore, it becomes necessary to redesign a signal processing circuit or the like for processing a detection signal obtained by the tilt detection device. If electrostatic capacity detection particles having a relative dielectric constant larger than that of the liquid are employed, an electrostatic capacity larger than that of a conventional apparatus using only the liquid can be obtained. Therefore, even when the tilt detection device is downsized so that the capacitance can be secured to the conventional level, the detection signal obtained by the tilt detection device can be secured at the same level as the conventional, and obtained by the tilt detection device. A conventional signal processing circuit or the like for processing the detected signal can be used as it is.
[0008]
According to a second aspect of the present invention, in the first aspect, the first capacitance detection electrode is a circular common electrode, and the second capacitance detection electrode is a semicircular region of the common electrode. And a semicircular first counter electrode facing the remaining semicircular region of the common electrode, and a semicircular second counter electrode facing the remaining semicircular region of the common electrode.
[0009]
The configuration in which the common electrode has a circular shape and the counter electrode that faces the common electrode has a semicircular shape facilitates the correspondence between the detected capacitance and the inclination angle.
According to a third aspect of the present invention, in the second aspect, an aggregate volume of the capacitance detection particles between the common electrode and the first counter electrode, and between the common electrode and the second counter electrode. The sum of the capacitance detection particles and the aggregate volume is the common electrode and the first volume. Opposite The volume between the electrodes, the common electrode and the second Opposite It was set to half the sum of the volume between the electrodes.
[0010]
Capacitance detection grain Of child Aggregate volume is a particle for capacitance detection Child Capacitance detection grains when they are settling down With child liquid Body and Mixed Have It is the volume of the part. Setting that the sum of the sets described above is half of the sum of the volumes described above makes it easier to associate the detected capacitance with the inclination angle.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
FIGS. 1A, 1B and 2 show an inclination detection device 11 for detecting an inclination angle. An insulative case 13 is attached to the front surface of the insulative flat plate base 12 constituting the inclination detecting device 11, and the upper portion of the case 13 is opened. To mouth The lid 14 is attached. The base 12, the case 13, and the lid 14 form a sealed chamber 15 between the base 12 and the case 13.
[0012]
A disc-shaped common electrode 16 is fixed to the inner surface of the case 13 facing the base 12. A predetermined potential is applied to the common electrode 16 as the first capacitance detection electrode.
[0013]
In the sealed chamber 15, a semicircular first counter electrode 17 and a semicircular second counter electrode 18 are fixed to the front surface of the base 12. The first counter electrode 17 and the second counter electrode 18 include a radial edge 171 that is a diameter line of the first counter electrode 17 and a radial line edge 181 that is a diameter line of the second counter electrode 18. It arrange | positions so that it may adjoin and be parallel without contacting. The first counter electrode 17 and the second counter electrode 18 are not electrically short-circuited in the case 13. The first counter electrode 17 and the second counter electrode 18 are second capacitance detection electrodes facing the common electrode 16.
[0014]
The first counter electrode 17 faces the semicircular region on the left side of the common electrode 16 in FIG. 1B in a parallel state, and the second counter electrode 18 is common in FIG. It faces the semicircular region on the right side of the electrode 16 in a parallel state. The first counter electrode 17 and the second counter electrode 18 have a circular shape having the same size as the common electrode 16. When viewed in a direction perpendicular to the common electrode 16, the first counter electrode 17 and the second counter electrode 18 are half of the counter electrodes 17, 18. The circumference of the arc overlaps with the circumference of the common electrode 16.
[0015]
The sealed chamber 15 is filled with an insulating liquid 19. In the present embodiment, the liquid 19 is silicone oil. Insulating capacitance detection particles 20 are mixed in the liquid 19. In the present embodiment, the capacitance detection particles 20 are spherical. The electrostatic capacity detection particles 20 are made of zirconia. The density of the capacitance detection particles 20 is larger than the density of the liquid 19, and the relative dielectric constant of the capacitance detection particles 20 is larger than the relative dielectric constant of the liquid 19. When the tilt detection device 11 is in a stationary state, the capacitance detection particles 20 are sunk and gathered as shown in FIGS. In this aggregated state, the aggregated upper surface 201 (shown in FIG. 1B) of the capacitance detection particles 20 coincides with the diameter line passing through the circle center of the circular common electrode 16.
[0016]
In the present invention, the capacitance detection particles 20 and the liquid 19 when the capacitance detection particles 20 are gathered by sinking are mixed. Have The volume of the part is referred to as an aggregate volume of the capacitance detection particles 20. In the present embodiment, the collective volume is half of the sum of the volume V1 between the common electrode 16 and the first counter electrode 17 and the volume V2 between the common electrode 16 and the second counter electrode 18. is there. The volumes V1 and V2 are both represented by πR2d / 2. R represents the radius of the circular common electrode 16. d represents the distance between the common electrode 16 and the counter electrodes 17, 18.
[0017]
FIG. 3 shows an electrical block diagram of the tilt detection device 11. The first capacitance detection means 21 includes the common electrode 16 and the first counter electrode 17, and the second capacitance detection means 22 includes the common electrode 16 and the second counter electrode 18. Contains. The first capacitance detection means 21 detects the capacitance between the common electrode 16 and the first counter electrode 17. The second capacitance detection means 22 detects the capacitance between the common electrode 16 and the second counter electrode 18.
[0018]
The difference calculation means 23 calculates the difference ΔC between the capacitance C1 obtained by the first capacitance detection means 21 and the capacitance C2 obtained by the second capacitance detection means 22. The difference calculation means 23 outputs the calculated capacitance difference ΔC to the tilt angle calculation means 24. The tilt angle calculation means 24 calculates the tilt angle θ (shown in FIG. 4) of the base 12 based on the capacitance difference ΔC.
[0019]
The tilt angle calculation means 24 calculates the tilt angle θ using the following equation (1).

In Expression (1), d represents the distance between the common electrode 16 and the counter electrodes 17 and 18. ε1 represents the dielectric constant of the liquid 19, δ1 represents the relative dielectric constant of the liquid 19, and δ2 represents the relative dielectric constant of the capacitance detection particle 20. In the present embodiment, δ1 <δ2
It is.
[0020]
Equation (1) is derived as follows.
FIG. 5A shows a simplified cross-sectional view of a portion where the liquid 19 and the capacitance detection particles 20 are mixed. The capacitance detection particles 20 are the most dense surface in the liquid 19. It is assumed that it exists in a collective state of a centered cubic structure. FIG. 5B is a cross-sectional view of the case where FIG. 5A is considered as a capacitor structure. That is, in the portion where the liquid 19 and the capacitance detection particle 20 are mixed, the dielectric 20A made of the same material as the capacitance detection particle 20 and the dielectric 19A made of the same liquid as the liquid 19 are alternately arranged. It can be considered as a series capacitor. FIG. 5C shows a state in which the dielectrics 19A in FIG. 5B are collected and arranged side by side, and the dielectrics 20A in FIG. 5B are collected and arranged side by side. Assume that the number of dielectrics 19A and the number of dielectrics 20A arranged alternately in FIG. In such a case, the ratio between the distance d1 of the dielectric 19A between the counter electrodes 17 and 18 in FIG. 5C and the distance d2 of the dielectric 20A between the counter electrodes 17 and 18 in FIG. This is considered to correspond to the ratio of the volume of the dielectric 19A in (c) to the volume of the dielectric 20A in FIG. 5 (c). Therefore, the ratio between the distance d1 and the distance d2 is 0.26: 0.74. That is, the following expressions (2) and (3) are established between the distances d1 and d2 and the distance d.
[0021]
d1 = 0.26d (2)
d2 = 0.74d (3)
The circular area of the common electrode 16 is S, and the semicircular areas of the first counter electrode 17 and the second counter electrode 18 are S / 2. The electrostatic capacitance Co1 between the common electrode 16 and the first counter electrode 17 in the state of FIG. 6A when the inclination angle θ is 0 ° is that the liquid 19 and the electrostatic capacitance detection particles 20 are the same. This is the sum of the capacitance C11 in the mixed portion and C12 in the portion of the liquid 19 only. The capacitance C11 is expressed by the following equation (4), and the capacitance C12 is expressed by the following equation (5).
[0022]
C11 = (εo × S / 4) / (d1 / δ1 + d2 / δ2) (4)
C12 = (ε1 × S / 4) / d (5)
In the equation (2), εo represents a vacuum dielectric constant. Capacitance Co1 between the common electrode 16 and the first counter electrode 17 in the state of FIG. 6A is represented by the sum of the capacitances C11 and C12 as in the following equation (6).
[0023]

Equation (6) can be transformed into the following equation (7).
[0024]

Since δ1 × εo = ε1, Equation (7) can be transformed into the following Equation (8).
[0025]

Substituting equations (2) and (3) into equation (8) yields the following equation (9).
[0026]

The capacitance Co2 between the common electrode 16 and the second counter electrode 18 when the tilt angle θ is 0 ° is equal to the capacitance Co2 between the common electrode 16 and the first counter electrode 17 when the tilt angle θ is 0 °. Capacitance Co1 between _When It is the same size.
[0027]
The electrostatic capacitance Ce1 between the common electrode 16 and the first counter electrode 17 in the state of FIG. 6B when the inclination angle θ is not 0 ° is a mixture of the liquid 19 and the electrostatic capacitance detection particles 20. This is the sum of the capacitance Ce11 at the portion where the liquid is applied and Ce12 at the portion where only the liquid 19 is present. In FIG. 6B, the area S11 of the first counter electrode 17 corresponding to the portion where the liquid 19 and the capacitance detection particles 20 are mixed is expressed by the following equation (10).
[0028]
S11 = S / 4 + (S / 4) (θ / 90) (10)
In FIG. 6B, the area S12 of the first counter electrode 17 corresponding to only the liquid 19 is represented by the following equation (11).
[0029]
S12 = S / 4- (S / 4) (θ / 90) (11)
The capacitance Ce11 is represented by the following equation (12), and the capacitance Ce12 is represented by the following equation (13).
[0030]
Ce11 = (ε1 × S11) / (d1 + d2 × δ1 / δ2) (12)
Ce12 = (ε1 × S12) / d (13)
The electrostatic capacitance Ce1 between the common electrode 16 and the first counter electrode 17 in the state of FIG. 6B is represented by the sum of the electrostatic capacitances Ce11 and Ce12 as shown in the following equation (14).
[0031]

Substituting the formulas (10) and (11) into the formula (14), the following formula (15) is obtained.
[0032]

Equation (15) can be transformed into the following equation (16).
[0033]

The following equation (17) is obtained from the equations (8) and (16).
[0034]

Substituting equations (2) and (3) into equation (17) yields the following equation (18).
[0035]

The capacitance Ce2 between the common electrode 16 and the second counter electrode 18 in the state of FIG. 6C when the inclination angle θ is not 0 ° is a mixture of the liquid 19 and the capacitance detection particles 20. This is the sum of the capacitance Ce21 in the portion where the liquid is applied and Ce22 in the portion where only the liquid 19 is present. The inclination angle θ in the states of FIGS. 6B and 6C is the same angle. In FIG. 6C, the area S21 of the second counter electrode 18 corresponding to the portion where the liquid 19 and the capacitance detection particles 20 are mixed is expressed by the following equation (19).
[0036]
S21 = S / 4- (S / 4) (θ / 90) (19)
In FIG. 6C, the area S22 of the second counter electrode 18 corresponding to only the liquid 19 is expressed by the following equation (20).
[0037]
S22 = S / 4 + (S / 4) (θ / 90) (20)
The electrostatic capacity Ce21 is represented by the following expression (21), and the electrostatic capacity Ce22 is represented by the following expression (22).
[0038]
Ce21 = (ε1 × S21) / (d1 + d2 × δ1 / δ2) (21)
Ce12 = (ε1 × S22) / d (22)
The electrostatic capacitance Ce2 between the common electrode 16 and the second counter electrode 18 in the state of FIG. 6C is expressed by the sum of the electrostatic capacitances Ce21 and Ce22 as in the following equation (23).
[0039]

Substituting the equations (19) and (20) into the equation (23), the following equation (24) is obtained.
[0040]

Expression (24) can be transformed into the following expression (25).
[0041]

The following equation (26) is obtained from the equations (8) and (25).
[0042]

Substituting equations (2) and (3) into equation (26) yields the following equation (27).
[0043]

A difference ΔC = (Ce1−Ce2) between the electrostatic capacitance Ce1 and the electrostatic capacitance Ce2 is expressed by the following equation (28).
[0044]

Area S = πR ² Is substituted into equation (28), equation (1) is obtained. When the inclination angle θ is 0 °, ΔC is zero. That is, when the detected capacitance Ce1 is equal to the detected capacitance Ce2 (when ΔC is zero), the calculated inclination angle θ is 0 °. When the inclination angle θ is not 0 °, ΔC takes a value other than zero. When the tilt detection device 11 tilts to the left from the state of FIG. 1B to the state of FIG. 4 (when the detected capacitance Ce1 is larger than the detected capacitance Ce2), it is calculated. The inclination angle θ is a positive value. When the tilt detector 11 tilts to the right from the state of FIG. 1B (when the detected capacitance Ce1 is smaller than the detected capacitance Ce2), the calculated tilt angle θ is negative. It becomes the value of.
[0045]
In the first embodiment, the following effects can be obtained.
(1) In the conventional configuration in which only about half of the liquid is placed in the case 13, the liquid adheres to the surfaces of the counter electrodes 17, 18 and the common electrode 16 at a position higher than the liquid level of the liquid due to surface tension. Therefore, as the case 13 is made smaller, the ratio of the adhering liquid adhering to the surface of the counter electrodes 17 and 18 and the surface of the common electrode 16 due to surface tension at a position higher than the liquid level (the counter electrodes 17 and 18 The ratio of the attached liquid to the amount of liquid between the common electrode 16 and the common electrode 16 increases. That is, the smaller the case 13 is, the closer the gas portion in the case becomes to the bubble shape due to the influence of the surface tension of the liquid. As the ratio of the adhering liquid increases, the ratio of the difference between the detection value of the capacitance between the counter electrodes 17 and 18 and the common electrode 16 and the detection value expected when there is no adhering liquid (expected) (The ratio of the difference to the detected value) increases. That is, in the conventional configuration in which only about half of the liquid is placed in the case 13, the detection accuracy decreases as the case 13 becomes smaller. On the other hand, in the configuration in which the liquid 19 is filled in the case 13, there is no gas portion in the case 13.
[0046]
In the configuration in which the capacitance detection particles 20 are mixed in the liquid 19, the capacitance between the common electrode 16 and the first counter electrode 17 is equal to the common electrode 16 corresponding to the inclination angle θ. It depends on the number of capacitance detection particles 20 between the electrodes 17. Similarly, the capacitance between the common electrode 16 and the second counter electrode 18 is the capacitance of the capacitance detection particles 20 between the common electrode 16 and the second counter electrode 18 according to the inclination angle θ. It depends on the number. The capacitance detection particles 20 mixed in the liquid 19 filled in the case 13 do not adhere to the surface of the common electrode 16 or the surfaces of the counter electrodes 17 and 18. That is, the capacitance detection particles 20 move so that the aggregate upper surface 201 of the capacitance detection particles 20 becomes horizontal according to the change in the inclination angle θ.
[0047]
In the present embodiment, there is no gas portion in the case 13, and the capacitance detection particles 20 move according to the change in the tilt angle θ. Therefore, even when the case 13 is made smaller than the conventional case, the capacitance between the counter electrodes 17 and 18 and the common electrode 16 detected at the inclination angle θ is expected at the inclination angle θ. The capacitance between the counter electrodes 17 and 18 and the common electrode 16 coincides with high accuracy. Therefore, even when the volume of the tilt detection device 11 is reduced from, for example, several tenths to one hundredth, compared with the existing tilt detection device, the tilt calculated using the equation (1) The angle θ reflects the actual inclination angle with high accuracy.
[0048]
(1-2) When the inclination angle θ is changed, the capacitance detection particles 20 are in a stable state (that is, a state where the aggregate upper surface 201 of the capacitance detection particles 20 aggregated by sinking is horizontal). The quick return to () is important in accurately detecting the changing inclination angle θ. The response time T of the capacitance detection particles 20 is defined by the following equation (29).
[0049]
T = R / v (29)
V in the equation (29) represents the sedimentation speed of the capacitance detection particles 20 in the liquid 19. Then, the response time T can be calculated by the following equation (30).
[0050]
T = 9 μR / [2r ² (M2-m1) g] ... (30)
In Expression (30), r represents the radius of the capacitance detection particle 20, and μ represents the viscosity coefficient of the liquid 19. M represents the volume of the capacitance detection particles 20, m 1 represents the density of the liquid 19, and m 2 represents the density of the capacitance detection particles 20. g is a gravitational acceleration.
[0051]
Equation (30) is derived from the equation of motion of the following equation (31).
M × m2 × α = −M × m2 × g + M × m1 × g + 6πμvr (31)
α represents the acceleration of the capacitance detection particle 20. (−M × m2 × g) in the equation (31) represents the gravity acting on the capacitance detection particle 20. (M × m1 × g) represents buoyancy acting on the capacitance detection particles 20. 6πμvr represents a viscous drag acting on the capacitance detection particle 20 by the liquid 19. Assuming that the settling velocity v is a constant value, the acceleration α in the equation (31) is 0, and the equation (31) becomes the following equation (32).
[0052]
0 = −M × m 2 × g + M × m 1 × g + 6π μvr (32)
The following equation (33) is derived from the equation (32).
v = M (m2−m1) g / (6πμr) (33)
The volume M of the spherical capacitance detection particle 20 is 4πr. ³ Therefore, the expression (33) can be transformed into the following expression (34).
[0053]
v = (4πr ³ / 3) (m2-m1) g / (6πμr) (33)
= 2r ² (M2-m1) g / (9μ) (34)
Substituting equation (34) into equation (29) yields equation (30). The response time T is the time required for the capacitance detection particles 20 to move by the radius R of the circular common electrode 16. That is, when the capacitance detection particles 20 settle from the state of FIG. 7A to the state of FIG. 7B, all of the capacitance detection particles 20 moving at the speed v sink and gather. The time required for is the response time T. The shorter the response time T, the shorter the time for the capacitance detection particles 20 to return to a stable state when the tilt angle θ changes.
[0054]
As is clear from the equation (30), the smaller the viscosity coefficient μ, the shorter the response time T, and the radius r of the capacitance detection particle 20 becomes smaller. large The response time T becomes shorter as the time elapses. In addition, the response time T becomes shorter as the difference between the density m1 of the liquid 19 and the density m2 of the capacitance detection particles 20 is larger. Accordingly, an insulating liquid having a small viscosity coefficient μ and a density m1 is appropriately selected, and the capacitance detection particle 20 having a large density m2 is used to increase the radius r of the capacitance detection particle 20 as much as possible. By doing so, the response time T can be shortened.
[0055]
When the material of the liquid 19 is silicone oil and the material of the capacitance detection particles 20 is zirconia, μ = 9.35 × 10. ^-3 [Pa · sec], m1 = 935 [kg / m ³ ], M2 = 6500 [kg / m ³ ]. When r = 100 [μm] and R = 2 [mm], the response time T is 0.15 [sec]. This response time is a value that causes no problem in practice, and zirconia is particularly suitable as a material for the capacitance detection particles 20 in order to improve the response of the tilt detection device 11 in accordance with a change in the tilt angle θ. is there.
[0056]
(1-3) If the capacitance detection particles 20 have a spherical shape, the occupied space of the capacitance detection particles 20 in the portion where the capacitance detection particles 20 are mixed in the liquid 19. And the ratio of the occupied space of the liquid 19 are always constant. Therefore, in the stable state in which the capacitance detection particles 20 are sunk, Equation (1) always associates the capacitance with the inclination angle θ with high accuracy. That is, the configuration in which the capacitance detection particles 20 are spherical is suitable for increasing the detection accuracy of the inclination detection device 11.
[0057]
(1-4) According to the equation (1), the larger the ratio between the relative permittivity δ1 of the liquid 19 and the relative permittivity δ2 of the capacitance detection particles 20, the more the change in the capacitance difference ΔC during tilting. Becomes larger. The greater the amount of change in the capacitance difference ΔC during tilting, the higher the detection accuracy of the tilt angle θ. The relative dielectric constant of silicone oil is 2.2, and the relative dielectric constant of zirconia is 46. Since the ratio (46 / 2.2) between the relative permittivity of silicone oil and the relative permittivity of zirconia is large, zirconia is used as a material for the capacitance detection particles 20 in order to improve the detection accuracy of the inclination angle θ. Particularly preferred.
[0058]
In the present invention, the following embodiments are also possible.
(1) In the above-described embodiment, the capacitance detection particles 20 having a density lower than that of the liquid 19 are used.
[0059]
In this case, when the tilt detection device 11 is in a stationary state, the capacitance detection particles 20 are lifted and gathered. In this aggregate state, if the aggregate lower surface of the capacitance detection particles 20 is made to coincide with the diameter line passing through the circle center of the circular common electrode 16, the inclination angle θ can be calculated using the equation (1). Can be calculated, and the same effect as the above-described embodiment can be obtained.
[0060]
(2) In the above-described embodiment, only one of the first counter electrode 17 and the second counter electrode 18 is used as the second capacitance detection electrode in the arrangement state of the above-described embodiment. thing.
[0061]
In this case, when the detected capacitance is the capacitance Co1, the inclination angle θ may be calculated using the equation (9). When the detected capacitance is larger than the capacitance Co1, the inclination angle θ may be calculated using the equation (18). When the detected capacitance is larger than the capacitance Co1, the inclination angle θ may be calculated using the equation (27).
[0062]
(3) In the above embodiment, Equation (1) is theoretically derived to associate the inclination angle θ with the capacitance. However, the correspondence between the inclination angle θ and the capacitance is obtained experimentally. May be.
[0063]
As an example, the inclination angle θ is changed at intervals of 1 ° such as 1 °, 2 °, 3 °, 4 °, 5 °,..., And the capacitance (Ce1, (Corresponding to Ce2) is detected by experiment, and an inclination angle θ of 1 °, 2 °, 3 °, 4 °, 5 °... Is assigned to the capacitance detected in this experiment. Then, for an inclination angle between n ° (n is an integer of 1, 2, 3, 4, 5,...) And (n + 1) °, for example, a capacitance calculated by linear interpolation is allocated. thing. That is, at an inclination angle (n + ρ) ° (0 <ρ <1) between n ° and (n + 1) °, the electrostatic capacity of C (n) + [C (n + 1) −C (n)] × ρ Capacity is allocated. C (n) is the capacitance allocated for n °, and C (n + 1) is the capacitance allocated for (n + 1) °.
[0064]
(4) The shape of the capacitance detection particles is not limited to a spherical shape, but may be other shapes such as a regular hexahedron. Alternatively, particles formed by pulverization may be used as capacitance detection particles. In the case of pulverized particles, it is difficult to derive a theoretical formula that correlates the capacitance and the inclination angle θ corresponding to the formula (1). As described in the above item (3), it is preferable to experimentally obtain the correspondence between the inclination angle θ and the capacitance when the pulverized particles are used as the capacitance detection particles.
[0065]
(5) Use hollow spherical particles as capacitance detection particles. The density of the hollow spherical particles may be larger or smaller than the density of the liquid. The relative permittivity of the hollow spherical particles may be larger or smaller than the relative permittivity of the liquid.
[0066]
(6) Capacitance detection particles having a relative dielectric constant smaller than that of the liquid are used.
(7) In the above-described embodiment, the aggregate volume of the capacitance detection particles between the counter electrodes 17 and 18 and the common electrode 16 is more than half the volume between the counter electrodes 17 and 18 and the common electrode 16. More or less.
[0067]
(8) Alumina (density 4.0 [g / cm ³ ], Relative dielectric constant 8.5), SiC (density 3.16 [g / cm ³ ], Relative dielectric constant 9.7), SiN (density 3.2 [g / cm ³ ], Relative permittivity 11.7), GaAs ((density 5.32 [g / cm ³ ], Dielectric constant 10.9) and the like.
[0068]
The invention that can be understood from the above-described embodiment will be described below.
[1] In Claim 2, an aggregate volume of the capacitance detection particles between the common electrode and the first counter electrode, and the capacitance between the common electrode and the second counter electrode Inclination detection device in which the sum of the volume of particles for detection is less than half of the sum of the volume between the common electrode and the first counter electrode and the volume between the common electrode and the second counter electrode .
[0069]
[2] In Claim 2, the aggregate volume of the capacitance detection particles between the common electrode and the first counter electrode, and the capacitance between the common electrode and the second counter electrode The sum of the detection particle aggregate volume is more than half of the sum of the volume between the common electrode and the first counter electrode and the volume between the common electrode and the second counter electrode. .
[0070]
[3] In any one of claims 2 and 3, the first capacitance detecting means for detecting the capacitance between the common electrode and the first counter electrode, the common electrode, A second capacitance detection means for detecting a capacitance between the second counter electrode and the second counter electrode, the capacitance detected by the first capacitance detection means, and the second electrostatic detection. An inclination detecting device comprising an inclination angle calculating means for calculating an inclination angle based on a difference from the capacitance detected by the capacitance detecting means.
[0071]
[4] In the above [3], the tilt angle calculating means calculates the tilt angle based on the formula (1).
[5] The tilt detection device according to any one of [1] to [3] and [1] to [4], wherein the capacitance detection particles have a spherical shape.
[0072]
[6] The inclination detection device according to any one of [1] to [3] and [1] to [5], wherein the density of the capacitance detection particles is larger than the density of the liquid.
[0073]
[7] The inclination detection device according to any one of [1] to [3] and [1] to [5], wherein the density of the capacitance detection particles is smaller than the density of the liquid.
[0074]
[8] In any one of [1] to [3] and [1] to [7], a specific dielectric constant of the capacitance detection particles is larger than a specific dielectric constant of the liquid. Tilt detection device.
[0075]
[9] In any one of [1] to [3] and [1] to [7], a relative dielectric constant of the capacitance detection particle is smaller than a relative dielectric constant of the liquid. Tilt detection device.
[0076]
[10] In any one of [1] to [3] and [1] to [9], the first capacitance detection electrode and the second capacitance detection electrode may be provided as a case. An inclination detecting device housed in the case and filled with the liquid in the case.
[0077]
【The invention's effect】
In the present invention, since the capacitance detection particles are mixed in the liquid interposed between the first capacitance detection electrode and the second capacitance detection electrode facing each other apart from each other, It is possible to reduce the size of the tilt detection device without causing a decrease in accuracy.
[Brief description of the drawings]
FIG. 1 shows an embodiment, and (a) is a partially broken perspective view. (B) is a front sectional view.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a block diagram.
FIG. 4 is a front sectional view.
FIG. 5A is an enlarged plan sectional view of a main part. (B) is a schematic diagram. (C) is a schematic diagram.
6A, 6B, and 6C are simplified diagrams for explaining the derivation of Equation (1).
FIGS. 7A and 7B are simplified diagrams for explaining the response time. FIGS.
[Explanation of symbols]
11: Tilt detection device. 13 ... Case. 16: Common electrode as a first capacitance detection electrode. 17: A first counter electrode as a second capacitance detection electrode. 18 ... A second counter electrode as a second capacitance detection electrode. 19 ... Liquid. 20: Particles for capacitance detection. θ: Inclination angle.

Claims (3)

A first capacitance detection electrode and a second capacitance detection electrode facing each other at a distance from each other are accommodated in the case, and are interposed between the pair of capacitance detection electrodes. A tilt detection device in which a liquid is filled in the case, and capacitance detection particles are mixed in the liquid ,
Differentiating the density of the capacitance detection particles and the density of the liquid, differentiating the relative permittivity of the capacitance detection particles and the relative permittivity of the liquid ,
The first electrostatic capacitance that depends on the number of the electrostatic capacitance detection particles between the first electrostatic capacitance detection electrode and the second electrostatic capacitance detection electrode according to an inclination angle. A tilt detection device that detects a tilt angle based on a capacitance between a capacitance detection electrode and the second capacitance detection electrode . The first capacitance detection electrode is a circular common electrode, and the second capacitance detection electrode is a semicircular first opposed to a semicircular region of the common electrode. The inclination detecting device according to claim 1, which is an electrode and a semicircular second counter electrode facing the remaining semicircular region of the common electrode. An aggregate volume of the capacitance detection particles between the common electrode and the first counter electrode, and an aggregate volume of the capacitance detection particles between the common electrode and the second counter electrode The inclination detection device according to claim 2, wherein the sum is half of the sum of the volume between the common electrode and the first counter electrode and the volume between the common electrode and the second counter electrode.

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