JPWO2002071041A1 - Deposit detection device and control device using the same - Google Patents

Abstract

Provided is an attached object detection device and a control device that can evaluate and detect distortion or obstruction of a field of view caused by an attached object on a detection surface. The detection surface 110 is provided on the transparent substrate 100. A reference pattern 200 having a fixed pattern is provided between the light source 10 and the detection surface 110. When light is emitted from the light source 10 to the detection surface 110, the irradiation light passes through the detection surface 110 and is received via the lens 40 by the light receiving element unit 50 in which the light receiving elements are arranged. Here, the focus on the incident side of the lens 40 is focused on the reference pattern 200, and the focus on the emission side is focused on the light receiving element 50, and a clear pattern image is obtained in the light receiving element section 50. The light detection signals are arranged in accordance with the arrangement of the light receiving elements to generate a signal pattern. If there is a distortion in the signal pattern, it is presumed that an adhering substance exists on the detection surface 110.

Description

ここで、図８（ｃ）のように雨滴１３０がない場合の外界の媒質、つまり、空気の屈折率としてｎ_１が１となり、ウィンドシールド１００の屈折率ｎ_２の例として約１．５１とすると（数１）より、４１．４７°＜θ_１となる。さらに、図８（ｂ）のように雨滴１３０付着の場合は、水の屈折率が約１．３３であるので、θ_１＜６１．７４°であれば良いこととなる。つまり、検知面１１０において（数１）で示した全反射条件の満足・不満足が切り換わる光入射角度θ_１は、４１．４７°＜θ_１＜６１．７４°の範囲で選ばれる。これら条件を満たす要素の配置および取り付け角度の例としてこの例では、光源１０からの照射光の検知面１１０への入射角度および反射角度を４７°となるように調整する。
次に、各要素を詳しく説明する。
光源１０は、複数のＬＥＤなどの光源を一端または両端など端部に持ち、線状に設けられている開口部から光を取り出すものであり、線状の開口部から光線が取り出される。光源１０は、光線が検知面１１０に対して所定角度で入射するような位置および角度で配置されている。なお、開口部には図７に示したような基準パターン２００を持つ。
図９（ａ）は光源１０の端面を表し、図９（ｂ）は開口部１４が見える面を正面から様子を示している。なお、開口部１４には基準パターン２００の図示を省略した。光源１０は例えば複数の微小光源を端部に設け、線状に設けられている開口部１４から取り出すものであり、線状の開口部１４から光１５として出射される。図９（ａ）において、１１が光源としてのＬＥＤ、１２が透光性材料よりなる導光体、１３が光を遮蔽するカバー、１４がＬＥＤ光を取り出す開口部、１５がＬＥＤ１１から出射された光線である。なお、ＬＥＤ１１は図９（ｂ）の左右の一端または両端部に設け、カバー１３の内面における反射を繰り返して開口部１４の各部分に導く構成である。また、ＬＥＤは導光体１２の開口部１４に対向する面に等間隔で配置しても良い。
図９（ｂ）の開口部１４から取り出された光はプリズム２０に入射する。
プリズム２０は、光源１０とウィンドシールド１００の両者を光学的にコンタクトさせる媒体となるプリズムであり、光源１０から照射された光をウィンドシールド１００内に導く働きをする。
検知面１１０は透明性基板１００の表面に設けられ、光源１０からの照射光が反射する面となっている。
次に、結像レンズ４０を説明する。結像レンズ４０は基準パターン２００の像を受光素子部５０の微小受光素子上に結像させる。結像レンズ４０と受光素子部５０は、基準パターン２００の像が受光素子部５０上で結像するように角度と距離が調整されている。図８に示すように、レンズ４０の入射側の焦点は光源１０の光発射口にある基準パターン２００に合わされており、検知面１１０に合わされてはいない。レンズ４０の出射側の焦点は受光素子部５０に合わされている。この構成により、受光素子部５０には基準パターン２００の像が明瞭に結像されることとなる。図１０は、結像レンズ４０の一例を模式的に示した図である。図１０の例は、等倍結像系の屈折率分布型レンズアレイの一種である、ＳＬＡ^（Ｒ）（Ｓｅｌｆｏｃ Ｌｅｎｓｅ Ａｒｒａｙ）の簡単な構成図である。４１が微小レンズとしてのロッドレンズ、４２黒色樹脂、４３がＦＲＰ板である。ロッドレンズ４１は棒状のものであり、図１０ではそのレンズ面が見えている。また、図８の構成図はこのロッドレンズ４１一つのみの側断面を示している。このＳＬＡを用いれば、入射された光線を屈曲させて所定位置に正立等倍の像を結像させることができる。つまり、ゼブラパターン等の基準パターン２００と受光面が結像関係にあり、基準パターン２００の像をそのまま受光素子上に結像させることができる。上記例は、ロッドレンズ４１が直線状に配置されたものであるが、光源１０から取り出す光線の並び、後述する受光素子部５０の各受光素子の配置に応じたレンズ配置とする。なお、上記説明は、等倍結像系の例であるが、受光素子部５０の微小受光素子であるそれぞれの受光素子受光面と基準パターンとが結像光学系を形成するものであれば良い。
受光手段である受光素子部５０は、照射光量に応じて光検出信号を出力する受光素子を備えているもので、レンズ４０と受光素子部５０の受光素子は、レンズ４０に入射した光が受光素子部５０の受光素子上で結像するように角度と距離が調整されている。この例では、受光素子は、図１１に示すように、直線状に配置した構成となっているものとする。なお、受光素子一つ当たりの大きさは基準パターン２００のゼブラパターンのピッチよりも細かいものであることが好ましい。必要な解像度をもってゼブラパターンの歪みを検出するためである。受光素子部５０は、全反射用光源１０からの照射光の検知面１１０への入射角度および反射角度に合わせて透明性基板１００に対して４７°の角度で配置する。５１は各受光素子であり受光面を概念的に示したものである。なお、受光素子５１内部のキャパシタやトランジスタ回路、センスアンプ回路などは図示を省略し、受光素子５１の受光面が直線状に配置されていることが分かる図とした。
次に、基準パターン２００を説明する。基準パターン２００の位置は、光源１０と検知面１１０の間に設けられていれば良い。従って基準パターン２００の位置は様々なパターンが有り得る。実施形態１の図１に示したような位置関係、本実施形態１の図６に示したような位置関係、さらに、光源１０がその光発射口において基準パターンを備えている実施形態１の図７の構成も可能である。本実施形態２では光源１０がその光発射口において基準パターンを備えている実施形態１の図７の構成とする。
付着物推定部６０は、受光素子部５０からの光検出信号を受け、光検出信号を解析することにより、各受光素子が受光した光検出信号を解析して基準パターンの像に歪みがあるか否かを検出し、検知面上での付着物の存在を推定する部分である。この実施形態２では付着物推定部６０は、信号パターン歪み検出部６１を備えている。
信号パターン歪み検出部６１は、受光素子部５０が受光した基準パターン２００の信号パターンを解析し、信号パターンの歪みを検出する部分である。なお、信号パターン歪み検出部６１は検出すべき信号パターンの歪みの大きさを解析・評価できるものであるとする。信号パターン歪みの大きさを解析・評価できれば付着物の光学的影響の大きさを解析・評価できる。この実施形態２では基準パターン２００の歪みを数量的に解析・評価する手法として、ＭＴＦ値を用いた方法を用いる。図１２は、ＭＴＦ値による解析・評価方法を模式的に説明する図である。まず、図１２（ａ）はＭＴＦ値の計算式を説明する図である。横軸は受光素子アレイ上の位置、縦軸は受光素子部５０で受光された光の強度の信号値を示している。ＭＴＦ値は（数２）で与えられる。

図１２（ｂ）上段は、ゼブラパターンを受光素子上に結像させた場合に得られた光の強度分布を示したものである。なお、図１２（ｂ）でも横軸は受光素子アレイ上の位置、縦軸は受光された光の強度を示している。ここで、受光素子には大きさがあるため、実際に得られる信号は、図１２（ｂ）上段のパターンをサンプリングしたとびとびの離散値が得られている。そこで、得られた画素数＞パターンの幅となることを条件とし、（数３）によりＭＴＦ値を計算する。

ここで、Ｓ_Ｎは、Ｎ番目の画素の信号を表わすものとする。
（数３）により得られた信号Ｍの値を用いて、検知面上の雨滴付着を判定する。
図１２（ｂ）下段は、（数３）で計算された信号Ｍをプロットした波形である。実線は雨滴が検知面に付着していない場合、破線は雨滴が検知面に付着している場合に得られる光の強度分布である。図１２（ｂ）下段に見るように、検知面に雨滴が付着するとＭＴＦ値の絶対値が低下し、検知面を覆う水膜部分が大きくなるにつれ、その周期がずれる（周期が変動するため符号が反転する場合も有り得る）。なお、周期ずれとは、信号パターンの周期が不安定になることをいう。
付着物推定部６０は、信号パターン歪み検出部６１が検出した信号パターンの歪みの大きさから検知面上１１０に付着した付着物の表面形状や種類を推定する。信号パターンにおける歪みの割合を評価し、当該歪みが付着物の表面形状効果によるものと推定するものである。表面形状効果が大きいほど雨滴など付着物の厚さが厚く盛り上がった形状をしていると評価する。
また、付着物推定部６０は、信号パターン歪み検出部６１が検出した信号パターンのぼかし度合いから検知面上１１０に付着した付着物の光散乱性を推定する。信号パターンにおけるぼかしを評価し、付着物の光散乱性により散乱された光により本来明瞭であるはずのエッジがぼやけてしまったと推定するものである。ぼかし度合いが大きいほど付着物の散乱性が大きいものであると推定するものである。散乱性をもって付着物の種類などの推定も可能となる。
次に、付着物の種類が変わった場合でも、図１２で示したようにＭＴＦ値を（数３）に従って計算し、その信号パターンを解析することにより、付着物検出部６０が付着物を検出し、その種類を推定できることを示す。
まず、付着物が小雨（霧雨）の場合を説明する。
図１３は、付着物が小雨（霧雨）の場合に得られるＭＴＦ値（Ｍ_Ｎ）分布である。小雨（霧雨）付着前のＭＴＦ値に比べると、小雨（霧雨）付着後のＭＴＦ値は、コントラストが低下（ＭＴＦ値が減少）する。小雨（霧雨）であって雨量が大きくないので、降雨当初には検知面を覆う水膜が小さいため周期のずれは見られない。このようなＭＴＦ信号パターンが得られた場合に、付着物推定部６０は、雨滴の付着を検出し、その雨滴が小雨（霧雨）であることを推定する。
次に、付着物が大粒の雨である場合を説明する。この場合、降る雨滴の粒が大きいが、降り始めなどでまだ水膜が検知面を覆う部分が大きくない状態とする。
図１４は、付着物が大粒の雨の場合に得られるＭＴＦ値（Ｍ_Ｎ）分布である。大粒の雨付着前のＭＴＦ値に比べると、大粒の雨付着後のＭＴＦ値は、コントラストが部分的に低下（ＭＴＦ値が減少）する。つまり雨粒が検知面の一部分しか付着しておらず、その部分のコントラストが大きく低下している。降雨当初であれば検知面を覆う水膜が小さいため周期のずれは見られない。このようなＭＴＦ信号パターンが得られた場合に、付着物推定部６０は、雨滴の付着を検出し、その雨滴が大粒の雨であることを推定する。
このように、雨滴の粒が小さい、中程度、大きいなど、雨滴の大きさは、ＭＴＦ値のコントラストの低下度合いを評価することにより可能となる。
次に、雨量が大きい場合を説明する。この場合、雨量が多いため、検知面を覆う水膜部分が大きい状態とする。
図１５は、雨量が大きい場合に得られるＭＴＦ値（Ｍ_Ｎ）分布である。雨滴付着前のＭＴＦ値に比べると、大量の雨付着後のＭＴＦ値はコントラストが低下するとともに周期のずれが見られる。信号パターンの山谷の位置がずれ、符号が反転する部分も散見される場合も有り得る。このようなＭＴＦ信号パターンが得られた場合に、付着物推定部６０は雨滴の付着を検出し、雨量が大きいと推定する。
このように、雨量が小さい、雨量が中程度、雨量が大きいなど、雨量の大小は、信号パターンにおける周期ずれの大きさを評価することにより可能となる。
次に、実際に透明基板上の雨滴越しに見たゼブラパターンの様子を撮影した例を示す。図１６に示した例は、上から、（ａ）検知面が撥水面で霧雨が付着した場合、（ｂ）検知面が撥水面で大粒の雨が付着した場合、（ｃ）検知面が撥水面で付着物がない場合、（ｄ）検知面が親水面で雨量が小さい場合、（ｅ）検知面が親水面で雨量が中程度の場合、（ｆ）検知面が親水面で雨量が大きい場合、（ｇ）検知面が親水面で水膜が張っている場合を示している。なお、（ｃ）の検知面が撥水面で付着物がない場合でも、右に行くにつれ、ゼブラパターンの周期が小さくなっているが、これはもともとこのようなゼブラパターンを用いたためである。各パターン（ａ），（ｂ），（ｄ）〜（ｇ）は、パターン（ｃ）を基準としてそのコントラスト低下や周期ずれを見れば良い。なお、図１６において、黒いゼブラパターンがぼやけている部分がコントラストが低下していることに対応している。
なお、図１６において、泥水など光散乱性を持つ付着物が付着している場合の実測データは示していないが、光散乱性が大きくなると光源の光が受光素子まで届かないので、コントラストは０、つまり、信号値Ｍ_Ｎの絶対値は０に近づく。このコントラスト低下を信号パターン歪み検出部６１で検出すれば良く、また、エッジの崩れも大きいのでコントラスト低下およびエッジ崩れの大きさより泥水の付着を推定する。
付着物検出部６０は、簡単には次の図１７のフローにより付着物の有無を検出する。
まず、受光素子部５０の各受光素子から信号を取り込む。つまり、各画素（総数Ｎ）データを取り込む（ステップＳ１７０１）。
次に、各画素データを使い、（数３）よりＭＴＦ信号値Ｍを計算する（ステップＳ１７０２）。これによりＮ−１個の信号値Ｍが得られる。
基準となる大きさの判定値（Ｘ）を設定しておき、各Ｍ値の絶対値とＸ値を比較し、｜Ｍ｜＜Ｘとなっている数Ｙをカウントする（ステップＳ１７０３）。
Ｙが０であるか否かをチェックし（ステップＳ１７０４）、Ｙ＝０ならば（ステップＳ１７０４：Ｙ）、検知面上に雨滴付着がないと判定し（ステップＳ１７０５）、Ｙ＞０ならば（ステップＳ１７０４：Ｎ）、検知面上に雨滴付着があると判定する（ステップＳ１７０６）。
なお、実施形態３に示すように、本発明の付着物検出装置をレインセンサとしてウィンドウワイパー制御装置に用いた場合であれば、本発明の付着物検出装置が、計算したＹをウィンドウワイパー制御装置に出力することにより、ウィンドウワイパー制御装置は、Ｙ＞０ならば、降雨があるとしてウィンドウワイパーを駆動させれば良い。
以上、本実施形態２の付着物検出装置によれば、基準パターンから検知面を通過した光を受光手段に結像させ、受光手段が受光した信号パターンを解析し、信号パターンの歪みを検出して付着物による視界の歪みや妨げを評価・検知することができる。
（実施形態３）
本実施形態３は、本発明の付着物検出装置を用いた制御装置の一実施形態として、付着物検出装置をレインセンサとして用いるウィンドウワイパー制御装置の装置構成例を示すものである。
図１８は、付着物検出装置をレインセンサとして用いるウィンドウワイパー制御装置のブロック図の例である。７００が実施形態１において示した本発明の付着物検出装置であるレインセンサの機能ブロック、７１０がウィンドウワイパー制御手段、７２０がウィンドウワイパー駆動手段、７３０がウィンドウワイパーであり、図示のように接続されている。また、図１９は、本実施形態３のウィンドウワイパー制御装置の処理動作の流れの一例を示すフローチャートである。
レインセンサ７００は実施形態１や実施形態２において説明したように各要素の取付け角度や材質が選択されたものであり、ウィンドシールドを検知面とし、例えば雨滴などを検知対象として各受光素子からの光検出信号を出力するものである。また、レインセンサとして使用する付着物検出装置の付着物推定部６０は、実施形態２で示したように雨滴など付着物による視界の歪みや妨げを評価・検知することができるものである。
レインセンサ７００は付着物推定部６０の出力信号として、“視界歪みなし”推定信号、“視界歪みあり”推定信号、“散乱性付着物あり”推定信号の検出信号を出力するものとする。
ウィンドウワイパー制御手段７１０は、レインセンサ７００の付着物推定部６０からの各種推定信号を入力とし、ウィンドウワイパー駆動手段７２０に対して、ウィンドシールド表面の各推定状態に応じたワイパー制御信号を出力するものである。
例えば、“視界歪みなし”推定信号に対しては、ワイパー停止状態とする制御信号を出力する。
“視界歪み有り”推定信号に対しては、ワイパー駆動状態とする制御信号を出力する。
“散乱性付着物あり”推定信号に対しては、洗浄液噴射とともにワイパー駆動状態とする制御信号を出力する。土や泥水など散乱性を有する付着物の払拭には洗浄液とともにワイパーで払拭することが好ましいと想定されるからである。
ウィンドウワイパー駆動手段７２０はウィンドウワイパー制御手段７１０からの制御信号を入力とし、ウィンドウワイパー７３０の駆動を制御するものである。
ウィンドウワイパー７３０は、ウィンドウワイパー駆動手段７２０によりトルクなどが与えられて駆動され、停止状態、駆動状態を持つ。駆動状態には間欠駆動のピッチが短いものや長いものなど複数の状態がありうる。駆動状態においてウィンドシールドの所定表面を払拭する。
図１９のフローチャートを参照しつつ、ウィンドウワイパー制御装置の処理動作の流れを説明する。
ウィンドウワイパー制御装置が稼動中の場合（ステップＳ１９０１：Ｙ）、ウィンドウワイパー制御手段７１０は、レインセンサ７００の付着物推定部６０からの制御信号をモニタする（ステップＳ１９０２）。
ウィンドウワイパー制御手段７１０は、付着物推定部６０からの制御信号をデコードし、その制御内容を解析する（ステップＳ１９０３）。
ウィンドウワイパー制御手段７１０は、ステップＳ１９０３で得た制御内容に従い、ウィンドウワイパー７３０の駆動を制御する（ステップＳ１９０４）。ステップＳ１９０４の後、再度ステップＳ１９０１にループして制御を継続する（ステップＳ１９０１へ戻る）。
図２０は、本発明の付着物検出装置をレインセンサとして用いたウィンドウワイパー制御装置の取り付け構成例を簡単に示した図である。図２０に示すように、付着物検出装置であるレインセンサ７００を、車のバックミラー９００の裏面にあるウィンドシールド部分９１０に取り付けている。このようにバックミラー９００の裏面のウィンドシールド部分９１０に取り付けることにより運転者の運転視界を不必要に遮ることなく、かつ、検知面をウィンドシールド上に確保できる。ウィンドウワイパー制御手段７１０とウィンドウワイパー駆動手段７２０は図示していないが、ウィンドウワイパー７３０付近の車装品としてキャビン内に格納されているものとする。
以上、本実施形態３に示した付着物検出装置を用いた制御装置は、一例であり、本発明の付着物検出装置は、上記の具体的装置構成例に限定されることなく、本発明の技術的思想に基づいて他の装置構成も可能であり、ウィンドウワイパー制御装置以外の用途にも用いることができることは言うまでもない。
産業上の利用可能性
本発明の付着物検出装置によれば、基準パターンから検知面を通過した光を受光手段に結像させ、受光手段が受光した信号パターンを解析し、信号パターンの歪みを検出して付着物による視界の歪みや妨げを評価・検知することができる。
本発明の付着物検出装置によれば、光検出信号の値の絶対値そのものを解析することなく、相対的な信号変化パターンを解析すれば正しく基準パターンに対応した光信号が得られているか否かを解析できる。
また、本発明の付着物検出装置を用いた制御装置によれば、本発明の付着物検出装置により付着物の存在や種類などの推定に応じてその制御内容を制御することができ、例えば、付着物検出装置をレインセンサとし、付着物検出装置を用いた制御装置をワイパー制御装置とすれば、付着物検出装置の検出結果に基づいてワイパー駆動状態を制御することができる。
【図面の簡単な説明】
図１は、本発明の実施形態１の付着物検出装置の構成例および検知面を見る者の視界の歪みや妨げを評価・検知する原理を説明する図である。
図２は、基準パターンの例を示す図である。
図３は、検知面上に付着物がない場合における本発明の付着物検出装置により検出される光検出信号の信号パターンを模式的に示した図である。
図４は、検知面上に雨滴などの形状効果を持つ付着物がある場合において検出される光検出信号の信号パターンを模式的に示した図である。
図５は、検知面上に光散乱性を持つ付着物がある場合において検出される光検出信号の信号パターンを模式的に示した図である。
図６は、本発明の実施形態２の付着物検出装置の構成例を簡単に示した図である。
図７は、開口部において基準パターンを備えている光源の例を示した図である。
図８は、本発明の実施形態２にかかる、開口部において基準パターンを備えている光源を用いた場合の付着物検出装置の構成例を示す図である。
図９（ａ）は、光源部１０ａの端面を模式的に示した図、図９（ｂ）は、光源部１０を開口部１４の見える面を正面とした図である。
図１０は、レンズ４０の一例を模式的に示した図である。
図１１は、受光素子部５０の受光素子の配列の例を示した図である。
図１２は、ＭＴＦ値による解析・評価方法を模式的に説明する図である。
図１３は、付着物が小雨（霧雨）の場合に得られるＭＴＦ値を示す図である。
図１４は、付着物が大粒の雨の場合に得られるＭＴＦ値を示す図である。
図１５は、雨量が大きい場合に得られるＭＴＦ値を示す図である。
図１６は、実際に透明基板上の雨滴越しに見たゼブラパターンの様子を撮影した例を示す図である。
図１７は、付着物検出部６０における、付着物の有無を検出する処理の流れを説明するフローチャートである。
図１８は、付着物検出装置をレインセンサとして用いるウィンドウワイパー制御装置のブロック図である。
図１９は、本実施形態３のウィンドウワイパー制御装置の処理動作の流れの一例を示すフローチャートである。
図２０は、本発明の付着物検出装置をレインセンサとして用いたウィンドウワイパー制御装置の取り付け構成例を簡単に示した図である。
図２１は、従来の反射光検知型レインセンサによる雨滴検出原理を簡単に説明した図である。Technical field
The present invention relates to an attached object detection device capable of detecting the presence of an attached object on a detection surface with high sensitivity, and a control device using the same.
Background art
There are various systems that detect the presence or absence of an adhering substance and change the control content in response to the detection of the presence of the adhering substance. Considering raindrops as an example of the deposit, it is necessary for the window wiper control device of the windshield of the car to change the control contents flexibly when the weather changes and the rainfall starts. One of the important issues for improving the convenience of the window wiper control device is the development of a rain sensor for detecting whether or not it is raining. Hereinafter, a conventional rain sensor that detects raindrops on a windshield of a car as a deposit will be described as a conventional deposit detection device.
In the case of a commonly used window wiper that is manually operated, the driver himself recognizes that rain has begun and considers the running conditions of the car and changes in the amount of raindrops attached to the windshield. It is necessary to manually switch the window wiper switch from off to on in order to secure a view through the windshield. In order to alleviate the trouble of manually switching the window wiper switch, a rain sensor is provided to detect the presence of extraneous matter such as raindrops on the detection surface of the windshield of the vehicle, and to determine whether the window needs to be wiped. Has been determined.
As a conventional rain sensor, a reflected light detection type rain sensor or the like is known according to a raindrop detection method. FIG. 21 is a diagram simply illustrating the principle of detecting raindrops by a conventional reflected light detecting rain sensor. In FIG. 21, reference numeral 1000 denotes an automobile windshield. For convenience of explanation, the upper space of the windshield 1000 is the inside of the vehicle, that is, the space on the driver side, and the lower space is the outside world. 1010 is a light source, 1020 is a prism, 1030 is a prism for guiding reflected light from inside the windshield, 1040 is a lens, 1050 is a light receiving element (charge coupled element), and 1110 is a detection surface. Reference numeral 1120 denotes a raindrop attached to the detection surface. The light source 1010 irradiates a light beam having a spread capable of covering the entire detection surface, of which 1130 is a trajectory of light incident on a portion where raindrops are attached, and 1140 other than 1130 is a detection surface where no raindrops are attached. Represents the trajectory of light incident on the light source.
In the reflected light detection type rain sensor, it is important to adjust the mounting angle and the material (particularly, the refractive index of the material) of each element. To put it simply, the principle of raindrop detection is that light incident on a portion of the detection surface to which raindrops are attached escapes to the outside world without satisfying the condition of total reflection at the outer interface of the windshield 1000, and the raindrop on the detection surface becomes The light incident on the non-adhered portion is totally reflected at the outer interface of the windshield 1000 under the condition that the total reflection is satisfied, and the intensity difference of the reflected light is detected.
Therefore, for the light source 1010 and the prism 1020, an angle and a material that satisfy an incident condition for irradiating light to enter the inside of the windshield 1000 are selected, and an angle of total reflection on a detection surface on an outer interface of the windshield 1000 is selected. . Further, the light incident angle with respect to the detection surface is selected such that the satisfaction / dissatisfaction of the total reflection condition on the detection surface 1110 is switched by the change in the refractive index due to the attachment of raindrops.
The material and angle of the prism 1030 are also selected so as to satisfy the emission condition so that the reflected light can be emitted to the outside of the windshield 1000, that is, the total reflection condition is not satisfied. The angle and the distance between the lens 1040 and the light receiving element 1050 are adjusted so that light incident on the lens 1040 is focused on the sensor portion of the light receiving element 1050.
Note that these elements 1010 to 1050 can be attached to places other than the windshield 1000, for example, on a hood or a roof. It is preferable to attach to the part. In addition, it is preferable to be attached so as not to narrow the field of view of the driver. For example, it is preferable to attach to a windshield or the like where a rearview mirror is originally attached to block the view.
The operation of the above-described conventional reflected light detection type rain sensor will be briefly described. A light beam emitted from the light source 1010 is introduced into the inside of the windshield 1000 by the prism 1020 and is incident on the entire detection surface 1110. Now, it is assumed that the raindrop 1120 has adhered to the detection surface 1110. Of the light incident on the detection surface 1110, the light 1130 incident on the portion where the raindrop 1120 is attached has a total reflection condition at the outer interface of the windshield 1000 due to the presence of the raindrop having a refractive index n of about 1.3. Unsatisfied, the light escapes to the outside world, and the light is not detected by the light receiving element 1050. On the other hand, of the light 1140 incident on the portion of the light incident on the detection surface 1110 where no raindrops adhere, the total reflection condition is reduced due to the presence of air having a refractive index n of 1 on the outer interface of the windshield 1000. Satisfied and totally reflected. The totally reflected light exits into the vehicle without being totally reflected due to the presence of the prism 1030 on the surface of the windshield 1000 inside the vehicle. The emitted light is condensed by the lens 1040 on the light sensor portion on the light receiving element 1050.
As described above, the amount of light detected by the light receiving element 1050 decreases when the raindrop 1120 is present, and the amount of light received decreases as the area of the raindrop 1120 covering the detection surface 1110 increases. By detecting the change in the amount of light, the presence of a raindrop on the detection surface 1110 is detected. The above is the principle of raindrop detection by the conventional reflected light detection type rain sensor.
Each type of rain sensor is configured to output a raindrop detection signal when detecting a signal change as described above. The raindrop detection signal from the rain sensor is input to the control unit of the window wiper, and the input of the raindrop detection signal triggers the control of a predetermined window wiper.
However, the conventional rain sensor has the following problems.
The conventional reflected light detection type rain sensor is installed in the windshield near the rearview mirror, etc., because it is necessary to secure the driver's view on the windshield 1000 and to secure the beauty of the car. Was constrained. However, since the raindrop detection probability depends on the detection area, the detection surface 1110 is made as wide as possible to increase the raindrop detection probability, and the light reflected from the detection surface 1110 is received by one light receiving element 1050 to detect the change in the amount of reflected light. I was
However, the reflected light detection type rain sensor in the related art has the following problems.
The first problem is that the reflected light detection type rain sensor according to the related art cannot detect the obstruction itself of the driver's view in consideration of human sensitivity. The primary purpose of detecting extraneous matter such as raindrops on the windshield 1000 is to detect extraneous matter such as raindrops on the windshield 1000 that may distort or obstruct the driver's view. If it is possible to detect the distortion of the field of view that the driver will recognize, it becomes possible to detect the extraneous matter according to human sensitivity.
The second problem is that the sensitivity is low in the conventional reflected light detection type rain sensor. In order to detect raindrops with the conventional reflected light detection type rain sensor, it is necessary to detect the change in the amount of light reflected from the detection surface 1110 on the windshield 1000 with high sensitivity. There are the following reasons that make it difficult to grasp the reflected light quantity change with high sensitivity.
In general, when a driver recognizes the presence of a deposit on the windshield such as raindrops and feels that it is necessary to wipe the windshield with a wiper, the area occupied by the deposit such as raindrops on the windshield is 0.5%. %. That is, even on the detection surface provided on the windshield surface, it is necessary to detect the presence of the adhering matter for an area of 0.5%. The reflected light detection type rain sensor in the prior art uses a lens to collect the reflected light from the entire detection area, so that the amount of light reflected from the entire detection area determines the reference signal value, and the raindrop is attached to the detection surface. Only the amount of light that escapes from the outside determines the signal change. After all, a signal change of 0.5% in the output signal must be detected. In view of the noise caused by the incidence of external light and the operation in a harsh environment such as a windshield surface of a running car, it is generally very difficult to detect a signal change of only 0.5%. As a result, in the related art, the signal change for the entire detection signal is buried depending on the difference between the area of the detection surface 1110 and the area of one raindrop to be detected.
For the above reasons, it is difficult for the conventional reflected light detecting rain sensor to detect the change in the amount of reflected light caused by the attachment of raindrops with high sensitivity.
A third problem is that the detection area is reduced. There is a trade-off relationship between the detection area and the sensitivity. In order to cover the low sensitivity, which is the first problem, a focus is set on the detection surface 1110 by the imaging optical system and a sharp image is formed on the light receiving element 1050. If an image is formed, the sensitivity is improved. However, since the focus is set on the detection surface 1110, the area of the detection surface 1110 that can be detected is reduced accordingly. If the light from the focal point of the imaging optical system is not formed on the light receiving element 1050, but the light in a defocused state is formed on the light receiving element 1050, a sharp image is formed. Therefore, it is impossible to obtain a light detection signal including a change required for sensitively determining the presence of a small attached matter.
Disclosure of the invention
The present invention has been made in view of the above-described problems, and has an object detection device and an object detection device capable of detecting an attachment such as raindrops attached on a detection surface with high sensitivity, and having a large detection area to increase the detection probability. It is an object to provide a control device used.
In addition, the present invention has been made in view of the above problems, and has an object detection device and an object detection device capable of evaluating and detecting distortion or obstruction of a driver's view due to an object such as raindrops adhering to a detection surface. It is an object of the present invention to provide a control device using the same.
In order to solve the above problem, the attached matter detection device of the present invention is provided with a transparent substrate having a detection surface, a light source that irradiates light to the detection surface, and provided between the light source and the detection surface. A reference pattern having portions with different light transmittances or light reflectances, a lens that focuses on the reference pattern, receives light passing through the reference pattern and the detection surface to form an image, and a plurality of minute light receiving elements. A light receiving means for receiving light imaged by the lens, and outputting a light detection signal of each minute light receiving element as a signal pattern by arranging them correspondingly to the minute light receiving elements, and a signal detected by the light receiving means A signal pattern distortion detecting unit that analyzes a pattern and detects distortion of the signal pattern based on the reference pattern, wherein the signal pattern distortion detecting unit detects distortion of the signal pattern; And detecting the presence of deposit on the sensing surface.
According to the above configuration, since the light received by each minute light receiving element passes through the detection surface, it is affected by the optical conditions on the detection surface, and the signal assumed from the shape of the reference pattern By comparing the pattern and the shape of the actually obtained signal pattern, it is possible to detect the optical influence on the detection surface. In other words, unlike the conventional attached matter detection device, it does not focus on the attached matter itself to detect its presence, but focuses itself on the reference pattern which is not the detection surface with the attached matter, and gives the focus by the attached matter. This is for detecting the influence on the signal pattern to be obtained, and can evaluate and detect distortion or obstruction of the field of view of the person who views the reference pattern. In addition, since the image of the reference pattern is received by the light receiving unit in a state where the reference pattern is in focus, the image of the reference pattern can be captured with high sensitivity and high sensitivity.
Further, in the above configuration, a kind of signal pattern (signal waveform) is obtained by arranging the light detection signals detected from the respective minute light receiving elements. This signal pattern is a pattern obtained by connecting the signal levels obtained from each of the minute light receiving elements, and the effect of the detection surface is expressed as a distortion of the signal pattern, that is, a relative change in a minute section. It becomes. The present invention analyzes and detects a relative change in a signal pattern, and evaluates and detects distortion or obstruction of a field of view of a person who views a reference pattern due to an influence of a deposit on a detection surface. Further, since the relative change between the minute sections of the signal pattern is analyzed, it is possible to accurately detect even a small influence, and it is hard to be affected by an environmental change due to a temperature characteristic or the like.
Further, according to the above configuration, the detection area can be increased. The detection surface on which the adhering matter is present is provided between the reference pattern and the light receiving unit, and the light receiving unit receives light based on the relationship between the focal length of the imaging optical system and the distance between the imaging optical system and the detection surface. The area on the detection surface through which light has passed is determined. By adjusting the relationship between the two distances, it is possible to increase the detection area in which the presence of the adhering matter on the detection surface can be detected.
The light source may have the reference pattern on a light emitting opening, and the light source and the reference pattern may be integrated.
With the above configuration, the device configuration can be simplified, and the size of the entire device can be reduced.
In the above configuration, the light receiving area per one of the light receiving elements, the number of the light receiving elements, and the arrangement of the light receiving elements in the light receiving unit can analyze the distortion of the signal pattern to be detected by the signal pattern distortion detecting unit. It is preferable that a signal pattern having a resolution can be obtained.
Since the rate at which the signal pattern is distorted is determined according to the ratio of the area of the attached matter to the detection area provided on the detection surface, the resolution required of the light receiving means is also determined according to the area of the attached matter to be detected. The light receiving area, number, and arrangement of the light receiving elements required for obtaining the resolution in the light receiving means may be set.
Further, the attached matter detection device of the present invention can estimate the surface shape of the attached matter attached to the detection surface from the magnitude of the distortion of the signal pattern detected by the signal pattern distortion detection unit.
Because the distortion generated in the signal pattern occurs according to the surface shape effect such as the thickness of the attached matter such as raindrops, the surface shape of the attached matter on the detection surface can be estimated by detecting the distortion of the signal pattern. Because.
Further, the attached matter detection device of the present invention can estimate the light scattering property of the attached matter attached to the detection surface from the degree of blurring of the signal pattern detected by the signal pattern distortion detection unit.
Because blurring in signal patterns is caused by light scattering of light-scattering deposits such as dust and muddy water, detecting signal pattern blurring makes it possible to estimate light scattering of deposits on the sensing surface. Because you can.
In the above-described attached matter detection device, if the detection surface is provided on a windshield of an automobile, it can be used as a rain sensor for detecting the presence of raindrops attached to the windshield.
Furthermore, in order to solve the above problems, a control device using the attached matter detection device of the present invention includes an attached matter detection device of the present invention used as the rain sensor, a window wiper driving unit, and a window wiper control unit, The window wiper control means receives a detection signal of an adhering substance from the adhering substance detection device, and changes the control content of the window wiper driving means based on the detection signal.
With the above configuration, it is possible to provide a window wiper device that can immediately and reliably detect the start of rainfall and start window wiper driving at an appropriate timing.
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of an attached matter detection device and a control device using the same according to the present invention will be described with reference to the drawings.
(Embodiment 1)
The attached matter detection apparatus according to the first embodiment is an apparatus capable of evaluating and detecting distortion and obstruction of the field of view of a person who views a detection surface. The attached matter detection device according to the first embodiment includes a reference pattern provided between a light source and a detection surface, an imaging optical system focused on the reference pattern, and a plurality of lights passing through the detection surface from the reference pattern. An image is formed on the light receiving means equipped with a small light receiving element, and the light detection signals received by each light receiving element are arranged side by side and analyzed as a signal pattern. It evaluates and detects distortion and obstruction.
First, the principle of evaluating and detecting distortion and obstruction of the field of view of the person who views the detection surface will be briefly described.
FIG. 1 schematically illustrates the configuration of the apparatus according to the first embodiment, schematically illustrating the configuration of the apparatus viewed from above, and has a horizontal cross section. In FIG. 1, reference numeral 100 denotes a transparent substrate, on the surface of which a detection surface 110 is provided. A light source 10 emits uniform light and irradiates it toward the reference pattern 200. Reference numeral 200 denotes a reference pattern, which is arranged between the light source 10 and the detection surface 110. It is drawn with a thickness (horizontal direction) for easy understanding. The reference pattern is a pattern having portions having different light transmittances and light reflectances. In the example of FIG. 1, the reference pattern is a zebra pattern having a black portion having a small light transmittance and a transparent portion having a large light transmittance. It schematically depicts the zebra pattern viewed from above. FIG. 2 shows an example of a reference pattern viewed from the front. (A) is a zebra pattern, (b) is a checkered pattern. The reference pattern may be any pattern as long as the edge of the boundary between the black portion having low light transmittance and the transparent portion having high light transmittance is clear and the contrast in the image is clear, and its shape is not particularly limited.
Light emitted from the light source 10 hits the reference pattern 200, and light having an image of the reference pattern 200 is emitted toward the lens 40 that is an optical imaging system.
Reference numeral 40 denotes a lens as an optical imaging system. In FIG. 1, the lens is shown as a single lens, but it goes without saying that a group lens may be used. In this example, the focus on the input side of the lens 40 is adjusted to the reference pattern, and the focus on the output side is adjusted to the minute light receiving element. That is, they are arranged so that the light passing through each part of the reference pattern forms an image on the minute light receiving element.
Reference numeral 50 denotes a light receiving element unit as light receiving means, which has an array configuration in which a plurality of light receiving elements are arranged in order to detect an image of a reference pattern at a fixed resolution as described later. As will be described later, the number and arrangement of the light receiving elements are adjusted so that a signal pattern having a resolution required for analyzing the magnitude of the distortion of the signal pattern to be detected is obtained. For example, a one-dimensional line sensor or a two-dimensional matrix sensor arranged at a constant pitch number is used. In the example of FIG. 1, a one-dimensional line sensor in which light receiving elements are arranged in the horizontal direction is used.
The light receiving element unit 50 connects the signal levels of the light detection signals detected by the respective light receiving elements according to the arrangement of the minute array configuration, and generates a signal pattern. That is, the light detection signal received by the light receiving element unit 50 can be obtained as one signal pattern corresponding to the arrangement of the minute light receiving elements.
FIG. 1 shows an example until the light emitted from the light source is received by the light receiving element unit 50. Light emitted from the light source hits the reference pattern, and light is transmitted and emitted from a gap between the reference patterns according to the shape of the reference pattern. FIG. 1 shows a state in which light emitted from a certain reference pattern gap is imaged on one of the light receiving element units 50 via the detection surface 110 and the lens 40. The focus on the input side of the optical imaging system is adjusted to match the reference pattern, and the reference pattern image is clearly formed across the plurality of minute light receiving elements of the light receiving element unit 50. A signal pattern having a pattern corresponding to the reference pattern can be obtained by joining light detection signals obtained over a plurality of minute light receiving elements.
Now, when following the path of the light emitted from the reference pattern gap, the light passes through the detection surface 110 and enters the lens 40. In other words, the focal point on the input side of the lens 40 is focused on the reference pattern, so that the light-receiving element clearly forms the reference pattern image. However, since the light passes through the detection surface 110, the surface shape of the attached matter on the detection surface 110 Optical effects such as effects can be obtained. Considering the relationship between the reference pattern 200, the detection surface 110, and the light detection signal received by the light receiving element unit 50, the relationship between the external object viewed by the driver, the windshield surface, and the driver's vision It turns out that it is. In other words, when there is an attachment on the detection surface 110 and the light detection signal received by the light receiving element unit 50 is affected, the attachment exists on the windshield surface, and the driver's vision is distorted or obstructed. It can be estimated that this is the case.
FIG. 3 schematically illustrates a signal pattern detected when there is no adhering substance having an optical effect on the detection surface 110. The upper part of FIG. 3 schematically shows the relationship between the shape of the reference pattern 200 and the arrangement of the minute light sources of the light receiving element unit 50 arranged. The arrangement of the zebra pattern and the arrangement of the light receiving element unit 50 viewed from the direction of the light emitted from the light source 10 are illustrated in an overlapping manner. As shown in the upper part of FIG. 3, there is a relationship in which the zebra pattern is on the front and the light receiving element units 50 arranged horizontally behind the zebra pattern. The lower part of FIG. 3 schematically shows a signal pattern of a light detection signal obtained in the light receiving element unit 50. In the signal pattern in the lower part of FIG. 3, the light detection signal levels of the respective light receiving elements are arranged on the horizontal axis according to the arrangement of the light receiving elements, and the vertical axis is the detected light signal level, for easy explanation. By analyzing the light detection signal of the light receiving element unit 50 and arranging each signal, a signal pattern corresponding to the case where the reference pattern of FIG. 2 is horizontally scanned as shown in the lower part of FIG. 3 is obtained.
Here, as shown in the lower part of FIG. 3, it can be seen that the light detection signal can be analyzed as a signal pattern. In other words, the signal at the portion corresponding to the black portion of the reference pattern drops, the signal at the portion corresponding to the transparent portion of the reference pattern is detected high, and corresponds to the light transmittance change pattern when the reference pattern is scanned in the horizontal direction. It can be seen that a change pattern of the signal value is obtained. As described above, the attached matter detection device of the present application does not analyze the absolute value of the value of the light detection signal itself, but analyzes the relative signal change pattern to determine whether an optical signal corresponding to the reference pattern is correctly obtained. Can be analyzed.
Next, FIG. 4 schematically illustrates a light detection signal that is detected when there is an attached matter having a surface shape effect, such as a raindrop 130, on the detection surface 110 and having an optical effect. . The arrangement of the zebra pattern, the position of the raindrop 130 on the detection surface, and the arrangement of the CCD unit 50 as viewed from the direction of the light emitted from the light source 10 are illustrated in an overlapping manner. As shown in the upper part of FIG. 4, a zebra pattern can be seen at the front, a raindrop 130 on the detection surface is behind the pattern, and the CCD units 50 arranged in the horizontal direction are behind the pattern. The lower part of FIG. 4 schematically shows a light detection signal obtained in the CCD unit 50, and shows a result of analyzing the light detection signal of the CCD unit 50 and arranging each signal. As in the lower part of FIG. 3, the light detection signal levels of the respective light receiving elements are arranged on the horizontal axis in accordance with the arrangement of the light receiving elements, and the vertical axis is a signal pattern indicating the detected light signal level, for easy explanation. As shown in the lower part of FIG. 4, the signal pattern detected in the lower part of FIG. 4 is different from the signal pattern in the lower part of FIG. I understand. This distortion is generated as a result of the light passing through the detection surface 110 being affected by the surface shape effect of the raindrop 130 attached to the detection surface 110.
Here, it can be seen that the distortion of the light detection signal shown in the lower part of FIG. 4 can be analyzed as a pattern. That is, it is sufficient to analyze the relative peak height, the change in pitch, and the distortion as the waveform of the signal pattern without analyzing the absolute value of the value of the light detection signal itself. Thus, by detecting the change and distortion of the signal pattern, the presence of the raindrop 130 on the detection surface can be detected.
Next, FIG. 5 schematically shows a light detection signal obtained in the CCD unit 50 when there is an attached matter 140 having light scattering properties such as dust, soil, muddy water on the detection surface 110. 5 shows a result obtained by analyzing a light detection signal of the unit 50 and arranging each signal. The upper part of FIG. 5 illustrates the arrangement of the zebra pattern, the position of the light scattering attachment 140 on the detection surface, and the arrangement of the CCD unit 50 as viewed from the direction of the light emitted from the light source 10. As shown in the upper part of FIG. 5, a zebra pattern can be seen in front, there is a deposit 140 such as mud on the detection surface behind the zebra pattern, and further there is a CCD unit 50 arranged horizontally in the back. . The lower part of FIG. 5 schematically shows a light detection signal obtained in the CCD unit 50, and shows a result of analyzing the light detection signal of the CCD unit 50 and arranging each signal. As in the lower part of FIG. 3, the light detection signal levels of the respective light receiving elements are arranged on the horizontal axis in accordance with the arrangement of the light receiving elements, and the vertical axis is a signal pattern indicating the detected light signal level, for easy explanation. As shown in the lower part of FIG. 5, it can be seen that the signal pattern detected in the lower part of FIG. The collapse and blurring of the edge are caused as a result of the light passing through the detection surface 110 being affected by the light scattering property of the deposit 140 attached to the detection surface 110.
As described above, it can be understood that the size and type of the attached matter can be estimated by analyzing the degree of blurring of the detected pattern image.
As described above, if the light detection signal of the light receiving element unit 50 is analyzed in consideration of the arrangement of the light receiving elements and the signal pattern is analyzed, it is possible to detect the collapse, blur, and distortion of the edge of the formed signal pattern. By detecting the collapse, blurring, and distortion of the edge, it is possible to evaluate and detect distortion or obstruction of the visual field due to the attached matter 140 on the detection surface 110.
The above is the principle of evaluating and detecting distortion or obstruction of the field of view of the person who views the detection surface.
Next, the point that the attached matter detection device of the present invention can keep the detection surface large will be described. As shown in FIG. 1, it can be seen that the light emitted from the reference pattern 200 passes through the region 120 having a certain spread when passing on the detection surface 110. If there is an attached matter on this area 120, the attached matter itself cannot be captured as a clear image in the light receiving element because the focus itself is not in the area 120, but may be captured as a distortion of the reference pattern. it can. By analyzing this distortion, the surface shape effect and the scattering property of the attached matter are estimated. The size of the region 120 is determined by the relationship between the focal length of the lens 40 and the distance between the lens 40 and the detection surface 110. The size of the region 120 can be adjusted by adjusting the distance between the two.
In addition, the evaluation and detection processing of the surface shape effect of the attached matter by the distortion detection of the reference pattern and the distortion or obstruction of the visual field due to the light scattering property are performed in an environment where there is a lot of optical noise such as a change in an external environment and the incidence of external light. Can also obtain a sufficient SN ratio. Although the influence of the incidence of external light or the like affects the absolute value of the light detection signal level of the light receiving element unit 50, the shape of the reference pattern observed between the signals by analyzing the light detection signal is maintained. Therefore, a sufficient SN ratio can be obtained even in an environment with a lot of optical noise.
As described above, the attached matter detection device according to the first embodiment can evaluate and detect distortion and obstruction of the field of view of a person who views the detection surface by applying the above principle.
(Embodiment 2)
The second embodiment is an example in which the position of the reference pattern 200 is devised. The position of the reference pattern 200 may be provided between the light source 10 and the detection surface 110. Therefore, in addition to the positional relationship of the reference pattern 200 as shown in FIG. 1 of the first embodiment, there can be various arrangement patterns. As an example, the positional relationship of the reference pattern 200 as shown in FIG. 6 is also possible. Further, a configuration in which the light source 10 is provided with the reference pattern described in the above basic principle at the light emitting opening thereof is also possible. This is shown in FIG. In FIG. 7, reference numeral 14 denotes a light emitting port from which irradiation light is emitted from the inside. In the present invention, a zebra pattern in which light shielding portions and light transmitting portions are alternately arranged in a horizontal direction is provided as a reference pattern 200. Eventually, light from the light transmitting portion of the reference pattern 200 is applied to the detection surface 110.
FIG. 8 is a configuration example to which the substance detection principle of the present invention shown in the first embodiment is applied. The apparatus configuration example of the substance detection apparatus based on the positional relationship of the reference pattern 200 in FIG. FIG. The light source 10 is provided with the reference pattern described in the above basic principle at its light emitting opening, and the light emitted from the light source 10 is totally reflected on the detection surface, and the reflected light is received.
In FIG. 8, reference numeral 100 denotes a windshield 100 as an example of a transparent substrate. The lower layer of the windshield 100 is the outside world. The detection surface 110 is located in a certain area on the boundary surface between the windshield 100 and the outside world. 10 is a light source, and 20 and 30 are prisms. Reference numeral 40 denotes a lens, and reference numeral 50 denotes a light receiving element as light receiving means. Reference numeral 60 denotes an attached matter estimation unit.
FIG. 8 shows a cross section of the device configuration. It is assumed that each component has a micro array configuration in a direction perpendicular to the paper surface.
Light emitted from the light source 10 and introduced into the windshield 100 via the prism 20 is incident on the detection surface 110, and when there is no adhering matter on the detection surface 110 as shown in FIG. In this case, adjustment is made so that the condition for total reflection on the detection surface is satisfied. In addition, the prism 30, the lens 40, and the light receiving element unit 50 emit reflected light totally reflected in the windshield 100 on the detection surface 110 through the prism 30 attached to the surface of the windshield 100, The lens 40 is adjusted so that an image is formed on the light receiving surface of the light receiving element unit 50. Further, the arrangement and the mounting angle of the light source 10 and the above elements are adjusted so that the condition of total reflection on the detection surface 110 is not satisfied when the raindrop 130 (moisture) is in contact as shown in FIG. You.
Now, let the refractive index of the external medium be n ₁ , The refractive index of the windshield 100 is n ₂ And the incident angle of the irradiation light on the detection surface is θ ₁ Then, the total reflection condition is represented by (Equation 1).

Here, as shown in FIG. 8C, when the raindrop 130 does not exist, the external medium, that is, the refractive index of air is n. ₁ Becomes 1 and the refractive index n of the windshield 100 ₂ If about 1.51 is given as an example of Equation (41), then from Equation 1, 41.47 ° <θ ₁ It becomes. Further, when the raindrop 130 adheres as shown in FIG. 8B, since the refractive index of water is about 1.33, θ ₁ <61.74 ° is sufficient. That is, the light incident angle θ at which the satisfaction / dissatisfaction of the total reflection condition represented by (Equation 1) is switched on the detection surface 110 ₁ Is 41.47 ° <θ ₁ <61.74 ° is selected. In this example, as an example of the arrangement and the mounting angle of the elements satisfying these conditions, the incident angle and the reflection angle of the irradiation light from the light source 10 to the detection surface 110 are adjusted to be 47 °.
Next, each element will be described in detail.
The light source 10 has a light source such as a plurality of LEDs at one end or both ends, and extracts light from a linear opening. Light is extracted from the linear opening. The light source 10 is arranged at a position and an angle such that the light beam enters the detection surface 110 at a predetermined angle. The opening has a reference pattern 200 as shown in FIG.
FIG. 9A illustrates an end face of the light source 10, and FIG. 9B illustrates a state where the opening 14 can be seen from the front. The reference pattern 200 is not shown in the opening 14. The light source 10 is provided with, for example, a plurality of minute light sources at an end thereof, and is taken out from a linear opening 14, and is emitted as light 15 from the linear opening 14. In FIG. 9A, 11 is an LED as a light source, 12 is a light guide made of a translucent material, 13 is a cover for shielding light, 14 is an opening for extracting LED light, and 15 is emitted from the LED 11. It is a ray. The LED 11 is provided at one end or both ends on the left and right in FIG. 9B, and has a configuration in which reflection on the inner surface of the cover 13 is repeated and guided to each part of the opening 14. Further, the LEDs may be arranged at equal intervals on the surface of the light guide 12 facing the opening 14.
The light extracted from the opening 14 in FIG. 9B enters the prism 20.
The prism 20 is a prism serving as a medium for bringing both the light source 10 and the windshield 100 into optical contact with each other, and functions to guide the light emitted from the light source 10 into the windshield 100.
The detection surface 110 is provided on the surface of the transparent substrate 100, and is a surface on which irradiation light from the light source 10 is reflected.
Next, the imaging lens 40 will be described. The imaging lens 40 forms an image of the reference pattern 200 on the minute light receiving element of the light receiving element unit 50. The angle and the distance between the imaging lens 40 and the light receiving element 50 are adjusted so that the image of the reference pattern 200 is formed on the light receiving element 50. As shown in FIG. 8, the focal point on the incident side of the lens 40 is focused on the reference pattern 200 at the light emitting opening of the light source 10, but not on the detection surface 110. The focal point on the emission side of the lens 40 is adjusted to the light receiving element unit 50. With this configuration, the image of the reference pattern 200 is clearly formed on the light receiving element unit 50. FIG. 10 is a diagram schematically illustrating an example of the imaging lens 40. The example in FIG. 10 is a type of SLA, which is a kind of a gradient index lens array of a unity magnification imaging system. ^(R) It is a simple block diagram of (Selfoc Lens Array). 41 is a rod lens as a micro lens, 42 black resin, and 43 is an FRP plate. The rod lens 41 has a rod shape, and its lens surface is visible in FIG. The configuration diagram of FIG. 8 shows a side cross section of only one rod lens 41. If this SLA is used, it is possible to bend an incident light beam and form an image of an erect equal-magnification at a predetermined position. That is, the reference pattern 200 such as a zebra pattern and the light receiving surface have an image forming relationship, and the image of the reference pattern 200 can be formed as it is on the light receiving element. In the above example, the rod lenses 41 are linearly arranged. However, the lens arrangement is set in accordance with the arrangement of light beams to be extracted from the light source 10 and the arrangement of each light receiving element of the light receiving element unit 50 described later. Note that the above description is an example of an equal-magnification image forming system, but it is sufficient that each light receiving element light receiving surface, which is a minute light receiving element of the light receiving element section 50, and the reference pattern form an image forming optical system. .
The light receiving element unit 50 as a light receiving unit includes a light receiving element that outputs a light detection signal in accordance with the amount of irradiation light. The light receiving element of the lens 40 and the light receiving element unit 50 receives light incident on the lens 40. The angle and the distance are adjusted so that an image is formed on the light receiving element of the element unit 50. In this example, it is assumed that the light receiving elements are arranged linearly as shown in FIG. It is preferable that the size per light receiving element is finer than the pitch of the zebra pattern of the reference pattern 200. This is for detecting the distortion of the zebra pattern with a required resolution. The light receiving element unit 50 is arranged at an angle of 47 ° with respect to the transparent substrate 100 in accordance with the incident angle and the reflection angle of the irradiation light from the total reflection light source 10 on the detection surface 110. Reference numeral 51 denotes each light receiving element, which conceptually shows a light receiving surface. In addition, a capacitor, a transistor circuit, a sense amplifier circuit, and the like inside the light receiving element 51 are not shown, and the figure shows that the light receiving surface of the light receiving element 51 is linearly arranged.
Next, the reference pattern 200 will be described. The position of the reference pattern 200 may be provided between the light source 10 and the detection surface 110. Therefore, the position of the reference pattern 200 may have various patterns. The positional relationship as shown in FIG. 1 of the first embodiment, the positional relationship as shown in FIG. 6 of the first embodiment, and the diagram of the first embodiment in which the light source 10 has a reference pattern at its light emitting opening. 7 is also possible. In the second embodiment, the light source 10 has the configuration shown in FIG. 7 of the first embodiment in which the light emitting port has a reference pattern.
The attached matter estimation unit 60 receives the light detection signal from the light receiving element unit 50, analyzes the light detection signal, analyzes the light detection signal received by each light receiving element, and checks whether the image of the reference pattern is distorted. This is a part that detects whether or not there is any extraneous matter on the detection surface. In the second embodiment, the attached matter estimation unit 60 includes a signal pattern distortion detection unit 61.
The signal pattern distortion detection unit 61 is a part that analyzes a signal pattern of the reference pattern 200 received by the light receiving element unit 50 and detects distortion of the signal pattern. It is assumed that the signal pattern distortion detection unit 61 can analyze and evaluate the magnitude of the distortion of the signal pattern to be detected. If the magnitude of the signal pattern distortion can be analyzed and evaluated, the magnitude of the optical influence of the attached matter can be analyzed and evaluated. In the second embodiment, as a method of quantitatively analyzing and evaluating the distortion of the reference pattern 200, a method using an MTF value is used. FIG. 12 is a diagram schematically illustrating an analysis / evaluation method using an MTF value. First, FIG. 12A is a diagram for explaining a formula for calculating the MTF value. The horizontal axis indicates the position on the light receiving element array, and the vertical axis indicates the signal value of the intensity of the light received by the light receiving element unit 50. The MTF value is given by (Equation 2).

The upper part of FIG. 12B shows the intensity distribution of light obtained when the zebra pattern is formed on the light receiving element. Also in FIG. 12B, the horizontal axis indicates the position on the light receiving element array, and the vertical axis indicates the intensity of the received light. Here, since the light receiving element has a size, the discrete signal obtained by sampling the pattern in the upper part of FIG. 12B is obtained as the actually obtained signal. Therefore, on condition that the obtained number of pixels> the width of the pattern, the MTF value is calculated by (Equation 3).

Where S _N Represents the signal of the N-th pixel.
Using the value of the signal M obtained by (Equation 3), it is determined whether raindrops have adhered to the detection surface.
The lower part of FIG. 12B is a waveform in which the signal M calculated by (Equation 3) is plotted. The solid line is the light intensity distribution obtained when the raindrops do not adhere to the detection surface, and the broken line is the light intensity distribution obtained when the raindrops adhere to the detection surface. As shown in the lower part of FIG. 12B, when raindrops adhere to the detection surface, the absolute value of the MTF value decreases, and as the water film portion covering the detection surface increases, the period shifts (the code changes because the period varies. May be reversed). Note that the period shift means that the period of the signal pattern becomes unstable.
The attached matter estimation unit 60 estimates the surface shape and type of the attached matter attached to the detection surface 110 from the magnitude of the signal pattern distortion detected by the signal pattern distortion detection unit 61. The ratio of distortion in the signal pattern is evaluated, and the distortion is estimated to be due to the surface shape effect of the attached matter. The larger the surface shape effect is, the thicker the attached matter such as raindrops is.
Further, the attached matter estimation unit 60 estimates the light scattering property of the attached matter attached to the detection surface 110 from the degree of blurring of the signal pattern detected by the signal pattern distortion detection unit 61. The blur in the signal pattern is evaluated, and it is presumed that light that is supposed to be clear is blurred by light scattered due to the light scattering property of the attached matter. It is estimated that the higher the degree of blur, the greater the scattering of the attached matter. It is possible to estimate the type of the attached matter with the scattering property.
Next, even if the type of the attached matter changes, the attached matter detection unit 60 detects the attached matter by calculating the MTF value according to (Equation 3) and analyzing the signal pattern as shown in FIG. And that the type can be estimated.
First, the case where the attached matter is light rain (mist drizzle) will be described.
FIG. 13 shows an MTF value (M) obtained when the attached matter is light rain (fog rain). _N ) Distribution. Compared to the MTF value before the light rain (mist drizzle) adheres, the contrast of the MTF value after the light rain (mist drizzle) adheres decreases (the MTF value decreases). Since it is light rain (drift rain) and the amount of rain is not large, there is no shift in the period at the beginning of the rain because the water film covering the detection surface is small. When such an MTF signal pattern is obtained, the attached matter estimation unit 60 detects the attachment of raindrops and estimates that the raindrops are light rain (fog rain).
Next, a case where the attached matter is a large grain of rain will be described. In this case, the raindrops that are falling are large, but the portion where the water film covers the detection surface is not large at the beginning of the rainfall.
FIG. 14 shows the MTF value (M _N ) Distribution. Compared to the MTF value before the large grains are attached to the rain, the contrast of the MTF value after the large grains is attached is partially reduced (the MTF value is reduced). That is, the raindrops adhere to only a part of the detection surface, and the contrast of that part is greatly reduced. At the beginning of the rainfall, the water film covering the detection surface is small, so no shift in the period is observed. When such an MTF signal pattern is obtained, the attached matter estimation unit 60 detects the attachment of raindrops and estimates that the raindrops are large rain.
As described above, the size of a raindrop, such as a small, medium, or large raindrop, can be determined by evaluating the degree of reduction in the MTF value contrast.
Next, a case where the rainfall is large will be described. In this case, since the amount of rainfall is large, the state where the water film portion covering the detection surface is large is set.
FIG. 15 shows the MTF value (M _N ) Distribution. Compared to the MTF value before the attachment of raindrops, the MTF value after the attachment of a large amount of rain has a lower contrast and a period shift. The positions of the peaks and valleys of the signal pattern may be shifted, and portions where the signs are inverted may be scattered. When such an MTF signal pattern is obtained, the attached matter estimation unit 60 detects the attachment of raindrops and estimates that the amount of rainfall is large.
As described above, the magnitude of the rainfall, such as a small rainfall, a moderate rainfall, and a large rainfall, can be made by evaluating the magnitude of the periodic shift in the signal pattern.
Next, an example in which the state of a zebra pattern actually observed through a raindrop on a transparent substrate is photographed will be described. In the example shown in FIG. 16, from the top, (a) when the detection surface is a water-repellent surface and drizzle rain adheres, (b) when the detection surface is a water-repellent surface and heavy rain adheres, and (c) when the detection surface is repellent. (D) when the detection surface is hydrophilic and the rainfall is small, (e) when the detection surface is hydrophilic and the rainfall is moderate, and (f) when the detection surface is hydrophilic and the rainfall is large. (G) shows a case where the detection surface is a hydrophilic surface and a water film is stretched. In addition, even if the detection surface in (c) is a water-repellent surface and there is no attached matter, the period of the zebra pattern decreases as going to the right. This is because such a zebra pattern was originally used. In each of the patterns (a), (b), (d) to (g), it is sufficient to check the contrast reduction and the period shift based on the pattern (c). In FIG. 16, a portion where the black zebra pattern is blurred corresponds to a decrease in contrast.
Note that FIG. 16 does not show actual measurement data in the case where an adhering substance having light scattering properties such as muddy water is attached. However, when the light scattering property is increased, the light of the light source does not reach the light receiving element, and thus the contrast is 0. That is, the signal value M _N Approaches an absolute value of zero. The signal pattern distortion detection unit 61 may detect this decrease in contrast, and since the collapse of the edge is large, adhesion of muddy water is estimated from the magnitude of the contrast decrease and the magnitude of the edge collapse.
The attached matter detection unit 60 simply detects the presence or absence of attached matter according to the following flow of FIG.
First, a signal is taken in from each light receiving element of the light receiving element section 50. That is, each pixel (total number N) data is fetched (step S1701).
Next, an MTF signal value M is calculated from (Equation 3) using each pixel data (step S1702). As a result, N-1 signal values M are obtained.
A determination value (X) of a reference size is set, and the absolute value of each M value is compared with the X value, and the number Y satisfying | M | <X is counted (step S1703).
It is checked whether or not Y is 0 (step S1704). If Y = 0 (step S1704: Y), it is determined that there is no raindrop on the detection surface (step S1705), and if Y> 0, Step S1704: N), it is determined that there is raindrop adhesion on the detection surface (step S1706).
As shown in the third embodiment, when the attached matter detection device of the present invention is used as a rain sensor in a window wiper control device, the attached matter detection device of the present invention uses the calculated Y as the window wiper control device. , The window wiper control device may drive the window wiper if there is rain if Y> 0.
As described above, according to the attached matter detection device of the second embodiment, light passing through the detection surface from the reference pattern is imaged on the light receiving unit, the signal pattern received by the light receiving unit is analyzed, and distortion of the signal pattern is detected. This makes it possible to evaluate and detect distortion and obstruction of the visual field caused by the attached matter.
(Embodiment 3)
Embodiment 3 shows an example of a device configuration of a window wiper control device using the attached matter detection device as a rain sensor as an embodiment of a control device using the attached matter detection device of the present invention.
FIG. 18 is an example of a block diagram of a window wiper control device using the attached matter detection device as a rain sensor. 700 is a functional block of a rain sensor, which is the attached matter detection device of the present invention described in the first embodiment, 710 is a window wiper control unit, 720 is a window wiper driving unit, and 730 is a window wiper, which is connected as shown in the figure. ing. FIG. 19 is a flowchart illustrating an example of a processing operation flow of the window wiper control device according to the third embodiment.
As described in the first and second embodiments, the rain sensor 700 has a mounting angle and a material of each element selected, and a windshield is used as a detection surface, and for example, raindrops and the like are detected and each of the rain sensors 700 is used as a detection target. It outputs a light detection signal. The attached matter estimation unit 60 of the attached matter detection device used as a rain sensor can evaluate and detect distortion or obstruction of the field of view due to attached matter such as raindrops as described in the second embodiment.
It is assumed that the rain sensor 700 outputs, as output signals of the attached matter estimation unit 60, detection signals of the “no visual distortion” estimation signal, the “visible distortion” estimation signal, and the “scattering attached matter” estimation signal.
The window wiper control unit 710 receives various estimated signals from the attached matter estimation unit 60 of the rain sensor 700 and outputs a wiper control signal corresponding to each estimated state of the windshield surface to the window wiper driving unit 720. Things.
For example, for a “no field distortion” estimation signal, a control signal for turning off the wiper is output.
In response to the “visual field distortion present” estimation signal, a control signal for setting the wiper drive state is output.
In response to the “scattering adhering matter” estimation signal, a control signal for setting the wiper driving state together with the ejection of the cleaning liquid is output. This is because it is presumed that it is preferable to wipe off scattering substances such as soil and muddy water with a wiper together with the cleaning liquid.
The window wiper driving unit 720 receives a control signal from the window wiper control unit 710 and controls driving of the window wiper 730.
The window wiper 730 is driven by applying a torque or the like by the window wiper driving unit 720, and has a stopped state and a driven state. The driving state may have a plurality of states such as a short or long intermittent driving pitch. In the driving state, a predetermined surface of the windshield is wiped.
The flow of the processing operation of the window wiper control device will be described with reference to the flowchart of FIG.
When the window wiper control device is operating (step S1901: Y), the window wiper control unit 710 monitors a control signal from the attached matter estimation unit 60 of the rain sensor 700 (step S1902).
The window wiper control unit 710 decodes the control signal from the attached matter estimation unit 60 and analyzes the control content (step S1903).
The window wiper control unit 710 controls the driving of the window wiper 730 according to the control content obtained in step S1903 (step S1904). After step S1904, the process loops back to step S1901 to continue the control (return to step S1901).
FIG. 20 is a diagram simply showing an example of a mounting configuration of a window wiper control device using the attached matter detection device of the present invention as a rain sensor. As shown in FIG. 20, a rain sensor 700 as an attached matter detection device is attached to a windshield portion 910 on the rear surface of a rearview mirror 900 of a car. By attaching to the windshield portion 910 on the rear surface of the rearview mirror 900 in this manner, the detection surface can be secured on the windshield without unnecessarily obstructing the driver's driving field of view. Although not shown, the window wiper control unit 710 and the window wiper driving unit 720 are assumed to be stored in the cabin as vehicle components near the window wiper 730.
As described above, the control device using the attached matter detection device described in the third embodiment is an example, and the attached matter detection device of the present invention is not limited to the above-described specific device configuration example. It goes without saying that other device configurations are possible based on the technical idea and can be used for applications other than the window wiper control device.
Industrial applicability
According to the attached matter detection device of the present invention, the light passing through the detection surface from the reference pattern is imaged on the light receiving means, the signal pattern received by the light receiving means is analyzed, and the distortion of the signal pattern is detected to detect the attached matter. Distortion and obstruction of the visual field can be evaluated and detected.
According to the attached matter detection device of the present invention, if the relative signal change pattern is analyzed without analyzing the absolute value itself of the value of the light detection signal, it is determined whether the optical signal corresponding to the reference pattern is correctly obtained. Can be analyzed.
Further, according to the control device using the attached matter detection device of the present invention, it is possible to control the control content according to the estimation of the presence or type of the attached matter by the attached matter detection device of the present invention, for example, If the attached matter detection device is a rain sensor and the control device using the attached matter detection device is a wiper control device, the wiper driving state can be controlled based on the detection result of the attached matter detection device.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of an attached matter detection device according to a first embodiment of the present invention and a principle of evaluating and detecting distortion and obstruction of a visual field of a person who views a detection surface.
FIG. 2 is a diagram illustrating an example of the reference pattern.
FIG. 3 is a diagram schematically showing a signal pattern of a light detection signal detected by the attached matter detection device of the present invention when there is no attached matter on the detection surface.
FIG. 4 is a diagram schematically illustrating a signal pattern of a light detection signal detected when there is an attached matter having a shape effect such as a raindrop on the detection surface.
FIG. 5 is a diagram schematically illustrating a signal pattern of a light detection signal detected when there is a light scattering adhering substance on the detection surface.
FIG. 6 is a diagram schematically illustrating a configuration example of the attached matter detection device according to the second embodiment of the present invention.
FIG. 7 is a diagram illustrating an example of a light source having a reference pattern in an opening.
FIG. 8 is a diagram illustrating a configuration example of an attached matter detection device according to the second embodiment of the present invention when a light source having a reference pattern in an opening is used.
FIG. 9A is a diagram schematically illustrating an end surface of the light source unit 10a, and FIG. 9B is a diagram illustrating the light source unit 10 with the surface where the opening 14 can be seen facing the front.
FIG. 10 is a diagram schematically illustrating an example of the lens 40.
FIG. 11 is a diagram illustrating an example of an array of light receiving elements in the light receiving element unit 50.
FIG. 12 is a diagram schematically illustrating an analysis / evaluation method using an MTF value.
FIG. 13 is a diagram showing an MTF value obtained when the attached matter is light rain (fog rain).
FIG. 14 is a diagram showing an MTF value obtained when the attached matter is heavy rain.
FIG. 15 is a diagram showing MTF values obtained when the rainfall is large.
FIG. 16 is a diagram illustrating an example in which a zebra pattern is actually photographed as seen through raindrops on a transparent substrate.
FIG. 17 is a flowchart illustrating a flow of a process of detecting the presence or absence of a deposit in the deposit detection unit 60.
FIG. 18 is a block diagram of a window wiper control device using the attached matter detection device as a rain sensor.
FIG. 19 is a flowchart illustrating an example of a processing operation flow of the window wiper control device according to the third embodiment.
FIG. 20 is a diagram simply showing an example of a mounting configuration of a window wiper control device using the attached matter detection device of the present invention as a rain sensor.
FIG. 21 is a diagram simply illustrating the principle of raindrop detection by a conventional reflected light detection type rain sensor.

Claims (8)

A transparent substrate having a detection surface,
A light source for irradiating the detection surface with light,
A reference pattern that is provided between the light source and the detection surface and has a portion where light transmittance or light reflectance is different,
A lens that focuses on the reference pattern, forms an image by receiving light passing through the reference pattern and the detection surface,
A light receiving unit comprising a plurality of minute light receiving elements, receiving light imaged by the lens, and outputting a light detection signal of each minute light receiving element as a signal pattern arranged in correspondence with the arrangement of the minute light receiving elements,
Analyzing the signal pattern detected by the light receiving means, comprising a signal pattern distortion detection unit that detects distortion of the signal pattern based on the reference pattern,
An adhering matter detection apparatus, wherein the signal pattern distortion detecting unit detects the presence of an adhering matter on the detection surface if the signal pattern distortion detecting unit detects the distortion of the signal pattern. The attached matter detection device according to claim 1, wherein the light source has the reference pattern on a light emitting opening, and the light source and the reference pattern are integrated. In the light receiving means, the light receiving area per one of the light receiving elements, the number of light receiving elements, and the arrangement of the light receiving elements can obtain a signal pattern having a resolution capable of analyzing a signal pattern distortion to be detected by the signal pattern distortion detecting section. The attached matter detection device according to claim 1 or 2, wherein the attached matter is detected. 3. The attached matter detection device according to claim 1, wherein the surface shape of the attached matter attached on the detection surface is estimated from the magnitude of the distortion of the signal pattern detected by the signal pattern distortion detection unit. 3. The attached matter detection device according to claim 1, wherein the light scattering property of the attached matter attached on the detection surface is estimated from a degree of blur of the signal pattern detected by the signal pattern distortion detection unit. The attached matter detection device according to any one of claims 1 to 5, wherein the detection surface is provided on a windshield of an automobile, and is a rain sensor that detects the presence of attached matter attached to the windshield. 7. The apparatus according to claim 6, further comprising: a window wiper driving unit; and a window wiper control unit.
A window wiper device, wherein the window wiper control unit changes the control content of the window wiper driving unit based on a result of estimation of the type and state of the deposit from the deposit estimation unit. The outer surface of the transparent substrate is used as the detection surface,
Irradiating light from the light source to the detection surface,
Provided between the light source and the detection surface a reference pattern having a portion where light transmittance or light reflectance is different,
Focus the lens on the reference pattern, receive light passing through the reference pattern and the detection surface to form an image,
By light receiving means having a plurality of minute light receiving elements, the light imaged by the lens is received, and the light detection signals of each minute light receiving element are arranged as corresponding to the minute light receiving elements and output as a signal pattern,
Analyzing the signal pattern detected by the light receiving means, detecting distortion of the signal pattern based on the reference pattern,
An attached matter detection method, wherein the presence of an attached matter on the detection surface is detected by detecting distortion of the signal pattern.

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