JP2004191071A

JP2004191071A - Inspection device of painted surface

Info

Publication number: JP2004191071A
Application number: JP2002355785A
Authority: JP
Inventors: Mari Iwata; 真理岩田
Original assignee: Daihatsu Motor Co Ltd
Current assignee: Daihatsu Motor Co Ltd
Priority date: 2002-12-06
Filing date: 2002-12-06
Publication date: 2004-07-08

Abstract

<P>PROBLEM TO BE SOLVED: To improve inspection accuracy of a painted surface (inspection accuracy of ridged parts, grooved parts or the like on the painted surface) concerning an inspection device of the painted surface. <P>SOLUTION: This device wherein a plurality of small independent bright parts are arranged at prescribed intervals in the first direction and in the second direction crossing the first direction, is equipped with an irradiation means 3 for irradiating the painted surface with inspection light so that parts other than the bright parts become dark parts. The device is also equipped with an imaging means 4 for receiving the inspection light irradiated from the irradiation means 3 and reflected by the painted surface, and an exclusion means for excluding a part corresponding to the normal outline of the bright part in image data received by the imaging means 4. The device is constituted so as to inspect the painted face from an edge processing result based on the image data received by the imaging means 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、塗装面の表面の状態を検査する塗装面の検査装置に関する。
【０００２】
【従来の技術】
例えば自動車のボディの塗装面を検査する検査装置として、例えば特許文献１及び２に開示されているように、所定の横幅を備えたストライプ状の明暗パターン（特許文献１の図１及び図２中の３，２ｃ）を、塗装面に対向するように配置し、明暗パターンに基づく検査光を明暗パターンから塗装面に照射する照射手段（特許文献１の図２中の２ａ）を備えて、照射手段から照射され塗装面で反射した検査光を受けて明暗パターンを撮像する撮像手段（特許文献１の図１中の５）を備えたものがある。
これにより、撮像手段により塗装面に映る明暗パターンを撮像して、撮像手段が受けた撮像データに基づくエッジ処理の結果により、塗装面の検査を行うように構成されている。
【０００３】
【特許文献１】
特開平８−１４５９０６号公報（図１及び図２）
【特許文献２】
特開平９−１２６７４４号公報（図１，３，４，５）
【０００４】
【発明が解決しようとする課題】
塗装面の検査としては一般に、塗装面の凸部や凹部等を検出するものがある。これにより、撮像手段が受けた撮像データに基づくエッジ処理の結果により塗装面の検査を行う場合に、高輝度の部分と低輝度の部分との境界部分の数が少ないと、塗装面の凸部や凹部等が見落とされ易くなる。
【０００５】
特許文献１及び２では、所定の横幅を備えたストライプ状の明暗パターンを使用しているので、明暗パターンの明部分に対応する高輝度の部分と明暗パターンの暗部分に対応する低輝度の部分との境界部分が、１本の直線状になっている。これにより、特許文献１及び２によると、ストライプと直交する方向では、明暗パターンの明部分に対応する高輝度の部分と明暗パターンの暗部分に対応する低輝度の部分との境界部分が、所定間隔を置いて存在する状態であるのに対して、ストライプと平行な方向では、明暗パターンの明部分に対応する高輝度の部分と明暗パターンの暗部分に対応する低輝度の部分との境界部分が、存在しない状態となっているので、ストライプと平行な方向では塗装面の凸部や凹部等が見落とされ易い状態になっている。
本発明は塗装面の検査装置において、塗装面の検査精度（塗装面の凸部や凹部等の検出精度）を向上させることを目的としている。
【０００６】
【課題を解決するための手段】
［Ｉ］
請求項１の特徴によると、独立した複数の小さな明部分が所定間隔を置いて第１方向及び第１方向と交差する第２方向に配置され、明部分以外の部分が暗部分となるように、検査光を塗装面に照射する照射手段、照射手段から照射され塗装面で反射した検査光を受ける撮像手段、撮像手段が受けた撮像データにおいて明部分の正常な外形に対応する部分を除く排除手段を備えており、撮像手段が受けた撮像データに基づくエッジ処理の結果により、塗装面を検査するように構成している。
【０００７】
これにより、請求項１の特徴によると、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が、１本の直線状ではなく、一つの閉じたループ状になっており（例えば円状や多角形状）、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が、所定間隔を置いて第１方向及び第１方向と交差する第２方向に配置される状態となる。
従って、請求項１の特徴によると、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が、一つの方向では存在するが別の方向では存在しないと言うような状態ではないので、塗装面の凸部や凹部等が見落とされ易い状態にはならない。
【０００８】
［ＩＩ］
請求項１の特徴によると、撮像手段が受けた撮像データにおいて明部分の正常な外形に対応する部分を除く排除手段を備えているので、撮像手段が受けた撮像データにおいて、塗装面の正常な部分に対応するものが除かれて、塗装面の凸部や凹部等の部分に対応するものが残る状態となる。
【０００９】
撮像手段が受けた撮像データにおいて、塗装面の正常な部分に対応するものでもノイズが含まれていることがあるので、請求項１の特徴のように、撮像手段が受けた撮像データにおいて、塗装面の正常な部分に対応するものを除くことにより、撮像手段が受けた撮像データに基づくエッジ処理の結果により塗装面を検査する場合のノイズの影響を少なくすることができる。
【００１０】
［ＩＩＩ］
請求項２の特徴によると、請求項１の場合と同様に前項［Ｉ］［ＩＩ］に記載の「作用」を備えており、これに加えて以下のような「作用」を備えている。
撮像手段が受けた撮像データを処理する手法としては、一般に２値化処理がある。２値化処理は塗装面に凸部や凹部等が存在するか否かを検出することはできるが、塗装面の凸部や凹部等の規模を精度良く検出することは困難である。
【００１１】
請求項２の特徴によると、撮像手段が受けた撮像データにおいて、明部分に対応する高輝度の部分と、暗部分に対応する低輝度の部分と、高輝度と低輝度との間の中間輝度の部分とを判別する判別手段を備えて、塗装面を検査するように構成している。これによって、請求項２の特徴によると、中間輝度の部分を判別して、中間輝度の部分を塗装面の凸部や凹部等と判断することにより、塗装面の凸部や凹部等の規模を精度良く検出することが可能になる。
【００１２】
［ＩＶ］
請求項３の特徴によると、請求項１又は２の場合と同様に前項［Ｉ］［ＩＩ］［ＩＩＩ］に記載の「作用」を備えており、これに加えて以下のような「作用」を備えている。
前項［Ｉ］に記載のように、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分を、１本の直線状ではなく、一つの閉じたループ状に構成する場合、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分を多角形状に構成すると、多角形状の角部の位置及び辺部の位置において、塗装面の凸部や凹部等の検出特性が異なるものになることが考えられる。
【００１３】
請求項３の特徴によると、明部分を円状に設定しており、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分、が円状になっているので、多角形状の角部の位置及び辺部の位置で塗装面の凸部や凹部等の検出特性が異なると言うような状態は生じない。
【００１４】
［Ｖ］
請求項４の特徴によると、請求項１〜３のうちのいずれか一つの場合と同様に前項［Ｉ］〜［ＩＶ］に記載の「作用」を備えており、これに加えて以下のような「作用」を備えている。
撮像手段が受けた撮像データに基づくエッジ処理の結果により塗装面を検査する場合、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が、明確であるほど（ニジミが少なく且つ乱れていない状態）、塗装面の検査精度（塗装面の凸部や凹部等の検出精度）が高いものとなる。
【００１５】
請求項４の特徴によると、発光ダイオードにより明部分が設定されるように構成している。発光ダイオードは一般に指向性が高く検査光が散乱し難いので、請求項４の特徴によると、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が、明確になり易くなっている（ニジミが少なく且つ乱れていない状態）。
【００１６】
【発明の実施の形態】
［１］
図１は自動車においてボディ１の塗装面の検査の状態を示しており、塗装の終了したボディ１がコンベア２により紙面左方に搬送されている。コンベア２に対し搬送上手側（図１の紙面右側）に照射装置３が配置され、コンベア２に対し搬送下手側（図１の紙面左側）に撮像装置４（例えばＣＣＤカメラ等）が配置されて、塗装面の検査装置が構成されている。コンベア２の搬送方向と直交する方向Ａ０に対して、照射装置３及び撮像装置４が略直交するように並べて配置されている。
【００１７】
図２に示すように、照射装置３は外枠部５、外枠部５の内部に配置された発光ダイオード６を備えて構成されている。発光ダイオード６は正面視で円状に構成されて、複数の発光ダイオード６が所定間隔を置いて上下方向及び上下方向と交差する左右方向に配置されている。外枠部５の内部が黒色に着色されている。
【００１８】
図１に示すように、撮像装置４に対してコントロールユニット７、画像処理装置８、コンピュータ９及びモニター１０等が備えられている。撮像装置４はボディ１の塗装面を介して照明装置３（発光ダイオード６）を撮像するように構成されており（照射装置３において、発光ダイオード６から検査光がボディ１の塗装面に照射され、ボディ１の塗装面で反射された検査光が撮像装置４に受けられる）、撮像装置４の焦点が照射装置３（発光ダイオード６）の位置に合わされるように構成されている。
【００１９】
以上のような塗装面の検査装置において、図１に示すようにボディ１がコンベア２により紙面左方に搬送されるのに伴って、前述のように撮像装置４がボディ１の塗装面を介して照射装置３（発光ダイオード６）を撮像する（撮像装置４の焦点が照射装置３（発光ダイオード６）の位置に合わされるように構成されている）。
【００２０】
［２］
前項［１］に記載のような塗装面の検査装置において、平面の塗装面では、撮像装置４が受けた撮像データは、図３（イ）及び図４に示すようなものとなる。この場合、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２が得られるのであり、塗装面の正常な部分では、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１が、円状になっている。塗装面の凸部や凹部等の部分では、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ３が、円状ではなく楕円状になるような状態になることがある。
【００２１】
塗装面の他の凸部や凹部等の部分によっては、図５（イ）（ロ）に示すように塗装面の凸部や凹部等の部分で、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ４が、中央に低い輝度の部分を備えたような状態になったり、図６（イ）（ロ）に示すように、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２において、少し高い輝度の部分Ｃ５が生じたりするようなことがある。以上のように塗装面の凸部や凹部等の部分によって状態が異なるのは、塗装面の凸部や凹部等の部分の表面形状の違いにより、発光ダイオード６からの検査光が乱反射する為であると考えられる。
【００２２】
この場合、撮像装置４の焦点が照射装置３（発光ダイオード６）の位置に合わされていることにより、図４，５（ロ），６（ロ）に示すように、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との境界部分が明確になり、且つ明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１の輝度が高いものになる（明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との差が、大きなものとなる）。
【００２３】
図３（イ）及び図４に示すような撮像装置４が受けた撮像データにおいて、図３（ロ）に示すように、撮像装置４が受けた撮像データが画像処理装置８によりエッジ処理されて（３値化処理等）、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２、高輝度Ｋ１と低輝度Ｋ２との間の中間輝度の部分Ｃ６が判別され、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、及び暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２が除かれる。これにより、図３（ロ）に示すように、中間輝度の部分Ｃ６が残り、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との境界部分Ｃ７が残る。
【００２４】
中間輝度の部分Ｃ６に比べて前述の境界部分Ｃ７は微小なので、前述の後に膨張及び収縮処理を数回行うと、図３（ハ）に示すように前述の境界部分Ｃ７が消えて、中間輝度の部分Ｃ６が残るのであり、中間輝度の部分Ｃ６をボディ１の塗装面の凸部や凹部等と判断することができる。これにより、残された中間輝度の部分Ｃ６に基づいて、面積判定処理、ラベリング処理、面積及び重心計算処理を行う。
【００２５】
［３］
前項［２］に記載のような平面の塗装面に対して、図７に示すように上下方向の軸芯を中心線とした曲面の塗装面では、撮像装置４が受けた撮像データは、図８（イ）に示すようなものとなる。
従って、前述と同様に図８（ロ）に示すように、撮像装置４が受けた撮像データが画像処理装置８によりエッジ処理されて（３値化処理等）、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２、高輝度Ｋ１と低輝度Ｋ２との間の中間輝度の部分Ｃ６が判別され、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、及び暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２が除かれる。
【００２６】
この後、図８（ハ）に示すように膨張及び収縮処理が数回行われて、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との境界部分Ｃ７が消えて、中間輝度の部分Ｃ６が残るのであり、中間輝度の部分Ｃ６をボディ１の塗装面の凸部や凹部等と判断することができる。これにより、残された中間輝度の部分Ｃ６に基づいて、面積判定処理、ラベリング処理、面積及び重心計算処理が行われる。
【００２７】
図９に示すように、前後方向の軸芯を中心線とした曲面の塗装面では、撮像装置４が受けた撮像データ、は図１０（イ）に示すようなものとなる。
従って、前述と同様に図１０（ロ）に示すように、撮像装置４が受けた撮像データが画像処理装置８によりエッジ処理されて（３値化処理等）、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２、高輝度Ｋ１と低輝度Ｋ２との間の中間輝度の部分Ｃ６が判別され、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、及び暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２が除かれる。
【００２８】
この後、図１０（ハ）に示すように膨張及び収縮処理が数回行われて、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との境界部分Ｃ７が消えて、中間輝度の部分Ｃ６が残るのであり、中間輝度の部分Ｃ６をボディ１の塗装面の凸部や凹部等と判断することができる。これにより、残された中間輝度の部分Ｃ６に基づいて、面積判定処理、ラベリング処理、面積及び重心計算処理が行われる。
【００２９】
［４］
前項［２］［３］に記載のように、撮像装置４が受けた撮像データにおいて、ボディ１の塗装色（例えば白色系や黒色系）により、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１や、中間輝度の部分Ｃ６の大きさが変化することがある。
【００３０】
図１１に示すように、一般に白色系のボディ１の塗装色では、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２の輝度が比較的高くなり、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との輝度差が、比較的小さなものとなる（濃淡差が小さい状態）。このような状態では、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１や、中間輝度の部分Ｃ６が比較的小さなものになる。
【００３１】
図１１に示すように、一般に黒色系のボディ１の塗装色では、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２の輝度が比較的低くなり、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との輝度差が、比較的大きなものとなる（濃淡差が大きい状態）。このような状態では、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１や、中間輝度の部分Ｃ６が比較的大きなものになる。
【００３２】
これにより、図１１に示すように、撮像装置４が受けた撮像データにおいて、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との輝度差に応じて、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１や、中間輝度の部分Ｃ６の大きさが基準の大きさとなるように補正される。
【００３３】
この後、前項［２］［３］に記載のように、撮像装置４が受けた撮像データの画像処理装置８によるエッジ処理（３値化処理等）、明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１、及び暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２の削除、膨張及び収縮処理、残された中間輝度の部分Ｃ６に基づく面積判定処理、ラベリング処理、面積及び重心計算処理が行われる。
【００３４】
［発明の実施の別形態］
前述の［発明の実施の形態］の図２に示す照射装置３において、発光ダイオード６の前側にブラックボード（図示せず）を配置し、発光ダイオード６の位置に対応するブラックボードの部分に、円状の開口を設けるように構成してもよい。このように構成すると、照射装置４において発光ダイオード６とブラックボードとの境界部分が明確になるので、図３（イ），５（イ），６（イ），８（イ），１０（イ）に示す明部分（発光ダイオード６）に対応する高輝度Ｋ１の部分Ｃ１と、暗部分（外枠部５）に対応する低輝度Ｋ２の部分Ｃ２との境界部分がさらに明確になる。
照射装置３における発光ダイオード６の配置としては、前述の［発明の実施の形態］の図２に示すような配置ばかりではなく、一つの中心から放射状（ガウス関数状）に配置したり、千鳥状に配置したりしてもよい。
【００３５】
【発明の効果】
請求項１の特徴によると塗装面の検査装置において、独立した複数の小さな明部分が所定間隔を置いて第１方向及び第１方向と交差する第２方向に配置され、明部分以外の部分が暗部分となるように、検査光を塗装面に照射することによって、塗装面の凸部や凹部等が見落とされ易い状態にならないようにすることができ、塗装面の検査精度（塗装面の凸部や凹部等の検出精度）を向上させることができた。
【００３６】
請求項１の特徴によると、撮像手段が受けた撮像データにおいて、塗装面の正常な部分に対応するものを除くことにより、撮像手段が受けた撮像データに基づくエッジ処理の結果により塗装面を検査する場合のノイズの影響を少なくすることができて、塗装面の検査精度（塗装面の凸部や凹部等の検出精度）を向上させることができた。
【００３７】
請求項２の特徴によると、請求項１の場合と同様に前述の請求項１の「発明の効果」を備えており、この「発明の効果」に加えて以下のような「発明の効果」を備えている。
請求項２の特徴によると、撮像手段が受けた撮像データにおいて、高輝度と低輝度との間の中間輝度の部分を判別することにより、中間輝度の部分を判別して中間輝度の部分を塗装面の凸部や凹部等と判断し、塗装面の凸部や凹部等の規模を精度良く検出することができるようになった。これにより、請求項２の特徴のように、塗装面の凸部や凹部等の規模を精度良く検出することができるようになれば、例えば塗装工程と塗装面の凸部や凹部等の規模との因果関係等の解析が行い易くなるのであり、塗装面の品質管理の面で有利なものとなる。
【００３８】
請求項３の特徴によると、請求項１又は２の場合と同様に前述の請求項１又は２の「発明の効果」を備えており、この「発明の効果」に加えて以下のような「発明の効果」を備えている。
請求項３の特徴によると、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が円状になっており、多角形状の角部の位置及び辺部の位置で塗装面の凸部や凹部等の検出特性が異なると言うような状態は生じないので、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分に対し、塗装面の凸部や凹部等がどの方向に位置していても、方向の影響を受けることなく、塗装面の凸部や凹部等が検出されるようになって、塗装面の検査精度（塗装面の凸部や凹部等の検出精度）を向上させることができた。
【００３９】
請求項４の特徴によると、請求項１〜３のうちのいずれか一つの場合と同様に前述の請求項１〜３の「発明の効果」を備えており、この「発明の効果」に加えて以下のような「発明の効果」を備えている。
請求項４の特徴によると、発光ダイオードにより明部分が設定されるように構成することにより、明部分に対応する高輝度の部分と暗部分に対応する低輝度の部分との境界部分が、明確になり易くなって（ニジミが少なく且つ乱れていない状態）、塗装面の検査精度（塗装面の凸部や凹部等の検出精度）を向上させることができた。
【図面の簡単な説明】
【図１】塗装面の検査装置の概要を示す平面図
【図２】照射装置の斜視図
【図３】撮像装置が受けた撮像データ、撮像装置が受けた撮像データに基づくエッジ処理（３値化処理等）、明部分（発光ダイオード）に対応する高輝度の部分及び暗部分（外枠部）に対応する低輝度の部分の削除、膨張及び収縮処理を行った状態を示す図
【図４】図３に示す撮像装置が受けた撮像データを３次元的に表現した図
【図５】撮像装置が受けた撮像データ（図３及び図４とは異なる）、並びに撮像装置が受けた撮像データ（図３及び図４とは異なる）を３次元的に表現した図
【図６】撮像装置が受けた撮像データ（図３，４，５とは異なる）、並びに撮像装置が受けた撮像データ（図３，４，５とは異なる）を３次元的に表現した図
【図７】上下方向の軸芯を中心線とした曲面の塗装面での検査の状態を示す斜視図
【図８】図７に示す撮像装置が受けた撮像データ、撮像装置が受けた撮像データに基づくエッジ処理（３値化処理等）、明部分（発光ダイオード）に対応する高輝度の部分及び暗部分（外枠部）に対応する低輝度の部分の削除、膨張及び収縮処理を行った状態を示す図
【図９】前後方向の軸芯を中心線とした曲面の塗装面での検査の状態を示す斜視図
【図１０】図９に示す撮像装置が受けた撮像データ、撮像装置が受けた撮像データに基づくエッジ処理（３値化処理等）、明部分（発光ダイオード）に対応する高輝度の部分及び暗部分（外枠部）に対応する低輝度の部分の削除、膨張及び収縮処理を行った状態を示す図
【図１１】ボディの塗装色に応じて行われる補正の状態を示す図
【符号の説明】
３照射手段
４撮像手段
６発光ダイオード
Ｋ１明部分に対応する高輝度
Ｋ２暗部分に対応する低輝度
Ｃ１明部分に対応する高輝度の部分
Ｃ２明部分に対応する低輝度の部分
Ｃ６高輝度と低輝度との間の中間輝度の部分[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a painted surface inspection apparatus for inspecting a surface state of a painted surface.
[0002]
[Prior art]
For example, as an inspection device for inspecting a painted surface of an automobile body, as disclosed in Patent Documents 1 and 2, for example, a stripe-shaped light and dark pattern having a predetermined width (see FIGS. 1 and 2 of Patent Document 1). 3, 2c) are arranged so as to face the painted surface, and are provided with irradiation means (2a in FIG. 2 of Patent Document 1) for irradiating the painted surface with the inspection light based on the light / dark pattern from the light / dark pattern. Some include an image pickup unit (5 in FIG. 1 of Patent Document 1) that receives an inspection light irradiated from the unit and reflected on the painted surface to image a light and dark pattern.
With this configuration, the light-dark pattern reflected on the painted surface is imaged by the imaging means, and the painted surface is inspected based on the result of the edge processing based on the image data received by the imaging means.
[0003]
[Patent Document 1]
JP-A-8-145906 (FIGS. 1 and 2)
[Patent Document 2]
JP-A-9-126744 (FIGS. 1, 3, 4, and 5)
[0004]
[Problems to be solved by the invention]
Inspection of a painted surface generally involves detecting a convex portion, a concave portion, or the like of the painted surface. Thereby, when inspecting the painted surface based on the result of the edge processing based on the imaging data received by the imaging means, if the number of boundary portions between the high luminance portion and the low luminance portion is small, the convex portion of the painted surface And concave portions are easily overlooked.
[0005]
In Patent Literatures 1 and 2, since a stripe-shaped light-dark pattern having a predetermined width is used, a high-luminance portion corresponding to a light portion of the light-dark pattern and a low-luminance portion corresponding to a dark portion of the light-dark pattern are used. Is a single straight line. Thus, according to Patent Documents 1 and 2, in the direction orthogonal to the stripe, the boundary between the high-luminance portion corresponding to the bright portion of the light-dark pattern and the low-luminance portion corresponding to the dark portion of the light-dark pattern is determined by a predetermined value. In the direction parallel to the stripe, the boundary portion between the high-luminance portion corresponding to the light portion of the light-dark pattern and the low-luminance portion corresponding to the dark portion of the light-dark pattern in the direction parallel to the stripe. However, since it does not exist, the projections and depressions of the painted surface are easily overlooked in the direction parallel to the stripe.
An object of the present invention is to improve the inspection accuracy of a painted surface (detection accuracy of a convex portion, a concave portion, or the like of a painted surface) in a painted surface inspection apparatus.
[0006]
[Means for Solving the Problems]
[I]
According to the features of claim 1, a plurality of independent small bright portions are arranged at a predetermined interval in the first direction and the second direction intersecting the first direction, and portions other than the bright portions become dark portions. Irradiating means for irradiating inspection light onto the painted surface, imaging means for receiving inspection light emitted from the irradiating means and reflected on the painted surface, and excluding portions corresponding to a normal shape of a bright portion in imaging data received by the imaging means Means for inspecting the painted surface based on the result of the edge processing based on the image data received by the imaging means.
[0007]
Thus, according to the first aspect of the present invention, the boundary between the high-brightness portion corresponding to the bright portion and the low-brightness portion corresponding to the dark portion is not a single straight line but a single closed loop. (For example, a circle or a polygon), and a boundary between a high-luminance portion corresponding to a bright portion and a low-luminance portion corresponding to a dark portion is separated from each other by a predetermined distance in the first direction and the first direction. Are arranged in the second direction intersecting with.
Therefore, according to the features of claim 1, it is said that a boundary portion between a high-luminance portion corresponding to a bright portion and a low-luminance portion corresponding to a dark portion exists in one direction but does not exist in another direction. Since it is not in such a state, a convex portion or a concave portion of the painted surface is not easily overlooked.
[0008]
[II]
According to the first aspect of the present invention, the image data received by the image pickup means includes an exclusion means for removing a portion corresponding to a normal outer shape of a bright portion. The parts corresponding to the parts are removed, and the parts corresponding to the parts such as the convex parts and the concave parts of the painted surface remain.
[0009]
The imaging data received by the imaging means may include noise even if it corresponds to a normal portion of the painted surface. By excluding a portion corresponding to a normal portion of the surface, it is possible to reduce the influence of noise when inspecting the painted surface based on the result of the edge processing based on the imaging data received by the imaging unit.
[0010]
[III]
According to the feature of the second aspect, similar to the case of the first aspect, the "action" described in the above [I] and [II] is provided, and in addition, the following "action" is provided.
As a method of processing the image data received by the imaging means, there is generally a binarization process. The binarization process can detect whether or not a convex portion or a concave portion exists on the painted surface, but it is difficult to accurately detect the scale of the convex portion or the concave portion on the painted surface.
[0011]
According to the feature of the second aspect, in the image data received by the imaging means, a high-luminance portion corresponding to a bright portion, a low-luminance portion corresponding to a dark portion, and an intermediate luminance between high luminance and low luminance. The apparatus is provided with a discriminating means for discriminating between the above-mentioned portions and inspecting the painted surface. Thus, according to the second aspect of the present invention, the intermediate luminance portion is determined, and the intermediate luminance portion is determined as a convex portion, a concave portion, or the like of the painted surface. It is possible to detect with high accuracy.
[0012]
[IV]
According to the feature of the third aspect, similar to the case of the first or second aspect, the "action" described in the above-mentioned [I], [II], and [III] is provided. It has.
As described in the preceding section [I], the boundary between the high-luminance part corresponding to the bright part and the low-luminance part corresponding to the dark part is formed not as one straight line but as one closed loop. In the case of configuring, if the boundary between the high-luminance part corresponding to the light part and the low-luminance part corresponding to the dark part is formed in a polygonal shape, the painted surface is formed at the positions of the corners and sides of the polygonal shape. It is conceivable that the detection characteristics of the convex portions, concave portions, and the like may be different.
[0013]
According to the feature of the third aspect, the bright portion is set in a circular shape, and a boundary portion between a high luminance portion corresponding to the bright portion and a low luminance portion corresponding to the dark portion is circular. As a result, a state does not occur in which the detection characteristics of the convex portion, the concave portion, and the like of the painted surface are different depending on the positions of the corners and the sides of the polygonal shape.
[0014]
[V]
According to the feature of the fourth aspect, similar to the case of any one of the first to third aspects, the "action" described in the above-mentioned [I] to [IV] is provided. It has various "actions".
When inspecting the painted surface based on the result of the edge processing based on the imaging data received by the imaging unit, the boundary between the high-luminance part corresponding to the bright part and the low-luminance part corresponding to the dark part is clearer. (In a state where the blur is small and not disturbed), the inspection accuracy of the painted surface (detection accuracy of the convex portion, the concave portion and the like of the painted surface) becomes high.
[0015]
According to the feature of the fourth aspect, the light portion is set by the light emitting diode. Since the light emitting diode generally has high directivity and the inspection light is hard to be scattered, according to the feature of claim 4, a boundary portion between a high brightness portion corresponding to a bright portion and a low brightness portion corresponding to a dark portion is clearly defined. (The state where bleeding is small and not disturbed).
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
[1]
FIG. 1 shows a state of inspection of a painted surface of a body 1 in an automobile. The painted body 1 is conveyed by a conveyor 2 to the left in the drawing. The irradiation device 3 is arranged on the upper side of the conveyor 2 (the right side of the paper of FIG. 1), and the imaging device 4 (for example, a CCD camera) is arranged on the lower side of the conveyor 2 (the left side of the paper of FIG. 1). And an inspection device for the painted surface. The irradiation device 3 and the imaging device 4 are arranged side by side so as to be substantially orthogonal to a direction A0 orthogonal to the transport direction of the conveyor 2.
[0017]
As shown in FIG. 2, the irradiation device 3 includes an outer frame 5 and a light emitting diode 6 disposed inside the outer frame 5. The light emitting diodes 6 are formed in a circular shape when viewed from the front, and a plurality of light emitting diodes 6 are arranged at predetermined intervals in the vertical direction and in the horizontal direction intersecting the vertical direction. The inside of the outer frame portion 5 is colored black.
[0018]
As shown in FIG. 1, a control unit 7, an image processing device 8, a computer 9, a monitor 10, and the like are provided for the imaging device 4. The imaging device 4 is configured to capture an image of the illumination device 3 (light emitting diode 6) through the painted surface of the body 1 (in the irradiation device 3, inspection light is emitted from the light emitting diode 6 to the painted surface of the body 1). The inspection light reflected by the painted surface of the body 1 is received by the image pickup device 4), and the focus of the image pickup device 4 is adjusted to the position of the irradiation device 3 (light emitting diode 6).
[0019]
In the inspection apparatus for the painted surface as described above, as shown in FIG. 1, as the body 1 is transported to the left of the paper by the conveyor 2, the imaging device 4 is moved through the painted surface of the body 1 as described above. To image the irradiation device 3 (light emitting diode 6) (configured such that the focus of the imaging device 4 is adjusted to the position of the irradiation device 3 (light emitting diode 6)).
[0020]
[2]
In the painted surface inspection apparatus as described in [1] above, on a planar painted surface, the imaging data received by the imaging device 4 is as shown in FIGS. 3A and 4. In this case, a portion C1 of high brightness K1 corresponding to a bright portion (light emitting diode 6) and a portion C2 of low brightness K2 corresponding to a dark portion (outer frame portion 5) are obtained. The portion C1 of the high luminance K1 corresponding to the bright portion (the light emitting diode 6) is circular. In a portion such as a convex portion or a concave portion of the painted surface, a portion C3 of the high luminance K1 corresponding to the bright portion (the light emitting diode 6) may be in an elliptical shape instead of a circular shape.
[0021]
As shown in FIGS. 5 (a) and 5 (b), depending on other portions such as convex portions or concave portions of the painted surface, the portions corresponding to the bright portions (light emitting diodes 6) may be formed at the convex portions or concave portions of the painted surface. The portion C4 of the brightness K1 has a low brightness portion at the center, or the low brightness K2 corresponding to the dark portion (outer frame portion 5) as shown in FIGS. In the portion C2, a portion C5 having a slightly higher luminance may occur. As described above, the state is different depending on the portion such as the convex portion or the concave portion of the painted surface because the inspection light from the light emitting diode 6 is irregularly reflected due to the difference in the surface shape of the portion such as the convex portion or the concave portion of the painted surface. It is believed that there is.
[0022]
In this case, since the focus of the imaging device 4 is adjusted to the position of the irradiation device 3 (light emitting diode 6), the bright portion (light emitting diode 6) as shown in FIGS. The boundary between the high-intensity K1 portion C1 corresponding to the dark portion (the outer frame portion 5) and the low-intensity K2 portion C2 corresponding to the dark portion (the outer frame portion 5) becomes clear, and the high brightness corresponding to the bright portion (the light emitting diode 6). The brightness of the portion C1 of K1 becomes higher (the difference between the portion C1 of high brightness K1 corresponding to the bright portion (light emitting diode 6) and the portion C2 of low brightness K2 corresponding to the dark portion (outer frame portion 5). But it will be bigger).
[0023]
In the image data received by the imaging device 4 as shown in FIGS. 3A and 4, the image data received by the imaging device 4 is subjected to edge processing by the image processing device 8 as shown in FIG. (Three-value processing, etc.), a portion C1 of high brightness K1 corresponding to a bright portion (light emitting diode 6), a portion C2 of low brightness K2 corresponding to a dark portion (outer frame portion 5), a high brightness K1 and a low brightness K2. Is determined, and a portion C1 of high brightness K1 corresponding to a bright portion (light emitting diode 6) and a portion C2 of low brightness K2 corresponding to a dark portion (outer frame portion 5) are removed. I will As a result, as shown in FIG. 3B, a portion C6 of the intermediate brightness remains, and a portion C1 of the high brightness K1 corresponding to the bright portion (the light emitting diode 6) and a low portion corresponding to the dark portion (the outer frame portion 5). A boundary portion C7 with the portion C2 of the luminance K2 remains.
[0024]
Since the above-described boundary portion C7 is smaller than the intermediate luminance portion C6, if the expansion and contraction processing is performed several times after the above, the above-described boundary portion C7 disappears as shown in FIG. The portion C6 of the intermediate brightness can be determined as a convex portion, a concave portion, or the like of the painted surface of the body 1. Thus, based on the remaining intermediate luminance portion C6, the area determination processing, the labeling processing, and the area and center-of-gravity calculation processing are performed.
[0025]
[3]
With respect to a flat painted surface as described in the preceding section [2], on a curved painted surface having a vertical axis as a center line as shown in FIG. 7, the imaging data received by the imaging device 4 is shown in FIG. The result is as shown in FIG.
Accordingly, similarly to the above, as shown in FIG. 8B, the image data received by the imaging device 4 is subjected to edge processing (ternarization processing or the like) by the image processing device 8 to form a bright portion (light emitting diode 6). A corresponding portion C1 of the high luminance K1, a portion C2 of the low luminance K2 corresponding to the dark portion (outer frame portion 5), and a portion C6 of the intermediate luminance between the high luminance K1 and the low luminance K2 are determined, and the bright portion ( The portion C1 of the high brightness K1 corresponding to the light emitting diode 6) and the portion C2 of the low brightness K2 corresponding to the dark portion (outer frame portion 5) are removed.
[0026]
Thereafter, as shown in FIG. 8C, the expansion and contraction processing is performed several times to correspond to the high-intensity K1 portion C1 corresponding to the bright portion (the light-emitting diode 6) and the dark portion (the outer frame portion 5). The boundary portion C7 with the low-luminance K2 portion C2 disappears, and the intermediate-luminance portion C6 remains, so that the intermediate-luminance portion C6 can be determined as a convex portion, a concave portion, or the like of the painted surface of the body 1. As a result, the area determination processing, the labeling processing, and the area and centroid calculation processing are performed based on the remaining intermediate luminance portion C6.
[0027]
As shown in FIG. 9, on a curved painted surface whose center line is the axis in the front-rear direction, the imaging data received by the imaging device 4 is as shown in FIG.
Therefore, similarly to the above, as shown in FIG. 10B, the image data received by the imaging device 4 is subjected to edge processing (eg, ternary processing) by the image processing device 8 to form a bright portion (light emitting diode 6). A corresponding portion C1 of the high luminance K1, a portion C2 of the low luminance K2 corresponding to the dark portion (outer frame portion 5), and a portion C6 of the intermediate luminance between the high luminance K1 and the low luminance K2 are determined, and the bright portion ( The portion C1 of the high brightness K1 corresponding to the light emitting diode 6) and the portion C2 of the low brightness K2 corresponding to the dark portion (outer frame portion 5) are removed.
[0028]
Thereafter, as shown in FIG. 10 (c), expansion and contraction processes are performed several times to correspond to the portion C1 of the high luminance K1 corresponding to the bright portion (the light emitting diode 6) and the dark portion (the outer frame portion 5). The boundary portion C7 with the low-luminance K2 portion C2 disappears, and the intermediate-luminance portion C6 remains, so that the intermediate-luminance portion C6 can be determined as a convex portion, a concave portion, or the like of the painted surface of the body 1. As a result, the area determination processing, the labeling processing, and the area and centroid calculation processing are performed based on the remaining intermediate luminance portion C6.
[0029]
[4]
As described in [2] and [3] above, in the imaging data received by the imaging device 4, a high luminance corresponding to a light portion (the light emitting diode 6) is obtained depending on a paint color (for example, white or black) of the body 1. The size of the portion C1 of K1 and the portion C6 of the intermediate luminance may change.
[0030]
As shown in FIG. 11, in the coating color of the white body 1 in general, the brightness of the portion C2 of the low brightness K2 corresponding to the dark portion (outer frame portion 5) becomes relatively high, and the light portion (light emitting diode 6) And the luminance difference between the high luminance K1 part C1 corresponding to the dark part (outer frame part 5) and the low luminance K2 part C2 becomes relatively small (in a state where the density difference is small). In such a state, the portion C1 of the high luminance K1 corresponding to the bright portion (the light emitting diode 6) and the portion C6 of the intermediate luminance become relatively small.
[0031]
As shown in FIG. 11, in general, in the coating color of the black body 1, the luminance of the portion C2 of the low luminance K2 corresponding to the dark portion (the outer frame portion 5) is relatively low, and the light portion (the light emitting diode 6). , And a portion C2 of low brightness K2 corresponding to the dark portion (outer frame portion 5) have a relatively large brightness difference (a state where the shading difference is large). In such a state, the portion C1 of the high luminance K1 corresponding to the bright portion (the light emitting diode 6) and the portion C6 of the intermediate luminance become relatively large.
[0032]
As a result, as shown in FIG. 11, in the imaging data received by the imaging device 4, a portion C1 of the high luminance K1 corresponding to the bright portion (the light emitting diode 6) and a low portion corresponding to the dark portion (the outer frame portion 5). According to the luminance difference between the luminance K2 and the part C2, the magnitude of the high luminance K1 part C1 corresponding to the bright part (the light emitting diode 6) and the magnitude of the intermediate luminance part C6 are corrected to the reference magnitude. .
[0033]
Thereafter, as described in [2] and [3] above, the image data corresponds to edge processing (eg, ternarization processing) by the image processing device 8 of the image data received by the imaging device 4 and a bright portion (the light emitting diode 6). Deletion, expansion and contraction processing of the high luminance K1 part C1 and the low luminance K2 part C2 corresponding to the dark part (outer frame part 5), area determination processing based on the remaining intermediate luminance part C6, labeling processing, The area and the center of gravity are calculated.
[0034]
[Another embodiment of the invention]
In the irradiation device 3 shown in FIG. 2 of the above-mentioned [Embodiment of the invention], a black board (not shown) is arranged in front of the light emitting diode 6, and a black board portion corresponding to the position of the light emitting diode 6 is provided. You may comprise so that a circular opening may be provided. With this configuration, the boundary between the light emitting diode 6 and the black board in the irradiation device 4 becomes clear, so that FIGS. 3 (a), 5 (a), 6 (a), 8 (a), 10 (a) The boundary between the portion C1 of high brightness K1 corresponding to the bright portion (light emitting diode 6) and the portion C2 of low brightness K2 corresponding to the dark portion (outer frame portion 5) becomes clearer.
The arrangement of the light emitting diodes 6 in the irradiation device 3 is not limited to the arrangement shown in FIG. 2 of the above-described [Embodiment of the Invention], but may be arranged radially (Gaussian function) from one center or in a staggered manner. Or may be arranged at
[0035]
【The invention's effect】
According to the feature of claim 1, in the inspection apparatus for painted surface, a plurality of independent small bright portions are arranged at predetermined intervals in a first direction and a second direction intersecting the first direction, and portions other than the bright portion are arranged. By irradiating the inspection surface with the inspection light so as to form a dark portion, it is possible to prevent the convex portions and the concave portions of the painted surface from being easily overlooked, and to improve the inspection accuracy of the painted surface (the convexity of the painted surface). (Accuracy of detecting a part, a concave part, and the like).
[0036]
According to the feature of claim 1, by removing the image data received by the imaging means corresponding to a normal portion of the painted surface, the painted surface is inspected by the result of the edge processing based on the image data received by the imaging means. In this case, the influence of noise can be reduced, and the inspection accuracy of the painted surface (detection accuracy of a convex portion, a concave portion, or the like of the painted surface) can be improved.
[0037]
According to the feature of the second aspect, similar to the case of the first aspect, the "effect of the invention" of the above-described claim 1 is provided. It has.
According to the second aspect of the present invention, in the imaging data received by the imaging means, the intermediate luminance portion between the high luminance and the low luminance is determined to determine the intermediate luminance portion and paint the intermediate luminance portion. It is possible to accurately detect the scale of the convex portion or the concave portion of the painted surface by judging the convex portion or the concave portion of the surface. As a result, if it is possible to accurately detect the scale of the convex portion or the concave portion of the painted surface as in the feature of the second aspect, for example, the coating process and the scale of the convex portion or the concave portion of the painted surface may be reduced. This makes it easier to analyze the causal relationship of the above, which is advantageous in terms of quality control of the painted surface.
[0038]
According to the feature of the third aspect, similar to the case of the first or second aspect, the present invention has the "effect of the invention" of the first or second aspect, and in addition to the "effect of the invention", the following " Effect of the Invention ".
According to the feature of claim 3, the boundary between the high-luminance part corresponding to the bright part and the low-luminance part corresponding to the dark part is circular, and the positions of the corners and the sides of the polygonal shape are determined. Since there is no state where the detection characteristics such as convexities and concaves of the painted surface differ depending on the position, the boundary between the high-luminance part corresponding to the bright part and the low-luminance part corresponding to the dark part Regardless of the direction in which the projections and depressions of the painted surface are located, the projections and depressions of the painted surface are detected without being affected by the direction, and the inspection accuracy of the painted surface ( It was possible to improve the accuracy of detecting the convex portions and concave portions of the painted surface.
[0039]
According to the features of claim 4, the "effects of the invention" of the above-mentioned claims 1 to 3 are provided similarly to the case of any one of the claims 1 to 3, and in addition to the "effects of the invention" The following "effects of the invention" are provided.
According to the fourth aspect of the present invention, by configuring the light-emitting diode so that the bright portion is set, the boundary between the high-luminance portion corresponding to the bright portion and the low-luminance portion corresponding to the dark portion is clearly defined. (In a state where blurring is small and not disturbed), and the inspection accuracy of the painted surface (detection accuracy of a convex portion, a concave portion, or the like of the painted surface) can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view showing an outline of a coating surface inspection apparatus. FIG. 2 is a perspective view of an irradiation apparatus. FIG. 3 is image data received by an image pickup apparatus and edge processing based on image data received by the image pickup apparatus (ternary value). FIG. 4 shows a state in which deletion, expansion, and contraction processing of a high-luminance portion corresponding to a light portion (light-emitting diode) and a low-luminance portion corresponding to a dark portion (outer frame portion) are performed. 3 is a three-dimensional representation of image data received by the image pickup apparatus shown in FIG. 3; FIG. 5 is image data received by the image pickup apparatus (different from FIGS. 3 and 4); and image data received by the image pickup apparatus FIG. 6 is a diagram expressing three-dimensionally (different from FIGS. 3 and 4) FIG. 6: imaging data received by the imaging device (different from FIGS. 3, 4, and 5) and imaging data received by the imaging device ( (Different from FIGS. 3, 4 and 5) in three dimensions [FIG. 7] Vertical axis FIG. 8 is a perspective view showing a state of inspection on a curved painted surface with a center line as the center line. FIG. 8 shows image data received by the image capturing apparatus shown in FIG. 7, and edge processing (ternarization processing) based on image data received by the image capturing apparatus FIG. 9 shows a state in which a high-brightness portion corresponding to a bright portion (light-emitting diode) and a low-brightness portion corresponding to a dark portion (outer frame portion) have been deleted, expanded, and contracted. FIG. 10 is a perspective view showing a state of inspection on a curved painted surface with a center axis of a direction as a center line. FIG. 10 shows image data received by the image capturing apparatus shown in FIG. 9 and edge processing based on image data received by the image capturing apparatus. Diagram showing a state in which deletion, expansion and contraction processing of a high-luminance portion corresponding to a light portion (light-emitting diode) and a low-luminance portion corresponding to a dark portion (outer frame portion) have been performed. FIG. 11 shows a state of correction performed according to the paint color of the body. DESCRIPTION OF SYMBOLS
3 irradiating means 4 imaging means 6 light emitting diode K1 high brightness K2 corresponding to a bright portion low brightness C1 corresponding to a dark portion high brightness portion C2 corresponding to a bright portion low brightness portion C6 corresponding to a bright portion C6 high brightness and low Part of the intermediate luminance between the luminance

Claims

The inspection light is applied to the painted surface so that a plurality of independent small bright portions are arranged at predetermined intervals in a first direction and a second direction intersecting the first direction, and portions other than the bright portions become dark portions. Irradiating means for irradiating;
Imaging means for receiving inspection light irradiated from the irradiation means and reflected on the painted surface;
Excluding means for removing a portion corresponding to a normal outer shape of the bright portion in the imaging data received by the imaging means,
A painted surface inspection apparatus configured to inspect the painted surface based on a result of edge processing based on imaging data received by the imaging unit.

In the imaging data received by the imaging means, a high-luminance portion corresponding to the bright portion, a low-luminance portion corresponding to the dark portion, and an intermediate-luminance portion between the high luminance and the low luminance. The painted surface inspection apparatus according to claim 1, further comprising a discriminating unit configured to inspect the painted surface.

The inspection device for a painted surface according to claim 1 or 2, wherein the bright portion is set in a circular shape.

The painted surface inspection device according to any one of claims 1 to 3, wherein the bright portion is set by a light emitting diode.