JP5297245B2 - Object surface inspection equipment - Google Patents

Object surface inspection equipment Download PDF

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JP5297245B2
JP5297245B2 JP2009077659A JP2009077659A JP5297245B2 JP 5297245 B2 JP5297245 B2 JP 5297245B2 JP 2009077659 A JP2009077659 A JP 2009077659A JP 2009077659 A JP2009077659 A JP 2009077659A JP 5297245 B2 JP5297245 B2 JP 5297245B2
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inspection
light
imaging
luminance
inspection surface
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JP2010230450A (en
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正治 杭ノ瀬
良介 三高
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Panasonic Corp
Panasonic Holdings Corp
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Panasonic Corp
Matsushita Electric Industrial Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an object surface inspection apparatus capable of clearly detecting a difference of glossiness at an inspected surface of an object surface. <P>SOLUTION: The object surface inspection apparatus includes an irradiation device 2 which irradiates an inspected surface 51 with line-like inspection light from a direction crossly intersecting with a normal line direction L1 of an inspected surface 51 of an inspected object 50; an imaging device 3 which is equipped with a light receiving element disposed in line-like, is arranged so that an angle &delta;2 between a light-receiving optical axis L3 of the light receiving element and the normal line direction of the inspected surface 51 is equal to an angle &delta;1 between a light projection optical axis L2 of the irradiation device 2 and the normal line direction L1 of the inspected surface 51, and images the inspected surface 51; in which the irradiation device 2 and the imaging device 3 are arranged so that the extending direction of the line-like inspection light and the extending direction L4 of a line-like visual field A intersect crossly to a conveying direction L5 of the inspected object 50 by a conveyer 4 at same angles &theta;1 and &theta;2 respectively. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

本発明は、検査対象物の検査面に光を照射させるとともに、検査面を撮像して得た画像を解析することによって検査面の検査を行う物体表面検査装置に関するものである。   The present invention relates to an object surface inspection apparatus that inspects an inspection surface by irradiating an inspection surface of an inspection object with light and analyzing an image obtained by imaging the inspection surface.

一般的に、検査対象物の表面(検査面)の光沢度を計測する検査装置として、検査面の法線方向と投光光軸のなす角度を約45度とした光源から検査面に光を照射させるとともに、検査面で反射された正反射光を、検査面の法線方向と受光光軸の成す角度を約45度とした撮像手段で撮像し、撮像手段の撮像画像から検査面の光沢度を観測するものがあった。   Generally, as an inspection device that measures the glossiness of the surface (inspection surface) of an inspection object, light is applied to the inspection surface from a light source whose angle between the normal direction of the inspection surface and the projection optical axis is about 45 degrees. The regular reflected light reflected by the inspection surface is imaged by the imaging means whose angle between the normal direction of the inspection surface and the light receiving optical axis is about 45 degrees, and the gloss of the inspection surface is obtained from the captured image of the imaging means. There was something to observe the degree.

また特許文献1に示されるように、検査対象物の一側方斜め上方に光源を配置して、光源から検査面に浅い入射角度で照明光を照射させると共に、検査対象物の他側方斜め上方に撮像装置を配置して、検査面を浅い撮像角度で撮像することで、検査面の異物や突起を影として捉えるようにした検査方法も従来提案されている。   Further, as shown in Patent Document 1, a light source is arranged obliquely above one side of the inspection object, and illumination light is irradiated from the light source to the inspection surface at a shallow incident angle, and the other side of the inspection object is oblique. There has also been proposed an inspection method in which an imaging device is arranged above and an inspection surface is imaged at a shallow imaging angle so that foreign matters and protrusions on the inspection surface are captured as shadows.

特開平8−5573号公報JP-A-8-5573

ところで、接着剤を塗布した合板に突板を重ねた上で、平滑な圧板により突板を合板に圧接して製造される床材の場合、突板が破損した箇所では、接着剤が圧板に直接押し付けられて平滑面ができ、部分的にツヤ(光沢)を生じるようになる。また金属板の表面において傷などが発生することによって、周囲の部位に比べて光沢度の高い部位が発生する場合があり、上述した従来の検査方法を用いて、光沢度の高い部位を光沢度が低い粗面と弁別して検出したいという要求があった。   By the way, in the case of flooring manufactured by stacking the veneer on the plywood coated with adhesive and then pressing the veneer against the plywood with a smooth pressure plate, the adhesive is directly pressed against the pressure plate at the location where the veneer is damaged. As a result, a smooth surface is formed, and gloss is partially produced. In addition, a scratch or the like on the surface of the metal plate may cause a portion having a higher gloss than the surrounding portion. Using the above-described conventional inspection method, a portion having a higher gloss is treated as a gloss. There is a demand to discriminate from low rough surfaces.

しかしながら、床材などの板材や表面にヘアライン加工などの微細な凹凸加工が施された金属板のように、特定の方向に対しては光を散乱反射しやすく、別の方向に対しては光を正反射しやすい表面性状を有する検査対象物の場合、表面の光沢度の差を明瞭に検出するためには、光が散乱反射される方向から検査対象物を観測する必要がある。ここで、床材や金属板のような長大物の製造現場において、合板の表面に突板を接着する工程や、金属板の表面に凹凸加工を施す工程の後で、床材や金属板からなる検査対象物の表面に対し、搬送方向と直交する方向に延びるライン光を照射させるとともに、ラインカメラで対象物表面を撮像して表面検査を行う場合、床材や金属板を搬送移動させる方向と、散乱反射が最大となる方向とが必ずしも一致しないため、撮像方向を搬送方向と一致させて撮像装置が設置されていると、散乱反射が最大となる方向から検査対象物を観測することができない場合があった。   However, it is easy to scatter and reflect light in a specific direction and light in another direction, such as a plate material such as a flooring or a metal plate whose surface has been subjected to fine irregularities such as hairline processing. In the case of an inspection object having a surface property that is likely to be regularly reflected, it is necessary to observe the inspection object from the direction in which light is scattered and reflected in order to clearly detect the difference in glossiness of the surface. Here, in a manufacturing site of a large material such as a flooring material or a metal plate, it is composed of the flooring material or the metal plate after the step of bonding the protruding plate to the surface of the plywood or the step of performing the uneven processing on the surface of the metal plate. When the surface of the inspection object is irradiated with line light extending in a direction perpendicular to the conveyance direction and the surface of the object is imaged with a line camera to perform surface inspection, the floor material or the metal plate is conveyed and moved. Since the direction in which the scattering reflection is maximum does not necessarily match, if the imaging device is installed with the imaging direction aligned with the transport direction, the inspection object cannot be observed from the direction in which the scattering reflection is maximum. There was a case.

本発明は上記問題点に鑑みて為されたものであり、その目的とするところは、物体表面の検査面において光沢度の差を明瞭に検出できる物体表面検査装置を提供することにある。   The present invention has been made in view of the above problems, and an object thereof is to provide an object surface inspection apparatus capable of clearly detecting a difference in glossiness on an inspection surface of an object surface.

上記目的を達成するために、請求項1の発明は、検査対象物の検査面の法線方向と斜めに交差する方向からライン状の検査光を検査面に照射する照明手段と、ライン状に配置された受光素子を具備し受光素子の受光光軸と検査面の法線方向との為す角度が照明手段の投光光軸と検査面の法線方向の為す角度と同じ角度になるように配置されて検査面を撮像する撮像手段と、撮像手段が撮像した画像を解析することによって検査面の検査を行う検査処理手段とを備え、照明手段および撮像手段は、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向が、照明手段および撮像手段に対して検査対象物が相対的に移動する移動方向に対して、それぞれ同じ角度で斜めに交差するように配置され、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向が移動方向と為す角度を計測する角度計測手段と、角度計測手段の計測結果に基づいて撮像手段が撮像した画像の変形を補正する画像補正手段と、検査面において光沢度が大きくなる方向に急変する光沢変化部を検出するために用いられる輝度の第1閾値と輝度変化量の第2閾値とを記憶する記憶部を備え、検査処理手段が、画像補正手段による補正後の画像を解析することによって検査面の検査を行い、検査処理手段が、検査面の撮像画像から第1閾値よりも輝度が高い領域を明部として抽出する明部抽出機能と、明部と明部の周辺部とでそれぞれ輝度の平均値を求め、明部における輝度の平均値と周辺部における輝度の平均値との輝度差が第2閾値より大きい場合を光沢変化部と判断する光沢変化判断機能とを備えることを特徴とする。 In order to achieve the above object, the invention of claim 1 is directed to an illumination means for irradiating the inspection surface with linear inspection light from a direction obliquely intersecting with the normal direction of the inspection surface of the inspection object, The light receiving element is arranged and the angle formed between the light receiving optical axis of the light receiving element and the normal direction of the inspection surface is the same as the angle formed between the light projecting optical axis of the illumination means and the normal direction of the inspection surface. An imaging unit arranged to image the inspection surface and an inspection processing unit that inspects the inspection surface by analyzing an image captured by the imaging unit, and the illumination unit and the imaging unit extend line-shaped inspection light. the extending direction of the direction and linear imaging region, the moving direction of the inspection object with respect to the illumination means and the imaging means moves relative, is arranged such that intersect obliquely at the same angle, the line Direction of the inspection light An angle measuring unit that measures an angle formed by the extending direction of the line-shaped imaging region and a moving direction, an image correcting unit that corrects deformation of an image captured by the imaging unit based on a measurement result of the angle measuring unit, and an inspection surface And a storage unit for storing a first threshold value for luminance and a second threshold value for the amount of change in luminance, which are used to detect a glossy change part that suddenly changes in the direction in which the glossiness increases. A bright portion extraction function for inspecting the inspection surface by analyzing the image after correction by the image processing means, wherein the inspection processing means extracts a region having a brightness higher than the first threshold as a bright portion from the captured image of the inspection surface; The average value of luminance is obtained for each of the bright part and the peripheral part of the bright part, and when the luminance difference between the average value of the luminance in the bright part and the average value of the luminance in the peripheral part is larger than the second threshold value, it is determined as the gloss changing part. Gloss change size Characterized in that it comprises a function.

請求項の発明は、請求項1の発明において、検査面において光沢度が小さくなる方向に急変する光沢変化部を検出するために用いられる輝度の第3閾値と輝度変化量の第4閾値を記憶部が記憶し、検査処理手段が、検査面の撮像画像から第3閾値よりも輝度が低い領域を暗部として抽出する暗部抽出機能と、暗部暗部の周辺部とでそれぞれ輝度の平均値を求め、暗部における輝度の平均値と周辺部における輝度の平均値との輝度差が第4閾値より大きい場合を光沢変化部と判断する光沢変化判断機能とを備えることを特徴とする。 According to a second aspect of the present invention, in the first aspect of the present invention, a third threshold value for luminance and a fourth threshold value for the amount of change in luminance used for detecting a glossy change portion that suddenly changes in the direction of decreasing glossiness on the inspection surface. the storage unit stores, inspection processing means, and the dark extracting function of extracting a region luminance is lower than the third threshold value from the captured image of the inspection surface as dark portions, the dark portion and the dark respectively between the peripheral area brightness average value And a gloss change determining function that determines that the brightness difference between the average brightness value in the dark area and the average brightness value in the peripheral area is larger than the fourth threshold value as the gloss change section.

請求項の発明は、検査対象物の検査面の法線方向と斜めに交差する方向からライン状の検査光を検査面に照射する照明手段と、ライン状に配置された受光素子を具備し受光素子の受光光軸と検査面の法線方向との為す角度が照明手段の投光光軸と検査面の法線方向の為す角度と同じ角度になるように配置されて検査面を撮像する撮像手段と、撮像手段が撮像した画像を解析することによって検査面の検査を行う検査処理手段とを備え、照明手段および撮像手段は、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向が、照明手段および撮像手段に対して検査対象物が相対的に移動する移動方向に対して、それぞれ同じ角度で斜めに交差するように配置され、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向が移動方向と為す角度を計測する角度計測手段と、角度計測手段の計測結果に基づいて撮像手段が撮像した画像の変形を補正する画像補正手段と、検査面において光沢度が小さくなる方向に急変する光沢変化部を検出するために用いられる輝度の第3閾値と輝度変化量の第4閾値とを記憶する記憶部を備え、検査処理手段が、画像補正手段による補正後の画像を解析することによって検査面の検査を行い、検査処理手段が、検査面の撮像画像から第3閾値よりも輝度が低い領域を暗部として抽出する暗部抽出機能と、暗部と当該暗部の周辺部とでそれぞれ輝度の平均値を求め、暗部における輝度の平均値と周辺部における輝度の平均値との輝度差が第4閾値より大きい場合を光沢変化部と判断する光沢変化判断機能とを備えることを特徴とする。 The invention of claim 3 comprises illumination means for irradiating the inspection surface with line-shaped inspection light from a direction obliquely intersecting the normal direction of the inspection surface of the inspection object, and light receiving elements arranged in a line. The inspection surface is picked up so that the angle formed by the light receiving optical axis of the light receiving element and the normal direction of the inspection surface is the same as the angle formed by the projection optical axis of the illumination means and the normal direction of the inspection surface. An imaging unit; and an inspection processing unit that inspects an inspection surface by analyzing an image captured by the imaging unit. The illumination unit and the imaging unit are configured to extend the line-shaped inspection light and the line-shaped imaging region. The extending direction is arranged so as to cross obliquely at the same angle with respect to the moving direction in which the inspection object moves relative to the illumination unit and the imaging unit, and the extending direction and the line of the line-shaped inspection light Of the imaging area And angle measuring means for direction to measure the angle formed by the direction of movement that the image correcting means for imaging means to correct the deformation of an image captured based on the measurement result of the angle measuring means, the direction in which the glossiness is decreased in the inspection surface And a storage unit for storing a third threshold value for luminance and a fourth threshold value for the amount of change in luminance used to detect a glossy change part that suddenly changes , and the inspection processing unit analyzes the image corrected by the image correction unit. Inspecting the inspection surface, the inspection processing means respectively extracts a dark portion extraction function that extracts a region having a luminance lower than the third threshold from the captured image of the inspection surface as a dark portion, and a dark portion and a peripheral portion of the dark portion, respectively. A gloss change determining function for obtaining an average value of brightness, and determining that the brightness difference between the average value of brightness in the dark part and the average value of brightness in the peripheral part is greater than a fourth threshold value as a gloss change part. And butterflies.

請求項の発明は、請求項1乃至の何れか1つの発明において、照明手段が、検査面にライン状の平行光を照射する光源を備えたことを特徴とする。 A fourth aspect of the invention is characterized in that, in any one of the first to third aspects of the invention, the illuminating means includes a light source that irradiates a line-shaped parallel light onto the inspection surface.

請求項1、3の発明によれば、照明手段が検査面の法線方向と斜めに交差する方向からライン状の検査光を照射させているので、検査面に凹凸がある場合には凹部の底部側には検査光が差し込まず、凸部の先端側のみに検査光が照射されることになり、且つ撮像手段は、受光素子の受光光軸と検査面の法線方向との為す角度が照明手段の投光光軸と検査面の法線方向の為す角度と同じ角度になるように配置されているので、検査面の凸部先端で正反射された光成分を撮像手段で受光することができる。したがって、検査面の模様や検査面で反射した周囲の迷光に影響されることなく、検査面の正反射率に比例した受光光量が得られるので、検査面の光沢度を正しく検出することができる。さらに、木目を有する突板が貼り付けられた木材やヘアライン加工が施された金属板のように、特定の方向に対しては光を散乱反射しやすく、別の方向に対しては光を正反射しやすい表面性状の検査対象物を検査する場合、貼着工程やヘアライン加工の加工工程を終えた製品を移動させる際の移動方向によって、散乱反射が最大となる方向が移動方向と平行になる場合や、散乱反射が最大となる方向が移動方向と直交する場合が考えられるが、照明手段および撮像手段は、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向がそれぞれ移動方向に対して同じ角度で斜めに交差するように配置されているので、散乱反射が最大となる方向が移動方向と平行になった場合でも移動方向と直交する場合でも、散乱光の影響を受けにくくし、検査面の正反射率に比例した受光光量を得ることで、検査面の光沢度を正しく検出して、光沢度の差を明瞭に検出することができる。 According to the first and third aspects of the present invention, the illumination means irradiates the line-shaped inspection light from a direction obliquely intersecting the normal direction of the inspection surface. Inspection light is not inserted into the bottom side, and inspection light is irradiated only on the tip side of the convex portion, and the imaging means has an angle formed between the light receiving optical axis of the light receiving element and the normal direction of the inspection surface. Since it is arranged to be at the same angle as the angle between the light projection optical axis of the illumination means and the normal direction of the inspection surface, the imaging device receives the light component regularly reflected by the tip of the convex portion of the inspection surface Can do. Therefore, the amount of received light proportional to the regular reflectance of the inspection surface can be obtained without being affected by the pattern of the inspection surface and the surrounding stray light reflected by the inspection surface, so that the glossiness of the inspection surface can be detected correctly. . Furthermore, light is easily scattered and reflected in a specific direction, such as wood with a veneer with wood grain and a metal plate with hairline processing, and regular reflection of light in another direction. When inspecting inspection objects with surface properties that are easy to do, when the direction of maximum scattering reflection is parallel to the direction of movement, depending on the direction of movement when moving the product after the pasting process or hairline processing process Although the case where the direction in which the scattered reflection is maximum is orthogonal to the moving direction, the illumination unit and the imaging unit are configured such that the extending direction of the line-shaped inspection light and the extending direction of the line-shaped imaging region are respectively moving directions. Since they are arranged so as to cross obliquely at the same angle, they are affected by scattered light regardless of whether the direction in which scattered reflection is maximum is parallel to the moving direction or orthogonal to the moving direction. Kukushi, to obtain a received light amount proportional to the specular reflectance of the test surface, it is possible to correctly detect the gloss of the test surfaces, clearly detect differences in gloss.

ここにおいて、検査面の法線方向に対して、照明手段の投光光軸および撮像手段の受光光軸を大きく傾ければ、検査面の微少な凹凸で乱反射され、検査面の色の影響で反射光量が変化した成分が撮像手段に入射しにくくなるから、検査面の模様の影響が軽減され、検査面において光沢度が変化した部位を確実に検出することができる。尚、検査対象物が木材である場合には、実験の結果、検査面の法線方向に対する照明手段の投光光軸および撮像手段の受光光軸の角度を70度以上とすれば、検査面の模様の影響を軽減できることが判明した。また、床材などの板材や表面に微細凹凸加工を施した金属板のように特定の方向に対して乱反射しやすい性状をもつ長大形状の検査対象物をラインカメラを用いて撮像する場合に、投受光光軸を移動方向に対して60°以上傾けて配設することによって、対象物の移動方向が表面の散乱反射が最大となる方向と直角又は平行になる場合でも、散乱反射しやすい方向から対象物表面のツヤ変化を観測することが可能となる。   Here, if the light projecting optical axis of the illuminating unit and the light receiving optical axis of the imaging unit are greatly tilted with respect to the normal direction of the inspection surface, irregular reflection will occur due to minute irregularities on the inspection surface, which is Since the component in which the amount of reflected light has changed is less likely to enter the imaging means, the influence of the pattern on the inspection surface is reduced, and the portion where the glossiness has changed on the inspection surface can be reliably detected. When the inspection object is wood, if the angle of the light projecting optical axis of the illuminating unit and the light receiving optical axis of the imaging unit with respect to the normal direction of the inspection surface is 70 degrees or more as a result of the experiment, the inspection surface It was found that the influence of the pattern can be reduced. In addition, when imaging a long inspection object with a property that tends to diffusely reflect in a specific direction, such as a plate material such as a flooring material or a metal plate with fine unevenness on the surface, using a line camera, By arranging the light projecting / receiving optical axis at an angle of 60 ° or more with respect to the moving direction, even if the moving direction of the object is perpendicular or parallel to the direction in which the scattering / reflection of the surface is maximum, the direction in which scattering / reflection is likely to occur It is possible to observe the gloss change on the surface of the object.

請求項の発明によれば、画像補正手段が角度計測手段の計測結果に基づいて画像の変形を補正することで、光沢度が変化した部位の寸法や面積の計測を容易に行うことができる。また、請求項1の発明によれば、輝度が第1閾値より高く且つ周辺部との輝度変化量が第2閾値よりも大きい部位を求めることで、周辺部に比べて面性状が滑らな部位を検出することができる。 According to the first aspect of the present invention, the image correction unit corrects the deformation of the image based on the measurement result of the angle measurement unit, so that it is possible to easily measure the size and area of the portion where the glossiness has changed. . According to the first aspect of the present invention, a part having a surface property that is smoother than that of the peripheral part is obtained by obtaining a part having a luminance higher than the first threshold and a luminance change amount with the peripheral part being larger than the second threshold. Can be detected.

請求項の発明によれば、輝度が第3閾値より低く且つ周辺部との輝度変化量が第4閾値よりも大きい部位を求めることで、周辺部に比べて面性状が粗い部位を検出することができる。 According to the invention of claim 2, a part having a rough surface property compared to the peripheral part is detected by obtaining a part having a luminance lower than the third threshold and a luminance change amount with the peripheral part being larger than the fourth threshold. be able to.

請求項の発明によれば、画像補正手段が角度計測手段の計測結果に基づいて画像の変形を補正することで、光沢度が変化した部位の寸法や面積の計測を容易に行うことができる。また、請求項3の発明によれば、輝度が第3閾値より低く且つ周辺部との輝度変化量が第4閾値よりも大きい部位を求めることで、周辺部に比べて面性状が粗い部位を検出することができる。 According to the invention of claim 3 , the image correction means corrects the deformation of the image based on the measurement result of the angle measurement means, so that the size and area of the part where the glossiness has changed can be easily measured. . Further, according to the invention of claim 3, by obtaining a part having a luminance lower than the third threshold and a luminance change amount with the peripheral part being larger than the fourth threshold, a part having a rough surface property compared to the peripheral part is obtained. Can be detected.

請求項の発明によれば、検査面に照射されるライン光の方向が一方向となる光源を用いることによって、検査面の凹部内に検査光が差し込むのを防止し、散乱光による影響を更に低減することができる。 According to the invention of claim 4 , by using a light source in which the direction of the line light irradiated onto the inspection surface is one direction, the inspection light is prevented from being inserted into the concave portion of the inspection surface, and the influence of the scattered light is prevented. Further reduction can be achieved.

本実施形態の物体表面検査装置を示し、(a)(b)は同上の検出原理を説明する説明図である。 The object surface inspection apparatus of this embodiment is shown, (a) (b) is explanatory drawing explaining the detection principle same as the above. (a)(b)は同上の検出原理を説明する説明図である。(A) (b) is explanatory drawing explaining the detection principle same as the above. 同上の撮像装置による撮像画像の説明図である。It is explanatory drawing of the captured image by the imaging device same as the above. 同上による光沢変化部の検出方法を説明する説明図である。It is explanatory drawing explaining the detection method of the glossy change part by the same as the above. 同上による光沢変化部の検出方法を説明する説明図である。It is explanatory drawing explaining the detection method of the glossy change part by the same as the above.

以下に、本発明の技術思想を、床材のような板材の表面欠陥を検出する物体表面検査装置に適用した実施形態について図1〜図5を参照して説明する。床材は、図2(a)に示すように接着剤を塗布した合板57に突板51を重ねた上で、平滑な圧板により突板51を合板57に圧接して製造されるのであるが、図2(b)に示すように突板51が破損している箇所(ヒビや割れが発生している箇所)では、接着剤54が直接圧板に押し付けられることによって、表面に微細な凹凸構造(凹部52および凸部53からなる)をもつ突板部分55に比べて、光沢度の高い滑面部56が形成されることになり、本実施形態の物体表面検査装置では、このような滑面部56を不良箇所として検出するとともに、周辺部に比べて面性状が粗い部位も不良箇所として検出する。尚、検査対象物は板材に限定されるものではなく、金属材の表面にできた傷を検出するものでもよいし、不良箇所として周辺部に比べて面性状が滑らかな部位および周辺部に比べて面性状が粗い部位の何れか一方のみを検出するものでもよい。   Hereinafter, an embodiment in which the technical idea of the present invention is applied to an object surface inspection apparatus for detecting a surface defect of a plate material such as a flooring material will be described with reference to FIGS. As shown in FIG. 2 (a), the flooring is manufactured by stacking the protruding plate 51 on the plywood 57 coated with an adhesive and then pressing the protruding plate 51 against the plywood 57 with a smooth pressure plate. As shown in FIG. 2 (b), at the place where the protruding plate 51 is broken (where the crack or crack is generated), the adhesive 54 is directly pressed against the pressure plate, so that a fine concavo-convex structure (recess 52) is formed on the surface. Compared with the projecting plate portion 55 having a convex portion 53), a smooth surface portion 56 having higher glossiness is formed. In the object surface inspection apparatus of the present embodiment, such a smooth surface portion 56 is replaced with a defective portion. In addition, a part having a rough surface property compared to the peripheral part is also detected as a defective part. Note that the inspection object is not limited to a plate material, and may be one that detects a scratch formed on the surface of a metal material, and as a defective part, compared to a part having a smooth surface property compared to the peripheral part and a peripheral part. Alternatively, only one of the parts having rough surface properties may be detected.

体検査装置は表面に突板が貼り付けられた板材50(検査対象物)にライン状の検査光を照射する照明装置2(照明手段)と、板材50の検査面51の画像を撮像する撮像装置3(撮像手段)と、撮像装置3によって撮像された画像を解析することによって板材50の検査面51における欠陥を検出する画像処理装置1とを主要な構成として備えている。 Imaging for imaging the illumination device 2 (illumination means), an image of the inspection surface 51 of the plate 50 for irradiating the line-like inspection light at the object body inspection apparatus plate sliced veneer is bonded to the surface 50 (test object) The apparatus 3 (imaging means) and the image processing apparatus 1 that detects a defect in the inspection surface 51 of the plate member 50 by analyzing an image captured by the imaging apparatus 3 are provided as main components.

照明装置2は、例えば直管形蛍光ランプのような細長い発光部を有する光源2aと、直線状のスリットが形成されたマスク2bとを備え、マスク2bを透過したライン状の平行光束が検査面51に対して照射される。この照明装置2は、検査面51の法線方向と斜めに交差する方向から検査面51に対してライン光を照射させる位置に配置されている。また照明装置2は、検査面51に照射する光束の方向が一方向となるような平行光照明を行っているので、図2に示すように検査面51に微少な凹凸がある場合でも光源からの迷光が凹部52内に回り込むのを防止でき、凸部53の頂部付近の平行な面で反射された光を撮像装置3に入射させることができる。 Illumination device 2 includes a light source 2a having an elongated light emitting unit such as example if a straight tube fluorescent lamp, and a mask 2b which linear slits are formed, when a parallel beam of the transmitted linear mask 2b inspection The surface 51 is irradiated. The illuminating device 2 is disposed at a position where the inspection surface 51 is irradiated with line light from a direction obliquely intersecting the normal direction of the inspection surface 51. Further, since the illumination device 2 performs parallel light illumination in which the direction of the light beam applied to the inspection surface 51 is one direction, even if the inspection surface 51 has minute irregularities as shown in FIG. Can be prevented from entering the concave portion 52, and the light reflected by the parallel surface near the top of the convex portion 53 can be incident on the imaging device 3.

撮像装置3は、CCD(Charge Coupled Device、電荷結合素子)やCMOS撮像素子のような受光素子をライン状に配置したラインカメラからなり、コンベヤのような搬送装置4によって検査対象である板材50が搬送方向L5(移動方向)に一定速度で搬送されることで、板材50の検査面上を走査し、検査面51の全面の画像が取得される。撮像装置3で撮像された画像は、後述する画像処理装置1の画像メモリ11に蓄積され、検査処理部10によって欠陥の検出処理が行われる。なお撮像装置3の受光素子としては、入射する光エネルギの対数に比例した出力が得られる素子を用いることが好ましく、具体的には対数変換型のCMOS撮像素子のような受光素子を用いればよい。このような受光素子を用いることで、検査面51における光沢度の変化が大きい場合でも撮像装置3によって取得される検査面51の光沢度を示す輝度値が飽和するのを防止でき、光沢度のダイナミックレンジを広げることができる。   The image pickup apparatus 3 is composed of a line camera in which light receiving elements such as a CCD (Charge Coupled Device) and a CMOS image pickup element are arranged in a line shape, and a plate material 50 to be inspected by a transfer device 4 such as a conveyor. By being transported at a constant speed in the transport direction L5 (moving direction), the inspection surface of the plate member 50 is scanned, and an image of the entire surface of the inspection surface 51 is acquired. An image picked up by the image pickup device 3 is stored in an image memory 11 of the image processing device 1 described later, and a defect detection process is performed by the inspection processing unit 10. As the light receiving element of the image pickup device 3, it is preferable to use an element that can obtain an output proportional to the logarithm of incident light energy. Specifically, a light receiving element such as a logarithmic conversion type CMOS image pickup element may be used. . By using such a light receiving element, it is possible to prevent the luminance value indicating the glossiness of the inspection surface 51 acquired by the imaging device 3 from being saturated even when the change in the glossiness on the inspection surface 51 is large. The dynamic range can be expanded.

ここで、検査光が照射されるライン状の視野Aと照明装置2とを結び、視野Aの延びる方向に対して直交する直線(以下、この直線を投光光軸という。)L2と検査面51の法線L1とが為す角度δ1(入射角)と、撮像装置3が検査面上を観測するライン状の視野Aと撮像装置3とを結び、視野Aの延びる方向に対して直交する直線(以下、この直線を受光光軸と言う。)と法線L1が為す角度δ2(反射角)は共に等しく、δ1=δ2≧70度となるように配設されている。すなわち、照明装置2および撮像装置3は、視野Aを挟んで入射角δ1と反射角δ2が一致するように配置されているので、撮像装置3には検査対象物である板材50の検査面51で正反射された光成分が主に入射することになる。   Here, the line-shaped visual field A irradiated with the inspection light and the illumination device 2 are connected, and a straight line (hereinafter, this straight line is referred to as a light projection optical axis) L2 and the inspection surface orthogonal to the direction in which the visual field A extends. The angle δ1 (incident angle) formed by the normal line L1 of 51 and the line-shaped visual field A observed by the imaging device 3 on the inspection surface and the imaging device 3, and a straight line orthogonal to the direction in which the visual field A extends. (Hereinafter, this straight line is referred to as the light receiving optical axis) and the angle δ2 (reflection angle) formed by the normal line L1 are both equal and δ1 = δ2 ≧ 70 degrees. That is, since the illumination device 2 and the imaging device 3 are arranged so that the incident angle δ1 and the reflection angle δ2 coincide with each other across the field of view A, the imaging device 3 includes the inspection surface 51 of the plate 50 that is an inspection object. The light component specularly reflected at is mainly incident.

また、図2(a)は検査対象物である板材50の検査面51を模式的に示した拡大断面図であり、ヘアライン加工が施された金属板や木材のように表面に微細な凹凸構造を有する検査対象物の場合には、入射角δ1を大きくとることによって、照明装置2から放射された光のうち、凹凸を構成する凸部53の頂上付近の水平に近い面を有する部位で正反射された成分だけが、撮像装置3の方向へ入射するようになる。正反射された光成分は、検査面51の色に依存せず、光源光の波長分布のままである特徴を持つので、照明装置2の投光光軸と検査面51の法線との為す角度δ1および撮像装置3の受光光軸と検査面51の法線との為す角度δ2を上記形態のように設定することで、検査面51の色に影響を受けることなく、検査面51のツヤ(光沢度)の差、つまり正反射率の差だけを画像化することが可能になる。ここにおいて、上述の角度δ1,δ2は検査対象物の面粗さに応じて適宜の値に設定すれば良く、例えば床材として用いられる面粗さが10〜20μm程度の板材を検査する場合には、上記の角度δ1,δ2を70度以上の角度とすることが好ましい。   FIG. 2A is an enlarged cross-sectional view schematically showing an inspection surface 51 of a plate material 50 that is an inspection object, and has a fine concavo-convex structure on the surface like a metal plate or wood subjected to hairline processing. In the case of an inspection target having a large incident angle δ1, the light emitted from the illuminating device 2 is positive at a portion having a nearly horizontal surface near the top of the convex portion 53 constituting the concave and convex portions of the light emitted from the illumination device 2. Only the reflected component is incident in the direction of the imaging device 3. The specularly reflected light component does not depend on the color of the inspection surface 51 and has a characteristic that the wavelength distribution of the light source light remains as it is, so that the light projection optical axis of the illumination device 2 and the normal line of the inspection surface 51 are used. By setting the angle δ1 and the angle δ2 formed between the light receiving optical axis of the imaging device 3 and the normal line of the inspection surface 51 as described above, the gloss of the inspection surface 51 is not affected by the color of the inspection surface 51. Only the difference in (glossiness), that is, the difference in regular reflectance can be imaged. Here, the above-mentioned angles δ1, δ2 may be set to appropriate values according to the surface roughness of the inspection object. For example, when inspecting a plate material having a surface roughness of about 10 to 20 μm used as a flooring material. The angles δ1 and δ2 are preferably 70 degrees or more.

ここで、表面にヘアライン加工などの微細加工が施された金属板や木材のように、検査対象物の表面に、一定方向に延びる溝状の微細構造が存在する場合、溝状の微細構造に対して直交する方向から観測すると、検査面は乱反射面(粗面)に近い反射特性を有し、溝状の微細構造と同じ方向から観測すると、検査面は正反射面(滑面)に近い反射特性を有することになる。例えば面性状が周辺部に比べて滑らかな部位或いは粗い部位を検出するために、検査面において光沢度の差を検出する場合に、照明装置2の投光光軸および撮像装置3の受光光軸は、検査面が乱反射面に近く見える方向に配設するのが望ましく、散乱反射が最大となる方向が搬送方向と一致する場合には、照明装置2の投光光軸および撮像装置3の受光光軸を搬送方向に一致させるように、照明装置2および撮像装置3を配置することが望ましい。しかしながら、産業分野では例えば検査対象物がロール品のように搬送方向が限定される場合も多くあり、検査対象物を、その表面に形成された溝状の微細構造に沿う方向にしか搬送できない場合もありえる。すなわち、検査対象物によって、搬送方向が溝状の微細構造と直交する場合や、搬送方向が溝状の微細構造と平行する場合があるため、本実施形態の物体表面検査装置では、ライン状の検査光の延びる方向およびライン状の撮像領域(視野A)の延びる方向がそれぞれ搬送方向L5に対して同じ角度θ1,θ2で斜めに交差するように配置されている。したがって、検査面の溝状の微細構造が搬送方向と直交する場合でも搬送方向と平行する場合でも、撮像装置3により検査対象物の検査面51を乱反射面に近く見える方向から観測することができ、検査面51において光沢度の差を明瞭に検出することができる。ここにおいて、検査対象物が床材のような板材50の場合には、照明装置2の投光光軸および撮像装置3の受光光軸がそれぞれ搬送方向と為す角度θ1,θ2を60度以上且つ90度未満の角度に設定するのが好ましい。但し、検査視野幅は検査対象物である板材50の幅寸法を、受光光軸と搬送方向の為す角度θ2の余弦で除した値となり(検査視野幅=検査視野幅÷cosθ2)、角度θ2が90度に近付くほど視野幅が極端に大きくなるので、光学系を実用的に構成できる範囲で、角度θ1,θ2をできるだけ大きい値に設定すればよい。 Here, when there is a groove-like microstructure extending in a certain direction on the surface of the object to be inspected, such as a metal plate or wood whose surface has been subjected to fine processing such as hairline processing, the groove-like microstructure is When observed from a direction perpendicular to the surface, the inspection surface has a reflection characteristic close to that of the irregular reflection surface (rough surface), and when observed from the same direction as the groove-like microstructure, the inspection surface is close to the regular reflection surface (smooth surface). It will have reflection characteristics. For example, when detecting a difference in glossiness on the inspection surface in order to detect a smoother or rougher surface than the peripheral portion, the light projecting optical axis of the illumination device 2 and the light receiving optical axis of the imaging device 3 are detected. Is preferably arranged in a direction in which the inspection surface can be seen close to the irregular reflection surface. When the direction in which the scattered reflection is maximum coincides with the transport direction, the light projecting optical axis of the illumination device 2 and the light reception of the imaging device 3 It is desirable to arrange the illumination device 2 and the imaging device 3 so that the optical axis matches the transport direction. However, in the industrial field, for example, there are many cases where the conveyance direction is limited, for example, the inspection object is a roll product, and the inspection object can be conveyed only in the direction along the groove-like microstructure formed on the surface. There can be. That is, depending on the inspection object, the conveyance direction may be perpendicular to the groove-like microstructure, or the conveyance direction may be parallel to the groove-like microstructure. same angle .theta.1, are arranged so as to intersect obliquely at θ2 with respect to better direction, each conveying direction L5 of extension of the direction and linear imaging area extension of the inspection light (field a). Therefore, even when the groove-like fine structure of the inspection surface is orthogonal to the conveyance direction or parallel to the conveyance direction, the inspection surface 51 of the inspection object can be observed from the direction in which the inspection object can be seen close to the irregular reflection surface. The difference in glossiness can be clearly detected on the inspection surface 51. Here, when the inspection object is a plate 50 such as a flooring, the angles θ1 and θ2 formed by the light projecting optical axis of the illuminating device 2 and the light receiving optical axis of the imaging device 3 with the transport direction are 60 degrees or more and It is preferable to set the angle to less than 90 degrees. However, the inspection visual field width is a value obtained by dividing the width dimension of the plate material 50, which is an inspection object, by the cosine of the angle θ2 formed between the light receiving optical axis and the conveyance direction (inspection visual field width = inspection visual field width ÷ cos θ2). Since the visual field width becomes extremely large as it approaches 90 degrees, the angles θ1 and θ2 may be set as large as possible within a range in which the optical system can be practically configured.

また、ライン状の撮像領域(視野A)の延びる方向L4が搬送方向L5に対して角度θ2で斜めに交差する場合、撮像装置3により取得される板材50の画像は、図3に示されるように平行四辺形状に歪みを生じることになるため、撮像装置3が画像データを画像メモリ11に転送する過程で、画像の歪みに応じて画像データのアドレスをシフトさせるといった方法で、画像の歪みを取り除いて、視野Aの延びる方向が搬送方向L5と直交した状態と同じ画像を得ることが好ましく、検査対象物において光沢度が変化した部位の寸法や面積の計測を容易に行うことができる。なお、撮像装置3が画像データを画像メモリ11に転送する過程で画像の歪みを補正しているが、撮像装置3で撮像された画像データを画像メモリ11にそのまま蓄積させ、検査処理部10側で画像の歪みを補正する処理を行ってもよい。すなわち、ライン状の撮像領域の延びる方向が搬送方向L5と為す角度θ2を計測する角度計測部13が画像処理装置1に設けられ、検査処理部10において、画像メモリ11から画像データを読み出して画像処理を行う過程で、画像補正機能部14が画像メモリ11から画像データを読み出すとともに、角度計測部13から角度θ2の計測結果を取り込み、角度θ2の計測結果に基づいて画像データのアドレスをシフトさせることによって画像の歪みを補正した後、補正後の画像データを用いて画像処理を行うことで、検査対象物において光沢度が変化した部位の寸法や面積の計測を容易に行うことができる。   Further, when the extending direction L4 of the line-shaped imaging region (field of view A) obliquely intersects with the conveyance direction L5 at an angle θ2, the image of the plate member 50 acquired by the imaging device 3 is as shown in FIG. Therefore, in the process in which the imaging device 3 transfers the image data to the image memory 11, the image distortion is reduced by shifting the address of the image data in accordance with the image distortion. It is preferable to obtain the same image as the state in which the extending direction of the visual field A is orthogonal to the conveyance direction L5, and it is possible to easily measure the size and area of the portion of the inspection target where the glossiness has changed. Although the image pickup device 3 corrects image distortion in the process of transferring the image data to the image memory 11, the image data picked up by the image pickup device 3 is stored in the image memory 11 as it is, and the inspection processing unit 10 side In this case, a process for correcting image distortion may be performed. That is, an angle measurement unit 13 that measures an angle θ2 that the extending direction of the line-shaped imaging region makes with the conveyance direction L5 is provided in the image processing apparatus 1, and the inspection processing unit 10 reads out image data from the image memory 11 and outputs an image. In the course of processing, the image correction function unit 14 reads out the image data from the image memory 11, fetches the measurement result of the angle θ 2 from the angle measurement unit 13, and shifts the address of the image data based on the measurement result of the angle θ 2. Thus, after correcting the distortion of the image, by performing image processing using the corrected image data, it is possible to easily measure the size and area of the portion of the inspection object whose glossiness has changed.

次に、検査処理部10が、画像メモリ11に蓄積された画像データから、検査面において周辺部に比べて光沢度が高い滑面部、及び、周辺部に比べて光沢度が低い粗面部を検出する処理について以下に説明する。ここで、撮像装置3によって撮像される画像においては、表面が乱反射面(粗面)に近ければ輝度が低く、表面が正反射面(滑面)に近ければ輝度が高く撮像される傾向がある。したがって、検査面において光沢度が相対的に大きい部位(明部)を検出するために用いられる輝度の第1閾値Th1と、光沢度が相対的に低い部位(暗部)を検出するために用いられる輝度の第3閾値Th3とを記憶部12に予め記憶させておき、検査処理部10の明部抽出機能部15が、検査対象物の画像において輝度が第1閾値Th1よりも明るい画素の集まりを滑面部(明部)として抽出するとともに、検査処理部10の暗部抽出機能部16が、検査対象物の画像において輝度が第3閾値Th3よりも暗い画素の集まりを粗面部(暗部)として抽出しており、例えば抽出された明部又は暗部の面積が所定の基準値以上であれば欠陥があると判断する。このように、各画素の輝度と閾値との高低を比較して明部および暗部を抽出する処理は、検査面の全域が一定の光沢度を有している対象物から、光沢度が規定の範囲を超えている部分(すなわち、光沢度が規定値よりも低い部分、又は規定値よりも高い部分)を検出する場合に適している。   Next, the inspection processing unit 10 detects, from the image data stored in the image memory 11, a smooth surface portion having a higher glossiness than the peripheral portion on the inspection surface and a rough surface portion having a lower glossiness than the peripheral portion. The processing to be performed will be described below. Here, in the image captured by the imaging device 3, the luminance tends to be low if the surface is close to the irregular reflection surface (rough surface), and the luminance is high if the surface is close to the regular reflection surface (smooth surface). . Accordingly, the first threshold value Th1 used for detecting a portion (bright portion) having a relatively high gloss level on the inspection surface and a portion (dark portion) having a relatively low gloss level are used. The third threshold value Th3 of luminance is stored in the storage unit 12 in advance, and the bright portion extraction function unit 15 of the inspection processing unit 10 collects a collection of pixels whose luminance is brighter than the first threshold value Th1 in the image of the inspection object. While extracting as a smooth surface part (bright part), the dark part extraction function part 16 of the test | inspection process part 10 extracts the collection of the pixels whose brightness | luminance is darker than 3rd threshold value Th3 as a rough surface part (dark part) in the image of a test object. For example, if the area of the extracted bright part or dark part is equal to or greater than a predetermined reference value, it is determined that there is a defect. In this way, the process of extracting the bright part and the dark part by comparing the brightness of each pixel with the threshold value and extracting the bright part and the dark part from the object having a constant glossiness over the entire inspection surface has a specified glossiness. This method is suitable for detecting a portion that exceeds the range (that is, a portion whose glossiness is lower than a specified value or a portion that is higher than a specified value).

一方、検査対象物の表面にできた傷や破損を検出する場合には、撮像装置3によって撮像された画像から検査面の光沢度が急変する部位だけを検出する必要があり、このような場合に上述した単純な閾値判定のみを行うと、検査面の光沢度に部分的なムラがある部位を誤検出する可能性があるので、検出された光沢変化部とその周辺部分とで光沢度の差を評価することも好ましい。   On the other hand, when detecting scratches or damages on the surface of the inspection object, it is necessary to detect only the part where the glossiness of the inspection surface changes suddenly from the image captured by the imaging device 3. If only the simple threshold determination described above is performed, there is a possibility that a portion where the glossiness of the inspection surface is partially uneven may be erroneously detected. It is also preferable to evaluate the difference.

そこで、検査面において光沢度が大きくなる方向に急変する光沢変化部を検出するために輝度変化量の第2閾値Th2を記憶部12に記憶させるとともに、検査面において光沢度が小さくなる方向に急変する光沢変化部を検出するために輝度変化量の第4閾値Th4(第2閾値Th2と同じ値でもよい)を記憶部12に記憶させており、例えば光沢度が大きくなる方向に急変する部位を検出する場合、図4に示すように明部抽出機能部15によって第1閾値Th1よりも輝度の大きい画素の集まりである光沢変化部61が抽出されると、検査処理部10の光沢変化判断機能部17が、上記光沢変化部61の外接矩形領域62を求めると共に、この外接矩形領域62を所定の拡張幅mだけ上下左右にそれぞれ拡張した検査領域63を設定し、光沢変化部61内の画素の平均輝度D1と、検査領域63から光沢変化部61を除いた領域の平均輝度D2を求め、両者の輝度差|D1−D2|が上述の第2閾値Th2を超える場合に明方向への光沢度急変部として検出する。   Therefore, the second threshold Th2 of the luminance change amount is stored in the storage unit 12 in order to detect a glossy change portion that suddenly changes in the direction in which the glossiness increases on the inspection surface, and suddenly changes in a direction in which the glossiness decreases on the inspection surface. In order to detect the gloss change part to be detected, a fourth threshold Th4 of the luminance change amount (may be the same value as the second threshold Th2) is stored in the storage unit 12, for example, a part that changes suddenly in a direction in which the glossiness increases. In the case of detection, when the gloss changing unit 61, which is a collection of pixels having a luminance greater than the first threshold Th1, is extracted by the bright portion extraction function unit 15 as shown in FIG. The unit 17 obtains a circumscribed rectangular region 62 of the gloss changing unit 61 and sets an inspection region 63 obtained by extending the circumscribed rectangular region 62 vertically and horizontally by a predetermined expansion width m. When the average luminance D1 of the pixels in the changing portion 61 and the average luminance D2 of the region obtained by removing the gloss changing portion 61 from the inspection region 63 are obtained, and the luminance difference | D1-D2 | of both exceeds the above-described second threshold Th2. It is detected as a sudden change in glossiness in the bright direction.

また光沢度が低くなる方向に急変する部位を検出する場合も同様に、暗部抽出機能部16によって第3閾値Th3よりも輝度の低い画素の集まりである光沢変化部61が抽出されると、検査処理部10の光沢変化判断機能部17が、上記光沢変化部61の外接矩形領域62を求めると共に、この外接矩形領域62を所定の拡張幅mだけ上下左右にそれぞれ拡張した検査領域63を設定し、光沢変化部61内の画素の平均輝度D1と、検査領域63から光沢変化部61を除いた領域の平均輝度D2を求め、両者の輝度差|D1−D2|が上述の第4閾値Th4を超える場合に暗方向への光沢度急変部として検出する。   Similarly, when detecting a region that changes suddenly in the direction in which the glossiness decreases, when the darkness extraction function unit 16 extracts the gloss change unit 61 that is a collection of pixels having lower luminance than the third threshold Th3, the inspection is performed. The gloss change determination function unit 17 of the processing unit 10 obtains a circumscribed rectangular area 62 of the gloss changing section 61 and sets an inspection area 63 in which the circumscribed rectangular area 62 is expanded vertically and horizontally by a predetermined expansion width m. The average luminance D1 of the pixels in the gloss changing portion 61 and the average luminance D2 of the region excluding the gloss changing portion 61 from the inspection region 63 are obtained, and the luminance difference | D1-D2 | If it exceeds, it is detected as a sudden change in glossiness in the dark direction.

このように検査処理部10では、画像内で輝度が第1閾値よりも明るい画素の集まりである明部又は輝度が第3閾値よりも暗い画素の集まりである暗部を抽出した後、明部又は暗部とその周辺部とで平均輝度の差が第2閾値Th2、第4閾値Th4より大きい部位のみを光沢度の急変部として検出しているので、光沢度のムラを誤検出する可能性を低減することができる。   As described above, the inspection processing unit 10 extracts a bright part, which is a group of pixels whose luminance is brighter than the first threshold, or a dark part, which is a group of pixels whose luminance is darker than the third threshold, in the image. Since only the portion where the difference in average luminance between the dark portion and its peripheral portion is larger than the second threshold Th2 and the fourth threshold Th4 is detected as the sudden change portion of the glossiness, the possibility of erroneously detecting uneven glossiness is reduced. can do.

なお、検査処理部10の光沢変化判断機能部17では、明部又は暗部とその周辺部とで平均輝度の差を所定の閾値と比較することで、光沢度の急変部位を検出する検出方法1に代えて、以下に説明する検出方法2で光沢度の急変部位を検出してもよい。例えば光沢度が大きくなる方向に急変する部位を検出する場合、図4に示すように明部抽出機能部15によって第1閾値Th1よりも輝度の大きい画素の集まりである光沢変化部61が抽出されると、検査処理部10の光沢変化判断機能部17が、上記光沢変化部61の外接矩形領域62を求めると共に、この外接矩形領域62を所定の拡張幅mだけ上下左右にそれぞれ拡張した検査領域63を設定し、検査領域63内の各画素の輝度分布のヒストグラムを求める。図5は、このようにして求められたヒストグラムの一例であり、光沢変化部61の輝度分布を示すピーク71と、光沢変化部61の周辺部(検査領域63から光沢変化部61を除いた領域)の輝度分布を示すピーク72について、それぞれ平均輝度e1,e2と輝度標準偏差d1,d2を求め、下記の式(1)で定義される明瞭度αを求める。   Note that the gloss change determination function unit 17 of the inspection processing unit 10 detects a sudden change site in glossiness by comparing the difference in average luminance between a bright part or dark part and its peripheral part with a predetermined threshold value. Instead of this, an abrupt change in glossiness may be detected by the detection method 2 described below. For example, when detecting a part that changes suddenly in the direction in which the glossiness increases, the bright portion extraction function unit 15 extracts the gloss changing unit 61 that is a collection of pixels having a luminance higher than the first threshold Th1, as shown in FIG. Then, the gloss change determination function unit 17 of the inspection processing unit 10 obtains the circumscribed rectangular region 62 of the gloss changing unit 61, and also inspects the circumscribed rectangular region 62 vertically and horizontally by a predetermined expansion width m. 63 is set, and a histogram of the luminance distribution of each pixel in the inspection area 63 is obtained. FIG. 5 is an example of the histogram obtained in this way. The peak 71 indicating the luminance distribution of the gloss changing portion 61 and the peripheral portion of the gloss changing portion 61 (the region obtained by removing the gloss changing portion 61 from the inspection region 63). The average luminance e1 and e2 and the standard luminance deviations d1 and d2 are obtained for the peak 72 indicating the luminance distribution of), and the clarity α defined by the following equation (1) is obtained.

Figure 0005297245
Figure 0005297245

ここで、図5に示すヒストグラムで検出された光沢変化部61の輝度分布71と、その周辺部の輝度分布72とが大きく分離するほど、式(1)で求められる明瞭度αは高い値となり、明瞭度αの値は、光沢変化部61とその周辺部との相対的な分布の差を表すことになる。したがって、検査処理部10の光沢変化判断機能部17では、上述の処理で求めた明瞭度αと、記憶部12に予め記憶された所定の閾値とを比較し、明瞭度が閾値を超える場合に光沢変化部61を光沢度の急変部として検出する。   Here, the greater the separation between the luminance distribution 71 of the gloss changing unit 61 detected by the histogram shown in FIG. 5 and the luminance distribution 72 of the peripheral portion thereof, the higher the clarity α obtained by Equation (1). The value of the clarity α represents a relative distribution difference between the gloss changing portion 61 and its peripheral portion. Accordingly, the gloss change determination function unit 17 of the inspection processing unit 10 compares the clarity α obtained by the above-described processing with a predetermined threshold value stored in advance in the storage unit 12, and when the clarity exceeds the threshold value. The gloss changing portion 61 is detected as a sudden change portion of the glossiness.

また、光沢度が低くなる方向に急変する部位を検出する場合も上述と同様に、暗部抽出機能部16によって第2閾値Th1よりも輝度の低い画素の集まりである光沢変化部61が抽出されると、検査処理部10の光沢変化判断機能部17が、上記光沢変化部61の外接矩形領域62を求めると共に、この外接矩形領域62を所定の拡張幅mだけ上下左右にそれぞれ拡張した検査領域63を設定して、検査領域63内の各画素の輝度分布のヒストグラムを求める。その後、検査処理部10の光沢変化判断機能部17では、検査領域63内の輝度分布のヒストグラムから、光沢変化部61の輝度分布を示すピーク71と、光沢変化部61の周辺部の輝度分布を示すピーク72について、それぞれ平均輝度e1,e2と輝度標準偏差d1,d2を求め、上述の式(1)で定義される明瞭度αを求めた後、この明瞭度αと所定の閾値とを比較し、明瞭度が閾値を超える場合に光沢変化部61を光沢度の急変部として検出する。   Further, when detecting a region that changes suddenly in the direction in which the glossiness decreases, the dark portion extraction function unit 16 extracts the gloss changing unit 61 that is a collection of pixels having a luminance lower than the second threshold Th1, as described above. Then, the gloss change determination function unit 17 of the inspection processing unit 10 obtains a circumscribed rectangular region 62 of the gloss changing unit 61, and an inspection region 63 in which the circumscribed rectangular region 62 is expanded vertically and horizontally by a predetermined expansion width m. And a histogram of the luminance distribution of each pixel in the inspection area 63 is obtained. Thereafter, the gloss change determination function unit 17 of the inspection processing unit 10 obtains the peak 71 indicating the luminance distribution of the gloss change unit 61 and the luminance distribution around the gloss change unit 61 from the luminance distribution histogram in the inspection region 63. For the peak 72 shown, average luminances e1 and e2 and luminance standard deviations d1 and d2 are obtained, respectively, and after obtaining the intelligibility α defined by the above formula (1), the intelligibility α is compared with a predetermined threshold value. When the articulation level exceeds the threshold value, the gloss changing unit 61 is detected as a sudden change unit of gloss level.

このように検査処理部10では、画像内で輝度が第1閾値よりも明るい画素の集まりである明部又は輝度が第3閾値よりも暗い画素の集まりである暗部を抽出するとともに、明部又は暗部とその周辺部とで平均輝度および輝度標準偏差を求めた後、式(1)で示される明瞭度を求めており、この明瞭度が所定の閾値を超える部位を光沢度の急変部位として検出している。したがって、検査面における光沢度のムラが大きいために、上述した検出方法1を用いても光沢度のムラを誤検出してしまう場合でも、平均輝度と輝度標準偏差から求めた明瞭度をもとに光沢度の急変部位を求めることによって、光沢度のムラを誤検出することなく光沢度の急変部位を求めることができる。   As described above, the inspection processing unit 10 extracts a bright part, which is a collection of pixels whose luminance is brighter than the first threshold, or a dark part, which is a collection of pixels whose luminance is darker than the third threshold, in the image. After calculating the average brightness and the brightness standard deviation in the dark area and its surrounding area, the clarity shown in Equation (1) is found, and the part where this clarity exceeds a predetermined threshold is detected as a sudden change in gloss. doing. Therefore, since the unevenness of the glossiness on the inspection surface is large, even if the unevenness of the glossiness is erroneously detected even if the above-described detection method 1 is used, the clarity obtained from the average brightness and the brightness standard deviation is used. Further, by obtaining the sudden change portion of the glossiness, the sudden change portion of the glossiness can be obtained without erroneously detecting uneven glossiness.

なお、本実施形態では検査対象物である板材50が搬送装置4によって搬送される場合を例に説明したが、照明装置2及び撮像装置3が図示しない搬送装置によって移動させられることによって、照明装置2及び撮像装置3が検査対象物に対して相対的に移動して、検査対象物を走査するようにしてもよい。   In the present embodiment, the case where the plate material 50 that is the inspection object is transported by the transport device 4 has been described as an example. However, the illumination device 2 and the imaging device 3 are moved by a transport device (not shown), thereby the illumination device. 2 and the imaging device 3 may move relative to the inspection object to scan the inspection object.

1 画像処理装置
2 照明装置
2a 光源
2b マスク
3 撮像装置
4 搬送装置
10 検査処理部
11 画像メモリ
12 記憶部
13 角度計測部
14 画像補正機能部
15 明部抽出機能部
16 暗部抽出機能部
17 光沢変化判断機能部
50 板材
50 検査対象物
51 検査面
DESCRIPTION OF SYMBOLS 1 Image processing apparatus 2 Illumination apparatus 2a Light source 2b Mask 3 Imaging apparatus 4 Conveyance apparatus 10 Inspection processing part 11 Image memory 12 Storage part 13 Angle measurement part 14 Image correction function part 15 Bright part extraction function part 16 Dark part extraction function part 17 Gloss change Judgment function unit 50 Plate material 50 Inspection object 51 Inspection surface

Claims (4)

検査対象物の検査面の法線方向と斜めに交差する方向からライン状の検査光を前記検査面に照射する照明手段と、ライン状に配置された受光素子を具備し前記受光素子の受光光軸と前記検査面の法線方向との為す角度が前記照明手段の投光光軸と前記検査面の法線方向の為す角度と同じ角度になるように配置されて前記検査面を撮像する撮像手段と、前記撮像手段が撮像した画像を解析することによって前記検査面の検査を行う検査処理手段とを備え、前記照明手段および前記撮像手段は、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向が、前記照明手段および前記撮像手段に対して前記検査対象物が相対的に移動する移動方向に対して、それぞれ同じ角度で斜めに交差するように配置され、
前記ライン状の検査光の延びる方向および前記ライン状の撮像領域の延びる方向が前記移動方向と為す角度を計測する角度計測手段と、前記角度計測手段の計測結果に基づいて前記撮像手段が撮像した画像の変形を補正する画像補正手段と、前記検査面において光沢度が大きくなる方向に急変する光沢変化部を検出するために用いられる輝度の第1閾値と輝度変化量の第2閾値とを記憶する記憶部を備え、
前記検査処理手段が、前記画像補正手段による補正後の画像を解析することによって前記検査面の検査を行い、
前記検査処理手段が、前記検査面の撮像画像から前記第1閾値よりも輝度が高い領域を明部として抽出する明部抽出機能と、前記明部と前記明部の周辺部とでそれぞれ輝度の平均値を求め、前記明部における輝度の平均値と前記周辺部における輝度の平均値との輝度差が前記第2閾値より大きい場合を光沢変化部と判断する光沢変化判断機能とを備えることを特徴とする物体表面検査装置。
Illuminating means a linear inspection light from a direction that intersects the normal direction and the oblique inspection surface of the inspection object is irradiated on the inspection surface, the received light of the light receiving element comprises a light receiving element arranged in a line Imaging for imaging the inspection surface arranged so that an angle formed between the axis and the normal direction of the inspection surface is the same as an angle formed by the projection optical axis of the illumination unit and the normal direction of the inspection surface means and said a test processing means for performing an inspection of the inspection surface by the imaging means to analyze a captured image and the illumination means and the imaging means, extension of linear inspection light direction and linear The extending direction of the imaging region is arranged so as to cross obliquely at the same angle with respect to the moving direction in which the inspection object moves relative to the illumination unit and the imaging unit ,
An angle measuring unit that measures an angle between the extending direction of the line-shaped inspection light and the extending direction of the line-shaped imaging region and the moving direction, and the imaging unit picks up an image based on a measurement result of the angle measuring unit. An image correction unit that corrects image deformation, and a first threshold value of luminance and a second threshold value of the amount of change in luminance that are used to detect a glossy change portion that suddenly changes in the direction in which the glossiness increases on the inspection surface are stored. A storage unit
The inspection processing means inspects the inspection surface by analyzing the image corrected by the image correction means,
The inspection processing means extracts a bright portion extraction function as a bright portion from the captured image of the inspection surface as a bright portion, and the brightness portion and the peripheral portion of the bright portion respectively. A gloss change determining function that obtains an average value and determines a gloss change portion when the brightness difference between the brightness average value in the bright portion and the brightness average value in the peripheral portion is greater than the second threshold value. Characteristic object surface inspection device.
前記検査面において光沢度が小さくなる方向に急変する光沢変化部を検出するために用いられる輝度の第3閾値と輝度変化量の第4閾値とを前記記憶部が記憶し、
前記検査処理手段が、前記検査面の撮像画像から前記第3閾値よりも輝度が低い領域を暗部として抽出する暗部抽出機能と、前記暗部と前記暗部の周辺部とでそれぞれ輝度の平均値を求め、前記暗部における輝度の平均値と前記周辺部における輝度の平均値との輝度差が前記第4閾値より大きい場合を光沢変化部と判断する光沢変化判断機能とを備えることを特徴とする請求項1記載の物体表面検査装置。
The storage unit stores a third threshold value of luminance and a fourth threshold value of the luminance change amount used to detect a glossy change portion that suddenly changes in a direction in which the glossiness decreases on the inspection surface,
The inspection processing unit obtains an average value of luminance for each of a dark portion extraction function for extracting a region having a luminance lower than the third threshold value as a dark portion from a captured image of the inspection surface, and a dark portion and a peripheral portion of the dark portion. And a gloss change determining function for determining that the difference in brightness between the average value of brightness in the dark part and the average value of brightness in the peripheral part is greater than the fourth threshold value as a gloss change part. The object surface inspection apparatus according to 1.
検査対象物の検査面の法線方向と斜めに交差する方向からライン状の検査光を前記検査面に照射する照明手段と、ライン状に配置された受光素子を具備し前記受光素子の受光光軸と前記検査面の法線方向との為す角度が前記照明手段の投光光軸と前記検査面の法線方向の為す角度と同じ角度になるように配置されて前記検査面を撮像する撮像手段と、前記撮像手段が撮像した画像を解析することによって前記検査面の検査を行う検査処理手段とを備え、前記照明手段および前記撮像手段は、ライン状の検査光の延びる方向およびライン状の撮像領域の延びる方向が、前記照明手段および前記撮像手段に対して前記検査対象物が相対的に移動する移動方向に対して、それぞれ同じ角度で斜めに交差するように配置され、
前記ライン状の検査光の延びる方向および前記ライン状の撮像領域の延びる方向が前記移動方向と為す角度を計測する角度計測手段と、前記角度計測手段の計測結果に基づいて前記撮像手段が撮像した画像の変形を補正する画像補正手段と、前記検査面において光沢度が小さくなる方向に急変する光沢変化部を検出するために用いられる輝度の第3閾値と輝度変化量の第4閾値とを記憶する記憶部を備え
前記検査処理手段が、前記画像補正手段による補正後の画像を解析することによって前記検査面の検査を行い、
前記検査処理手段が、前記検査面の撮像画像から前記第3閾値よりも輝度が低い領域を暗部として抽出する暗部抽出機能と、前記暗部と前記暗部の周辺部とでそれぞれ輝度の平均値を求め、前記暗部における輝度の平均値と前記周辺部における輝度の平均値との輝度差が前記第4閾値より大きい場合を光沢変化部と判断する光沢変化判断機能とを備えることを特徴とする物体表面検査装置。
Illuminating means for irradiating the inspection surface with a line-shaped inspection light from a direction obliquely intersecting with the normal direction of the inspection surface of the inspection object, and a light receiving element arranged in a line, and receiving light of the light receiving element Imaging for imaging the inspection surface arranged so that an angle formed between the axis and the normal direction of the inspection surface is the same as an angle formed by the projection optical axis of the illumination unit and the normal direction of the inspection surface And an inspection processing means for inspecting the inspection surface by analyzing an image captured by the imaging means, wherein the illumination means and the imaging means are arranged in the direction in which the line-shaped inspection light extends and the line-shaped inspection light. The extending direction of the imaging region is arranged so as to cross obliquely at the same angle with respect to the moving direction in which the inspection object moves relative to the illumination unit and the imaging unit,
An angle measuring unit that measures an angle between the extending direction of the line-shaped inspection light and the extending direction of the line-shaped imaging region and the moving direction, and the imaging unit picks up an image based on a measurement result of the angle measuring unit. Image correction means for correcting the deformation of the image, and a third threshold value of luminance and a fourth threshold value of the luminance change amount used to detect a glossy change portion that suddenly changes in the direction of decreasing glossiness on the inspection surface are stored. a storage unit that,
The inspection processing means inspects the inspection surface by analyzing the image corrected by the image correction means,
The inspection processing unit determines and dark extracting function of extracting a region lower luminance than the third threshold value from the captured image of the inspection surface as dark portions, each average value of the brightness between the dark portion and the dark portion of the peripheral portion , those you anda gloss change determination function luminance difference between the average value of the brightness in the average value and the peripheral portion of the brightness in the dark portion is determined to change in gloss portion is larger than the fourth threshold value Body surface inspection device.
前記照明手段が、前記検査面にライン状の平行光を照射する光源を備えたことを特徴とする請求項1乃至3の何れか1項に記載の物体表面検査装置 4. The object surface inspection apparatus according to claim 1 , wherein the illumination unit includes a light source that irradiates the inspection surface with a line-shaped parallel light . 5.
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