JP4775946B2 - Edge detection device - Google Patents

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JP4775946B2
JP4775946B2 JP2005249220A JP2005249220A JP4775946B2 JP 4775946 B2 JP4775946 B2 JP 4775946B2 JP 2005249220 A JP2005249220 A JP 2005249220A JP 2005249220 A JP2005249220 A JP 2005249220A JP 4775946 B2 JP4775946 B2 JP 4775946B2
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喜彦 岡山
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本発明は、透明フィルムやガラス等の透明体のエッジ位置を検出し、例えば上記透明体の位置制御に用いるに好適なエッジ検出装置に関する。   The present invention relates to an edge detection apparatus suitable for detecting the edge position of a transparent body such as a transparent film or glass and for controlling the position of the transparent body, for example.

レーザ光に代表される単色光の光路に物体が存在すると、該物体のエッジ位置にてフレネル回折が生じる。そこでラインセンサを用いて上記フレネル回折の光強度分布を求め、この光強度分布を解析することで上記物体のエッジ位置を検出するエッジ検出装置が開発されている。即ち、図６に示すように複数の画素を配列したラインセンサ１に向けて投光部２から単色平行光を照射した光路の一部を遮るように検出対象物３を位置付けると、上記ラインセンサ１の出力は図７に示すように上記検出対象物３のエッジ位置を境として大きく変化する。特にラインセンサ１上の光強度分布は、エッジ位置の近傍におけるフレネル回折の影響を受けて一定の変化傾向を示す。   If an object exists in the optical path of monochromatic light typified by laser light, Fresnel diffraction occurs at the edge position of the object. Therefore, an edge detection apparatus has been developed that uses a line sensor to determine the light intensity distribution of the Fresnel diffraction and detects the edge position of the object by analyzing the light intensity distribution. That is, when the detection object 3 is positioned so as to block a part of the optical path irradiated with the monochromatic parallel light from the light projecting unit 2 toward the line sensor 1 in which a plurality of pixels are arranged as shown in FIG. The output of 1 greatly changes with the edge position of the detection object 3 as a boundary as shown in FIG. In particular, the light intensity distribution on the line sensor 1 shows a certain change tendency under the influence of Fresnel diffraction in the vicinity of the edge position.

従ってラインセンサ１の各画素の出力を正規化すれば、その光量が２５％となる位置をラインセンサ１の画素配列方向における前記検出対象物３のエッジ位置として検出することができる。またこのようにしてフレネル回折の光強度分布を解析する場合には、仮に上記検出対象物３が透明フィルムやガラス等の透明体であっても、そのエッジ位置を精度良く検出することができる（例えば特許文献１を参照）。
特開２００４−１７７３３５号公報 Therefore, if the output of each pixel of the line sensor 1 is normalized, the position where the light amount becomes 25% can be detected as the edge position of the detection object 3 in the pixel array direction of the line sensor 1. Further, when analyzing the light intensity distribution of Fresnel diffraction in this way, even if the detection object 3 is a transparent body such as a transparent film or glass, the edge position can be detected accurately ( For example, see Patent Document 1).
JP 2004-177335 A

しかしながら検出対象物３が透明体である場合、図８(ａ)〜(ｃ)に検出対象物３が存在しないとき（ラインセンサ１の全入光状態）、検出対象物３光路の略半分を遮るとき（エッジ検出状態）、そして検出対象物３が上記光路の全てを覆うとき（ラインセンサ１の全遮光状態）のそれぞれにおける前記ラインセンサ１の出力（光強度分布）を示すように、全入光状態と全遮光状態との区別が非常に付き難い。換言すれば全入光状態および全遮光状態においては、検出対象物３のエッジにおけるフレネル回折が生じないので、ラインセンサ１の出力からその光量が前述した２５％となる位置を検出することができない。   However, when the detection target 3 is a transparent body, when the detection target 3 does not exist in FIGS. 8A to 8C (total light incident state of the line sensor 1), approximately half of the optical path of the detection target 3 is obtained. In order to show the output (light intensity distribution) of the line sensor 1 at each time when it is blocked (edge detection state) and when the detection object 3 covers all of the optical path (all light shielding state of the line sensor 1), It is very difficult to distinguish between the incident light state and the total light shielding state. In other words, since the Fresnel diffraction does not occur at the edge of the detection target 3 in the total light incident state and the total light shielding state, the position where the light amount is 25% cannot be detected from the output of the line sensor 1. .

これ故、エッジ検出装置の検出特性を図９に示すように、検出対象物３による全遮光状態であっても、これを全入光状態として誤検出してしまうことになる。従って、例えば検出対象物３のエッジ位置を検出しながら上記検出対象物３の位置を調整するような場合、全入光状態であるか、或いは全遮光状態であるかが不明なので、検出対象物３の位置を修正すべき向きが判定できない等の不具合が生じる。   Therefore, as shown in FIG. 9, the detection characteristics of the edge detection device are erroneously detected as the total light incident state even in the total light shielding state by the detection target 3. Therefore, for example, when the position of the detection target 3 is adjusted while detecting the edge position of the detection target 3, it is unknown whether the light is in a completely incident state or a total light-shielded state. There arises a problem such that the direction in which position 3 should be corrected cannot be determined.

本発明はこのような事情を考慮してなされたもので、その目的は、透明体のエッジ位置を正確に検出することのできることは勿論のこと、ラインセンサが全入光状態であるか、或いは全遮光状態であるかを確実に判定することができ、例えば上記透明体の位置制御に用いるに好適なエッジ検出装置を提供することにある。   The present invention has been made in view of such circumstances, and the object of the present invention is that the edge position of the transparent body can be accurately detected, and the line sensor is in a fully incident state, or An object of the present invention is to provide an edge detection device that can reliably determine whether or not all light is shielded, and is suitable for use in, for example, position control of the transparent body.

上述した目的を達成するべく本発明に係るエッジ検出装置は、複数の画素を所定のピッチで配列したラインセンサと、このラインセンサに向けて単色光を照射する光源と、上記単色光の光路に位置付けられた透明体のエッジにおけるフレネル回折の光強度分布から前記ラインセンサの画素配列方向における上記透明体のエッジ位置を検出するエッジ位置解析手段とを備え、
更に上記エッジ位置解析手段にて前記透明体のエッジ位置が検出できないとき、前記ラインセンサによる全受光量が予め記憶した該ラインセンサの全入光状態での全受光量よりも小さいときには前記透明体による全遮光状態として判断する全遮光状態判断手段を備えたことを特徴としている。 The edge detection apparatus according to the present invention in order to achieve the above object, a line sensor in which a plurality of pixels at a predetermined pitch, a light source for irradiating monochromatic light toward the line sensor, the optical path of the upper Symbol monochromatic light Edge position analysis means for detecting the edge position of the transparent body in the pixel array direction of the line sensor from the light intensity distribution of Fresnel diffraction at the edge of the transparent body positioned at
Further, when the edge position of the transparent body cannot be detected by the edge position analyzing means, the transparent body when the total amount of light received by the line sensor is smaller than the total amount of light received in the full incident state of the line sensor. The present invention is characterized in that it includes a total light shielding state judging means for judging as a total light shielding state.

ちなみに前記全遮光状態判断手段は、前記ラインセンサを構成する複数の画素での各受光量の総和または平均を全受光量として検出するものであって、予め記憶した全入光状態での全受光量に比較して前記透明体のエッジ位置検出時における全受光量が予め設定した割合（例えば１０％の光量変動を見込んで設定される９０％の光量）よりも低下しているとき、前記透明体による全遮光状態として判断するように構成される。   Incidentally, the total light blocking state determination means detects the sum or average of the respective light receiving amounts at a plurality of pixels constituting the line sensor as the total light receiving amount, and the total light receiving state in the preliminarily stored all light incident state. When the total amount of received light at the time of detecting the edge position of the transparent body is lower than a preset ratio (for example, 90% light quantity set in anticipation of light quantity fluctuation of 10%), the transparent It is comprised so that it may judge as all the light-shielding states by a body.

また前記エッジ位置解析手段は、前記ラインセンサの各画素での受光量を全入光状態となっている画素側から順に辿ってその受光量が全受光状態から所定の割合だけ低下した画素の位置、具体的には検出対象物が透明体であることを考慮して、例えば光量が７５％または５０％となる画素の位置を検出し、この画素位置と上記受光量の低下の割合とから前記透明体のエッジ位置（光量が２５％となる位置）を検出するように構成すれば良い。   Further, the edge position analyzing means sequentially detects the amount of light received by each pixel of the line sensor from the pixel side in the total light incident state, and the position of the pixel in which the amount of received light has decreased by a predetermined ratio from the total light reception state. Specifically, considering that the detection target is a transparent body, for example, the position of a pixel whose light amount is 75% or 50% is detected, and the ratio of the decrease in the amount of received light is detected from the pixel position. What is necessary is just to comprise so that the edge position (position where a light quantity will be 25%) of a transparent body is detected.

尚、透明体の透明度が高い場合には、例えば前記ラインセンサと光源を、前記透明体の表面に対して傾斜した光路を形成するように位置決めすれば良い。また前記エッジ位置解析手段においては、前記フレネル回折により生じた前記ラインセンサの各画素での受光量の変化を近似曲線関数（例えばハイパボリック関数）を用いて近似し、上記近似曲線関数を用いて前記ラインセンサでの画素配列方向において所定光量となる位置を前記透明体のエッジ位置として解析するように構成すれば良い。   When the transparency of the transparent body is high, for example, the line sensor and the light source may be positioned so as to form an optical path inclined with respect to the surface of the transparent body. In the edge position analyzing means, a change in the amount of received light at each pixel of the line sensor caused by the Fresnel diffraction is approximated using an approximate curve function (for example, hyperbolic function), and the approximate curve function is used to What is necessary is just to comprise so that the position which becomes a predetermined light quantity in the pixel array direction in a line sensor may be analyzed as an edge position of the said transparent body.

上記構成のエッジ検出装置によれば、ラインセンサの出力を解析して透明体のエッジ位置を検出することができないとき、即ち、フレネル回折により光量が大きく低下した位置を検出することができないときには、透明体であると雖も多少の反射があることに着目して上記ラインセンサを構成する複数の画素の各受光量の総和、またはその平均としてその全受光量を求め、この受光量が全入光時における全受光量に比較してどの程度変化しているかを調べるので、この比較結果から全入光状態（光路に透明体が存在しない状態）であるか、或いは全遮光状態（ラインセンサが透明体により覆われている状態）であるかを簡易に判定することができる。   According to the edge detection device having the above configuration, when the edge position of the transparent body cannot be detected by analyzing the output of the line sensor, that is, when the position where the amount of light has greatly decreased due to Fresnel diffraction cannot be detected, Focusing on the fact that a transparent body has some reflection, the total received light amount of the plurality of pixels constituting the line sensor is calculated as the sum or the average of the received light amounts. Since the degree of change compared to the total amount of light received at the time of light is examined, it can be determined from this comparison result whether the light is in a completely incident state (a state where no transparent body is present in the optical path), It is possible to easily determine whether it is covered with a transparent body.

従って透明体のエッジ位置が検出できない場合であっても、その状態が全入光状態であるか、或いは全遮光状態であるかを判定することができるので、例えば透明体のエッジ位置を検出しながら該透明体の位置を調整するような場合であっても、上記透明体の位置を修正すべき向きを正確に判定することが可能となる。特にラインセンサの出力から光路中における透明体の有無を簡易に判定することができるので、例えば透明体の製造・検査ラインにエッジ検出装置を組み込んで該透明体の位置合わせを行うような場合、例えば透明体の有無を検出するための専用のセンサを必要としないので、その工業的利点が非常に大きい。   Therefore, even when the edge position of the transparent body cannot be detected, it can be determined whether the state is the total light incident state or the total light shielding state. For example, the edge position of the transparent body is detected. However, even when the position of the transparent body is adjusted, the direction in which the position of the transparent body should be corrected can be accurately determined. In particular, since it is possible to easily determine the presence or absence of a transparent body in the optical path from the output of the line sensor, for example, when positioning the transparent body by incorporating an edge detection device in the production / inspection line of the transparent body, For example, since a dedicated sensor for detecting the presence or absence of a transparent body is not required, its industrial advantage is very great.

以下、図面を参照して本発明の一実施形態に係るエッジ検出装置について説明する。
図１はこの実施形態に係るエッジ検出装置の要部概略構成を示す図で、１は複数の画素を所定のピッチで配列したラインセンサ、２はこのラインセンサ１に対峙させて設けられて上記ラインセンサ１に向けて単色平行光を照射する光源である。この光源２は、例えばレーザ素子２ａと、このレーザ素子２ａが発したレーザ光を平行光として前記ラインセンサ１に照射する投光レンズ２ｂとを備えて構成される。上記ラインセンサ１と光源２との間の上記単色平行光が照射される光路は、被検出対象物３のエッジを検出する為の検出領域として用いられる。 Hereinafter, an edge detection apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a main part of an edge detection apparatus according to this embodiment. Reference numeral 1 denotes a line sensor in which a plurality of pixels are arranged at a predetermined pitch. Reference numeral 2 denotes a line sensor that is provided facing the line sensor 1. This is a light source that emits monochromatic parallel light toward the line sensor 1. The light source 2 includes, for example, a laser element 2a and a light projecting lens 2b that irradiates the line sensor 1 with a laser beam emitted from the laser element 2a as parallel light. The optical path irradiated with the monochromatic parallel light between the line sensor 1 and the light source 2 is used as a detection region for detecting the edge of the detection target 3.

また上記ラインセンサ１の出力信号（光強度信号）を入力するマイクロコンピュータ４は、上記出力信号を解析して前記ラインセンサ１の画素配列方向における前記被検出対象物３のエッジ位置を検出するエッジ位置解析手段４ａを備える。更にこのマイクロコンピュータ４は、前記被検出対象物３が透明体であり、上記エッジ位置解析手段４ａにて被検出対象物（透明体）３のエッジ位置が検出できないとき、前記ラインセンサ１の出力信号から前記被検出対象物（透明体）３によってラインセンサ１が覆われた状態である否かを判定する全遮光状態判定手段４ｂを備えている。   The microcomputer 4 that receives the output signal (light intensity signal) of the line sensor 1 analyzes the output signal to detect the edge position of the detection target 3 in the pixel array direction of the line sensor 1. Position analysis means 4a is provided. Further, the microcomputer 4 outputs the output of the line sensor 1 when the detected object 3 is a transparent body and the edge position analyzing means 4a cannot detect the edge position of the detected object (transparent body) 3. All light shielding state determination means 4b for determining whether or not the line sensor 1 is covered with the detection target object (transparent body) 3 from the signal is provided.

ちなみにエッジ位置解析手段４ａは、前述した特許文献１に記載されるように前記ラインセンサ１の出力信号を画素毎に正規化する正規化手段と、正規化された各画素による受光強度を示す出力信号（光強度）を解析して、光強度が２５％となる位置を前記ラインセンサ１の画素配列方向における前記被検出対象物（透明体）３のエッジ位置として検出するように構成される。より具体的には上記エッジ位置解析手段４ａは、正規化された各画素１１,１２〜１ｎの出力信号（光強度）を調べて、例えばその光強度が２５％の前後となる２つの画素１ｋ,１ｋ＋１（ｋ＝１〜ｎ−１）を求める。そしてこれらの画素１ｋ,１ｋ＋１の各光強度の違いは、フレネル回折により生じた光強度分布に依存しているとしてその光強度の変化（光強度分布）をハイパボリック関数等の近似曲線関数を用いて近似する。その上でこの近似曲線関数（光強度分布）を用いて前記画素の配列方向において光強度が２５％となる位置を前記被検出対象物（透明体）３のエッジ位置として求めるものとなっている。 Incidentally, the edge position analyzing means 4a includes a normalizing means for normalizing the output signal of the line sensor 1 for each pixel as described in Patent Document 1 described above, and an output indicating the received light intensity by each normalized pixel. By analyzing the signal (light intensity), the position where the light intensity is 25% is detected as the edge position of the detection target object (transparent body) 3 in the pixel array direction of the line sensor 1. More specifically, the edge position analyzing means 4a examines the output signals (light intensity) of the normalized pixels 1 1 , 1 2 to 1 n , and the light intensity is, for example, about 2%. Two pixels 1 k , 1 k + 1 (k = 1 to n−1) are obtained. The difference between the light intensities of the pixels 1 k and 1 k + 1 depends on the light intensity distribution generated by Fresnel diffraction, and the change of the light intensity (light intensity distribution) is expressed by an approximate curve function such as a hyperbolic function. Use to approximate. Then, using this approximate curve function (light intensity distribution), the position where the light intensity is 25% in the pixel arrangement direction is obtained as the edge position of the detection target (transparent body) 3. .

一方、前記全遮光状態判定手段４ｂは、予め該エッジ検出装置の起動時等に、前述した光路中に被検出対象物（透明体）３を介在させない状態で検出される全入光状態でのラインセンサ１の出力信号からその全受光量を求め、これを初期値として記憶する手段を備える。ちなみに上記全受光量は、ラインセンサ１を構成する複数の画素１１,１２〜１ｎの各出力信号（光強度）の総和を求めることによって求められる。そして全遮光状態判定手段４ｂは、その運用時（エッジ検出時）に前記エッジ位置解析手段４ａにおいて被検出対象物（透明体）３のエッジ位置を検出できないとき、そのときのラインセンサ１の各画素１１,１２〜１ｎの出力信号（光強度）の総和を求めることで全受光量を求めている。そしてこの全受光量が前述した如く記憶した初期値としての全受光量よりも所定の割合以上に低いとき、これを前記ラインセンサ１が被検出対象物（透明体）３にて覆われた全遮光状態であるとして判定している。 On the other hand, the total light-shielding state determination means 4b is preliminarily detected in a state where all light is detected in a state where the detection target (transparent body) 3 is not interposed in the above-described optical path when the edge detection device is activated. Means for obtaining the total amount of received light from the output signal of the line sensor 1 and storing it as an initial value is provided. Incidentally, the total amount of received light is obtained by calculating the sum of the output signals (light intensity) of the plurality of pixels 1 1 , 1 2 to 1 n constituting the line sensor 1. When all the light shielding state determination means 4b cannot detect the edge position of the detection target (transparent body) 3 in the edge position analysis means 4a during its operation (at the time of edge detection), each line sensor 1 at that time The total received light amount is obtained by obtaining the sum of the output signals (light intensity) of the pixels 1 1 , 1 2 to 1 n . When the total amount of received light is lower than a predetermined rate by the total amount of received light as the initial value stored as described above, the total amount of the line sensor 1 covered with the object to be detected (transparent body) 3 is detected. It is determined that the light is blocked.

この判定結果に従って前記エッジ位置解析手段４ａの出力が制御され、エッジ位置が検出されない場合であっても、全遮光状態の場合と全入光状態の場合とで異なる出力結果が得られるようになっている。具体的には全入光状態でエッジ位置（エッジ検出位置）が最大となり、光路への被検出対象物（透明体）３の進入量（遮光幅）が増えるに従って上記エッジ位置が減少するようにその検出特性が定められている場合、図２に示すように全遮光状態となったときにはそのエッジ位置を最小に維持することが可能となる。換言すれば従来のように全遮光状態となったとき、これを全入光状態と区別することができないことに起因してそのエッジ位置が急激に最大値に変化するような不具合を抑えることが可能となる。   According to this determination result, the output of the edge position analyzing means 4a is controlled, and even when the edge position is not detected, different output results can be obtained in the case of the total light shielding state and the case of the total light incident state. ing. Specifically, the edge position (edge detection position) is maximized in the total light incident state, and the edge position decreases as the amount of the object to be detected (transparent body) 3 entering the optical path (the light shielding width) increases. When the detection characteristics are defined, the edge position can be kept to a minimum when the entire light shielding state is reached as shown in FIG. In other words, it is possible to suppress a problem that the edge position suddenly changes to the maximum value due to the fact that it cannot be distinguished from the total light incident state when the total light shielding state is reached as in the prior art. It becomes possible.

この結果、光路への被検出対象物（透明体）３の進入量（遮光幅）に応じたエッジ位置を正確に得ることが可能となるので、例えばそのエッジ位置に応じて被検出対象物（透明体）３をラインセンサ１の画素配列方向に変位させてそのエッジ位置を調整することが可能となる。特にエッジ位置を検出することができなかった場合であっても、被検出対象物（透明体）３をどの向きに変位させれば、光路中に被検出対象物（透明体）３のエッジ位置を位置付けて、そのエッジ位置の検出を可能とし得るかを容易に判断することが可能となるので、被検出対象物（透明体）３の位置調整に有効に役立てることが可能となる。   As a result, it is possible to accurately obtain the edge position according to the amount of entry (light-shielding width) of the detection target object (transparent body) 3 into the optical path. For example, the detection target object (in accordance with the edge position ( The edge position can be adjusted by displacing the transparent body 3 in the pixel array direction of the line sensor 1. In particular, even if the edge position cannot be detected, if the detected object (transparent body) 3 is displaced in any direction, the edge position of the detected object (transparent body) 3 in the optical path It is possible to easily determine whether or not the edge position can be detected, so that the position of the detection target object (transparent body) 3 can be effectively used.

ところで被検出対象物３が透明体である場合、光源２からの単色光を完全に遮光することができないので、該被検出対象物（透明体）３のエッジで生じたフレネル回折の光強度分布が上記被検出対象物（透明体）３の透過光に埋もれ、前述した２５％となる光量の位置が検出し難くなることがある。特に被検出対象物（透明体）３の透明度が高い場合、２５％となる光量の位置からのエッジ位置検出が難しくなることがある。従ってこのような場合には前述したエッジ位置解析手段４ａにおいて、例えば図３に示すように光量が７５％となる位置を求めるようにしても良い。   By the way, when the detected object 3 is a transparent body, the monochromatic light from the light source 2 cannot be completely shielded, so the light intensity distribution of Fresnel diffraction generated at the edge of the detected object (transparent body) 3. May be buried in the transmitted light of the object to be detected (transparent body) 3 and it may be difficult to detect the position of the light amount of 25%. In particular, when the transparency of the detection target object (transparent body) 3 is high, it may be difficult to detect the edge position from the position of the light amount of 25%. Therefore, in such a case, the edge position analyzing means 4a described above may obtain the position where the light quantity becomes 75% as shown in FIG.

具体的には前記エッジ位置解析手段４ａにおいて、正規化された各画素１１,１２〜１ｎの出力信号（光強度）を調べて、例えばその光強度が７５％の前後となる２つの画素１ｇ,１ｇ＋１（ｇ＝１〜ｎ−１）を求める。これらの画素１ｇ,１ｇ＋１の各光強度の違いも前述したフレネル回折により生じた光強度分布に依存しているので、その光強度の変化（光強度分布）をハイパボリック関数等の近似曲線関数を用いて近似する。その上でこの近似曲線関数（光強度分布）を用いて前記画素の配列方向において光強度が２５％となる位置を前記被検出対象物（透明体）３のエッジ位置として求めるようにすれば良い。換言すれば上述した光強度が７５％となる位置は、図３に示すように光強度が２５％となるエッジ位置からΔｘだけオフセットしたものであり、そのオフセット量は単色光の波長λ、ラインセンサ１と被検出対象物（透明体）３との距離ｚ等によって定まる。従って上述したように光強度が２５％となる位置を直接的に求めなくても、上述した如く求められる光強度が７５％となる位置から上記オフセットΔｘの補正を施すことにより、被検出対象物（透明体）３のエッジ位置を間接的に求めることができる。 Specifically, in the edge position analyzing means 4a, the normalized output signals (light intensity) of the respective pixels 1 1 , 1 2 to 1 n are examined, and for example, two light intensity values of around 75% are obtained. Pixels 1 g and 1 g + 1 (g = 1 to n−1) are obtained. Since the difference in light intensity between these pixels 1 g and 1 g + 1 also depends on the light intensity distribution generated by the Fresnel diffraction described above, the change in the light intensity (light intensity distribution) is approximated by an approximate curve function such as a hyperbolic function. Approximate using Then, using this approximate curve function (light intensity distribution), the position where the light intensity is 25% in the arrangement direction of the pixels may be obtained as the edge position of the detection object (transparent body) 3. . In other words, the position where the light intensity is 75% is offset by Δx from the edge position where the light intensity is 25% as shown in FIG. 3, and the offset amount is the wavelength λ of the monochromatic light, the line It is determined by the distance z between the sensor 1 and the object to be detected (transparent body) 3 or the like. Therefore, the object to be detected is corrected by correcting the offset Δx from the position where the light intensity obtained as described above becomes 75% without directly obtaining the position where the light intensity becomes 25% as described above. The edge position of (transparent body) 3 can be obtained indirectly.

尚、上述した如くしてエッジ位置を検出するに際しては、被検出対象物（透明体）３を透過する光の影響を受けることのない、いわゆる入光側のラインセンサ１の端部からその受光量をサーチし、受光量が低下する、いわゆる光強度分布の立ち下がり部分にエッジ位置が存在するとして上記エッジ位置の検出処理を実行することが好ましい。このようにすれば被検出対象物（透明体）３の表面に付着した汚れ等の影響を受けることなしに、そのエッジ位置を正確に検出することが可能となる。   When the edge position is detected as described above, the light is received from the end portion of the so-called light incident side line sensor 1 that is not affected by the light transmitted through the detection object (transparent body) 3. It is preferable to perform the edge position detection process by searching for the amount and assuming that the edge position exists at the falling portion of the so-called light intensity distribution where the received light amount decreases. In this way, it is possible to accurately detect the edge position without being affected by dirt attached to the surface of the object to be detected (transparent body) 3.

また前述した全遮光状態判定手段４ｂにおいては、ラインセンサ１による全受光量に着目して全遮光状態を判定したが、全遮光状態においては前述した図７(ｃ)に示すようにラインセンサ１の各画素１１,１２〜１ｎの出力信号（光強度）にバラツキが生じるので、このバラツキの度合いを調べて全遮光状態であるか否かを判定するようにしても良い。但し、ラインセンサ１の経年変化に起因して各画素１１,１２〜１ｎの出力信号（光強度）にバラツキが生じるので、定期的にラインセンサ１の出力特性をチェックした上で上述した各画素１１,１２〜１ｎの出力信号（光強度）のバラツキを判定することが望ましい。また被検出対象物（透明体）３の仕様によっても上述したバラツキの程度が変化するので、これを考慮して全遮光状態であるか否かの判定を行うことが好ましい。 In the above-described total light shielding state determination means 4b, the total light shielding state is determined by paying attention to the total amount of light received by the line sensor 1, but in the total light shielding state, the line sensor 1 as shown in FIG. Since the output signals (light intensity) of each of the pixels 1 1 , 1 2 to 1 n vary, the degree of this variation may be examined to determine whether or not all the light is blocked. However, since the output signals (light intensity) of the pixels 1 1 , 1 2 to 1 n vary due to the secular change of the line sensor 1, the output characteristics of the line sensor 1 are periodically checked before the above-mentioned. It is desirable to determine the variation in the output signal (light intensity) of each of the pixels 1 1 , 1 2 to 1 n . In addition, since the degree of variation described above varies depending on the specification of the detection target object (transparent body) 3, it is preferable to determine whether or not the entire light shielding state is taken into consideration.

ところで被検出対象物（透明体）３の透明度が高い場合、前述したように全遮光状態判定手段４ｂにてラインセンサ１での受光量の総和（全受光量）を調べても、１０％以上の受光量の変化が生じないことが想定される。このような不具合を回避するには、例えば図４にその概念を示すように、ラインセンサ１と光源２との間に形成される光路を、前記被検出対象物（透明体）３の表面に対して傾斜させて設けるようにすれば良い。そして上記被検出対象物（透明体）３の表面に対して光路が傾いている分、エッジ位置解析手段４ａにおいて検出されるエッジ位置を上記傾きの角度θに従って補正すれば、これによって被検出対象物（透明体）３のエッジ位置を正確に検出することが可能となる。   By the way, when the transparency of the object to be detected (transparent body) 3 is high, as described above, even if the total amount of light received by the line sensor 1 (total amount of received light) is checked by the total light shielding state determination means 4b, it is 10% or more. It is assumed that no change in the amount of received light occurs. In order to avoid such problems, for example, as shown in FIG. 4, an optical path formed between the line sensor 1 and the light source 2 is formed on the surface of the detection target (transparent body) 3. It may be provided to be inclined with respect to it. If the edge position detected by the edge position analyzing means 4a is corrected according to the inclination angle θ by the amount that the optical path is inclined with respect to the surface of the detection target object (transparent body) 3, this results in the detection target object. The edge position of the object (transparent body) 3 can be accurately detected.

即ち、被検出対象物（透明体）３の透明度が高くても、該被検出対象物（透明体）３の表面に対して光路が傾くことによりその表面での反射が増えるので、被検出対象物（透明体）３を透過してラインセンサ１に到達する光量が減少する。この結果、図５(ａ)(ｂ)に被検出対象物（透明体）３の表面に対して光路を直角に設定した場合と、上記光路を斜めに設定した場合とにおけるラインセンサ１の出力を対比して示すように、光路を斜めに設定した場合にはその受光量が低下すると共に、各画素１１,１２〜１ｎでの受光量のバラツキが大きくなる。従って被検出対象物（透明体）３の表面に対して光路を傾けて設定すれば、被検出対象物（透明体）３の透明度が高い場合であってもその表面反射を大きくすることができるので、光路を遮る被検出対象物（透明体）３の存在を確実に検出することが可能となる。 That is, even if the object to be detected (transparent body) 3 has high transparency, the light path is inclined with respect to the surface of the object to be detected (transparent body) 3 so that reflection on the surface increases. The amount of light that passes through the object (transparent body) 3 and reaches the line sensor 1 is reduced. As a result, the output of the line sensor 1 in the case where the optical path is set at right angles to the surface of the detection target object (transparent body) 3 in FIGS. 5A and 5B and the case where the optical path is set obliquely. As shown by contrast, when the optical path is set obliquely, the amount of received light decreases and the variation in the amount of received light at each of the pixels 1 1 , 1 2 to 1 n increases. Therefore, if the optical path is set to be inclined with respect to the surface of the detection target object (transparent body) 3, the surface reflection can be increased even when the detection target object (transparent body) 3 is highly transparent. Therefore, it is possible to reliably detect the presence of the detection target object (transparent body) 3 that blocks the optical path.

尚、本発明は上述した実施形態に限定されるものではない。例えばエッジ位置解析手段４ａにおいては、ここではハイパボリックセカンド関数を用いてフレネル回折の光強度分布を解析するものとして説明したが、他の近似曲線関数を用いても良いことは勿論のことである。またラインセンサ１の全受光量の情報として、複数の画素の各受光量の平均を求めるようにしても良いことは言うまでもない。更には全遮光状態の判定条件についても、エッジ検出対象とする透明体３の透明度や外光等の外乱要因を考慮して設定すれば良いものである。その他、本発明はその要旨を逸脱しない範囲で種々変形して実施することができる。   The present invention is not limited to the embodiment described above. For example, the edge position analyzing means 4a has been described here as analyzing the light intensity distribution of Fresnel diffraction using a hyperbolic second function, but it goes without saying that other approximate curve functions may be used. Needless to say, the average of the amounts of light received by a plurality of pixels may be obtained as information on the total amount of light received by the line sensor 1. Further, the determination conditions for the total light blocking state may be set in consideration of disturbance factors such as transparency of the transparent body 3 to be edge detected and external light. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

本発明の一実施形態に係るエッジ検出装置の要部概略構成図。The principal part schematic block diagram of the edge detection apparatus which concerns on one Embodiment of this invention. 本発明に係るエッジ検出装置のエッジ位置検出特性を示す図。The figure which shows the edge position detection characteristic of the edge detection apparatus which concerns on this invention. エッジ位置検出の別の手法を示す図。The figure which shows another method of edge position detection. 透明体の透明度が高い場合におけるエッジ位置検出の手法を示す図。The figure which shows the method of edge position detection in case transparency of a transparent body is high. 透明体の表面に対して光路が直角の場合と傾斜している場合とにおける受光量の変化を対比して示す図。The figure which contrasts and shows the change of the light-receiving amount in the case where an optical path is at right angle with respect to the surface of a transparent body, and the case where it inclines. 従来のエッジ検出装置の概略構成図。The schematic block diagram of the conventional edge detection apparatus. エッジ検出器におけるエッジ検出原理を説明するためのラインセンサの出力例を示す図。The figure which shows the output example of the line sensor for demonstrating the edge detection principle in an edge detector. 透明体の有無によるラインセンサの出力の変化の例を示す図。The figure which shows the example of the change of the output of a line sensor by the presence or absence of a transparent body. 従来のエッジ検出器におけるエッジ検出特性を示す図。The figure which shows the edge detection characteristic in the conventional edge detector.

符号の説明Explanation of symbols

１ ラインセンサ
２ 光源
３ 被検出物（透明体）
４ マイクロコンピュータ
４ａ エッジ位置解析手段
４ｂ 全遮光状態判定手段 1 Line sensor 2 Light source 3 Object to be detected (transparent body)
4 microcomputer 4a edge position analysis means 4b total light shielding state determination means

Claims (4)

複数の画素を所定のピッチで配列したラインセンサと、
このラインセンサに向けて単色光を照射する光源と、
上記単色光の光路に位置付けられた透明体のエッジにおけるフレネル回折の光強度分布から前記ラインセンサの画素配列方向における上記透明体のエッジ位置を検出するエッジ位置解析手段と、
このエッジ位置解析手段にて前記透明体のエッジ位置が検出できないとき、前記ラインセンサによる全受光量が予め記憶した該ラインセンサの全入光状態での全受光量よりも小さいときには前記透明体による全遮光状態として判断する全遮光状態判断手段と、を備え、
前記全遮光状態判断手段は、前記ラインセンサを構成する複数の画素での各受光量の総和または平均を全受光量として検出するものであって、予め記憶した全入光状態での全受光量に比較して前記透明体のエッジ位置検出時における全受光量が予め設定した割合よりも低下しているとき、前記透明体による全遮光状態として判断する、ことを特徴とするエッジ検出装置。 A line sensor in which a plurality of pixels are arranged at a predetermined pitch;
A light source that emits monochromatic light toward the line sensor;
Edge position analysis means for detecting the edge position of the transparent body in the pixel array direction of the line sensor from the light intensity distribution of Fresnel diffraction at the edge of the transparent body positioned in the optical path of the monochromatic light;
When the edge position of the transparent body cannot be detected by the edge position analyzing means, when the total amount of light received by the line sensor is smaller than the total amount of light received in the full incident state of the line sensor, the transparent body A total light shielding state determining means for determining as a total light shielding state,
The total light blocking state determination means detects the sum or average of the respective light receiving amounts at a plurality of pixels constituting the line sensor as a total light receiving amount, and the total light receiving amount in a pre-stored total light incident state Compared to the above, when the total amount of received light at the time of detecting the edge position of the transparent body is lower than a preset ratio, it is determined as the total light shielding state by the transparent body. 前記エッジ位置解析手段は、前記ラインセンサの各画素での受光量を全入光状態となっている画素側から順に辿ってその受光量が全受光状態から所定の割合だけ低下した画素の位置を検出し、この画素位置と上記受光量の低下の割合とから前記透明体のエッジ位置を検出するものである請求項１に記載のエッジ検出装置。 The edge position analysis means sequentially detects the amount of light received at each pixel of the line sensor from the pixel side in the total light incident state, and determines the position of the pixel where the amount of received light has decreased by a predetermined percentage from the total light reception state. 2. The edge detection apparatus according to claim 1, wherein the edge position of the transparent body is detected from the pixel position and the rate of decrease in the amount of received light. 前記ラインセンサと光源は、前記透明体の表面に対して傾斜した光路を形成したものである請求項１に記載のエッジ検出装置。 The edge detection device according to claim 1, wherein the line sensor and the light source form an optical path inclined with respect to a surface of the transparent body. 前記エッジ位置解析手段は、前記フレネル回折により生じた前記ラインセンサの各画素での受光量の変化を近似曲線関数を用いて近似し、上記近似曲線関数を用いて前記ラインセンサでの画素配列方向において所定光量となる位置を前記透明体のエッジ位置として解析するものである請求項１に記載のエッジ検出装置。 The edge position analyzing means approximates the change in the amount of light received by each pixel of the line sensor caused by the Fresnel diffraction using an approximate curve function, and uses the approximate curve function to align the pixel arrangement direction in the line sensor. The edge detection apparatus according to claim 1, wherein a position having a predetermined light quantity is analyzed as an edge position of the transparent body.
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