JPH0776758B2 - Defect detection method for sheet - Google Patents
Defect detection method for sheetInfo
- Publication number
- JPH0776758B2 JPH0776758B2 JP15918286A JP15918286A JPH0776758B2 JP H0776758 B2 JPH0776758 B2 JP H0776758B2 JP 15918286 A JP15918286 A JP 15918286A JP 15918286 A JP15918286 A JP 15918286A JP H0776758 B2 JPH0776758 B2 JP H0776758B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- receiving element
- planar body
- light receiving
- transmitted
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8901—Optical details; Scanning details
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
- Microscoopes, Condenser (AREA)
- Optical Filters (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明はシート状、フイルム状、板状等各種面状体の欠
陥を光学的に検出するための方法に関する。TECHNICAL FIELD The present invention relates to a method for optically detecting a defect in various sheet-like, film-like, plate-like sheet-like bodies.
〔従来の技術〕 合成樹脂シート（フイルムも含む）、金属板、ガラス板
等、これらの面状体を光学的に検査する手段として、フ
ライング・スポット法が広く採用されている。[Prior Art] The flying spot method has been widely adopted as a means for optically inspecting sheet materials such as synthetic resin sheets (including films), metal plates, and glass plates.
この方法では、第３図に示すように光照射系１のレーザ
光源２から出射された平行光をレンズ３で絞り、光走査
手段４を介してその光ビームを矢印方向に走行する面状
体（被検体）５の表面に照射しながら走査し、この際の
反射光または透過光を受光素子６にて検出し、その光信
号を光→電気変換して電気的に処理している。In this method, as shown in FIG. 3, the parallel light emitted from the laser light source 2 of the light irradiation system 1 is narrowed by the lens 3 and the light beam travels in the direction of the arrow through the light scanning means 4. Scanning is performed while irradiating the surface of the (subject) 5 and the reflected light or transmitted light at this time is detected by the light receiving element 6, and the optical signal is converted from light to electrical and processed electrically.
このような方法によるとき、面状体５からの反射光また
は透過光は、その面状体５の正常部と欠陥部とで異な
り、受光素子６へ入射される光量も異なるので、この受
光素子６において受光量の変化を検出することにより、
面状体５の欠陥の有無、その欠陥部位等が判明する。In such a method, the reflected light or the transmitted light from the planar body 5 is different between the normal portion and the defective portion of the planar body 5 and the amount of light incident on the light receiving element 6 is different. By detecting the change in the amount of received light in 6,
The presence / absence of a defect in the sheet 5 and the defective portion thereof are determined.
ところで上記フライング・スポット法の受光手段として
光フアイバ受光法がある。この方法は同じく第３図に示
すように、面状体５が例えば透過性を有する場合、面状
体５の上方から走査光を照射することにより、下方に透
過した透過光を、面状体５の下部に走査幅相当分だけ並
べられた光フアイバ７の一端から入射して光フアイバ７
内に案内し、１つに結束された光フアイバ７の他端から
出射して直接受光素子６に導く方法である。By the way, there is an optical fiber light receiving method as a light receiving means of the flying spot method. In this method, as shown in FIG. 3, when the planar body 5 has a transmissive property, for example, by irradiating scanning light from above the planar body 5, the transmitted light transmitted downward is converted into a planar body. The optical fiber 7 is incident on one end of the optical fiber 7 arranged in the lower part of the section 5 by the width corresponding to the scanning width.
This is a method in which the light is guided inward and emitted from the other end of the optical fibers 7 which are bundled into one, and is directly guided to the light receiving element 6.
しかしながら、上記光フアイバ受光法では、前記光フア
イバ７がレーザ光以外の他の波長光も伝送案内するた
め、検査装置周辺の光も外乱光として光フアイバ内に入
射し、検出感度（S/N比）が低下する問題があり、この
ため、外乱光の入射を防止する特別な遮光装置を設けな
ければならず、検査に要する費用が高くつく欠点があっ
た。However, in the above optical fiber receiving method, since the optical fiber 7 also guides light of other wavelengths other than the laser light, the light around the inspection device also enters the optical fiber as disturbance light and the detection sensitivity (S / N There is a problem in that the cost required for inspection is high because a special light-shielding device for preventing the incidence of ambient light must be provided.
また、前記受光素子６の受光面積が大きいので、受光す
る位置により感度にバラツキが生じやすく、即ち、光フ
アイバ７に入射した前記透過光（反射光の場合も含む）
の位置により、受光素子６に感度むらが生じ、面状体５
の欠陥に応じた電気信号が得られず、走査光の走査方向
での検出感度差が生じる不都合があった。In addition, since the light receiving area of the light receiving element 6 is large, the sensitivity is likely to vary depending on the light receiving position, that is, the transmitted light incident on the optical fiber 7 (including the case of reflected light).
Unevenness occurs in the light receiving element 6 depending on the position of the
However, there is a problem in that an electric signal corresponding to the defect is not obtained and a difference in detection sensitivity occurs in the scanning direction of the scanning light.
本発明は上記の問題点を解決し、受光素子に外乱光が入
らないようにし、また受光素子での検出感度が均一にな
るようにして、面状体の欠陥を精度よく検出できるよう
にしたもので、光走査手段を備えた光照射系により面状
体の表面を光走査して、その走査光を面状体より反射ま
たは透過させ、その反射光または透過光を光フアイバで
案内して受光素子を導き、その受光素子で面状体の欠陥
の有無による前記反射光または透過光の変化を検出する
面状体の欠陥検出方法において、前記光フアイバで案内
された前記反射光または透過光を干渉フイルタとコンデ
ンサレンズを通して前記受光素子に導くことを特徴とす
るものである。The present invention solves the above problems, prevents ambient light from entering the light-receiving element, and makes the detection sensitivity of the light-receiving element uniform so that defects in the planar body can be accurately detected. The surface of a planar body is optically scanned by a light irradiation system equipped with a light scanning means, the scanning light is reflected or transmitted from the planar body, and the reflected light or transmitted light is guided by an optical fiber. In a defect detection method for a planar body, which guides a light receiving element and detects a change in the reflected light or the transmitted light depending on the presence or absence of a defect in the planar body, the reflected light or the transmitted light guided by the optical fiber. Is guided to the light receiving element through an interference filter and a condenser lens.
本発明方法の場合、上記のように、光フアイバで案内さ
れた面状体からの反射光または透過光が、干渉フイルタ
に入射する際、フイルタの面に垂直な方向から入射した
光即ち面状相からの欠陥有無を検出する光のみが干渉フ
イルタを通過し、それ以外の光即ち外乱光は通過を阻止
される。また干渉フイルタを通過した光がコンデンサレ
ンズを通過後、受光阻止の受光面で一点に集中するよう
に受光素子に導かれることになり、前記受光素子での感
度むらが減少する。In the case of the method of the present invention, as described above, when the reflected light or the transmitted light from the planar body guided by the optical fiber enters the interference filter, the light that is incident from the direction perpendicular to the surface of the filter, that is, the planar shape Only the light that detects the presence or absence of a defect from the phase passes through the interference filter, and the other light, that is, ambient light, is blocked from passing. Further, after the light passing through the interference filter passes through the condenser lens, it is guided to the light receiving element so as to be concentrated at one point on the light receiving surface of the light receiving block, so that the unevenness of sensitivity in the light receiving element is reduced.
次に本発明の一実施例を第１図及び第２図により詳細に
説明する。なお説明の都合上、従来と同一構成のものに
は、同一符号をつけるものとする。Next, an embodiment of the present invention will be described in detail with reference to FIGS. For convenience of explanation, the same components as those of the conventional one will be denoted by the same reference numerals.
まず第１図に示すように、欠陥を検出すべき例えば透明
な合成樹脂シートからなる面状体５が矢印方向に走行
し、この面状体５の表面には、光照射系１のレーザ光源
２から出射された平行光をレンズ３で絞った光ビームが
上方から照射され、かつこの光ビームは、回転ミラー等
の光走査手段４により面状体５の幅方向に走査される。First, as shown in FIG. 1, a sheet-like body 5 made of, for example, a transparent synthetic resin sheet, in which a defect is to be detected, travels in the direction of the arrow, and the surface of the sheet-like body 5 is a laser light source of the light irradiation system 1. A light beam obtained by narrowing the parallel light emitted from the lens 2 by the lens 3 is emitted from above, and the light beam is scanned in the width direction of the planar body 5 by the light scanning means 4 such as a rotating mirror.
次にこの面状体５を通過した透過光は、面状体５の下部
に走査幅相当分だけ並べられた光フアイバ７の一端から
入射して光フアイバ７内に案内され、１つに結束された
光フアイバ７の他端から出射される。Next, the transmitted light that has passed through the planar body 5 enters from one end of the optical fiber 7 arranged in the lower portion of the planar body 5 by the width corresponding to the scanning width, is guided into the optical fiber 7, and is bundled into one. The emitted light is emitted from the other end of the optical fiber 7.
次に前記透過光は第２図に示すように、干渉フイルタ８
とコンデンサレンズ（集光レンズ）９を通過する。干渉
フイルタ８は例えばAuからなる金属製のフイルタで、干
渉現象を利用した透過光のバンドパスフイルタである。Next, the transmitted light is transmitted to the interference filter 8 as shown in FIG.
And a condenser lens (condensing lens) 9. The interference filter 8 is a metal filter made of Au, for example, and is a bandpass filter for transmitted light using an interference phenomenon.
上記干渉フイルタ８は、周知の次式により通過波長をあ
らわすことができる。The interference filter 8 can express the passing wavelength by the following well-known equation.
2t・cosθ＝ｍλ t :フイルタ金属の厚さ λ：透過波長 m :整数 θ：フイルタの法線に対する入射光の傾き ここで、レーザ光を用いると仮定した場合、λは一定で
あり、レーザ光のみ透過させる干渉フイルタを使用する
と、ｔも決定される。2t ・ cos θ = mλ t: thickness of filter metal λ: transmission wavelength m: integer θ: inclination of incident light with respect to the normal line of the filter Here, if laser light is used, λ is constant and laser light Using an interference filter that only allows transmission, t is also determined.
即ち、θ＝０°（干渉フイルタに対して垂直）な光以外
は、同じλであっても通過しない。That is, other than the light of θ = 0 ° (perpendicular to the interference filter), the light of the same λ does not pass.
従って、第２図のように、光フアイバ７の内部を全反射
して干渉フイルタ８へ入射しようとする光は当然θ＝０
°であるのでカットされ、即ち、外乱光は干渉フイルタ
８内の通過を阻止され、面状体５を通過した透過光の如
きレーザ光は、θ＝０°であるので、干渉フイルタ８内
を通過することになり、検出感度が高められる。Therefore, as shown in FIG. 2, the light that is totally reflected inside the optical fiber 7 and is about to enter the interference filter 8 is naturally θ = 0.
Therefore, the disturbance light is blocked from passing through the interference filter 8, and the laser light such as the transmitted light that has passed through the planar member 5 has θ = 0 °. As a result, the detection sensitivity is increased.
次に前記干渉フイルタ８を通過したレーザ光である透過
光は平行になってコンデンサレンズ９に入り、そこを通
過後、受光素子６の受光面で一点に集中するように位置
決めされた受光素子６に入射される。受光素子６として
は、フオトダイオード（PD）やアパランシエフオトダイ
オード（APD）等の光検出器からなり、電気的、電子的
な信号処理回路、記録計等を備えた検出装置に接続され
ている。Next, the transmitted light, which is the laser light that has passed through the interference filter 8, becomes parallel and enters the condenser lens 9, and after passing through it, the light receiving element 6 positioned so that it is concentrated at one point on the light receiving surface of the light receiving element 6. Is incident on. As the light receiving element 6, a photo detector such as a photo diode (PD) or an apalanche photo diode (APD) is used, which is connected to a detection device equipped with an electrical and electronic signal processing circuit, a recorder and the like. There is.
受光素子６では面状体５の欠陥の有無による前記透過光
の光量の変化を検出する。The light receiving element 6 detects a change in the amount of the transmitted light depending on the presence or absence of a defect in the planar body 5.
即ち、面状体５の正常部に走査光が照射されていると
き、その透過光が定常状態で受光素子６に入射されるの
で、受光レベルに変化がなく、検出装置は面状体に欠陥
がないことを認識する。ところが面状体５に傷、異物混
入、汚れ等の欠陥部があり、これに走査光が照射される
と、面状体５を透過する透過光の光量が変化し、その透
過光が定常状態となる状態で受光素子６に入射されるこ
とになる。これにより、受光レベルが変化し、検出装置
は面状体５に欠陥があることを認識する。このようにし
て面状体の欠陥有無を検出する。That is, when the normal portion of the planar body 5 is irradiated with the scanning light, the transmitted light is incident on the light receiving element 6 in a steady state, so that the light receiving level does not change, and the detection device has a defect in the planar body. Recognize that there is no. However, the planar member 5 has defects such as scratches, foreign substances, stains, etc. When this is irradiated with scanning light, the amount of transmitted light that passes through the planar member 5 changes, and the transmitted light is in a steady state. Then, the light is incident on the light receiving element 6 in such a state. As a result, the light reception level changes, and the detection device recognizes that the planar body 5 has a defect. In this way, the presence or absence of defects in the sheet is detected.
本発明では、受光素子６に入射される透過光が、コンデ
ンサレンズ９の作用により受光素子６の一点に集中する
ので、受光素子６の受光する位置の違いによる感度のバ
ラツキの影響を受けなくなり、感度むらが生じなくな
る。In the present invention, since the transmitted light incident on the light receiving element 6 is concentrated on one point of the light receiving element 6 by the action of the condenser lens 9, it is not affected by the variation in sensitivity due to the difference in the light receiving position of the light receiving element 6. The uneven sensitivity does not occur.
なお前記干渉フイルタ８を通過する光は、フイルタに対
する垂直成分即ちθ＝０°の分だけであるので、受光素
子６に導かれる光量が少ない場合がある。例えば面状体
５に照射される走査光は光学走査されている関係で、こ
の走査光が特に幅広の面状体の幅方向側に照射されたと
き、ここを通過した透過光が光フアイバ７の軸線方向に
入射せず、この軸線に対して角度を持った方向から入射
され、かつ出射される場合であり、このような光は干渉
フイルタでカットされるからである。Since the light passing through the interference filter 8 is only the vertical component with respect to the filter, that is, θ = 0 °, the light quantity guided to the light receiving element 6 may be small. For example, since the scanning light applied to the planar body 5 is optically scanned, when the scanning light is applied to the width direction side of a wide planar body, the transmitted light passing therethrough is transmitted by the optical fiber 7. This is a case where the light does not enter in the axial direction of the above, but enters and exits from a direction having an angle with respect to this axial line, and such light is cut by the interference filter.
このような場合、光フアイバ７の出口側端面と干渉フイ
ルタ８との間に拡散板を入れ光フアイバのNA（開口数）
で規定されるすべての出射光を拡散して均一化させる
と、受光素子への光量不足による検出精度の低下、誤作
動を防止でき検出装置の性能が向上する。In such a case, a diffusing plate is inserted between the exit end face of the optical fiber 7 and the interference filter 8 to set the NA (numerical aperture) of the optical fiber.
By diffusing and homogenizing all the emitted light defined by, the detection accuracy can be prevented from lowering due to insufficient light amount to the light receiving element, and malfunction can be prevented, so that the performance of the detection device is improved.
なお面状体５が金属板のような不透明体の場合には、走
査光が面状体を通過せず反射することになるが、この反
射光を光フアイバで案内して前記干渉フイルタとコンデ
ンサレンズを通し受光素子に導くようにしても、同様に
面状体の欠陥の有無を精度よく検出できるものである。When the planar body 5 is an opaque body such as a metal plate, the scanning light is reflected without passing through the planar body, and the reflected light is guided by an optical fiber to the interference filter and the condenser. Even if the light is guided to the light receiving element through the lens, the presence or absence of the defect of the planar body can be detected with high accuracy.
以上説明したように、本発明に係る面状体の欠陥検出方
法によれば、前記光フアイバで案内された面状体からの
反射光または透過光を干渉フイルタとコンデンサレンズ
を通して受光素子に導くことにより、面状体の欠陥有無
を検出するのに必要な光だけを選択して受光素子に導く
ことができ、検出感度（S/N比）を向上させることがで
きる。従って、外乱光のような検出に不要な光をカット
する特別な遮光装置を設ける必要がなく、検査装置が安
価となり検査コストを低減させることができる。As described above, according to the defect detection method for a sheet according to the present invention, the reflected light or the transmitted light from the sheet guided by the optical fiber is guided to the light receiving element through the interference filter and the condenser lens. Thereby, only the light necessary for detecting the presence or absence of a defect in the planar body can be selected and guided to the light receiving element, and the detection sensitivity (S / N ratio) can be improved. Therefore, it is not necessary to provide a special light-shielding device that cuts out unnecessary light such as ambient light for detection, and the inspection device becomes inexpensive, and the inspection cost can be reduced.
また干渉フイルタを通過した反射光または透過光はコン
デンサレンズで絞られて受光素子に入射するので、受光
素子の受光位置の違いによる感度のバラツキの影響を受
けなくなり、感度むらが生じなくなる。従って、前記検
出感度の向上とあいまって、面状体の微小な欠陥の有無
や部位を精度よく検出することができる。Further, since the reflected light or the transmitted light that has passed through the interference filter is focused by the condenser lens and is incident on the light receiving element, it is not affected by the variation in sensitivity due to the difference in the light receiving position of the light receiving element, and the sensitivity unevenness does not occur. Therefore, together with the improvement in the detection sensitivity, it is possible to accurately detect the presence or absence of a minute defect in the sheet and the site.
第１図は本発明の一実施例を示す説明図、第２図は本発
明の要部を拡大して示す説明図、第３図は従来方法を示
す説明図である。 １……光照射系、４……光走査手段、５……面状体、６
……受光素子、７……光フアイバ、８……干渉フイル
タ、９……コンデンサレンズ。FIG. 1 is an explanatory view showing an embodiment of the present invention, FIG. 2 is an explanatory view showing an enlarged main part of the present invention, and FIG. 3 is an explanatory view showing a conventional method. 1 ... Light irradiation system, 4 ... Light scanning means, 5 ... Planar body, 6
...... Light receiving element, 7 ... Optical fiber, 8 ... Interference filter, 9 ... Condenser lens.
Claims (1)
の表面を光走査して、その走査光を面状体より反射また
は透過させ、その反射光または透過光を光フアイバで案
内して受光素子に導き、その受光素子で面状体の欠陥の
有無による前記反射光または透過光の変化を検出する面
状体の欠陥検出方法において、前記光フアイバで案内さ
れた前記反射光または透過光を干渉フイルタとコンデン
サレンズを通して前記受光素子に導くことを特徴とする
面状体の欠陥検出方法。1. A surface of a planar body is optically scanned by a light irradiation system equipped with an optical scanning means, the scanning light is reflected or transmitted by the planar body, and the reflected light or transmitted light is guided by an optical fiber. Then led to the light receiving element, in the defect detection method of the planar body for detecting the change of the reflected light or the transmitted light depending on the presence or absence of a defect of the planar body in the light receiving element, the reflected light guided by the optical fiber or A method for detecting defects in a planar body, characterized in that transmitted light is guided to the light receiving element through an interference filter and a condenser lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15918286A JPH0776758B2 (en) | 1986-07-07 | 1986-07-07 | Defect detection method for sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15918286A JPH0776758B2 (en) | 1986-07-07 | 1986-07-07 | Defect detection method for sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6315143A JPS6315143A (en) | 1988-01-22 |
| JPH0776758B2 true JPH0776758B2 (en) | 1995-08-16 |
Family
ID=15688098
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15918286A Expired - Fee Related JPH0776758B2 (en) | 1986-07-07 | 1986-07-07 | Defect detection method for sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0776758B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0711494B2 (en) * | 1988-06-16 | 1995-02-08 | 松下電工株式会社 | Inspection method for translucent containers |
| JP2501884B2 (en) * | 1988-10-15 | 1996-05-29 | 松下電工株式会社 | Inspection method for translucent containers |
-
1986
- 1986-07-07 JP JP15918286A patent/JPH0776758B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6315143A (en) | 1988-01-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |