JP2005214887A - Detection head for optical fiber sensor - Google Patents

Detection head for optical fiber sensor Download PDF

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JP2005214887A
JP2005214887A JP2004024545A JP2004024545A JP2005214887A JP 2005214887 A JP2005214887 A JP 2005214887A JP 2004024545 A JP2004024545 A JP 2004024545A JP 2004024545 A JP2004024545 A JP 2004024545A JP 2005214887 A JP2005214887 A JP 2005214887A
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optical fiber
light
detection head
tip
light receiving
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Kazuhiro Otsuka
数博 大塚
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Panasonic Industrial Devices SUNX Co Ltd
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Sunx Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized detection head for a optical fiber sensor of high detection precision. <P>SOLUTION: In this detection head, a photoreception lens 4 is arranged in a tip of a photoreception side optical fiber 2B, and only light incident substantially in parallel to an optical axis of the photoreception side optical fiber 2B gets incident into a tip face of the photoreception side optical fiber 2B through the photoreception lens 4. Reflected light from an end face 13A of a lid plate part 13 of a large incident angle is thereby evaded from getting incident into the photoreception side optical fiber 2B, even when the photoreception side optical fiber 2B is provided closely near to a projection side optical fiber 2A. As a result thereof, an S/N ratio is precluded from getting low even when the both optical fibers 2A, 2B are arranged closely, so as to reduce a size of the detection head and to enhance the detection precision. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、反射型光ファイバセンサの検出ヘッドに関する。   The present invention relates to a detection head of a reflective optical fiber sensor.

この種のファイバセンサは、投受光回路や投受光素子からなる電気回路を備えたセンサ本体に光ファイバを接続し、その光ファイバの先端に検出ヘッドを設け、その検出ヘッドを検出箇所に配置する構成である。   In this type of fiber sensor, an optical fiber is connected to a sensor body having an electric circuit composed of a light emitting / receiving circuit and a light emitting / receiving element, a detection head is provided at the tip of the optical fiber, and the detection head is disposed at a detection location. It is a configuration.

このような光学式センサの１種として、腐食性の高い薬品・油等に対応させた構造のものがある（特許文献１参照）。このものは、図５に示すように、被覆ケーブル１００内に、それぞれセンサ本体の投光部および受光部に接続された光ファイバ１０１が備えられている。被覆ケーブル１００の先端からは、各光ファイバ１０１の先端部が露出されており、この露出部分が耐薬品性の樹脂により形成された筒状のハウジング１０２によって覆われている。そして、このハウジング１０２における先端側の開口部は、平板状に形成された蓋板部１０３を嵌め付けることによって塞がれている。
実開平３−３３４０４号公報 One type of such an optical sensor has a structure corresponding to highly corrosive chemicals and oils (see Patent Document 1). As shown in FIG. 5, the optical fiber 101 connected to the light projecting unit and the light receiving unit of the sensor main body is provided in the covered cable 100. From the tip of the covered cable 100, the tip of each optical fiber 101 is exposed, and this exposed part is covered with a cylindrical housing 102 formed of a chemical-resistant resin. And the opening part of the front end side in this housing 102 is block | closed by fitting the cover plate part 103 formed in flat form.
Japanese Utility Model Publication No. 3-33404

ところで、この種のセンサにおいては、近年、小型化の要請がますます高まっている。このような要請に応えるためには、ハウジング１０２内で、一対の光ファイバ１０１を出来るだけ近接して配することが好ましい。しかし、ファイバ素線は通常６０°程度の開口角をもっているため、投光側の光ファイバ１０１から投光された光の一部がハウジング１０２における蓋板部１０３の端縁に跳ね返されて受光側の光ファイバに入光してしまう、いわゆる回り込み現象が起こる場合がある。このような場合には、被検出物を検出していない状態でも受光部に常に一定量の受光が発生している状態となり、検出時のＳ／Ｎ比が減少してしまう。したがって、これを防止するためには両ファイバ１０１間に一定の距離を置かなければならず、センサの小型化に限界がある。   Meanwhile, in recent years, there is an increasing demand for downsizing of this type of sensor. In order to meet such a demand, it is preferable to arrange the pair of optical fibers 101 as close as possible in the housing 102. However, since the fiber strand usually has an opening angle of about 60 °, a part of the light projected from the optical fiber 101 on the light projecting side is bounced back to the edge of the cover plate portion 103 in the housing 102 to receive the light. In some cases, a so-called wraparound phenomenon that enters the optical fiber occurs. In such a case, even if the detection object is not detected, a constant amount of light is always generated in the light receiving unit, and the S / N ratio at the time of detection decreases. Therefore, in order to prevent this, a certain distance must be placed between the two fibers 101, and there is a limit to downsizing the sensor.

本発明は上記のような事情に基づいて完成されたものであって、小型で検出精度の高いセンサの検出ヘッドを提供することを目的とする。   The present invention has been completed based on the above-described circumstances, and an object thereof is to provide a detection head of a small sensor with high detection accuracy.

上記の目的を達成するための手段として、請求項１の発明は、センサ本体の投光部および受光部に接続された一対の光ファイバが並列されると共に、この一対の光ファイバの先端面側が光透過性のカバーにより覆われてなる光ファイバセンサの検出ヘッドであって、前記一対の光ファイバのうち一方の光ファイバの先端部が前記カバーに当接されており、他方の光ファイバはその先端部を前記一方の光ファイバの先端部よりもその軸方向に後退させて配されているとともに、前記他方の光ファイバの先端部と前記カバーとの間には前記他方の光ファイバからの出射光または前記他方の光ファイバへの入射光をこの光ファイバの軸方向に対して略平行方向とする光芒制限手段が配されている。
なお、「略並行方向」とは、光ファイバの軸方向に対して完全に平行なもののみではなく、僅かに傾き（１０°程度まで）を有するものまでを含む意である。また、光芒制限手段としては、例えばレンズ部材、スリット部材等が挙げられる。 As means for achieving the above object, the invention of claim 1 is characterized in that a pair of optical fibers connected to the light projecting portion and the light receiving portion of the sensor body are arranged in parallel, and the front end face side of the pair of optical fibers is A detection head of an optical fiber sensor covered with a light-transmitting cover, wherein a tip portion of one of the pair of optical fibers is in contact with the cover, and the other optical fiber is The tip of the one optical fiber is disposed so as to recede in the axial direction from the tip of the one optical fiber, and the exit from the other optical fiber is between the tip of the other optical fiber and the cover. There is provided a light beam limiting means for setting the incident light or the incident light to the other optical fiber in a direction substantially parallel to the axial direction of the optical fiber.
The “substantially parallel direction” is intended to include not only those that are completely parallel to the axial direction of the optical fiber but also those that have a slight inclination (up to about 10 °). Examples of the light beam limiting means include a lens member and a slit member.

請求項２の発明は、請求項１に記載の検出ヘッドであって、前記光芒制限手段は、前記一対の光ファイバのうち受光側の光ファイバに設けられていることを特徴とする。
請求項３の発明は、請求項１または請求項２に記載の検出ヘッドであって、前記光芒制限手段がレンズ部材であるとともに、前記レンズ部材が収容されるレンズ収容部と、光ファイバを前記レンズ部材に対して所定の位置に固定するファイバ収容部とが設けられたホルダ部材を備えることを特徴とする。 A second aspect of the invention is the detection head according to the first aspect, wherein the light beam limiting means is provided in an optical fiber on a light receiving side of the pair of optical fibers.
A third aspect of the present invention is the detection head according to the first or second aspect, wherein the light beam limiting means is a lens member, a lens housing portion in which the lens member is housed, and an optical fiber. It is characterized by comprising a holder member provided with a fiber housing portion that is fixed at a predetermined position with respect to the lens member.

請求項４の発明は、請求項１〜請求項３のいずれかに記載の検出ヘッドであって、前記一対の光ファイバの先端部が耐薬品性を有するハウジングにより覆われており、前記カバーがこのハウジングにおいて前記光ファイバの先端面側に覆い付けられた蓋板部であることを特徴とする。   Invention of Claim 4 is a detection head in any one of Claims 1-3, Comprising: The front-end | tip part of a pair of said optical fiber is covered with the housing which has chemical resistance, The said cover is In this housing, it is a cover plate part covered on the front end surface side of the optical fiber.

請求項１の発明によれば、光芒制限手段を一対の光ファイバのうちいずれかに取り付けることによって、出射光または入射光が光ファイバの軸方向に対して略並行方向となるようにする。このような構成によれば、カバーからの反射光が受光側の光ファイバに入光してしまう確率を大きく低減することができる。   According to the first aspect of the present invention, the light beam limiting means is attached to any one of the pair of optical fibers so that the emitted light or the incident light is substantially parallel to the axial direction of the optical fiber. According to such a configuration, the probability that the reflected light from the cover enters the optical fiber on the light receiving side can be greatly reduced.

すなわち、投光側の光ファイバに光芒制限手段を取り付け、光ファイバから出射される拡散光を光ファイバの軸方向に対して略並行な平行光として出射させれば、出射光のカバー端面に対する入射角、反射角が小さくなる。これにより、両光ファイバを近接させても、カバー端面からの反射光が受光側光ファイバの開口径内に入る確率を低減できる。一方、受光側の光ファイバに光芒制限手段を取り付けて開口角を絞れば、両光ファイバを近接させても、入射角の大きいカバー端面からの反射光を遮光することができ、反射光の影響を低減することができる。これにより、検出精度を維持しつつ検出ヘッドを小型化することができる。   That is, if the light beam limiting means is attached to the optical fiber on the light projecting side, and the diffused light emitted from the optical fiber is emitted as parallel light substantially parallel to the axial direction of the optical fiber, the incident light is incident on the cover end surface. The angle and reflection angle are reduced. Thereby, even if both optical fibers are brought close to each other, it is possible to reduce the probability that the reflected light from the cover end face enters the opening diameter of the light receiving side optical fiber. On the other hand, if the light angle limiting means is attached to the optical fiber on the light receiving side and the aperture angle is narrowed, the reflected light from the cover end face with a large incident angle can be shielded even if both optical fibers are close to each other, and the influence of the reflected light Can be reduced. Thereby, a detection head can be reduced in size, maintaining detection accuracy.

請求項２の発明によれば、光芒制限手段を受光側の光ファイバに取り付けている。このような構成によれば、外乱光の受光を防止するという効果を併せて得ることができるため、Ｓ／Ｎ比が向上し、検出精度の向上、安定化が期待できる。   According to the invention of claim 2, the light beam limiting means is attached to the optical fiber on the light receiving side. According to such a configuration, the effect of preventing the reception of disturbance light can be obtained together, so that the S / N ratio is improved, and the detection accuracy can be improved and stabilized.

請求項３の発明によれば、光芒制限手段としてレンズを使用する。このような構成によれば、入射光がレンズにより集光されるため、スリット部材等を使用する場合と比較してより強度の高い光を出射または入射させることができ、検出精度の安定化が図れる。   According to the invention of claim 3, a lens is used as the light beam limiting means. According to such a configuration, since incident light is collected by the lens, light having higher intensity can be emitted or incident as compared with the case of using a slit member or the like, and detection accuracy can be stabilized. I can plan.

請求項４の発明によれば、一対の光ファイバの先端部が耐薬品性を有するハウジングにより覆われており、前記カバーがこのハウジングにおいて前記光ファイバの先端面側に覆い付けられた蓋板部である。このように、耐薬品性を要求され、光ファイバの先端部がハウジングによって覆われることが必須である構成のものに、光芒制限手段を一対の光ファイバのうちいずれかに取り付ける構成を適用することによって、カバー（蓋板部）からの反射光の影響を低減し、検出精度の向上、安定化を図ることができる。   According to invention of Claim 4, the front-end | tip part of a pair of optical fiber is covered with the housing which has chemical resistance, The said cover is the cover-plate part covered on the front end surface side of the said optical fiber in this housing It is. As described above, a configuration in which the optical wing limiting means is attached to one of a pair of optical fibers is applied to a configuration in which chemical resistance is required and the tip of the optical fiber is indispensable to be covered by the housing. Therefore, it is possible to reduce the influence of the reflected light from the cover (cover plate part), and to improve and stabilize the detection accuracy.

以下、本発明の光ファイバセンサの検出ヘッドを具体化した実施形態について、図１〜図３を参照しつつ詳細に説明する。   Hereinafter, an embodiment in which the detection head of the optical fiber sensor of the present invention is embodied will be described in detail with reference to FIGS.

図１には、本実施形態の検出ヘッド１を示す。この検出ヘッド１は、図示しないセンサ本体に接続された一対の光ファイバ２Ａ、２Ｂの先端に、耐薬品性のハウジング１０が取り付けられたものである。なお、以下の説明において、光ファイバ２Ａ、２Ｂの先端方向（センサ本体に接続された側と逆側）を前方として説明する。   FIG. 1 shows a detection head 1 of this embodiment. This detection head 1 has a chemical-resistant housing 10 attached to the tips of a pair of optical fibers 2A and 2B connected to a sensor body (not shown). In the following description, the tip direction of the optical fibers 2A and 2B (the side opposite to the side connected to the sensor body) will be described as the front.

光ファイバ２Ａ、２Ｂは、ＰＭＭＡ（ポリメチルメタクリレート）を主材としたプラスチック光ファイバであって、コア材３とその外周を覆うクラッド材とからなるファイバ芯線に、ポリエチレン樹脂による被覆が施されたものである。一対の光ファイバ２Ａ、２Ｂのうち一方（投光側光ファイバ２Ａ）は、センサ本体の投光部に接続され、他方（受光側光ファイバ２Ｂ）は、センサ本体の受光部に接続されている。   The optical fibers 2A and 2B are plastic optical fibers mainly composed of PMMA (polymethyl methacrylate), and a fiber core wire composed of a core material 3 and a clad material covering the outer periphery thereof is coated with a polyethylene resin. Is. One of the pair of optical fibers 2A and 2B (light projecting side optical fiber 2A) is connected to the light projecting part of the sensor body, and the other (light receiving side optical fiber 2B) is connected to the light receiving part of the sensor body. .

この光ファイバ２Ａ、２Ｂの先端に取り付けられるハウジング１０は、光ファイバ２Ａ、２Ｂを挿通可能なテフロンチューブ１１の内部に、光ファイバ２Ａ、２Ｂを固定する先端金具１２を設けたものである。先端金具１２は、テフロンチューブ１１よりもやや短い略円筒状に形成されており、テフロンチューブ１１の前端付近に配されている。また、この先端金具１２の前方には、樹脂により円盤状に形成された透光性の蓋板部１３が嵌め付けられており、これにより、ハウジング１０の前方が塞がれている。   The housing 10 attached to the tips of the optical fibers 2A, 2B is provided with a tip fitting 12 for fixing the optical fibers 2A, 2B inside a Teflon tube 11 into which the optical fibers 2A, 2B can be inserted. The tip metal fitting 12 is formed in a substantially cylindrical shape slightly shorter than the Teflon tube 11, and is arranged near the front end of the Teflon tube 11. In addition, a translucent cover plate portion 13 formed in a disc shape with resin is fitted in front of the tip fitting 12, thereby closing the front of the housing 10.

この先端金具１２の前端から中央よりもやや後方にかけての位置には、筒の軸方向に貫通して各光ファイバ２Ａ、２Ｂをほぼ緊密に挿通可能な挿通路１４Ａ、１４Ｂが並べて設けられている。このうち受光側の挿通路１４Ｂの前端部は拡径されてレンズ収容部１５とされており、ここには、受光側光ファイバ２Ｂへの入射光を規制するための受光レンズ４が収容されている。受光レンズ４は、その先端縁を蓋板部１３に当接させた状態で収容されている。一方、投光側の挿通路１４Ａの前端部は、光ファイバ２Ａにおけるコア材３の外径とほぼ等しい径にまで縮径されている。光ファイバ２Ａ、２Ｂは、その先端付近の被覆およびクラッド材を剥いてコア材３を露出させた状態でそれぞれの挿通路１４Ａ、１４Ｂに挿入されている。投光側光ファイバ２Ａの先端面は蓋板部１３に当接されており、受光側光ファイバ２Ｂの先端は受光レンズ４の後端部に接続されている。   Insertion passages 14A and 14B that pass through in the axial direction of the cylinder and can be inserted almost tightly through the optical fibers 2A and 2B are provided side by side at a position from the front end of the tip metal fitting 12 to a position slightly behind the center. . Among them, the front end portion of the light receiving side insertion passage 14B is enlarged in diameter to form a lens housing portion 15, which houses the light receiving lens 4 for restricting incident light to the light receiving side optical fiber 2B. Yes. The light receiving lens 4 is housed in a state in which the tip edge thereof is in contact with the lid plate portion 13. On the other hand, the front end portion of the light insertion side insertion path 14A is reduced to a diameter substantially equal to the outer diameter of the core material 3 in the optical fiber 2A. The optical fibers 2A and 2B are inserted into the insertion paths 14A and 14B in a state in which the core material 3 is exposed by stripping the coating and the cladding material near the tips. The front end surface of the light projecting side optical fiber 2 </ b> A is in contact with the cover plate portion 13, and the front end of the light receiving side optical fiber 2 </ b> B is connected to the rear end portion of the light receiving lens 4.

この検出ヘッド１の組立工程は、以下のようである（図２参照）。   The assembly process of the detection head 1 is as follows (see FIG. 2).

まず、投光側光ファイバ２Ａにおける先端付近の被覆およびクラッド材を剥いてコア材３を露出させる。この状態で、光ファイバ２Ａの先端部を先端金具１２における投光側の挿通路１４Ａへ挿通させ、挿通路１４Ａの内壁と光ファイバ２Ａにおける被覆の外周を接着剤で接着することにより、光ファイバ２Ａを固定する（図２Ａ）。次いで、光ファイバ２Ａの先端を先端金具１２とともに鏡面加工することにより、光ファイバ２Ａの先端面と先端金具１２の前端面とを面一とする。   First, the core material 3 is exposed by peeling off the coating and cladding material near the tip of the light projecting side optical fiber 2A. In this state, the distal end portion of the optical fiber 2A is inserted into the light insertion side insertion passage 14A of the distal end fitting 12, and the inner wall of the insertion passage 14A and the outer periphery of the coating of the optical fiber 2A are bonded with an adhesive. 2A is fixed (FIG. 2A). Next, the front end surface of the optical fiber 2A and the front end surface of the front end fitting 12 are flush with each other by subjecting the front end of the optical fiber 2A to a mirror finish together with the front end fitting 12.

次いで、受光側光ファイバ２Ｂにおいても先端付近の被覆およびクラッド材を剥いてコア材３を露出させる。次いで、この光ファイバ２Ｂを先端金具１２における受光側の挿通路１４Ｂへ挿通させ、コア材３を露出した先端部分が挿通路１４Ｂ前方の開口から突出されるまで押し入れる。そして、光ファイバ２Ｂの先端に受光レンズ４を接続する（図２Ｂ）。   Next, also in the light receiving side optical fiber 2 </ b> B, the core material 3 is exposed by peeling off the coating and clad material near the tip. Next, the optical fiber 2B is inserted into the light receiving side insertion passage 14B of the distal end fitting 12, and pushed in until the tip portion where the core material 3 is exposed protrudes from the opening in front of the insertion passage 14B. Then, the light receiving lens 4 is connected to the tip of the optical fiber 2B (FIG. 2B).

この状態で、受光レンズ４がレンズ収容部１５内に収容されるまで光ファイバ２Ｂを後方に引き戻し、投光側光ファイバ２Ａと同様に接着剤によって光ファイバ２Ｂを挿通路１４Ｂ内に固定する（図２Ｃ）。
最後に、テフロンチューブ１１の内部にこの先端金具１２を挿入し、このテフロンチューブ１１の前端よりも蓋板部１３の厚さ分だけ後退した位置に固定する。そして、チューブ１１の前端に蓋板部１３を嵌め入れ、両者を熱融着する（図２Ｄ）。このようにして、検出ヘッド１の組み立てが完了する。 In this state, the optical fiber 2B is pulled back until the light receiving lens 4 is accommodated in the lens accommodating portion 15, and the optical fiber 2B is fixed in the insertion path 14B with an adhesive similarly to the light-projecting side optical fiber 2A ( FIG. 2C).
Finally, the end fitting 12 is inserted into the Teflon tube 11 and fixed at a position retracted from the front end of the Teflon tube 11 by the thickness of the lid plate portion 13. And the cover board part 13 is inserted in the front end of the tube 11, and both are heat-sealed (FIG. 2D). In this way, the assembly of the detection head 1 is completed.

次に、上記のように構成された本実施形態の作用および効果について説明する。   Next, the operation and effect of the present embodiment configured as described above will be described.

センサ本体を作動させると、投光部からの光は投光側光ファイバ２Ａを通ってその先端から出射される（図３参照）。このとき、投光部側には特にレンズ等が設けられていないので、出射される光は光ファイバ２Ａの開口角に応じて拡散する拡散光である。さて、検出ヘッド１の前方に検出物であるワークＷが存在すれば、出射された光はワークＷの端面によって反射されて受光側光ファイバ２Ｂに入光する。このとき、受光側光ファイバ２Ｂの先端には開口角の小さな受光レンズ４が配されているため、受光側光ファイバ２Ｂの光軸に対してほぼ平行に入射してきた光のみが、この受光レンズ４を通過して受光側光ファイバ２Ｂの先端面から入光する。入光した光は受光側光ファイバ２Ｂを通ってセンサ本体の受光部に受光され、センサ本体に備えられた受光回路等によってワークＷが存在しているとの判定がなされる。   When the sensor body is actuated, the light from the light projecting section is emitted from its tip through the light projecting side optical fiber 2A (see FIG. 3). At this time, since no lens or the like is provided on the light projecting unit side, the emitted light is diffused light that diffuses according to the opening angle of the optical fiber 2A. If the workpiece W as a detection object is present in front of the detection head 1, the emitted light is reflected by the end face of the workpiece W and enters the light receiving side optical fiber 2B. At this time, since the light receiving lens 4 having a small opening angle is disposed at the tip of the light receiving side optical fiber 2B, only the light incident substantially parallel to the optical axis of the light receiving side optical fiber 2B is the light receiving lens. 4 enters the light from the front end surface of the light receiving side optical fiber 2B. The incident light is received by the light receiving portion of the sensor body through the light receiving side optical fiber 2B, and it is determined that the workpiece W is present by a light receiving circuit or the like provided in the sensor body.

ところで、投光側光ファイバ２Ａから出射された光の一部は、蓋板部１３における前端側の端面１３Ａで反射される。ここで、出射光のうち蓋板部１３の端面１３Ａに対する入射角θが大きいものほど、この端面１３Ａでの反射成分が大きくなる。したがって、端面１３Ａでの反射光の多くは反射角θの比較的大きな光、すなわち受光レンズ４に対する入射角が大きい光となるから、受光レンズ４によって規制され、受光側光ファイバ２Ｂに到達することができない。一方、端面１３Ａに対する入射角θが小さい光は蓋板部１３を透過してワークＷの端面によって反射される。このワークＷからの反射光は受光レンズ４に対する入射角が小さい光、すなわち受光側光ファイバ２Ｂの軸方向とほぼ平行方向の光となるから、受光レンズ４を通過して受光側光ファイバ２２Ｂに到達することができる。   By the way, a part of the light emitted from the light projecting side optical fiber 2 </ b> A is reflected by the end surface 13 </ b> A on the front end side in the cover plate part 13. Here, the larger the incident angle θ with respect to the end surface 13A of the cover plate portion 13 in the emitted light, the greater the reflection component at the end surface 13A. Therefore, most of the reflected light at the end face 13A is light having a relatively large reflection angle θ, that is, light having a large incident angle with respect to the light receiving lens 4, and is thus regulated by the light receiving lens 4 and reaches the light receiving side optical fiber 2B. I can't. On the other hand, light having a small incident angle θ with respect to the end surface 13A passes through the cover plate portion 13 and is reflected by the end surface of the workpiece W. The reflected light from the workpiece W is light having a small incident angle with respect to the light receiving lens 4, that is, light in a direction substantially parallel to the axial direction of the light receiving side optical fiber 2B, and therefore passes through the light receiving lens 4 to the light receiving side optical fiber 22B. Can be reached.

このように本実施形態によれば、受光側光ファイバ２Ｂの軸方向にほぼ沿って入ってくるワークＷからの反射光は、受光レンズ４を通って受光側光ファイバ２Ｂに入ることができるが、入射角の大きい蓋板部１３の端面１３Ａからの反射光が受光側光ファイバ２Ｂに入ることは回避される。したがって、両光ファイバ２Ａ、２Ｂを近接させてもＳ／Ｎ比が低下することがなく、検出ヘッドの小型化、および検出精度の向上を図ることができる。また、受光側光ファイバ２Ｂにレンズを取り付けているから、外乱光が受光されることを防止するという効果を併せて得ることができ、検出精度の向上、安定化が期待できる。   As described above, according to the present embodiment, the reflected light from the work W that enters substantially along the axial direction of the light receiving side optical fiber 2B can enter the light receiving side optical fiber 2B through the light receiving lens 4. The reflected light from the end face 13A of the cover plate portion 13 having a large incident angle is prevented from entering the light receiving side optical fiber 2B. Therefore, even if both optical fibers 2A and 2B are brought close to each other, the S / N ratio does not decrease, and the detection head can be downsized and the detection accuracy can be improved. In addition, since the lens is attached to the light receiving side optical fiber 2B, it is possible to obtain the effect of preventing disturbance light from being received, and improvement in detection accuracy and stabilization can be expected.

＜他の実施形態＞
本発明は上記記述及び図面によって説明した実施形態に限定されるものではなく、例えば次のような実施形態も本発明の技術的範囲に含まれ、さらに、下記以外にも要旨を逸脱しない範囲内で種々変更して実施することができる。 <Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

（１）本実施形態では、受光側の光ファイバ２Ｂに光芒制限手段である受光レンズ４を取り付けたが、投光側光ファイバ２Ａに投光レンズ５を取り付けても構わない。このような場合には、図４に示すように、投光レンズ５から出射される光は投光側光ファイバ２Ａの軸方向とほぼ平行になる。このため、蓋板部１３の端面１３Ａに対する入射角、反射角が小さくなり、反射光は出射位置からきわめて近接した範囲にしか到達しないこととなる。したがって、この反射光が受光側光ファイバ２Ｂの開口径内に入る確率を低減できる。なお、反射光が蓋板部１３内で複数回の反射を繰り返して受光側光ファイバ２Ｂに到達することも考えられるが、反射を繰り返すごとにその強度が減衰されていくため、たとえ受光側光ファイバ２Ｂに到達したとしてもその影響は小さいものである。
（２）上記実施形態では、光芒制限手段として受光レンズ４レンズを使用したが、光芒制限手段の種類としては上記実施形態に限るものではなく、例えばスリット部材を用いても良い。また、一方の光ファイバの先端部を相手側の光ファイバの先端部よりも軸方向に沿って後退させて配し、この光ファイバの先端部と前記カバーとの間に存在する光の通路を光芒制限手段として利用することによって、出射光または入射光が光ファイバの軸方向に対して略平行方向となるようにしても良い。 (1) In the present embodiment, the light receiving lens 4 as the light beam limiting means is attached to the light receiving side optical fiber 2B, but the light projecting lens 5 may be attached to the light projecting side optical fiber 2A. In such a case, as shown in FIG. 4, the light emitted from the light projecting lens 5 is substantially parallel to the axial direction of the light projecting side optical fiber 2A. For this reason, the incident angle and the reflection angle with respect to the end surface 13A of the cover plate portion 13 are reduced, and the reflected light reaches only a range very close to the emission position. Therefore, it is possible to reduce the probability that this reflected light enters the aperture diameter of the light receiving side optical fiber 2B. Although it is conceivable that the reflected light reaches the light receiving side optical fiber 2B by repeating the reflection a plurality of times in the cover plate portion 13, the intensity of the reflected light is attenuated each time the reflection is repeated. Even if it reaches the fiber 2B, its influence is small.
(2) In the above embodiment, the light receiving lens 4 lens is used as the light beam limiting means. However, the type of the light beam limiting means is not limited to the above embodiment, and for example, a slit member may be used. In addition, the tip of one optical fiber is disposed so as to recede in the axial direction from the tip of the counterpart optical fiber, and a light path existing between the tip of the optical fiber and the cover is provided. By using it as a light beam limiting means, the emitted light or the incident light may be substantially parallel to the axial direction of the optical fiber.

本実施形態のセンサの検出ヘッドを示す側断面図Side sectional view showing a detection head of the sensor of this embodiment 検出ヘッドの組立工程を示す側断面図Side sectional view showing the assembly process of the detection head 検出ヘッドの部分拡大断面図Partial enlarged sectional view of the detection head 他の実施形態の検出ヘッドの部分拡大断面図Partial enlarged sectional view of a detection head of another embodiment 従来のセンサの検出ヘッドを示す側断面図Side sectional view showing a detection head of a conventional sensor

符号の説明Explanation of symbols

１…検出ヘッド
２Ａ、２Ｂ…光ファイバ
４…受光レンズ（レンズ部材）
１０…ハウジング
１３…蓋板部 DESCRIPTION OF SYMBOLS 1 ... Detection head 2A, 2B ... Optical fiber 4 ... Light receiving lens (lens member)
10 ... Housing 13 ... Cover plate

Claims (4)

センサ本体の投光部および受光部に接続された一対の光ファイバが並列されると共に、この一対の光ファイバの先端面側が光透過性のカバーにより覆われてなる光ファイバセンサの検出ヘッドであって、
前記一対の光ファイバのうち一方の光ファイバの先端部が前記カバーに当接されており、他方の光ファイバはその先端部を前記一方の光ファイバの先端部よりも軸方向に沿って後退させて配されているとともに、前記他方の光ファイバの先端部と前記カバーとの間には前記他方の光ファイバからの出射光または前記他方の光ファイバへの入射光をこの光ファイバの軸方向に対して略平行方向とする光芒制限手段が配されていることを特徴とする検出ヘッド。 This is a detection head of an optical fiber sensor in which a pair of optical fibers connected to the light projecting part and the light receiving part of the sensor body are arranged in parallel, and the front end surfaces of the pair of optical fibers are covered with a light-transmitting cover. And
The tip of one optical fiber of the pair of optical fibers is in contact with the cover, and the other optical fiber has its tip retreated in the axial direction from the tip of the one optical fiber. Between the tip of the other optical fiber and the cover, light emitted from the other optical fiber or light incident on the other optical fiber is placed in the axial direction of the optical fiber. A detection head characterized in that a light beam limiting means is provided in a direction substantially parallel to the head. 前記光芒制限手段は、前記一対の光ファイバのうち受光側の光ファイバに設けられていることを特徴とする請求項１に記載の検出ヘッド。 The detection head according to claim 1, wherein the light beam limiting unit is provided on a light receiving side optical fiber of the pair of optical fibers. 前記光芒制限手段がレンズ部材であるとともに、
前記レンズ部材が収容されるレンズ収容部と、前記光ファイバを前記レンズ部材に対して所定の位置に固定するファイバ収容部とが設けられたホルダ部材を備えることを特徴とする請求項１または請求項２に記載の検出ヘッド。 The light beam limiting means is a lens member,
The holder member provided with the lens accommodating part in which the said lens member is accommodated, and the fiber accommodating part which fixes the said optical fiber to a predetermined position with respect to the said lens member is provided. Item 3. The detection head according to Item 2. 前記一対の光ファイバの先端部が耐薬品性を有するハウジングにより覆われており、前記カバーがこのハウジングにおいて前記光ファイバの先端面側に覆い付けられた蓋板部であることを特徴とする請求項１〜請求項３のいずれかに記載の検出ヘッド。 The distal ends of the pair of optical fibers are covered with a chemical-resistant housing, and the cover is a cover plate portion that is covered on the distal end side of the optical fiber in the housing. The detection head according to claim 1.
JP2004024545A 2004-01-30 2004-01-30 Detection head for optical fiber sensor Pending JP2005214887A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150083768A (en) * 2014-01-10 2015-07-20 파나소닉 디바이스 썬크스 주식회사 Light projection head and optical sensor
CN105352595A (en) * 2015-11-20 2016-02-24 高佳 Diagonal fiber detection head

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150083768A (en) * 2014-01-10 2015-07-20 파나소닉 디바이스 썬크스 주식회사 Light projection head and optical sensor
JP2015132699A (en) * 2014-01-10 2015-07-23 パナソニック デバイスＳｕｎｘ株式会社 Light projection head and optical sensor
KR101725797B1 (en) 2014-01-10 2017-04-11 파나소닉 디바이스 썬크스(주) Light projection head and optical sensor
CN105352595A (en) * 2015-11-20 2016-02-24 高佳 Diagonal fiber detection head

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