JPH09288939A - Reflected light detecting device - Google Patents
Reflected light detecting deviceInfo
- Publication number
- JPH09288939A JPH09288939A JP12791996A JP12791996A JPH09288939A JP H09288939 A JPH09288939 A JP H09288939A JP 12791996 A JP12791996 A JP 12791996A JP 12791996 A JP12791996 A JP 12791996A JP H09288939 A JPH09288939 A JP H09288939A
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- Japan
- Prior art keywords
- light
- reflected
- polarization
- reflected light
- projected
- 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.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、投受光同軸型の反
射光検出装置及びこれを用いた物体検出装置に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection / reception coaxial type reflected light detection device and an object detection device using the same.
【０００２】[0002]
【従来の技術】従来より、投光した光の検知対象物体か
らの反射光を受光して検知対象物体の有無等を検知する
反射光検出装置が知られている。図１３は、この従来の
反射光検出装置を示す図で、（ａ）は投光と受光の軸が
同じでない型の反射光検出装置を、（ｂ）はその場合の
不都合を、また（ｃ）はこの不都合を改良した投受光同
軸型の反射光検出装置をそれぞれ模式的に示している。2. Description of the Related Art Conventionally, there has been known a reflected light detecting device which receives reflected light of a projected light from a detection target object and detects the presence or absence of the detection target object. 13A and 13B are views showing this conventional reflected light detecting device. FIG. 13A shows a reflected light detecting device of a type in which the projection and reception axes are not the same, FIG. 13B shows the disadvantage in that case, and FIG. ) Schematically shows the reflected light detection device of the light-transmitting / receiving-light coaxial type in which this inconvenience is improved.
【０００３】図１３（ａ）に示すように、反射光検出装
置４０は、光Ｌｅを発光する発光素子４１と、この発光
素子４１が発光した光Ｌｅを投光する投光レンズ４２
と、この光Ｌｅが検知対象物体Ｍにより反射される場合
の反射光Ｌｒを集光する受光レンズ４４と、受光レンズ
４４により集光された反射光Ｌｒを受光する受光素子４
５とから構成されている。発光素子４１と投光レンズ４
２による投光軸４６と、受光レンズ４４と受光素子４５
による受光軸４７とは同軸ではない。As shown in FIG. 13A, a reflected light detecting device 40 includes a light emitting element 41 which emits light Le and a light projecting lens 42 which projects light Le emitted by the light emitting element 41.
A light receiving lens 44 that collects the reflected light Lr when the light Le is reflected by the detection target object M, and a light receiving element 4 that receives the reflected light Lr collected by the light receiving lens 44.
And 5. Light emitting element 41 and light projecting lens 4
2, the light projecting axis 46, the light receiving lens 44, and the light receiving element 45.
Is not coaxial with the light receiving axis 47.
【０００４】この構成においては、発光素子４１によっ
て発光された光Ｌｅは、投光レンズ４２を介して投光さ
れ、そして、投光された光Ｌｅの光路中に、反射光検出
装置４０から距離Ｄを隔てて検知対象物体Ｍが存在すれ
ば、光Ｌｅがこの検知対象物体Ｍにより反射され、反射
光Ｌｒは受光レンズ４４により集光され、受光素子４５
で受光される。受光素子４５は、この反射光Ｌｒの変化
に基づいて検知対象物体Ｍを検知する。In this structure, the light Le emitted by the light emitting element 41 is projected through the light projecting lens 42, and is separated from the reflected light detecting device 40 in the optical path of the projected light Le. If the detection target object M exists across D, the light Le is reflected by the detection target object M, the reflected light Lr is condensed by the light receiving lens 44, and the light receiving element 45 is received.
Is received at. The light receiving element 45 detects the detection target object M based on the change in the reflected light Lr.
【０００５】このような反射光検出装置４０において、
図１３（ｂ）に示すように、検知対象物体Ｍが反射光検
出装置４０に接近し、距離Ｄが小さい場合、反射光Ｌｒ
が受光素子４５で受光されなくなる。このようなとき、
光Ｌｅの光路中に検知対象物体Ｍが存在しても、存在し
ないとの検知が行われ、反射光検出装置４０は誤動作す
るという問題がある。In such a reflected light detecting device 40,
As shown in FIG. 13B, when the detection target object M approaches the reflected light detection device 40 and the distance D is small, the reflected light Lr
Is not received by the light receiving element 45. In such a case,
Even if the detection target object M exists in the optical path of the light Le, it is detected that it does not exist, and the reflected light detection device 40 malfunctions.
【０００６】この問題を解決すべく改良を加えた投受光
同軸型の反射光検出装置４０を図１３（ｃ）に示す。こ
の反射光検出装置４０は、上記構成の他に、さらに反射
光Ｌｒの方向を変えるためのハーフミラー５０を有し、
また、発光素子４１及び投光レンズ４２の並びと受光レ
ンズ４４及び受光素子４５の並びとが、ほぼ直角に交わ
っている。そして、発光素子４１により発光された光Ｌ
ｅは投光レンズ４２を経てハーフミラー５０を透過して
検知対象物体Ｍに投光される。この検知対象物体Ｍで反
射された反射光Ｌｒは、投光された光Ｌｅの光路と同じ
光路を逆行してハーフミラー５０にて反射され、その光
路はほぼ直角方向に変えられ、受光レンズ４４により集
光され、受光素子４５で受光される。この構成において
は、検知対象物体Ｍが反射光検出装置４０に接近して距
離Ｄが小さくなる場合でも、検知対象物体Ｍで反射され
た反射光Ｌｒが受光され、対象物の有無等を検知するこ
とができる。FIG. 13 (c) shows a reflected light detection device 40 of a light emitting / receiving coaxial type, which is improved to solve this problem. The reflected light detection device 40 further includes a half mirror 50 for changing the direction of the reflected light Lr, in addition to the above configuration.
Further, the arrangement of the light emitting element 41 and the light projecting lens 42 and the arrangement of the light receiving lens 44 and the light receiving element 45 intersect at a substantially right angle. Then, the light L emitted by the light emitting element 41
The light e passes through the light projecting lens 42, passes through the half mirror 50, and is projected onto the detection target object M. The reflected light Lr reflected by the detection target object M goes backward in the same optical path as the projected light Le and is reflected by the half mirror 50, and the optical path is changed to a substantially right angle direction, and the light receiving lens 44 Is received by the light receiving element 45. In this configuration, even when the detection target object M approaches the reflected light detection device 40 and the distance D becomes small, the reflected light Lr reflected by the detection target object M is received and the presence or absence of the target object is detected. be able to.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、図１３
（ｃ）に示す様な投受光同軸でハーフミラー５０を有す
る構成とした場合でも、発光素子４１によって発光され
た光Ｌｅの一部がハーフミラー５０を透過することなく
反射され、投光されず迷光Ｌｗとなるため、この迷光Ｌ
ｗはノイズ成分となる。このノイズ成分が多くなると、
信号対雑音比Ｓ／Ｎが悪くなり、反射光検出装置４０が
正しく動作せず、誤動作の原因となる。このように、投
受光同軸型の反射光検出装置４０においては、迷光を低
減させることが大きな課題となる。本発明は、上述した
問題点を解決するためになされたものであり、投受光同
軸型において、迷光の低減が可能で、誤動作が少ない反
射光検出装置を提供することを目的とする。However, FIG.
Even when the half mirror 50 is coaxially arranged as shown in (c), a part of the light Le emitted by the light emitting element 41 is reflected without passing through the half mirror 50 and is not projected. Stray light Lw, so this stray light L
w is a noise component. When this noise component increases,
The signal-to-noise ratio S / N deteriorates, and the reflected light detection device 40 does not operate correctly, which causes malfunction. As described above, reducing the stray light is a major issue in the reflected light detection device 40 of the light emitting and receiving coaxial type. The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a reflected light detection device that is capable of reducing stray light and is less likely to malfunction in the coaxial projection / reception type.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するため
に本発明は、投光される光と、光の検知対象物による反
射光とが同軸の光路をなす反射光検出装置において、直
線偏光を投光する投光手段と、投光手段による投光光路
を逆行する検知対象物による反射光を投光光路から分離
する光路分離手段と、光路分離手段により分離された反
射光を受光する受光手段と、受光手段により受光される
光を、投光される光の偏光方向に対して直交する偏光方
向のものとする受光偏光手段とを備えたものである。In order to achieve the above object, the present invention provides a linearly polarized light in a reflected light detecting device in which projected light and light reflected by an object to be detected form a coaxial optical path. A light projecting means for projecting light, a light path separating means for separating the light reflected by the object to be detected, which reverses the light projecting light path by the light projecting means, from the light projecting light path, and a light receiving for receiving the light reflected by the light path separating means And a light-receiving polarization unit that makes the light received by the light-receiving unit have a polarization direction orthogonal to the polarization direction of the projected light.
【０００９】上記構成においては、投光手段により直線
偏光が投光され、検知対象物がその光路中に存在すると
き、検知対象物による反射光が投光光路を逆行して光路
分離手段により投光光路から分離され、この分離された
反射光のうち、投光された光の偏光方向に対して直交す
る偏光方向の光が受光偏光手段の作用により受光手段に
受光される。検知対象物が投光光路中に存在しないとき
は、反射光は発生しない。このため、受光手段での受光
量より、検知対象物の有無が判別される。In the above-mentioned structure, when the linearly polarized light is projected by the light projecting means and the object to be detected is present in its optical path, the light reflected by the object to be detected goes backward in the light projecting optical path and is projected by the optical path separating means. Of the reflected light separated from the light optical path, light having a polarization direction orthogonal to the polarization direction of the projected light is received by the light receiving means by the action of the light receiving polarization means. When the object to be detected is not present in the projection light path, no reflected light is generated. Therefore, the presence or absence of the detection target is determined based on the amount of light received by the light receiving means.
【００１０】この場合、投光手段による投光は直線偏光
であり、検知対象物による反射光として受光手段により
受光される光は、検知対象物により反射され投光光路か
ら分離され、かつ、投光された光の偏光方向に対して直
交する偏光方向のものである。従って、光路分離手段に
おいて、発光の一部が投光されずに迷光となっても、こ
の迷光が投光と同じ直線偏光の光である限り、受光偏光
手段によって遮蔽され、受光手段に受光されることがな
くなる。このため、迷光による検出の誤動作が低減され
る。In this case, the light projected by the light projecting means is linearly polarized light, and the light received by the light receiving means as the reflected light by the object to be detected is reflected by the object to be detected and separated from the light projecting optical path, and the light is projected. The polarization direction is orthogonal to the polarization direction of the emitted light. Therefore, even if part of the emitted light is not projected and becomes stray light in the optical path separation means, as long as this stray light is light of the same linear polarization as the projected light, it is blocked by the light receiving polarization means and is received by the light receiving means. Will not be lost. Therefore, malfunction of detection due to stray light is reduced.
【００１１】また、本発明は、上記構成において、光路
分離手段及び受光偏光手段として偏光ビームスプリッタ
を用いてもよい。この構成においては、偏光ビームスプ
リッタのみでもって、検知対象物からの反射光につい
て、投光される光の偏光方向と直交する偏光方向の光を
透過又は反射して投光光路から分離し受光手段に受光さ
せることができる。Further, in the present invention, in the above structure, a polarization beam splitter may be used as the optical path separating means and the light receiving and polarizing means. In this configuration, with only the polarization beam splitter, with respect to the reflected light from the object to be detected, the light having the polarization direction orthogonal to the polarization direction of the projected light is transmitted or reflected to be separated from the projection optical path, and the light receiving means. Can be made to receive light.
【００１２】また、本発明は、上記構成において、投光
手段が投光した光を、その直線偏光の偏光方向と直交す
る偏光成分を含む光に変換する投光偏光変換手段をさら
に備えたものであってもよい。この構成においては、検
知対象物に向う光には、投光手段により投光された直線
偏光と、その直線偏光の偏光方向と直交する偏光成分を
含む光の双方が含まれている。従って、検知対象物が拡
散反射物や鏡面反射物であることに関係なく、検知対象
物から反射される光は、互いに直交する２つの直線偏光
が混在したものとなる。その光のうち、一部は受光偏光
手段の作用により受光手段に受光される。これにより検
知対象物の有無などを拡散反射物や鏡面反射物に関係な
く検知することができる。Further, the present invention, in the above structure, further comprises a projection polarization conversion means for converting the light projected by the light projection means into light containing a polarization component orthogonal to the polarization direction of the linearly polarized light. May be In this configuration, the light directed to the detection target includes both the linearly polarized light projected by the light projecting unit and the light including the polarization component orthogonal to the polarization direction of the linearly polarized light. Therefore, regardless of whether the object to be detected is a diffuse reflector or a specular reflector, the light reflected from the object to be detected is a mixture of two linearly polarized lights that are orthogonal to each other. A part of the light is received by the light receiving means by the action of the light receiving polarization means. Thus, the presence or absence of the detection target can be detected regardless of the diffuse reflector or the specular reflector.
【００１３】また、本発明は、上記の反射光検出装置を
用い、その受光手段の出力に基いて反射光を変化させる
検知対象物の有無を判別する信号処理手段をさらに備え
た物体検出装置である。この装置においては、上記の反
射光検出装置の受光手段の出力に基いて検知対象物の有
無が判別されるので、その判別は迷光などに影響された
ものでなく、対象物からの反射光に基くものである。こ
のため、対象物の有無の判別精度が高い。Further, the present invention is an object detecting device using the above-mentioned reflected light detecting device, further comprising signal processing means for judging the presence or absence of a detection object which changes the reflected light based on the output of the light receiving means. is there. In this device, the presence or absence of the detection target object is determined based on the output of the light receiving unit of the reflected light detection device, so the determination is not influenced by stray light or the like, and the reflected light from the target object is not detected. It is based. Therefore, the accuracy of determining the presence or absence of the object is high.
【００１４】また、本発明は、上記の反射光検出装置を
用い、その受光手段の出力に基いて反射光を変化させる
検知対象物の有無を判別する信号処理手段と、投光手段
が投光した光を、その直線偏光の偏光方向と直交する偏
光成分を含む光に変換する投光偏光変換手段をさらに備
え、その投光偏光変換手段が検知対象物側の先端に斜面
を有する光ファイバであることを特徴とする液面レベル
検出装置である。Further, according to the present invention, the above-mentioned reflected light detecting device is used, and the signal processing means for judging the presence / absence of a detection object which changes the reflected light based on the output of the light receiving means, and the light projecting means project light. Further comprises a projection polarization conversion means for converting the light to a light containing a polarization component orthogonal to the polarization direction of the linearly polarized light, and the projection polarization conversion means is an optical fiber having a slope at the tip on the detection target side. The liquid level detecting device is characterized by being present.
【００１５】この装置においては、検知対象物が液面で
あるとき、この光ファイバ先端面が空中にあるときに
は、空気と光ファイバ先端斜面との屈折率差が大きい状
態であり、投光された光は、該先端斜面で反射され、受
光手段で受光される。一方、光ファイバ先端面が液中に
あるときには、光ファイバと液体との屈折率差が小さく
なり、投光された光は反射されにくく、受光手段での受
光量が小さくなる。この受光量の差で液面の上下を検知
することができる。また、投光軸と受光軸とが同軸であ
りながら、迷光の影響が小さいという作用も得られる。In this device, when the object to be detected is the liquid surface and when the tip end surface of the optical fiber is in the air, the refractive index difference between the air and the sloped tip end of the optical fiber is large, and the light is projected. The light is reflected by the tip slope and is received by the light receiving means. On the other hand, when the front end surface of the optical fiber is in the liquid, the difference in refractive index between the optical fiber and the liquid is small, the projected light is difficult to be reflected, and the amount of light received by the light receiving means is small. The upper and lower sides of the liquid surface can be detected by the difference in the amount of received light. In addition, the effect of stray light is small even though the light projecting axis and the light receiving axis are coaxial.
【００１６】また、本発明は、上記の反射光検出装置を
用い、その受光手段の出力に基いて反射光を変化させる
検知対象物の有無を判別する信号処理手段と、投光手段
が投光した光を、その直線偏光の偏光方向と直交する偏
光成分を含む光に変換する投光偏光変換手段をさらに備
え、その投光偏光変換手段が回帰反射板であることを特
徴とする物体検出装置である。Further, according to the present invention, the above-mentioned reflected light detecting device is used, and the signal processing means for judging the presence or absence of the detection object which changes the reflected light based on the output of the light receiving means, and the light projecting means project light. The object detection device further comprises a projection polarization conversion means for converting the generated light into light containing a polarization component orthogonal to the polarization direction of the linearly polarized light, and the projection polarization conversion means is a recursive reflection plate. Is.
【００１７】この装置においては、投光された直線偏光
の反射光が回帰反射板により反射されると、その反射光
には投光の直線偏光の偏光方向と直交する偏光成分が生
じる。この回帰反射板の前の光路中に検知対象物が存在
しないと、直線偏光の投光は回帰反射板で該偏光方向と
直交する偏光成分を生じて反射されるので、受光手段に
受光される。検知対象物が光路中に存在すると、その検
知対象物での反射で、多少は投光の偏光方向と直交する
偏光成分の光を含むが、全てはそうはならないため、受
光手段で受光される光量は少ない。この受光量差でもっ
て検知対象物の有無を検知することができる。In this apparatus, when the projected reflected light of the linearly polarized light is reflected by the regressive reflection plate, a polarized light component which is orthogonal to the polarization direction of the linearly polarized light of the projected light is generated in the reflected light. If the object to be detected does not exist in the optical path in front of the retroreflective plate, the projected light of linearly polarized light is reflected by the retroreflective plate to generate a polarized component orthogonal to the polarization direction, and is reflected by the light receiving means. . When the object to be detected is present in the optical path, it is reflected by the object to be detected and contains light of a polarization component that is slightly orthogonal to the polarization direction of the projected light, but not all, so it is received by the light receiving means. Light intensity is low. The presence or absence of the detection target can be detected by this difference in the amount of received light.
【００１８】[0018]
【発明の実施の形態】以下、本発明を具体化した実施の
形態を図面を参照して説明する。 （実施例１）図１（ａ），（ｂ）はそれぞれ、対象物の
有無等を検知する投・受光軸が同軸の反射光検出装置の
断面図、その装置の処理系の概略ブロック図である。図
１（ａ）に示すように、反射光検出装置１は、筐体２
と、この筐体２中に設けられた光Ｌｅを発光する発光素
子（投光手段）３と、この発光素子３により発光された
光Ｌｅのうち特定の成分のみを通す投光側の偏光フィル
タ（投光手段）４と、光学多層膜が形成され投・受光の
分離機能等を有する偏光ビームスプリッタ（以下、ＰＢ
Ｓという。光路分離手段及び受光偏光手段）６と、発光
された光Ｌｅを投光すると共に検知対象物Ｍの反射光Ｌ
ｒを集光するレンズ８（投光偏光変換手段）と、反射光
Ｌｒを受光する受光素子（受光手段）９とからなる。レ
ンズ８は複屈折性を持つ材質でなり、その一面（筐体２
の内部側）Ａが鏡面で、他面（筐体２の外部側）Ｂに反
射防止膜が形成されているものである。Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIGS. 1 (a) and 1 (b) are a cross-sectional view of a reflected light detection device having a coaxial projection / reception axis for detecting the presence or absence of an object, and a schematic block diagram of a processing system of the device, respectively. is there. As shown in FIG. 1A, the reflected light detection device 1 includes a housing 2
A light emitting element (light emitting means) 3 for emitting the light Le provided in the housing 2; and a light emitting side polarization filter for passing only a specific component of the light Le emitted by the light emitting element 3. (Light projecting means) 4 and a polarization beam splitter (hereinafter referred to as PB) having an optical multi-layered film and having a function of separating light projecting and receiving light.
Called S. (Optical path separating means and light receiving and polarizing means) 6, and the reflected light L of the detection object M while projecting the emitted light Le
It is composed of a lens 8 (projected light polarization conversion means) that collects r and a light receiving element (light receiving means) 9 that receives the reflected light Lr. The lens 8 is made of a birefringent material, and one surface (the housing 2
The inner surface A) is a mirror surface, and the other surface (outer side of the housing 2) B is provided with an antireflection film.
【００１９】ＰＢＳ６は、発光素子３が設けられた空間
と受光素子９が設けられた空間とを分離するように、投
・受光軸Ｘに対しほぼ４５度の傾きをもって設けられて
いる。ＰＢＳ６は、投光された直線偏光のうちＳ偏光の
光を反射し、このＳ偏光の光に対して偏光方向が直交す
るＰ偏光の光を透過させる特性を有するものを用いてい
る。The PBS 6 is provided with an inclination of about 45 degrees with respect to the light emitting / receiving axis X so as to separate the space in which the light emitting element 3 is provided and the space in which the light receiving element 9 is provided. The PBS 6 has a characteristic of reflecting the S-polarized light of the projected linearly polarized light and transmitting the P-polarized light whose polarization direction is orthogonal to the S-polarized light.
【００２０】また、図１（ｂ）に示すように、物体検出
装置の処理系は発光素子３を駆動させる駆動回路１０
と、受光素子９によって受光された検知対象物Ｍの反射
光Ｌｒの受光信号を増幅するアンプ１１及び増幅された
受光信号と所定のしきい値とを比較し物体の有無を判断
するコンパレータ１２から構成されている。Further, as shown in FIG. 1B, the processing system of the object detecting apparatus has a drive circuit 10 for driving the light emitting element 3.
From an amplifier 11 that amplifies the received light signal of the reflected light Lr of the detection target M received by the light receiving element 9 and a comparator 12 that compares the amplified received light signal with a predetermined threshold value to determine the presence or absence of an object. It is configured.
【００２１】上記構成の反射光検出装置１の動作を説明
すると、発光素子３から光Ｌｅが発せられ、その光Ｌｅ
は偏光フィルタ４を透過し、特定の偏光方向（例えば、
Ｓ偏光）を有する直線偏光になり、ＰＢＳ６で反射し、
レンズ８を介して投光される。投光光路中に検知対象物
Ｍが存在する場合は、光Ｌｅはこの検知対象物Ｍで反射
されて反射光Ｌｒとして、レンズ８に入射する。また、
検知対象物Ｍが投光光路中に存在しない場合は、光Ｌｅ
は反射されず、レンズ８への反射光Ｌｒの入射はない。The operation of the reflected light detecting device 1 having the above structure will be described. The light Le is emitted from the light emitting element 3, and the light Le is emitted.
Is transmitted through the polarization filter 4 and has a specific polarization direction (for example,
It becomes a linearly polarized light having S polarization) and is reflected by PBS6,
The light is projected through the lens 8. When the detection target M is present in the projection optical path, the light Le is reflected by the detection target M and enters the lens 8 as reflected light Lr. Also,
When the detection target M does not exist in the light projection optical path, the light Le
Is not reflected, and the reflected light Lr does not enter the lens 8.
【００２２】投光光路中に検知対象物Ｍが存在する場
合、検知対象物Ｍにより反射され、レンズ８に入射した
反射光Ｌｒは、レンズ８によって集光され、その反射光
Ｌｒのうちの特定の光のみがＰＢＳ６を透過し、受光素
子９で受光される。この受光素子９の受光信号はアンプ
１１で増幅され、増幅された受光信号は、所定のしきい
値を設定したコンパレータ１２において、しきい値と比
較される。その比較の結果は、例えば、しきい値に対し
て受光信号が大きいときは検知対象物有り、しきい値に
対して受光信号が小さいときは対象物無しとして出力さ
れる。When the object M to be detected is present in the projection optical path, the reflected light Lr reflected by the object M to be detected and incident on the lens 8 is condensed by the lens 8 and is identified from the reflected light Lr. Only the light of (4) passes through the PBS 6 and is received by the light receiving element 9. The light receiving signal of the light receiving element 9 is amplified by the amplifier 11, and the amplified light receiving signal is compared with the threshold value in the comparator 12 in which a predetermined threshold value is set. As a result of the comparison, for example, when the received light signal is larger than the threshold value, the object to be detected is present, and when the received light signal is smaller than the threshold value, the object is not output.
【００２３】上記の検知動作において、投受光同軸型の
反射光検出装置で問題とされている迷光の低減について
以下に説明する。投光は発光素子３からの光Ｌｅを偏光
フィルタ４を用いてＳ偏光とし、ＰＢＳ６としてＰ偏光
の光を透過させるものを用いたことで、投光のうちＰＢ
Ｓ６を透過する光を減らし、迷光となって受光素子９で
受光される光を減らすようにした。In the above detection operation, the reduction of stray light, which is a problem in the reflected light detecting device of the light emitting and receiving coaxial type, will be described below. The light emitted from the light emitting element 3 is converted into S-polarized light using the polarization filter 4, and the PBS 6 is used to transmit P-polarized light.
The light transmitted through S6 is reduced, and the light that becomes stray light and is received by the light receiving element 9 is reduced.
【００２４】レンズ８についても迷光の低減が図られて
いる。ＰＢＳ６で反射した光Ｌｅがレンズ８を介して投
光される際、レンズ８の第１面Ａで反射が生じるが、こ
の第１面Ａは、ほぼ鏡面としているため、反射する光は
偏光方向（Ｓ偏光）を変えずに反射され、ＰＢＳ６を透
過せず受光素子９に至らず、従って迷光として受光され
ることがない。また、レンズ８の第２面Ｂには反射防止
膜が形成されていて、第２面Ｂでの反射を防止してい
る。The lens 8 is also designed to reduce stray light. When the light Le reflected by the PBS 6 is projected through the lens 8, reflection occurs on the first surface A of the lens 8, but since the first surface A is almost a mirror surface, the reflected light has a polarization direction. The light is reflected without changing (S-polarized light), does not pass through the PBS 6 and does not reach the light receiving element 9, and thus is not received as stray light. Further, an antireflection film is formed on the second surface B of the lens 8 to prevent reflection on the second surface B.
【００２５】さらに、発光素子３からの光Ｌｅのうち、
レンズ８を介して投光されなかった光は、筐体２内で反
射され迷光となるが、筐体２内を黒色アルマイト等で処
理することにより、筐体２内での反射を低減し、迷光の
低減を図っている。このように、偏光フィルタ４、ＰＢ
Ｓ６、さらにはレンズ８により、受光素子９で受光され
る迷光の低減を図っている。Further, of the light Le from the light emitting element 3,
Light that is not projected through the lens 8 is reflected in the housing 2 and becomes stray light. However, by processing the inside of the housing 2 with black alumite or the like, reflection inside the housing 2 is reduced, We are trying to reduce stray light. In this way, the polarization filter 4, PB
The stray light received by the light receiving element 9 is reduced by S6 and the lens 8.
【００２６】また、レンズ８には、複屈折性を有するも
の（ポリカーボネートレンズ等）を用いて、偏光方向を
ランダムにしている（以下、この光をランダム光とい
う）。レンズ８でランダム光とすることで、検知対象物
が拡散反射物や鏡面反射物であることに関係なく、対象
物体から反射される光はランダム光となる。その光のう
ちの一部（Ｐ偏光）はＰＢＳ６を透過し、受光素子９で
受光されるため、検知対象物Ｍからの反射光を受光でき
る。よって、拡散反射物や鏡面反射物に関係なく、対象
物の有無等を検知することができる。A lens having a birefringence (polycarbonate lens or the like) is used as the lens 8 to make the polarization direction random (hereinafter, this light is referred to as random light). By making the lens 8 random light, the light reflected from the target object becomes random light regardless of whether the detection target is a diffuse reflector or a specular reflector. Part of the light (P-polarized light) passes through the PBS 6 and is received by the light receiving element 9, so that the reflected light from the detection target M can be received. Therefore, it is possible to detect the presence or absence of the object regardless of the diffuse reflector or the specular reflector.
【００２７】（実施例２）図２は第２実施例による反射
光検出装置の断面図である。この実施例は、複屈折性を
有さない材料によりレンズ８１を構成した他は実施例１
と同じである。この構成により、表面が拡散反射面であ
る検知対象物Ｍの有無を検知することができる。つま
り、複屈折のないレンズ８１では、入射時の偏光方向が
維持されるため、偏光フィルタ４によりＳ偏光とされた
光ＬｅがＳ偏光のまま投光される。このとき、投光光路
中にその表面が拡散反射面である検知対象物Ｍが存在す
ると、この検知対象物Ｍで反射された反射光Ｌｒの偏光
方向はランダムとなる。このランダムな反射光Ｌｒの一
部であるＰ偏光の光は、上記の実施例の場合と同様に、
迷光が少ない状態で受光素子９で受光される。この受光
素子９の受光信号により、表面が拡散反射面である検知
対象物Ｍの有無が検知できる。(Embodiment 2) FIG. 2 is a sectional view of a reflected light detecting device according to a second embodiment. This example is the same as Example 1 except that the lens 81 is made of a material having no birefringence.
Is the same as With this configuration, it is possible to detect the presence or absence of the detection target M whose surface is a diffuse reflection surface. That is, in the lens 81 having no birefringence, the polarization direction at the time of incidence is maintained, so that the light Le that has been S-polarized by the polarization filter 4 is projected as it is as S-polarized light. At this time, if the detection target M whose surface is a diffuse reflection surface exists in the projection optical path, the polarization direction of the reflected light Lr reflected by the detection target M becomes random. The P-polarized light, which is a part of the random reflected light Lr, is the same as in the above-described embodiment.
The light is received by the light receiving element 9 with a small amount of stray light. The presence or absence of the detection target M whose surface is a diffuse reflection surface can be detected by the light reception signal of the light receiving element 9.
【００２８】（実施例３）図３は第３実施例による反射
光検出装置の断面図であり、この実施例は、投光光路中
に回帰反射板１３を設けたものである。回帰反射板１３
は、投光された光Ｌｅの偏光方向を、反射により、それ
と直交する偏光方向に変化させる。このため、投光光路
中に検知対象物Ｍが存在しない場合には、Ｓ偏光で投光
された光Ｌｅは、回帰反射板１３でＰ偏光の反射光Ｌｒ
として反射され、ＰＢＳ６を透過し受光素子９で受光さ
れる。(Embodiment 3) FIG. 3 is a sectional view of a reflected light detecting device according to a third embodiment. In this embodiment, a return reflection plate 13 is provided in the light projecting optical path. Retro-reflective plate 13
Changes the polarization direction of the projected light Le to a polarization direction orthogonal to it by reflection. Therefore, when the detection target M does not exist in the light projecting optical path, the light Le projected with S polarization is reflected light Lr of P polarization by the recurrence reflection plate 13.
Is reflected by the light receiving element 9 and transmitted through the PBS 6.
【００２９】一方、検知対象物Ｍが投光光路中に存在す
る場合には、Ｓ偏光で投光された光Ｌｅは検知対象物Ｍ
で反射され、その一部は多少のＰ偏光を含む反射光Ｌｒ
に変わるが、その全てはＰ偏光とならない。従って、受
光素子９で受光される反射光Ｌｒは、回帰反射板１３で
Ｐ偏光の反射光Ｌｒとして反射される場合に比べて、大
幅に減少する。これら受光量の相違に基づき、検知対象
物Ｍの有無を検知することができる。On the other hand, when the object M to be detected is present in the light projecting optical path, the light Le projected with S polarization is the object M to be detected.
The reflected light Lr that is reflected by
, But not all of them are P-polarized. Therefore, the reflected light Lr received by the light receiving element 9 is significantly reduced as compared with the case where the regressive reflection plate 13 reflects it as the P-polarized reflected light Lr. The presence or absence of the detection target M can be detected based on these differences in the amount of received light.
【００３０】また、検知対象物Ｍの反射面が鏡面である
場合には、この面で反射された反射光ＬｒはＳ偏光のま
まである。従って、この反射光ＬｒはＰＢＳ６を透過せ
ず、受光素子９で受光されることがない。本実施例にお
いては、その表面状態について、鏡面を含め、より多種
の検知対象物Ｍの検知が可能となる。なお、上記のよう
に、反射光Ｌｒが投光されたままの光Ｌｅであるとき
（この例ではＳ偏光のまま）、受光素子に反射光Ｌｒが
入射されないようにする機能をミラー・サーフェイス・
リジェクション（ＭＳＲ機能）という。When the reflecting surface of the object M to be detected is a mirror surface, the reflected light Lr reflected by this surface remains S-polarized. Therefore, the reflected light Lr does not pass through the PBS 6 and is not received by the light receiving element 9. In the present embodiment, it is possible to detect a wider variety of detection objects M including the mirror surface with respect to the surface state. Note that, as described above, when the reflected light Lr is the light Le that is still being projected (in this example, it is S-polarized light), a function of preventing the reflected light Lr from entering the light receiving element is provided on the mirror surface.
It is called rejection (MSR function).
【００３１】（実施例４）図４は第４実施例による反射
光検出装置の断面図である。この実施例では、受光素子
９の前面に、Ｐ偏光の光のみを透過させ、Ｓ偏光の光を
透過させない偏光フィルタ５を設け、かつ、その内部を
鏡面仕上げとした筐体２１を用いている。なお、レンズ
８については、複屈折性の有無を問わない。(Embodiment 4) FIG. 4 is a sectional view of a reflected light detecting device according to a fourth embodiment. In this embodiment, the front side of the light receiving element 9 is provided with a polarization filter 5 that transmits only P-polarized light but does not transmit S-polarized light, and uses a housing 21 having a mirror-finished interior. . The lens 8 may or may not have birefringence.
【００３２】この構成においては、発光素子３からＰＢ
Ｓ６に対して発光されたＳ偏光の光Ｌｅのうち、わずか
にＰＢＳ６を透過して迷光となる光も受光されることが
ない。このことにより、迷光による誤動作をさらに防止
することができる。また、筐体２１の内部を鏡面仕上げ
としたため、筐体２１の内部で反射された光Ｌｅの偏光
方向は、反射の前後で違わず、Ｓ偏光のまま維持され
る。従って、このＳ偏光の光Ｌｅが迷光となっても、受
光素子９の前面にはＰ偏光のみを透過させる偏光フィル
タ５が設けられているので、この迷光は受光素子９で受
光されることはない。このことにより、迷光による誤動
作をさらに低減することができる。In this structure, from the light emitting element 3 to the PB
Of the S-polarized light Le emitted for S6, light that slightly passes through the PBS 6 and becomes stray light is not received. This makes it possible to further prevent malfunction due to stray light. Further, since the inside of the housing 21 is mirror-finished, the polarization direction of the light Le reflected inside the housing 21 does not change before and after the reflection, and is maintained as S-polarized light. Therefore, even if the S-polarized light Le becomes stray light, the stray light is not received by the light receiving element 9 because the polarization filter 5 that transmits only the P polarized light is provided on the front surface of the light receiving element 9. Absent. As a result, malfunctions due to stray light can be further reduced.
【００３３】（実施例５）図５は第５実施例による反射
光検出装置の断面図である。この実施例では、上記の第
４実施例の反射光検出装置１の構成において、ＰＢＳ６
に代えてハーフミラー７を用いたものである。この構成
においては、ハーフミラー７を透過して迷光となったＳ
偏光の光が、受光素子９の前面に設けられている偏光フ
ィルタ５のため、受光素子９で受光されることがない。
従って、迷光による誤動作を低減することができる。し
かも、本構成では、ＰＢＳ６に代えてハーフミラー７を
用いているので製作コストを下げることができる。(Embodiment 5) FIG. 5 is a sectional view of a reflected light detecting apparatus according to a fifth embodiment. In this embodiment, in the configuration of the reflected light detecting device 1 of the fourth embodiment described above, the PBS 6
Instead of this, a half mirror 7 is used. In this configuration, the S that has passed through the half mirror 7 and has become stray light
Polarized light is not received by the light receiving element 9 because of the polarization filter 5 provided on the front surface of the light receiving element 9.
Therefore, malfunction due to stray light can be reduced. Moreover, in this configuration, since the half mirror 7 is used instead of the PBS 6, the manufacturing cost can be reduced.
【００３４】（実施例６）図６は第６実施例による反射
光検出装置の断面図である。この実施例では、上記の第
１乃至３の実施例構成の光学系において、発光素子３と
受光素子９の位置を入れ換えた構成としている。つま
り、発光素子３からの光Ｌｅは、偏光フィルタ４を透過
することによりＰ偏光の直線偏光にされ、ＰＢＳ６を透
過して投光される。受光される反射光Ｌｒは、ＰＢＳ６
で反射され、投光された光Ｌｅと直交する偏光成分（Ｓ
偏光）のみが受光素子９で受光される。この構成におい
ても、上記の実施例１乃至３と同等の作用を奏する。ま
た、このような配置によれば、投光軸の設定が容易とな
る。(Embodiment 6) FIG. 6 is a sectional view of a reflected light detecting apparatus according to a sixth embodiment. In this embodiment, the positions of the light emitting element 3 and the light receiving element 9 are interchanged in the optical system of the first to third embodiments. That is, the light Le from the light emitting element 3 is converted into the linearly polarized light of P polarization by passing through the polarization filter 4, and is transmitted through the PBS 6 to be projected. The reflected light Lr received is the PBS 6
And a polarization component (S
Only the polarized light is received by the light receiving element 9. Also in this configuration, the same operation as that of the above-described first to third embodiments is achieved. Also, with such an arrangement, it becomes easy to set the projection axis.
【００３５】（実施例７）本実施例は、上記の実施例に
用いた、片面に偏光特性を有する光学多層膜を設けたＰ
ＢＳ６に代えて、両面に光学多層膜を形成したＰＢＳ６
１を用いたものである。図７（ａ），（ｂ）は両面に光
学多層膜を形成したＰＢＳ６１の構成及び反射率の特性
を示す図である。ＰＢＳ６１は、その基板６１ｂの両面
に光学多層膜６１ｆが形成されており、光は両面の光学
多層膜６１ｆによって多段階的に反射される。このた
め、このＰＢＳ６１の反射率は、片面が光学多層膜であ
るＰＢＳ６に比べて大きくなる。すなわち、片面に光学
多層膜が形成されたＰＢＳ６におけるＳ偏光の反射率は
０．８９、透過率は０．１１であるのに対し、両面に光
学多層膜を形成したＰＢＳ６１においては、その反射率
は、０．９３、透過率は０．０７となり、発光素子から
の光がＰＢＳ６１を透過して迷光となるのを低減するこ
とができる。なお、発光素子からの光のうち、対象物体
に投光されずに筐体内に存在する光が迷光成分となるの
であるから、ＰＢＳ６１の反射効率の向上によって、対
象物体による反射光の発光素子への光量が増加しても動
作上、問題とはならない。(Embodiment 7) In this embodiment, P used in the above embodiment is provided with an optical multilayer film having polarization characteristics on one surface.
Instead of BS6, PBS6 with optical multilayer film formed on both sides
1 is used. FIGS. 7A and 7B are diagrams showing the structure and reflectance characteristics of the PBS 61 in which optical multilayer films are formed on both sides. The PBS 61 has an optical multilayer film 61f formed on both surfaces of its substrate 61b, and light is reflected in multiple stages by the optical multilayer films 61f on both surfaces. For this reason, the reflectance of the PBS 61 is higher than that of the PBS 6 having an optical multilayer film on one surface. That is, the reflectance of S-polarized light is 0.89 and the transmittance is 0.11 in the PBS 6 in which the optical multilayer film is formed on one surface, whereas the reflectance is in the PBS 61 in which the optical multilayer film is formed in both surfaces. Is 0.93 and the transmittance is 0.07, and it is possible to reduce light from the light emitting element that is transmitted through the PBS 61 and becomes stray light. Note that, among the light from the light emitting element, the light existing in the housing without being projected onto the target object becomes a stray light component. Therefore, by improving the reflection efficiency of the PBS 61, the light reflected by the target object is emitted to the light emitting element. Even if the amount of light is increased, there is no problem in operation.
【００３６】（実施例８）図８は第８実施例による反射
光検出装置の断面図である。本実施例においては、プリ
ズム状のＰＢＳ６２を用いている。プリズム状のＰＢＳ
６２を用いることにより、収差の低減を図ることがで
き、また、投光と受光の光軸が交叉するように（光学多
層膜への入射角は４５度とする）光学系を構成できるた
め、小型化が図れる。(Embodiment 8) FIG. 8 is a sectional view of a reflected light detecting device according to an eighth embodiment. In this embodiment, a prismatic PBS 62 is used. Prismatic PBS
By using 62, the aberration can be reduced, and the optical system can be configured so that the optical axes of the light projection and the light reception intersect (the incident angle to the optical multilayer film is 45 degrees). Can be miniaturized.
【００３７】プリズム状のＰＢＳ６２を用いる場合、そ
れを形成する材料の屈折率の組み合わせにより、光学多
層膜への入射角を４５度に設定し得るＰＢＳ６２が実現
可能となる。これにより、発光素子３等の格納に要する
スペースを小さくでき、装置の小型化を図ることができ
る。When the prism-shaped PBS 62 is used, the PBS 62 capable of setting the incident angle to the optical multilayer film at 45 degrees can be realized by combining the refractive indexes of the materials forming the PBS 62. As a result, the space required for storing the light emitting element 3 and the like can be reduced, and the device can be downsized.
【００３８】次に、プリズム状のＰＢＳ６２による反射
光検出装置１における収差の低減について説明する。図
９は、板状のＰＢＳを光が通過するときの焦点位置につ
いて説明する図で、（ａ）はその概要を示す斜視図、
（ｂ）は焦点の位置を説明する拡大図である。板状のＰ
ＢＳ６を光が透過する場合に、その受光面と光軸が直交
しないとき、図９（ａ）に示されている焦点の位置は、
図９（ｂ）に示すように、厳密には、Ｘ軸方向とＹ軸方
向で異なっている。すなわち、Ｘ軸方向についてはＡ点
であり、Ｙ軸方向ではＢ点である。これは、板状のＰＢ
Ｓ６の受光面と光軸が直交しないときは、Ｘ軸方向とＹ
軸方向で光路長が異なるためであり、これにより収差が
生じる。本実施例のようにプリズム状のＰＢＳ６２を用
いた場合には、Ｘ軸方向とＹ軸方向で光路長が異ならな
いので、収差を低減することができる。Next, the reduction of the aberration in the reflected light detecting device 1 by the prism-shaped PBS 62 will be described. FIG. 9 is a diagram illustrating a focal position when light passes through a plate-shaped PBS, and FIG. 9A is a perspective view showing an outline thereof,
(B) is an enlarged view for explaining the focus position. Plate-shaped P
When light is transmitted through BS6 and its light receiving surface is not orthogonal to the optical axis, the focus position shown in FIG.
Strictly speaking, as shown in FIG. 9B, the X-axis direction and the Y-axis direction are different. That is, it is point A in the X-axis direction and point B in the Y-axis direction. This is a plate-shaped PB
When the light-receiving surface of S6 and the optical axis are not orthogonal, the X-axis direction and Y
This is because the optical path length differs in the axial direction, which causes aberration. When the prism-shaped PBS 62 is used as in the present embodiment, the optical path length does not differ between the X-axis direction and the Y-axis direction, so that the aberration can be reduced.
【００３９】（実施例９）図１０は、第９実施例による
ファイバ式の反射光検出装置１の構成図、図１１はその
光ファイバの検知対象物側の端面のバリエーションを説
明する図である。図１０に示すように、この実施例は、
上記実施例１の構成において、複屈折性を有するレンズ
８に代え、複屈折性を有さないレンズ８１と光ファイバ
１４とを用いたものである。この構成では、レンズで投
光する光の偏光方向をランダムにする代わりに、光ファ
イバ１４を通すことによりランダムにしている。(Embodiment 9) FIG. 10 is a configuration diagram of a fiber type reflected light detecting device 1 according to a ninth embodiment, and FIG. 11 is a diagram for explaining variations of the end face of the optical fiber on the side of the object to be detected. . This embodiment, as shown in FIG.
In the structure of the first embodiment, a lens 81 having no birefringence and an optical fiber 14 are used instead of the lens 8 having birefringence. In this configuration, instead of randomizing the polarization direction of the light projected by the lens, the optical fiber 14 is used to make the polarization direction random.
【００４０】なお、光ファイバ１４の端面１４ａについ
ては、研磨、熱処理、透明樹脂によるコートなどで鏡面
とすることにより、光の反射による偏光方向の変化を抑
制している。また、光ファイバ１４の端面１４ｂについ
ては、図１１に示すように、その先端部に反射防止膜
（無反射コート）を形成したロッドレンズを設ける
（ａ）、斜めにカットする（ｂ）、先球ファイバを用い
る（ｃ）、透明樹脂をコートする（ｄ）などの処理を施
すことにより、端面１４ｂにおける反射を抑制してい
る。これにより、光ファイバ１４の端面１４ａや１３ｂ
において反射して迷光となり受光素子９で受光される光
を低減している。The end face 14a of the optical fiber 14 is mirror-finished by polishing, heat treatment, coating with a transparent resin or the like to suppress the change of the polarization direction due to the reflection of light. As for the end face 14b of the optical fiber 14, as shown in FIG. 11, a rod lens having an antireflection film (non-reflection coating) formed on its tip is provided (a), cut obliquely (b), and first. By performing processing such as using a spherical fiber (c) and coating a transparent resin (d), reflection at the end face 14b is suppressed. Thereby, the end faces 14a and 13b of the optical fiber 14 are
The light reflected by the light-receiving element 9 becomes stray light and is reduced by the light-receiving element 9.
【００４１】（実施例１０）図１２（ａ），（ｂ）は、
上記実施例９の応用として、反射光検出装置１を液面レ
ベルセンサとした構成図及びファイバの先端部分の拡大
図である。本実施例においては、光ファイバ１４の端面
１４ｂに、プリズム１４ｐが取り付けられている。この
構成の場合、図示の液面２の状態では、プリズム１４ｐ
の周囲の空気の屈折率とプリズム１４ｐの屈折率との差
が大きい状態であるため、投光された光Ｌｅはプリズム
１４ｐで反射され、比較的多量の光が反射光Ｌｒとし
て、受光素子で受光される。液面１の状態では、プリズ
ム１４ｐの周囲の液体の屈折率とプリズム１４ｐの屈折
率との差が小さくなり、投光された光Ｌｅはプリズム１
４ｐで反射され難く、反射光Ｌｒとして、受光素子で受
光される光量は小さくなる。この光量の違いにより液面
の上下位置を検知することができる。しかも、迷光の小
さい投・受光同軸型の液面レベルセンサを実現すること
ができる。また、光ファイバ１４の端面１４ｂにプリズ
ム１４ｐが取り付けられているため、光ファイバ１４の
液切れが良くなる。(Embodiment 10) FIGS. 12 (a) and 12 (b) show
As an application of the ninth embodiment, it is a configuration diagram in which the reflected light detection device 1 is used as a liquid level sensor and an enlarged view of the tip portion of the fiber. In this embodiment, a prism 14p is attached to the end face 14b of the optical fiber 14. In the case of this configuration, in the state of the liquid surface 2 shown, the prism 14p
Since the difference between the refractive index of the surrounding air and the refractive index of the prism 14p is large, the projected light Le is reflected by the prism 14p, and a relatively large amount of light is reflected by the light receiving element as reflected light Lr. Received light. In the state of the liquid surface 1, the difference between the refractive index of the liquid around the prism 14p and the refractive index of the prism 14p becomes small, and the projected light Le is reflected by the prism 1.
It is difficult to be reflected at 4p, and the amount of light received by the light receiving element as the reflected light Lr becomes small. The vertical position of the liquid surface can be detected by this difference in the amount of light. In addition, it is possible to realize a liquid level sensor of a light emitting / receiving coaxial type with little stray light. Further, since the prism 14p is attached to the end surface 14b of the optical fiber 14, the liquid out of the optical fiber 14 becomes better.
【００４２】なお、本発明の反射光検出装置は、受光手
段において受光される反射光が投光光路から分離され、
さらに、受光手段において受光される反射光の偏光方向
が投光される光の偏光方向と直交する直線偏光であれば
よく、上記の各実施例の構成、例えば、レンズ、ＰＢ
Ｓ、ハーフミラーなどの組み合わせ、受光素子の前面の
偏光フィルタの存否、レンズ面の処理、筐体内部の処
理、等々はこれらに限られるものではない。In the reflected light detecting device of the present invention, the reflected light received by the light receiving means is separated from the light projecting optical path,
Further, linearly polarized light in which the polarization direction of the reflected light received by the light receiving means is orthogonal to the polarization direction of the projected light may be used, and the configuration of each of the above embodiments, for example, a lens, PB
The combination of S, half mirror, etc., presence / absence of a polarizing filter on the front surface of the light receiving element, processing of the lens surface, processing inside the housing, etc. are not limited to these.
【００４３】[0043]
【発明の効果】以上のように、本発明の反射光検出装置
によれば、投光手段により直線偏光が投光され、光路分
離手段により投光光路を逆行する投光された光の検知対
象物による反射光が投光光路から分離され、この分離さ
れた反射光のうち投光された光の偏光方向に対して直交
する偏光方向の光が受光偏光手段の作用により受光手段
に受光される。従って、受光手段によって受光される光
は、検知対象物に反射され投光光路から分離され、か
つ、投光された光の偏光方向に対して直交する偏光方向
の光であるので、投光の偏光方向と同じ偏光方向の迷光
が生じたとしても、その迷光が受光手段に受光されるこ
とがなくなる。このため、投・受光同軸型でありながら
も、迷光の影響を受けて誤動作を起こすことが低減さ
れ、物体検出精度が高くなる。また、本発明によれば、
直線偏光の光を、その偏光方向と直交する偏光成分を含
む光に変換する投光偏光変換手段を付加することによ
り、検知対象物体が拡散反射物や鏡面反射物であって
も、精度良く該物体の有無検出を行うことができる。ま
た、本発明によれば、迷光の影響を受けることが少なく
検出精度の良い液面レベル検出装置を実現できる。As described above, according to the reflected light detecting device of the present invention, the linearly polarized light is projected by the light projecting means, and the object of detection of the projected light which travels backward in the light projecting optical path by the optical path separating means. The light reflected by the object is separated from the light projecting light path, and the light of the separated reflected light in the polarization direction orthogonal to the polarization direction of the projected light is received by the light receiving means by the action of the light receiving polarization means. . Therefore, the light received by the light receiving means is reflected by the object to be detected, separated from the projection light path, and has a polarization direction orthogonal to the polarization direction of the projected light. Even if stray light having the same polarization direction as the polarization direction is generated, the stray light is not received by the light receiving means. For this reason, even though it is the projection / reception coaxial type, it is possible to reduce the occurrence of malfunction due to the influence of stray light, and to improve the object detection accuracy. According to the present invention,
Even if the detection target object is a diffuse reflection object or a specular reflection object by adding a projection polarization conversion means for converting linearly polarized light into light containing a polarization component orthogonal to the polarization direction, The presence / absence of an object can be detected. Further, according to the present invention, it is possible to realize a liquid surface level detection device that is not affected by stray light and has high detection accuracy.
【図１】（ａ）は本発明の第１実施例による物体検出装
置の断面図、（ｂ）は処理系の概略ブロック図である。1A is a sectional view of an object detection device according to a first embodiment of the present invention, and FIG. 1B is a schematic block diagram of a processing system.
【図２】第２実施例による反射光検出装置の断面図であ
る。FIG. 2 is a sectional view of a reflected light detecting device according to a second embodiment.
【図３】第３実施例による反射光検出装置の断面図であ
る。FIG. 3 is a sectional view of a reflected light detecting device according to a third embodiment.
【図４】第４実施例による反射光検出装置の断面図であ
る。FIG. 4 is a sectional view of a reflected light detecting device according to a fourth embodiment.
【図５】第５実施例による反射光検出装置の断面図であ
る。FIG. 5 is a sectional view of a reflected light detecting device according to a fifth embodiment.
【図６】第６実施例による反射光検出装置の断面図であ
る。FIG. 6 is a sectional view of a reflected light detecting device according to a sixth embodiment.
【図７】（ａ）は両面に光学多層膜を形成したＰＢＳの
構成図、（ｂ）は光学多層膜の反射率特性を示す図であ
る。7A is a configuration diagram of a PBS in which an optical multilayer film is formed on both surfaces, and FIG. 7B is a diagram showing reflectance characteristics of the optical multilayer film.
【図８】第８実施例による反射光検出装置の断面図であ
る。FIG. 8 is a sectional view of a reflected light detecting device according to an eighth embodiment.
【図９】（ａ）は板状のＰＢＳを光が通過するときの焦
点位置を示す斜視図、（ｂ）は焦点位置を説明する拡大
図である。FIG. 9A is a perspective view showing a focal position when light passes through a plate-shaped PBS, and FIG. 9B is an enlarged view for explaining the focal position.
【図１０】第９実施例による反射光検出装置の断面図で
ある。FIG. 10 is a sectional view of a reflected light detecting device according to a ninth embodiment.
【図１１】光ファイバの検知対象物側の端面を示す図で
ある。FIG. 11 is a diagram showing an end surface of the optical fiber on the side of a detection target.
【図１２】（ａ）は第１０実施例による反射光検出装置
を示す図、（ｂ）は光ファイバの先端部分の拡大図であ
る。FIG. 12A is a diagram showing a reflected light detecting device according to a tenth embodiment, and FIG. 12B is an enlarged view of a tip portion of an optical fiber.
【図１３】（ａ）は従来の反射光検出装置において投光
と受光の軸が同じでない型の構成を示す図、（ｂ）は
（ａ）の型の不都合を示す図、（ｃ）はその不都合を改
良した投受光同軸型の構成を示す図である。13A is a diagram showing a configuration of a mold in which the axes of light projection and light reception are not the same in the conventional reflected light detection device, FIG. 13B is a diagram showing inconvenience of the mold of FIG. 13A, and FIG. It is a figure which shows the structure of the light emitting / receiving coaxial type which improved the inconvenience.
１ 反射光検出装置 ２，２１ 筐体 ３ 発光素子（投光手段） ４ 偏光フィルタ（投光手段） ５ 偏光フィルタ（受光手段） ６ 偏光ビームスプリッタ（ＰＢＳ、光路分離手
段及び受光偏光手段） ６１ 偏光ビームスプリッタ ６２ プリズム状の偏光ビームスプリッタ ７ ハーフミラー ８ 複屈折性を有するレンズ（投光偏光変換手
段） ８１ 複屈折性を有さないレンズ ９ 受光素子 １０ 駆動回路 １１ アンプ １２ コンパレータ １３ 回帰反射板（投光偏光変換手段） １４ 光ファイバ（投光偏光変換手段）DESCRIPTION OF SYMBOLS 1 Reflected light detection device 2, 21 Housing 3 Light emitting element (light projecting means) 4 Polarizing filter (light projecting means) 5 Polarizing filter (light receiving means) 6 Polarizing beam splitter (PBS, optical path separating means and light receiving polarizing means) 61 Polarized light Beam splitter 62 Prism-shaped polarization beam splitter 7 Half mirror 8 Lens having birefringence (projection polarization conversion means) 81 Lens having no birefringence 9 Light receiving element 10 Driving circuit 11 Amplifier 12 Comparator 13 Regressive reflection plate ( Projection polarization conversion means) 14 Optical fiber (projection polarization conversion means)
───────────────────────────────────────────────────── フロントページの続き (72)発明者 細川 速美 京都府京都市右京区花園土堂町10番地 オ ムロン株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hayami Hosokawa 10 Odoron-cho, Hanazono Tadodo-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture OMRON Corporation
Claims (6)
反射光とが同軸の光路をなす反射光検出装置において、 直線偏光を投光する投光手段と、 前記投光手段による投光光路を逆行する検知対象物によ
る反射光を前記投光光路から分離する光路分離手段と、 前記光路分離手段により分離された反射光を受光する受
光手段と、 前記受光手段により受光される光を、投光される光の偏
光方向に対して直交する偏光方向のものとする受光偏光
手段とを備えたことを特徴とする反射光検出装置。1. A reflected light detecting device in which the projected light and the reflected light of the detected light from an object to be detected form a coaxial optical path, a projecting means for projecting linearly polarized light, and a projecting means by the projecting means. An optical path separating unit that separates the reflected light from the detection object that travels in the reverse direction of the optical path from the light projecting optical path, a light receiving unit that receives the reflected light separated by the optical path separating unit, and a light received by the light receiving unit. A reflected light detecting device, comprising: a light receiving and polarizing means having a polarization direction orthogonal to the polarization direction of the projected light.
が偏光ビームスプリッタであることを特徴とする請求項
１に記載の反射光検出装置。2. The reflected light detection device according to claim 1, wherein the optical path separation means and the light receiving polarization means are polarization beam splitters.
偏光の偏光方向と直交する偏光成分を含む光に変換する
投光偏光変換手段をさらに備えたことを特徴とする請求
項１に記載の反射光検出装置。3. The light-projection polarization conversion means for converting the light projected by the light-projecting means into light containing a polarization component orthogonal to the polarization direction of the linearly polarized light. The reflected light detection device described in 1.
象物の有無を判別する信号処理手段をさらに備えたこと
を特徴とする物体検出装置。4. The reflected light detecting device according to claim 1, further comprising signal processing means for determining the presence or absence of a detection target whose reflected light is changed based on the output of the light receiving means. Object detection device.
象物の有無を判別する信号処理手段と、 投光手段が投光した光を、その直線偏光の偏光方向と直
交する偏光成分を含む光に変換する投光偏光変換手段を
さらに備え、 前記投光偏光変換手段が検知対象物側の先端に斜面を有
する光ファイバであることを特徴とする液面レベル検出
装置。5. A signal processing means for using the reflected light detection device according to claim 1 to determine the presence or absence of an object to be detected which changes reflected light based on the output of the light receiving means, and the light projecting means for projecting light. The projection polarization conversion means for converting light into light containing a polarization component orthogonal to the polarization direction of the linearly polarized light is further provided, and the projection polarization conversion means is an optical fiber having a slope at the tip on the object side. A liquid level detecting device characterized in that
象物の有無を判別する信号処理手段と、 投光手段が投光した光を、その直線偏光の偏光方向と直
交する偏光成分を含む光に変換する投光偏光変換手段を
さらに備え、 前記投光偏光変換手段が回帰反射板であることを特徴と
する物体検出装置。6. A reflected light detecting device according to claim 1, wherein the signal processing means for judging the presence or absence of an object to be detected which changes the reflected light based on the output of the light receiving means, and the light projecting means emits light. An object detection apparatus further comprising a projection polarization conversion means for converting light into light containing a polarization component orthogonal to the polarization direction of the linearly polarized light, wherein the projection polarization conversion means is a recursive reflection plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12791996A JPH09288939A (en) | 1996-04-23 | 1996-04-23 | Reflected light detecting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12791996A JPH09288939A (en) | 1996-04-23 | 1996-04-23 | Reflected light detecting device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09288939A true JPH09288939A (en) | 1997-11-04 |
Family
ID=14971891
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12791996A Pending JPH09288939A (en) | 1996-04-23 | 1996-04-23 | Reflected light detecting device |
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| Country | Link |
|---|---|
| JP (1) | JPH09288939A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005180943A (en) * | 2003-12-16 | 2005-07-07 | Azuma Systems:Kk | Surroundings monitoring apparatus for work vehicle |
| JP2015115278A (en) * | 2013-12-13 | 2015-06-22 | オムロン株式会社 | Photoelectric sensor head |
-
1996
- 1996-04-23 JP JP12791996A patent/JPH09288939A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005180943A (en) * | 2003-12-16 | 2005-07-07 | Azuma Systems:Kk | Surroundings monitoring apparatus for work vehicle |
| JP2015115278A (en) * | 2013-12-13 | 2015-06-22 | オムロン株式会社 | Photoelectric sensor head |
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