JP3726750B2 - Photoelectric sensor and manufacturing method thereof - Google Patents

Description

【０００８】
つまり、受光素子３の出力から得られるΔＬ１をもとに三角測量の原理を利用してΔＬを求めることができる。
【０００９】
ところで、受光レンズの中心Ｒと受光素子３の受光面との距離をＬ２とすると、点Ｒから投光レンズ２ａの光軸への垂線の両端と点Ｐ１とを頂点とする３角形と、点Ｐ２から投光レンズ２ａの光軸への垂線の両端と点Ｐ１とを頂点とする３角形との相似からＬ１はＬ２を用いて次式で表される。
【００１０】
【数２】

【００１１】
言い換えると、ΔＬ１とΔＬとの関係およびＬ１は、ＢＬ１、ＢＬＤ１およびＬ２つまり投光素子１、受光素子３およびレンズ２ａ，２ｂの相互の位置関係によって決定される。光電センサの性能との関連を説明するため、上の２つの式からＢＬＤ１を消去して変形した次の式を用いる。
【００１２】
【数３】

【００１３】
上の式から分かるように、受光レンズの中心Ｒと受光素子３の受光面との距離Ｌ２を変化させずに受光レンズ２ｂの中心Ｒと投光レンズ２ａの光軸との距離ＢＬ１を大きくすると、同じＬ１とΔＬとに対してΔＬ１が大きくなる。すなわち受光レンズ２ｂの受光面の幅は限られているから測定可能な距離の範囲は狭くなるが、同じΔＬに対して受光素子３の出力がより大きく変化するから距離測定の分解能が高くなる。受光素子３と投光レンズ２ａの光軸との位置関係および受光素子３と受光レンズ２ｂとの位置関係も同様に光電センサの性能に影響を与える。
【００１４】
測定可能な距離の範囲および距離測定の分解能を設計通りとするために投光素子１、受光素子３、および各レンズ２ａ，２ｂの相互の位置関係は製造時に調整される。一般的には、投光素子１および受光素子３は器体４に対して固定された回路基板（図示せず）にそれぞれ実装することにより位置を決定し、各レンズ２ａ，２ｂを固定する位置をそれぞれ調整する。
【００１５】
レンズ２ａ，２ｂを固定する位置の調整を容易にするために、以下に説明する技術が提案されている。図８に示すようにレンズ２ａ，２ｂは矩形板状の表裏の面の中央部にレンズ部が形成された形状とし、器体４にはレンズ２ａ，２ｂを露出させるレンズ窓４ｄを設け、レンズ窓２ｄの周縁において互いに対向する一対の面にはレンズ２ａ，２ｂの両側縁の各一方がそれぞれ挿入される保持溝４ａを設ける。そして、器体４に例えば投光レンズ２ａを装着するにあたっては、投光レンズ２ａの両側縁をそれぞれ保持溝４ａに挿入し、図８の矢印Ａで示すように保持溝４ａに沿った方向に投光レンズ２ａを器体４に対してスライドさせて位置を調整し、その後に接着剤を用いて投光レンズ２ａを器体４に固定する。このとき、従来は接着剤を矢印Ｄ１で示すように投光レンズ２ａの角部から保持溝４ａに沿って保持溝４ａと投光レンズ２ａとの間に注入していた。
【００１６】
【発明が解決しようとする課題】
しかし、レンズ２ａ，２ｂの保持溝４ａに沿った方向の端部に付着した接着剤が硬化時に収縮することにより、レンズ２ａ，２ｂが保持溝４ａに沿った方向の引っ張り力を受けて接着剤の硬化前に調整した位置から移動し、かつ移動距離が一様でないことから光電センサの性能にばらつきが生じていた。ネジなどの部品を追加すれば接着剤が硬化した後にレンズの位置を調整することも可能ではあるが、この場合は追加する部品のためのコストがかかるという問題があった。
【００１７】
上記においては測距用の反射型光電センサについて述べたが、例えば投光レンズから照射された光ビームを受光レンズへ反射する反射体を備え、反射体と器体との間に検出対象が存在した場合に受光素子への入射光量の減少から検出対象の存在を検出する光電センサであっても、投光レンズおよび受光レンズの位置がずれることによって光ビームが設計通りの向きに照射されなかったり受光素子の受光部から一部が外れて集光されたりすれば光の利用効率が低下し感度の低下に繋がるので、接着剤の硬化に伴うレンズの移動を防止することは重要である。
【００１８】
本発明は上記事由に鑑みてなされたものであり、その目的は、レンズを器体に固定する接着剤の硬化に伴うレンズの移動を防ぐことができる光電センサおよびその製造方法を提供することにある。
【００１９】
【課題を解決するための手段】
請求項１の発明は、光を放射する投光素子と、前記投光素子が放射した光から光ビームを形成する矩形状の第１のレンズと、前記第１のレンズで形成された光ビ−ムが検出対象に照射されて生じる光スポットからの光を集光する矩形状の第２のレンズと、前記第２のレンズが集光した光を受光する受光素子と、各レンズをそれぞれ保持する器体とを備え、前記器体には、各レンズの両側縁の各一方がそれぞれ収納され内面が各レンズの表裏両面にそれぞれ対向する保持溝と、器体にレンズを固定するための接着剤を各レンズの前記保持溝に収納された側縁の中間部に注入する注入口とが設けられていることを特徴とする。
【００２０】
請求項２の発明は、請求項１の発明において、前記注入口は前記保持溝において前記レンズの表裏の一面に面した部位に設けられていることを特徴とする。
【００２１】
請求項３の発明は、請求項１の発明において、前記注入口は前記保持溝において前記レンズの表裏の面に交差した部位に設けられていることを特徴とする。
【００２２】
請求項４の発明は、請求項１の発明において、前記第１のレンズを挟んで前記第２のレンズが２つ設けられ、前記第２のレンズの側縁が収納された保持溝はそれぞれ前記レンズが並んだ方向に沿って延び、前記第１のレンズの側縁が収納された保持溝は前記レンズが並んだ方向に交差する方向に沿って延びていることを特徴とする。
【００２３】
請求項５の発明は、請求項１の発明の製造方法であって、前記レンズの各側縁を前記保持溝にそれぞれ挿入した後に、前記注入口から接着剤を前記レンズの前記保持溝に収納された側縁の中間部に接着剤が付着するように注入することにより前記レンズを前記器体に固定することを特徴とする。
【００２４】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。
【００２５】
（実施形態１）
本実施形態における光電センサの基本的な構成は従来例で述べた測距用の反射型光電センサと同様であるから、共通の部分については図７を用いて説明する。本実施形態における光電センサは、図７に示すように、光を放射する投光素子１と、投光素子１が放射した光から光ビームを形成する第１のレンズとしての投光レンズ２ａと、投光レンズ２ａから照射された光ビームによって検出対象Ｔに生じる光スポットからの光を集光する第２のレンズとしての受光レンズ２ｂと、受光レンズ２ｂによって集光された光を検出する受光素子３と、投光レンズ２ａおよび受光レンズ２ｂを保持する器体４とを備える。
【００２６】
図１に示すように、レンズ２ａ，２ｂは矩形板状の表裏の面の中央部にレンズ部が形成された形状であって、器体４にはレンズ２ａ，２ｂのレンズ部を露出させるレンズ窓４ｄが設けられている。そして、器体４のレンズ窓４ｄの周縁において互いに対向する面にレンズ２ａ，２ｂの両側縁の各一方がそれぞれ挿入される保持溝４ａが設けられている。また、器体４において保持溝４ａの側部にはレンズ２ａ，２ｂの保持溝４ａに収納される側縁の中間部を露出させレンズ窓４ｄの内側へ開放された注入切欠き４ｂが注入口として設けられている。すなわち注入切欠き４ｂは保持溝４ａにおいてレンズ２ａ，２ｂの表裏の一面に面した部位に設けられている。
【００２７】
この光電センサにおいて例えば投光レンズ２ａを器体４に固定する際は、投光レンズ２ａの両側縁をそれぞれ保持溝４ａに挿入し投光レンズ２ａの位置を調整した後に矢印Ｄ２で示すように注入切欠き４ｂから接着剤を注入する。このとき投光レンズ２ａの角部に接着剤が付着しないように接着剤の注入量を調節する。受光レンズ２ｂも同様にして器体４に固定する。
【００２８】
本実施形態によれば、レンズ２ａ，２ｂを器体４に固定する接着剤は注入切欠き４ｂを通してレンズ２ａ，２ｂの保持溝４ａに沿った側縁の中間部に注入され、レンズ２ａ，２ｂの角部に付着しないので、接着剤が硬化時に収縮してもレンズ２ａ，２ｂは保持溝４ａに沿った方向の引っ張り力をほとんど受けない。つまり接着剤の硬化に伴うレンズ２ａ，２ｂの移動を防ぐことができ、従って接着剤の硬化後にレンズ２ａ，２ｂの位置を調整するためのネジなどの部品の追加を不要としながらもレンズ２ａ，２ｂの位置を設計通りとすることができるから品質のばらつきが抑えられる。また、レンズ２ａ，２ｂが器体４の外部へ一面を向けて固定される光電センサの場合は注入切欠き４ｂは保持溝４ａにおいてレンズ２ａ，２ｂの外側の面に面した部位に設ければ接着剤の注入が容易である。
【００２９】
なお、注入口はレンズ２ａ，２ｂの保持溝４ａに沿った側縁の中間部に開口していればよい。例えば図２のように各保持溝４ａの底部すなわちレンズ２ａ，２ｂの表裏の面に交差した各部位にそれぞれ貫設された注入穴４ｆを注入口として矢印Ｄ３で示す方向から接着剤を注入すれば、レンズ２ａ，２ｂの両側における接着剤の硬化時の収縮による引っ張り力が互いに打ち消し合うことによりレンズ２ａ，２ｂの位置を更にずれにくくすることができる。さらに、図３のように注入切欠き４ｂと注入穴４ｆとの両方を設けてもよい。この場合、矢印Ｄ２の方向と矢印Ｄ３の方向とのどちらから接着剤を注入してもよい。以上に述べたどの形状の注入口であっても、接着剤の硬化時にレンズが移動することを防ぐ効果はあるので、接着剤を注入する装置の仕様に合わせて注入口の形状を適宜選択することができる。
【００３０】
上記実施形態においては測距用の反射型光電センサについて述べたが、例えば従来例において述べた検出対象の有無を判定する光電センサであっても、同様にして投光レンズおよび受光レンズを固定することにより、接着剤の硬化に伴うレンズの移動が防止され、投光レンズで形成される光ビームの向きのずれや受光レンズが集光する位置のずれ等に起因する光の利用効率の低下によって感度が低下することを防ぐことができる。
【００３１】
（実施形態２）
本実施形態における光電センサは実施形態１と同様の受光素子を備えた測距用の反射型光電センサであって、図４に示すように１つの投光素子１が放射した光が投光レンズ２ａを通過して形成された光ビームが検出対象Ｔに形成する光スポットを検出する受光素子３と受光レンズ２ｂとを２組備える。受光レンズ２ｂは発光レンズ２ａを挟んで配置されている。
【００３２】
受光素子３と受光レンズ２ｂとが投光レンズ２ａの光軸を挟んで２組配置されているので、検出対象Ｔに形成される光スポットの位置が機械的な誤差や光の反射むらによって投光レンズ２ａの光軸と受光レンズ２ｂの光軸とが並ぶ方向の一方にずれることによる誤差が例えば２つの受光素子３の出力を加算することによって相殺されるから、受光素子３と受光レンズ２ｂとを１組のみ備える測距用の光電センサに比べて、より誤差の少ない距離測定に用いることができる。
【００３３】
この光電センサに用いられる器体４は図５に示すように直方体形に形成されている。以下、方向は図５を基準とし、紙面奥を前方として説明する。器体４の前面の中央部には発光レンズ２ａが図５の矢印Ｂの向きに挿入されるレンズ挿入口（図示せず）が開口し、器体４の左右両面にはそれぞれ受光レンズ２ｂが図５の矢印Ｃの向きに挿入されるレンズ挿入口４ｃが開口している。各レンズ挿入口４ｃの両側部は保持溝４ａとして機能する。また、器体の上面には各１つのレンズ挿入口４ｃに連通してそれぞれレンズ２ａ，２ｂを露出させる３つの矩形状のレンズ窓４ｄが左右に並設されている。さらに、受光レンズ２ｂの側縁の中間部へ接着剤を注入するための注入口として注入穴４ｆが左右両端の各レンズ挿入口４ｃの両側方において器体４の前後面に開口している。また、投光レンズ２ａを器体４に固定する接着剤を注入するための貫通穴４ｅが器体４の後面の中央部に開口している。
【００３４】
本実施形態によれば、受光レンズ２ｂを器体４に固定する接着剤は注入穴４ｆを通して受光レンズ２ｂの側縁の中間部へ注入され、受光レンズ２ｂの左右の端部には付着しないので接着剤が硬化時に収縮しても受光レンズ２ｂはレンズ挿入穴４ｃに沿った方向の引っ張り力をほとんど受けず、従って接着剤の硬化に伴う受光レンズ２ｂの移動を防ぐことができる。
【００３５】
ここで、従来例の説明で述べたように光電センサの距離測定の分解能と測定可能な距離の範囲とは受光レンズ２ｂの光軸と投光レンズ２ａの光軸との距離に依存する。一方、本実施形態においては投光レンズ２ａを挟んで受光レンズ２ｂが２つ設けられていて、受光レンズ２ｂが収納されるレンズ挿入口４ｃはそれぞれ前記レンズが並んだ方向に沿って延びているので、各受光レンズ２ｂをそれぞれレンズ挿入口４ｃに沿ってスライドさせて投光レンズ２ａの光軸と各受光レンズ２ｂの光軸との距離をそれぞれ調整することにより、光電センサの距離測定の分解能と測定可能な距離の範囲とを容易に設定することができる。
【００３６】
ここで、上記実施形態において注入口は注入穴４ｆのみとしたが、例えば図６に示すように各レンズ窓４ｄのレンズ２ａ，２ｂが挿入される方向に沿った各側部の中間部にそれぞれ注入切欠き４ｂを注入口としてさらに設ければ、投光レンズ２ａを器体４に固定する際には接着剤を中央のレンズ窓４ｄの側部に設けた注入切欠き４ｂから注入することにより接着剤の硬化時に投光レンズ２ａがほとんど移動しないので、従来の方法で投光レンズ２ａを固定する場合と比べて光ビームの照射方向を精度良く設定でき、光の利用効率の低下による感度の低下を防ぐことができる。
【００３７】
【発明の効果】
請求項１の発明は、レンズを器体に固定する接着剤は注入口を通してレンズの保持溝に沿った側縁の中間部に注入され、レンズの保持溝に沿った方向の端部に付着しないので、接着剤が硬化時に収縮してもレンズの位置がほとんどずれない。従ってレンズを固定した後にレンズの位置を調整するためのねじなどの部品を追加することなく接着剤の硬化に伴うレンズの移動を防ぐことができる。
【００３８】
請求項２の発明は、請求項１の発明において、注入口を保持溝においてレンズの表裏の一面に面した部位に設けるので、レンズが器体の外部へ一面を向けて固定される光電センサの場合、レンズの外側の面に面した部位に注入口を設ければ接着剤の注入が容易である。
【００３９】
請求項４の発明は、請求項１の発明において、第１のレンズを挟んで第２のレンズが２つ設けられていて、前記第２のレンズの側縁が収納された保持溝はそれぞれ前記レンズが並んだ方向に沿って延びているので、第２のレンズをレンズ挿入口に沿ってスライドさせて第１のレンズの光軸と各第２のレンズの光軸との距離をそれぞれ調整することにより検出対象を検出可能な距離の範囲などを容易に調整することができる。
【００４０】
請求項５の発明は、請求項１記載の発明の製造方法であって、レンズの各側縁を保持溝にそれぞれ挿入した後に、注入口から接着剤をレンズの保持溝に収納された側縁の中間部に接着剤が付着するように注入することにより、接着剤がレンズの保持溝に沿った方向の端部に付着しないので、接着剤の硬化時の収縮に伴うレンズの移動を防ぐことができる。
【図面の簡単な説明】
【図１】本発明の実施形態１の要部を示す斜視図である。
【図２】同上の別の形態を示す斜視図である。
【図３】同上の更に別の形態を示す斜視図である。
【図４】本発明の実施形態２を示す説明図である。
【図５】同上の要部を示す斜視図である。
【図６】同上の別の形態を示す斜視図である。
【図７】光電センサの例を示す説明図である。
【図８】従来の光電センサの要部を示す斜視図である。
【符号の説明】
１ 投光素子
２ａ 投光レンズ
２ｂ 受光レンズ
３ 受光素子
４ 器体
４ａ 保持溝
４ｂ 注入切欠き
４ｃ レンズ挿入口
４ｆ 注入穴[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoelectric sensor that detects the presence / absence of a detection target, the distance to the detection target, and the like by optical means, and a method for manufacturing the photoelectric sensor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a photoelectric sensor that detects the presence or absence of a detection target, a distance to the detection target, and the like by detecting light emitted from a light projecting element by a light receiving element has been provided.
[0003]
As a photoelectric sensor, as shown in FIG. 7, a photoelectric sensor that detects a distance to a detection target among so-called reflection type photoelectric sensors that detect light reflected by the detection target T and detected by the light receiving element 3. Will be described as an example. The light receiving element 3 used in this photoelectric sensor is a semiconductor position detecting element (PSD) whose output changes depending on the position of incident light, a two-divided photodiode in which two photodiodes are adjacent, or the like. As the light projecting element 1, for example, an LED or a laser diode that emits infrared rays is used.
[0004]
The light emitted from the light projecting element 1 is formed into a light beam through a light projecting lens (first lens) 2a, and the light from the light spot P1 generated on the detection target T by this light beam is a light receiving lens (second lens). A light spot P2 is formed on the light receiving surface of the light receiving element 3 by being condensed by 2b. The light projecting lens 2 a and the light receiving lens 2 b are held by the container 4. Here, the optical axes of the light projecting lens 2a and the light receiving lens 2b are both perpendicular to the light receiving surface of the light receiving element 3, and are separated in a direction in which the light receiving element 3 is sensitive to changes in the position of incident light. Are arranged as follows.
[0005]
By arranging the light projecting lens 2a and the light receiving lens 2b as described above, the position of the light spot P2 is further away from the optical axis of the light projecting lens 2a as the distance to the detection target T is shorter. Therefore, the distance from the output of the light receiving element 3 to the detection target T is obtained. This will be specifically described below. The distance between the optical axis of the light projecting lens 2a and the optical axis of the light receiving lens 2b is BL1, and the intersection of the perpendicular line from the center R of the light receiving lens 2b to the optical axis of the light projecting lens 2a and the optical axis of the light projecting lens 2a. Is a point r. When the light spot P2 is formed at the measurement reference position (for example, an intermediate portion of the light receiving surface) on the light receiving surface of the light receiving element 3 whose distance from the optical axis of the light projecting lens 2a is BLD1 by the light from the light spot P1. The distance between the point r and the detection target T is L1.
[0006]
By the light from the light spot P1 ′ formed on the detection target T whose distance from the point r is shorter than L1 by ΔL, the light spot P2 is located at a position away from the optical axis of the projection lens 2a by the distance ΔL1 from the measurement reference position. 'Is formed. A triangle having apexes at both ends of a perpendicular line from the point R to the optical axis of the light projecting lens 2a and a point P1 ′, and both ends of a perpendicular line from the point P2 ′ to the optical axis of the light projecting lens 2a and a point P1 ′ ΔL is expressed by the following equation using ΔL1 from the similarity to the triangle as the apex.
[0007]
[Expression 1]

[0008]
That is, ΔL can be obtained by using the principle of triangulation based on ΔL1 obtained from the output of the light receiving element 3.
[0009]
By the way, assuming that the distance between the center R of the light receiving lens and the light receiving surface of the light receiving element 3 is L2, a triangle having apexes at both ends of a perpendicular line from the point R to the optical axis of the light projecting lens 2a and a point P1, L1 is expressed by the following equation using L2 from the similarity of a triangle having apexes at both ends of the perpendicular line from P2 to the optical axis of the projection lens 2a and the point P1.
[0010]
[Expression 2]

[0011]
In other words, the relationship between ΔL1 and ΔL and L1 is determined by the positional relationship between BL1, BLD1, and L2, that is, the light projecting device 1, the light receiving device 3, and the lenses 2a and 2b. In order to explain the relationship with the performance of the photoelectric sensor, the following equation obtained by deleting BLD1 from the above two equations is used.
[0012]
[Equation 3]

[0013]
As can be seen from the above equation, if the distance BL1 between the center R of the light receiving lens 2b and the optical axis of the light projecting lens 2a is increased without changing the distance L2 between the center R of the light receiving lens and the light receiving surface of the light receiving element 3. .DELTA.L1 increases with respect to the same L1 and .DELTA.L. That is, the range of the measurable distance is narrow because the width of the light receiving surface of the light receiving lens 2b is limited, but the resolution of the distance measurement is increased because the output of the light receiving element 3 changes more greatly for the same ΔL. Similarly, the positional relationship between the light receiving element 3 and the optical axis of the light projecting lens 2a and the positional relationship between the light receiving element 3 and the light receiving lens 2b also affect the performance of the photoelectric sensor.
[0014]
In order to make the measurable distance range and the distance measurement resolution as designed, the positional relationship between the light projecting element 1, the light receiving element 3, and the lenses 2a and 2b is adjusted at the time of manufacture. Generally, the positions of the light projecting element 1 and the light receiving element 3 are determined by mounting them on a circuit board (not shown) fixed to the body 4 and positions for fixing the lenses 2a and 2b. Adjust each.
[0015]
In order to facilitate the adjustment of the positions where the lenses 2a and 2b are fixed, a technique described below has been proposed. As shown in FIG. 8, the lenses 2a and 2b have a shape in which a lens portion is formed at the center of the front and back surfaces of a rectangular plate, and the container body 4 is provided with a lens window 4d that exposes the lenses 2a and 2b. A pair of surfaces facing each other at the periphery of the window 2d are provided with holding grooves 4a into which one of the side edges of the lenses 2a and 2b is inserted. For example, when the projection lens 2a is attached to the container 4, both side edges of the projection lens 2a are inserted into the holding grooves 4a, respectively, and in the direction along the holding grooves 4a as shown by an arrow A in FIG. The position of the light projecting lens 2a is adjusted by sliding the light projecting lens 2a with respect to the body 4, and then the light projecting lens 2a is fixed to the body 4 using an adhesive. At this time, conventionally, an adhesive is injected between the holding groove 4a and the light projecting lens 2a along the holding groove 4a from the corner of the light projecting lens 2a as indicated by an arrow D1.
[0016]
[Problems to be solved by the invention]
However, the adhesive attached to the end portions of the lenses 2a and 2b in the direction along the holding groove 4a contracts during curing, so that the lenses 2a and 2b receive the tensile force in the direction along the holding groove 4a and are adhesive. Since the movement distance is not uniform and the movement distance is not uniform, the performance of the photoelectric sensor varies. If a part such as a screw is added, the position of the lens can be adjusted after the adhesive is cured. However, in this case, there is a problem that the cost for the added part is high.
[0017]
In the above description, the reflective photoelectric sensor for distance measurement has been described. For example, a reflector that reflects the light beam emitted from the light projecting lens to the light receiving lens is provided, and a detection target exists between the reflector and the body. Even if it is a photoelectric sensor that detects the presence of a detection target due to a decrease in the amount of light incident on the light receiving element, the light beam may not be irradiated in the designed direction due to the displacement of the light projecting lens and the light receiving lens. If a part is removed from the light receiving portion of the light receiving element and the light is collected, the light use efficiency is lowered and the sensitivity is lowered. Therefore, it is important to prevent the movement of the lens accompanying the curing of the adhesive.
[0018]
This invention is made | formed in view of the said reason, The objective is to provide the photoelectric sensor which can prevent the movement of a lens accompanying the hardening of the adhesive agent which fixes a lens to a container, and its manufacturing method. is there.
[0019]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a light projecting element that emits light, a rectangular first lens that forms a light beam from light emitted by the light projecting element, and an optical beam formed by the first lens. A rectangular second lens for condensing light from a light spot generated by irradiating the object to be detected; a light receiving element for receiving the light collected by the second lens; and each lens. A holding groove in which each one of both side edges of each lens is housed and the inner surface faces the front and back surfaces of each lens, and an adhesive for fixing the lens to the body. An injection port for injecting the agent into an intermediate portion of the side edge accommodated in the holding groove of each lens is provided.
[0020]
According to a second aspect of the present invention, in the first aspect of the present invention, the injection port is provided in a portion of the holding groove facing the front and back surfaces of the lens.
[0021]
According to a third aspect of the present invention, in the first aspect of the present invention, the injection port is provided at a portion intersecting the front and back surfaces of the lens in the holding groove.
[0022]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the two second lenses are provided across the first lens, and the holding grooves in which the side edges of the second lens are housed are respectively The holding groove in which the side edge of the first lens is accommodated extends along a direction in which the lenses are arranged, and extends in a direction intersecting the direction in which the lenses are arranged.
[0023]
The invention of claim 5 is the manufacturing method of the invention of claim 1, wherein after each side edge of the lens is inserted into the holding groove, the adhesive is stored in the holding groove of the lens from the injection port. The lens is fixed to the container by injecting so that an adhesive is attached to an intermediate portion of the side edge.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0025]
(Embodiment 1)
Since the basic configuration of the photoelectric sensor in this embodiment is the same as that of the reflection-type photoelectric sensor for distance measurement described in the conventional example, common portions will be described with reference to FIG. As shown in FIG. 7, the photoelectric sensor in the present embodiment includes a light projecting element 1 that emits light, and a light projecting lens 2a as a first lens that forms a light beam from the light emitted by the light projecting element 1. The light receiving lens 2b as a second lens for condensing the light from the light spot generated on the detection target T by the light beam irradiated from the light projecting lens 2a, and the light receiving for detecting the light collected by the light receiving lens 2b. An element 3 and a container 4 that holds a light projecting lens 2a and a light receiving lens 2b are provided.
[0026]
As shown in FIG. 1, the lenses 2 a and 2 b have a shape in which a lens portion is formed in the center portion of the front and back surfaces of a rectangular plate shape, and the lens body 4 exposes the lens portions of the lenses 2 a and 2 b. A window 4d is provided. And the holding groove | channel 4a in which each one of the both-sides edge of lens 2a, 2b is each inserted in the surface which mutually opposes in the periphery of the lens window 4d of the container 4 is provided. Further, in the container 4, an injection notch 4 b opened at the inner side of the lens window 4 d by exposing an intermediate portion of the side edge accommodated in the holding groove 4 a of the lenses 2 a and 2 b is formed on the side of the holding groove 4 a. It is provided as. That is, the injection notch 4b is provided in a portion of the holding groove 4a facing the front and back surfaces of the lenses 2a and 2b.
[0027]
In this photoelectric sensor, for example, when the light projecting lens 2a is fixed to the body 4, as shown by the arrow D2 after both side edges of the light projecting lens 2a are inserted into the holding grooves 4a and the position of the light projecting lens 2a is adjusted. Adhesive is injected from the injection notch 4b. At this time, the injection amount of the adhesive is adjusted so that the adhesive does not adhere to the corner of the light projecting lens 2a. The light receiving lens 2b is fixed to the container 4 in the same manner.
[0028]
According to the present embodiment, the adhesive for fixing the lenses 2a and 2b to the container 4 is injected into the middle portion of the side edge along the holding groove 4a of the lenses 2a and 2b through the injection notch 4b, and the lenses 2a and 2b. Therefore, the lenses 2a and 2b receive almost no tensile force in the direction along the holding groove 4a even if the adhesive shrinks during curing. That is, it is possible to prevent the movement of the lenses 2a and 2b accompanying the curing of the adhesive, and therefore it is unnecessary to add a part such as a screw for adjusting the position of the lenses 2a and 2b after the curing of the adhesive. Since the position 2b can be made as designed, variations in quality can be suppressed. Further, in the case of a photoelectric sensor in which the lenses 2a and 2b are fixed with the entire surface facing the outside of the vessel 4, the injection notch 4b can be provided at a portion of the holding groove 4a facing the outer surface of the lenses 2a and 2b. Easy to inject adhesive.
[0029]
In addition, the injection port should just open to the intermediate part of the side edge along holding groove | channel 4a of lens 2a, 2b. For example, as shown in FIG. 2, the adhesive is injected from the direction indicated by the arrow D3 using the injection hole 4f penetrating the bottom part of each holding groove 4a, that is, each part intersecting the front and back surfaces of the lenses 2a and 2b. For example, the positions of the lenses 2a and 2b can be made more difficult to shift by canceling out the pulling forces caused by the shrinkage of the adhesive on both sides of the lenses 2a and 2b. Furthermore, both the injection notch 4b and the injection hole 4f may be provided as shown in FIG. In this case, the adhesive may be injected from either the direction of the arrow D2 or the direction of the arrow D3. Any shape of the injection port described above has the effect of preventing the lens from moving when the adhesive is cured, so the shape of the injection port is appropriately selected according to the specifications of the device for injecting the adhesive. be able to.
[0030]
In the above embodiment, the reflective photoelectric sensor for distance measurement has been described. For example, even in the case of the photoelectric sensor for determining the presence / absence of the detection target described in the conventional example, the light projecting lens and the light receiving lens are similarly fixed. This prevents the movement of the lens with the curing of the adhesive, and reduces the light utilization efficiency due to the deviation of the direction of the light beam formed by the light projecting lens and the deviation of the position where the light receiving lens condenses. Sensitivity can be prevented from decreasing.
[0031]
(Embodiment 2)
The photoelectric sensor in the present embodiment is a reflection photoelectric sensor for distance measurement having the same light receiving element as that in the first embodiment, and the light emitted from one light projecting element 1 is a light projecting lens as shown in FIG. Two sets of a light receiving element 3 and a light receiving lens 2b for detecting a light spot formed on the detection target T by the light beam formed through 2a are provided. The light receiving lens 2b is disposed with the light emitting lens 2a interposed therebetween.
[0032]
Since two sets of the light receiving element 3 and the light receiving lens 2b are arranged with the optical axis of the light projecting lens 2a interposed therebetween, the position of the light spot formed on the detection target T is projected due to mechanical error or uneven reflection of light. Since an error caused by shifting the optical axis of the optical lens 2a and the optical axis of the light receiving lens 2b to one of the aligned directions is canceled by adding the outputs of the two light receiving elements 3, for example, the light receiving element 3 and the light receiving lens 2b Can be used for distance measurement with fewer errors compared to a photoelectric sensor for distance measurement that includes only one set.
[0033]
The container 4 used for this photoelectric sensor is formed in a rectangular parallelepiped shape as shown in FIG. Hereinafter, the direction will be described with reference to FIG. A lens insertion opening (not shown) through which the light emitting lens 2a is inserted in the direction of arrow B in FIG. 5 is opened at the center of the front surface of the container body 4, and the light receiving lenses 2b are provided on the left and right surfaces of the container body 4, respectively. A lens insertion opening 4c inserted in the direction of arrow C in FIG. 5 is opened. Both side portions of each lens insertion opening 4c function as holding grooves 4a. In addition, three rectangular lens windows 4d that are in communication with the respective lens insertion openings 4c and expose the lenses 2a and 2b are juxtaposed on the upper surface of the container. Further, as injection holes for injecting the adhesive into the middle part of the side edge of the light receiving lens 2b, injection holes 4f are opened on the front and rear surfaces of the body 4 on both sides of the left and right lens insertion openings 4c. In addition, a through hole 4 e for injecting an adhesive for fixing the light projecting lens 2 a to the container body 4 is opened at the center of the rear surface of the container body 4.
[0034]
According to the present embodiment, the adhesive for fixing the light receiving lens 2b to the container 4 is injected into the middle portion of the side edge of the light receiving lens 2b through the injection hole 4f and does not adhere to the left and right end portions of the light receiving lens 2b. Even if the adhesive shrinks upon curing, the light receiving lens 2b receives almost no pulling force in the direction along the lens insertion hole 4c. Therefore, the movement of the light receiving lens 2b accompanying the curing of the adhesive can be prevented.
[0035]
Here, as described in the description of the conventional example, the distance measurement resolution of the photoelectric sensor and the measurable distance range depend on the distance between the optical axis of the light receiving lens 2b and the optical axis of the light projecting lens 2a. On the other hand, in the present embodiment, two light receiving lenses 2b are provided across the light projecting lens 2a, and the lens insertion openings 4c in which the light receiving lenses 2b are housed extend along the direction in which the lenses are arranged. Therefore, the distance measurement resolution of the photoelectric sensor is adjusted by sliding each light receiving lens 2b along the lens insertion opening 4c to adjust the distance between the optical axis of the light projecting lens 2a and the optical axis of each light receiving lens 2b. And a measurable distance range can be set easily.
[0036]
Here, in the above embodiment, the injection port is only the injection hole 4f. For example, as shown in FIG. 6, each lens window 4d has an intermediate portion at each side portion along the direction in which the lenses 2a and 2b are inserted. If the injection notch 4b is further provided as an injection port, the adhesive is injected from the injection notch 4b provided on the side of the central lens window 4d when the projection lens 2a is fixed to the body 4. Since the projection lens 2a hardly moves when the adhesive is cured, the irradiation direction of the light beam can be set with higher accuracy than in the case where the projection lens 2a is fixed by the conventional method, and the sensitivity due to the decrease in light utilization efficiency Decline can be prevented.
[0037]
【The invention's effect】
In the first aspect of the present invention, the adhesive for fixing the lens to the body is injected into the middle portion of the side edge along the holding groove of the lens through the injection port, and does not adhere to the end portion in the direction along the holding groove of the lens. Therefore, even if the adhesive shrinks during curing, the lens position hardly shifts. Therefore, it is possible to prevent the movement of the lens accompanying the curing of the adhesive without adding a part such as a screw for adjusting the position of the lens after fixing the lens.
[0038]
According to a second aspect of the present invention, in the photoelectric sensor according to the first aspect of the present invention, since the injection port is provided at a portion of the holding groove facing the front and back surfaces of the lens, the lens is fixed with the entire surface facing the outside of the body. In this case, if an injection port is provided at a portion facing the outer surface of the lens, the injection of the adhesive is easy.
[0039]
According to a fourth aspect of the present invention, in the first aspect of the present invention, two second lenses are provided across the first lens, and the holding grooves in which the side edges of the second lens are housed are respectively Since the lenses extend along the direction in which the lenses are arranged, the second lens is slid along the lens insertion opening to adjust the distance between the optical axis of the first lens and the optical axis of each second lens. Accordingly, it is possible to easily adjust the distance range in which the detection target can be detected.
[0040]
The invention according to claim 5 is the manufacturing method according to claim 1, wherein each side edge of the lens is inserted into the holding groove and then the adhesive is stored in the lens holding groove from the injection port. By injecting the adhesive so that it adheres to the middle part of the lens, the adhesive does not adhere to the end of the lens along the holding groove. Can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main part of Embodiment 1 of the present invention.
FIG. 2 is a perspective view showing another embodiment of the same.
FIG. 3 is a perspective view showing still another embodiment of the above.
FIG. 4 is an explanatory view showing Embodiment 2 of the present invention.
FIG. 5 is a perspective view showing a main part of the above.
FIG. 6 is a perspective view showing another embodiment of the same.
FIG. 7 is an explanatory diagram illustrating an example of a photoelectric sensor.
FIG. 8 is a perspective view showing a main part of a conventional photoelectric sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light projecting element 2a Light projecting lens 2b Light receiving lens 3 Light receiving element 4 Body 4a Holding groove 4b Injection notch 4c Lens insertion port 4f Injection hole

Claims (5)

A light projecting element that emits light, a rectangular first lens that forms a light beam from light emitted by the light projecting element, and a light beam formed by the first lens are irradiated to a detection target. A rectangular second lens that collects light from the generated light spot, a light receiving element that receives the light collected by the second lens, and a container that holds each lens, The container has a holding groove in which each one of both side edges of each lens is housed and the inner surface faces the front and back surfaces of each lens, and an adhesive for fixing the lens to the container. A photoelectric sensor comprising an injection port for injecting into an intermediate portion of a side edge accommodated in the groove. The photoelectric sensor according to claim 1, wherein the injection port is provided in a portion of the holding groove facing the front and back surfaces of the lens. The photoelectric sensor according to claim 1, wherein the injection port is provided in a portion of the holding groove that intersects the front and back surfaces of the lens. Two second lenses are provided across the first lens, and holding grooves in which the side edges of the second lens are housed extend in the direction in which the lenses are arranged, respectively. 2. The photoelectric sensor according to claim 1, wherein the holding groove in which the side edge of the lens is accommodated extends in a direction intersecting the direction in which the lenses are arranged. 2. The method of manufacturing a photoelectric sensor according to claim 1, wherein after each side edge of the lens is inserted into the holding groove, an adhesive is supplied from the injection port to the side edge accommodated in the holding groove of the lens. A method for manufacturing a photoelectric sensor, wherein the lens is fixed to the container by injecting an adhesive so as to adhere to an intermediate portion.

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