JP3778085B2 - Reflective photoelectric sensor - Google Patents

Reflective photoelectric sensor Download PDF

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JP3778085B2
JP3778085B2 JP2001401535A JP2001401535A JP3778085B2 JP 3778085 B2 JP3778085 B2 JP 3778085B2 JP 2001401535 A JP2001401535 A JP 2001401535A JP 2001401535 A JP2001401535 A JP 2001401535A JP 3778085 B2 JP3778085 B2 JP 3778085B2
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light
light receiving
lens
light projecting
distance
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JP2003204077A (en
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充 小林
豊 阿部
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Panasonic Electric Works Co Ltd
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Matsushita Electric Works Ltd
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  • Length Measuring Devices By Optical Means (AREA)
  • Measurement Of Optical Distance (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、光を前方に射出して検出対象で反射した光を受光する反射型光電センサに関するものである。
【０００２】
【従来の技術】
図３に従来の反射型光電センサの構成図を示す。図３において、従来の反射型光電センサは、投光レンズ１と、この投光レンズ１を介して前方に光を射出する投光素子２と、受光レンズ３と、この受光レンズ３を介して前方から入来する光を受光する受光素子４と、これらの各部品を保持するセンサボディ（筐体）６PAとを備えている。
【０００３】
投光素子２および受光素子４は図示しない基板に実装され、これら投光素子２および受光素子４と投光レンズ１および受光レンズ３は、図３に示すようにセンサボディ６PAによって幾何学的に位置決めされる。
【０００４】
投光素子２は、電流を流すと発光するＬＥＤまたはレーザダイオードなどである。受光素子４は、受光面における入射光の位置の移動に応じて出力が変化するＰＳＤ（位置検出素子）または２分割ＰＤ（フォトダイオード）などである。
【０００５】
このような構成の反射型光電センサでは、投光素子２が赤外線などの光を射出すると、その光は、投光レンズ１で集光された後、前方に検出対象があればその検出対象で反射する。そして反射した光が受光レンズ３で集光された後に受光素子４で受光されたとすると、受光された光は電気的信号に変換されて反射型光電センサの出力信号として用いられる。
【０００６】
ところで、この種の反射型光電センサでは、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとの離間距離、より具体的には、投光レンズ１と受光レンズ３との離間距離ＢＬ１、並びに投光素子２と受光素子４との離間距離ＢＬＤ１が短いと、遠方の検出対象に対する検出分解能が悪くなるという問題がある。
【０００７】
図４に図３の構成では遠方の検出対象に対する検出分解能が悪くなる様子を示す。図４の検出対象ＤＯは図３のそれよりも遠い位置（Ｌ２＞Ｌ１）にあり、反射型光電センサ自体は図３のそれと同じものである。
【０００８】
図３に示すように、検出対象が図４のそれよりも近い位置にある場合、検出対象ＤＯが位置Ｐ３から位置Ｐ４にまたは位置Ｐ４から位置Ｐ３に移動したとき、その移動距離ΔＬに対応する受光素子４の受光面上での変位長はΔＬ１となる。
【０００９】
これに対し、図４に示すように、検出対象が図３のそれよりも遠い位置にある場合、検出対象ＤＯが位置Ｐ１から位置Ｐ２にまたは位置Ｐ２から位置Ｐ１に、図３の場合と同じ距離だけ移動したとき、その移動距離ΔＬに対応する受光素子４の受光面上での変位長はΔＬ２となり、このΔＬ２は明らかにΔＬ１よりも短くなる。つまり、検出対象が遠い位置にあるほど、同じ距離だけ移動したとしても、受光素子４上の変位が幾何学的に小さくなるので、検出素子４から出力される信号変化も小さくなり、センサ感度が悪くなるのである（例えばＬ１≪Ｌ２のとき、ΔＬ１≫ΔＬ２となり、ΔＬ２≒０となる）。この場合、ΔＬ２を受光素子４にて電気信号に変換することが難しくなる。
【００１０】
図５に図３，図４のものよりも遠方の検出対象に対する検出分解能を良くした反射型光電センサの構成図を示す。図５の反射型光電センサは、投光レンズ１と、投光素子２と、受光レンズ３と、受光素子４とを図３，４の反射型光電センサと同様に備えているほか、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとを、図３，４よりも離して保持するセンサボディ６PBを備えている。つまり、図５の反射型光電センサでは、投光レンズ１と受光レンズ３との離間距離ＢＬ２は図３，４のＢＬ１よりも長く、投光素子２と受光素子４との離間距離ＢＬＤ２は図３，４のＢＬＤ１よりも長くなっている。
【００１１】
このように離間距離ＢＬ２，ＢＬＤ２をより長く設定することにより、遠方の検出対象に対する検出分解能を良くすることができる。例えば、図５に示すように、図４と同様に検出対象ＤＯが位置Ｐ１から位置Ｐ２にまたは位置Ｐ２から位置Ｐ１に移動したとすると、その移動距離ΔＬに対応する受光素子４の受光面上での変位長はΔＬ３となり、このΔＬ３は明らかに図４のΔＬ２よりも長くなるので、検出素子４から出力される信号変化がより大きくなり、センサ感度が良くなる。
【００１２】
【発明が解決しようとする課題】
しかしながら、図５の反射型光電センサでは、前方に検出不能範囲（不感帯ともいう）が生じるという課題がある。
【００１３】
図６に図５の反射型光電センサにおける不感帯の説明図を示す。離間距離ＢＬ２，ＢＬＤ２を長めに設定すると、図６に示すように、前方に位置する検出対象が所定距離Ｄ外の遠距離範囲にある場合、その遠距離範囲にある検出対象で投光素子２から射出された光が受光素子４の受光範囲内に反射するが、前方に位置する検出対象が所定距離Ｄ内にある場合、その所定距離Ｄ内にある検出対象で投光素子２から射出された光が受光素子４の受光範囲外に反射する。図６の例では、所定距離Ｄの遠端に検出対象が位置するとき、その検出対象で反射した光が受光素子４の受光範囲の外縁に入光することになるので、所定距離Ｄ内に検出対象が位置すれば、その検出対象で反射した光はもはや受光素子４の受光範囲に入光することができなくなるから、所定距離Ｄ内が不感帯の範囲となる。そして、この不感帯の範囲は、離間距離ＢＬ２，ＢＬＤ２をより長く設定するほどより拡大する。
【００１４】
この課題を解決するべく、従来では、図３の構成の反射型光電センサと図５の構成の反射型光電センサとを併用する場合がある。しかし、異なる種類の反射型光電センサを２個使用する構成では、設置スペースの確保およびコスト高が新たな課題となる。
【００１５】
本発明は、上記事情に鑑みてなされたものであり、別の反射型光電センサと併用することなく、遠距離範囲にある検出対象に対する検出分解能を上げることができるとともに、不感帯の範囲を縮小することができる反射型光電センサを提供することを目的とする。
【００１６】
【課題を解決するための手段】
上記課題を解決するための請求項１記載の発明は、投光レンズと、この投光レンズを介して前方に光を射出する遠距離用投光素子と、受光レンズと、この受光レンズを介して前方から入来する光を受光する受光素子とを備え、前方に位置する検出対象が所定距離外の遠距離範囲にある場合、その遠距離範囲にある検出対象で前記遠距離用投光素子から射出された光が前記受光素子の受光範囲内に反射するとともに、前方に位置する検出対象が前記所定距離内にある場合、その所定距離内にある検出対象で前記遠距離用投光素子から射出された光が前記受光素子の受光範囲外に反射するように、前記投光レンズおよび遠距離用投光素子の組みと前記受光レンズおよび受光素子の組みとが離間して設けられる反射型光電センサであって、前記投光レンズおよび遠距離用投光素子の組みを一組、前記受光レンズおよび受光素子の組みを二組備え、それぞれ前方に光を射出する２個の近距離用投光素子をさらに備え、前記受光レンズおよび受光素子の各組みの間に前記投光レンズおよび遠距離用投光素子の組みを配置するとともに、前記所定距離内の近距離範囲にある検出対象で前記近距離用投光素子から射出された光が前記受光素子の受光範囲内に反射するように、前記投光レンズおよび遠距離用投光素子の組みと一方の組みの受光レンズおよび受光素子との間に一方の近距離用投光素子を配置し、前記投光レンズおよび遠距離用投光素子の組みと他方の組みの受光レンズおよび受光素子との間に他方の近距離用投光素子を配置してなることを特徴とする。
【００２０】
【発明の実施の形態】
本発明に係る実施形態について説明する前に、本発明に関連した参考例について説明する。
（参考例）
図１は本発明に関連した参考例の反射型光電センサの構成図であり、この図を用いて参考例について説明する。
【００２１】
参考例の反射型光電センサは、図１に示すように、投光レンズ１と、ＬＥＤまたはレーザダイオードなどによりなり投光レンズ１を介して前方に光を射出する遠距離用の投光素子２と、受光レンズ３と、ＰＳＤまたは２分割ＰＤなどによりなり受光レンズ３を介して前方から入来する光を受光する受光素子４と、レンズ一体型形状のＬＥＤまたはチップＬＥＤ（図では砲弾形状のＬＥＤ）によりなり前方に光を射出する近距離用の投光素子５と、これらの各部品を保持するセンサボディ６とを備えている。
【００２２】
このセンサボディ６は、前方に位置する検出対象が所定距離Ｄ外の遠距離範囲ＲLDにある場合、遠距離範囲ＲLDにある検出対象で投光素子２から射出された光が受光素子４の受光範囲内に反射するとともに、前方に位置する検出対象が所定距離Ｄ内にある場合、所定距離Ｄ内にある検出対象で投光素子２から射出された光が受光素子４の受光範囲外（図では受光範囲外上方）に反射するように、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとを離間して保持している。図１の例では、図５の従来の反射型光電センサと同様に、投光レンズ１と受光レンズ３との離間距離はＢＬ２に設定され、投光素子２と受光素子４との離間距離はＢＬＤ２に設定されている。
【００２３】
また、センサボディ６は、所定距離Ｄ内の近距離範囲ＲSD（図１の例では近端側を除くＤの一部）にある検出対象で投光素子５から射出された光が受光素子４の受光範囲内に反射するように、投光素子５を、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとの間に配置して保持している。
【００２４】
上記構成の反射型光電センサによれば、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとを任意に適当な距離だけ離間することにより、検出対象が遠距離範囲ＲLDで前後方向に移動した場合におけるその移動距離に対応する受光素子４の受光面上での変位長を、任意に設定することができる。図１の例では、図５の反射型光電センサと同様に、離間距離ＢＬ２，ＢＬＤ２に設定されているので、遠距離範囲ＲLDにおいて、検出対象ＤＯが位置Ｐ１から位置Ｐ２にまたは位置Ｐ２から位置Ｐ１に、図５の場合と同じ距離だけ移動したとすれば、その移動距離ΔＬに対応する受光素子４の受光面上での変位長は、図５と同様にΔＬ３となる。
【００２５】
この場合、図５の従来構成例では、図６で説明したように不感帯の範囲Ｄが生じることになるが、参考例では、投光素子５を設け、この投光素子５から射出された光が所定距離Ｄ内の近距離範囲ＲSDにある検出対象で受光素子４の受光範囲内に向けて反射するようにしたので、近距離範囲ＲSDの分だけ不感帯の範囲Ｄを縮小することができる。図１の例では、不感帯の範囲Ｄのほとんどが近距離範囲ＲSDでカバーされている。
【００２６】
以上、参考例によれば、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとを任意に適当な距離だけ離すことにより、遠距離範囲にある検出対象に対する検出分解能を上げることができる。
【００２７】
近距離範囲ＲSDにある検出対象で投光素子５から射出された光が受光素子４の受光範囲内に反射するように、投光素子５が、投光レンズ１および投光素子２の組みと受光レンズ３および受光素子４の組みとの間に配置されるので、不感帯の範囲Ｄを縮小することができる。この場合、従来の反射型光電センサと比較した場合、投光素子５を１個追加するだけであるから、安価であるほか、別の反射型光電センサと併用することなく、寸法を大きくすることなく不感帯の範囲Ｄを縮小することができる。
【００２８】
さらに、近距離用の投光素子５が砲弾形状のＬＥＤまたはチップＬＥＤによりなるので、近距離用の投光素子と投光レンズとを使用する構成と比べ、小型化およびコスト低減が可能となる。また、一般的な部品であるので、入手が容易である。
【００２９】
（実施形態）
図２は本発明に係る実施形態の反射型光電センサの構成図であり、この図を用いて実施形態について説明する。
【００３０】
実施形態の反射型光電センサは、図２に示すように、投光素子５を２個、投光レンズ１および遠距離用の投光素子２の組みを一組、そして受光レンズ３および受光素子４の組みを二組備えるとともに、これらの各組みの間に投光レンズ１および投光素子２の組みを配置し、この投光レンズ１および投光素子２の組みと一方の組みの受光レンズ３および受光素子４との間に一方の投光素子５を配置し、そして投光レンズ１および投光素子２の組みと他方の組みの受光レンズ３および受光素子４との間に他方の投光素子５を配置して保持するセンサボディ６Ａを備えている。
【００３１】
このような構成の反射型光電センサでも、一方の組みの受光レンズ３および受光素子４と、投光レンズ１および投光素子２の組みと、これらの間に設けられる投光素子５とが参考例の反射型光電センサと同様に機能し、他方の組みの受光レンズ３および受光素子４と、投光レンズ１および投光素子２の組みと、これらの間に設けられる投光素子５とが参考例の反射型光電センサと同様に機能するから、参考例と同様に、別の反射型光電センサと併用することなく、遠距離範囲にある検出対象に対する検出分解能を上げることができるとともに、不感帯の範囲を縮小することができる。
【００３２】
【発明の効果】
以上のことから明らかなように、請求項１記載の発明は、投光レンズと、この投光レンズを介して前方に光を射出する遠距離用投光素子と、受光レンズと、この受光レンズを介して前方から入来する光を受光する受光素子とを備え、前方に位置する検出対象が所定距離外の遠距離範囲にある場合、その遠距離範囲にある検出対象で前記遠距離用投光素子から射出された光が前記受光素子の受光範囲内に反射するとともに、前方に位置する検出対象が前記所定距離内にある場合、その所定距離内にある検出対象で前記遠距離用投光素子から射出された光が前記受光素子の受光範囲外に反射するように、前記投光レンズおよび遠距離用投光素子の組みと前記受光レンズおよび受光素子の組みとが離間して設けられる反射型光電センサであって、前記投光レンズおよび遠距離用投光素子の組みを一組、前記受光レンズおよび受光素子の組みを二組備え、それぞれ前方に光を射出する２個の近距離用投光素子をさらに備え、前記受光レンズおよび受光素子の各組みの間に前記投光レンズおよび遠距離用投光素子の組みを配置するとともに、前記所定距離内の近距離範囲にある検出対象で前記近距離用投光素子から射出された光が前記受光素子の受光範囲内に反射するように、前記投光レンズおよび遠距離用投光素子の組みと一方の組みの受光レンズおよび受光素子との間に一方の近距離用投光素子を配置し、前記投光レンズおよび遠距離用投光素子の組みと他方の組みの受光レンズおよび受光素子との間に他方の近距離用投光素子を配置してなるので、別の反射型光電センサと併用することなく、投光レンズおよび遠距離用投光素子の組みと受光レンズおよび受光素子の組みとを任意に適当な距離だけ離すことにより、遠距離範囲にある検出対象に対する検出分解能を上げることができ、近距離範囲にある検出対象で近距離用投光素子から射出された光が受光素子の受光範囲内に反射するように、近距離用投光素子を、投光レンズおよび遠距離用投光素子の組みと受光レンズおよび受光素子の組みとの間に配置することにより、不感帯の範囲を縮小することができる。
【図面の簡単な説明】
【図１】 本発明に関連した参考例の反射型光電センサの構成図である。
【図２】 本発明に係る実施形態の反射型光電センサの構成図である。
【図３】 従来の反射型光電センサの構成図である。
【図４】 図３の構成では遠方の検出対象に対する検出分解能が悪くなる様子を示す図である。
【図５】 図３，図４のものよりも遠方の検出対象に対する検出分解能を良くした反射型光電センサの構成図である。
【図６】 図５の反射型光電センサにおける不感帯の説明図である。
【符号の説明】
１ 投光レンズ
２ 投光素子
３ 受光レンズ
４ 受光素子
５ 投光素子
６，６Ａ センサボディ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective photoelectric sensor that emits light forward and receives light reflected by a detection target.
[0002]
[Prior art]
FIG. 3 shows a configuration diagram of a conventional reflective photoelectric sensor. In FIG. 3, the conventional reflective photoelectric sensor includes a light projecting lens 1, a light projecting element 2 that emits light forward through the light projecting lens 1, a light receiving lens 3, and a light receiving lens 3. It includes a light receiving element 4 that receives light coming from the front, and a sensor body (housing) 6PA that holds these components.
[0003]
The light projecting element 2 and the light receiving element 4 are mounted on a substrate (not shown). The light projecting element 2, the light receiving element 4, the light projecting lens 1, and the light receiving lens 3 are geometrically arranged by a sensor body 6PA as shown in FIG. Positioned.
[0004]
The light projecting element 2 is an LED or a laser diode that emits light when an electric current is passed. The light receiving element 4 is a PSD (position detecting element) or a two-part PD (photodiode) whose output changes in accordance with the movement of the position of incident light on the light receiving surface.
[0005]
In the reflection type photoelectric sensor having such a configuration, when the light projecting element 2 emits light such as infrared light, the light is collected by the light projecting lens 1 and then, if there is a detection target ahead, the detection target. reflect. If the reflected light is collected by the light receiving lens 3 and then received by the light receiving element 4, the received light is converted into an electrical signal and used as an output signal of the reflective photoelectric sensor.
[0006]
By the way, in this type of reflective photoelectric sensor, the distance between the combination of the light projecting lens 1 and the light projecting element 2 and the group of the light receiving lens 3 and the light receiving element 4, more specifically, the light projecting lens 1 and the light receiving lens. 3 and the separation distance BLD1 between the light projecting element 2 and the light receiving element 4 are short, there is a problem that the detection resolution with respect to a far detection target is deteriorated.
[0007]
FIG. 4 shows a state in which the detection resolution for a far detection target is deteriorated in the configuration of FIG. The detection target DO in FIG. 4 is at a position farther than that in FIG. 3 (L2> L1), and the reflective photoelectric sensor itself is the same as that in FIG.
[0008]
As shown in FIG. 3, when the detection target is at a position closer to that of FIG. 4, when the detection target DO moves from the position P3 to the position P4 or from the position P4 to the position P3, it corresponds to the movement distance ΔL. The displacement length on the light receiving surface of the light receiving element 4 is ΔL1.
[0009]
On the other hand, as shown in FIG. 4, when the detection target is at a position farther than that of FIG. 3, the detection target DO is from position P1 to position P2 or from position P2 to position P1, as in FIG. When moved by the distance, the displacement length on the light receiving surface of the light receiving element 4 corresponding to the moving distance ΔL is ΔL2, and this ΔL2 is clearly shorter than ΔL1. In other words, the farther the detection target is, the smaller the displacement on the light receiving element 4 is, even if it is moved by the same distance, so that the change in the signal output from the detection element 4 is reduced, and the sensor sensitivity is reduced. (For example, when L1 << L2, ΔL1 >> ΔL2 and ΔL2≈0). In this case, it becomes difficult to convert ΔL2 into an electrical signal by the light receiving element 4.
[0010]
FIG. 5 shows a configuration diagram of a reflective photoelectric sensor in which the detection resolution for a detection object farther than that of FIGS. 3 and 4 is improved. The reflective photoelectric sensor in FIG. 5 includes a light projecting lens 1, a light projecting element 2, a light receiving lens 3, and a light receiving element 4 in the same manner as the reflective photoelectric sensor in FIGS. A sensor body 6PB is provided that holds the set of the lens 1 and the light projecting element 2 and the set of the light receiving lens 3 and the light receiving element 4 apart from those in FIGS. That is, in the reflective photoelectric sensor of FIG. 5, the distance BL2 between the light projecting lens 1 and the light receiving lens 3 is longer than BL1 in FIGS. 3 and 4, and the distance BLD2 between the light projecting element 2 and the light receiving element 4 is shown in FIG. It is longer than 3 or 4 BLD1.
[0011]
By setting the separation distances BL2 and BLD2 longer as described above, it is possible to improve the detection resolution for a far detection target. For example, as shown in FIG. 5, if the detection object DO moves from the position P1 to the position P2 or from the position P2 to the position P1 as in FIG. 4, on the light receiving surface of the light receiving element 4 corresponding to the movement distance ΔL. Since the displacement length at ΔL3 becomes ΔL3, which is clearly longer than ΔL2 in FIG. 4, the change in the signal output from the detection element 4 becomes larger and the sensor sensitivity is improved.
[0012]
[Problems to be solved by the invention]
However, the reflective photoelectric sensor of FIG. 5 has a problem that an undetectable range (also referred to as a dead zone) is generated in the front.
[0013]
FIG. 6 is an explanatory diagram of the dead zone in the reflective photoelectric sensor of FIG. When the separation distances BL2 and BLD2 are set longer, as shown in FIG. 6, when the detection target located in the front is in a long distance range outside the predetermined distance D, the light projecting element 2 is detected by the detection target in the long distance range. Is reflected within the light receiving range of the light receiving element 4, but when the detection target located in the front is within the predetermined distance D, the light is emitted from the light projecting element 2 with the detection target within the predetermined distance D. The reflected light is reflected outside the light receiving range of the light receiving element 4. In the example of FIG. 6, when the detection target is located at the far end of the predetermined distance D, the light reflected by the detection target enters the outer edge of the light receiving range of the light receiving element 4. If the detection target is located, the light reflected by the detection target can no longer enter the light receiving range of the light receiving element 4, and therefore the dead zone is within the predetermined distance D. The range of the dead zone is further expanded as the separation distances BL2 and BLD2 are set longer.
[0014]
In order to solve this problem, conventionally, the reflective photoelectric sensor having the configuration of FIG. 3 and the reflective photoelectric sensor having the configuration of FIG. 5 may be used in combination. However, in a configuration in which two different types of reflective photoelectric sensors are used, securing installation space and high costs are new issues.
[0015]
The present invention has been made in view of the above circumstances, and can increase the detection resolution for a detection target in a long-distance range and reduce the range of the dead zone without using it in combination with another reflective photoelectric sensor. It is an object of the present invention to provide a reflective photoelectric sensor that can be used.
[0016]
[Means for Solving the Problems]
The invention according to claim 1 for solving the above-described problems is a light projecting lens, a long distance light projecting element that emits light forward through the light projecting lens, a light receiving lens, and a light receiving lens. A light receiving element that receives light coming from the front, and when the detection target located in the front is in a long distance range outside a predetermined distance, the long distance light projecting element is a detection target in the long distance range. The light emitted from the light receiving element is reflected in the light receiving range of the light receiving element, and when the detection target located in the front is within the predetermined distance, the detection target within the predetermined distance from the long distance light projecting element. A reflection type photoelectric device in which the set of the light projecting lens and the long distance light projecting element and the set of the light receiving lens and the light receiving element are spaced apart so that the emitted light is reflected outside the light receiving range of the light receiving element. a sensor, said light projecting A pair of light emitting elements for light and long distance, two pairs of light receiving lenses and light receiving elements, each of which further comprises two light projecting elements for short distance that emit light forward, A pair of the light projecting lens and the long distance light projecting element is disposed between each pair of light receiving elements, and the light is emitted from the short distance light projecting element at a detection target in a short distance range within the predetermined distance. So that the reflected light is reflected within the light receiving range of the light receiving element, and one short distance light projecting between the pair of the light projecting lens and the long distance light projecting element and the one light receiving lens and the light receiving element. An element is disposed, and the other short distance light projecting element is disposed between the combination of the light projecting lens and the long distance light projecting element and the other light receiving lens and the light receiving element. .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Before describing embodiments according to the present invention, reference examples related to the present invention will be described.
( Reference example )
FIG. 1 is a configuration diagram of a reflective photoelectric sensor of a reference example related to the present invention, and the reference example will be described with reference to this figure.
[0021]
As shown in FIG. 1, the reflective photoelectric sensor of the reference example includes a light projecting lens 1 and a long distance light projecting element 2 that emits light forward through the light projecting lens 1. A light receiving lens 3, a light receiving element 4 that receives light coming from the front through the light receiving lens 3 and includes a lens-integrated LED or chip LED (in the figure, a bullet-shaped LED). A short-distance projecting element 5 that emits light forward and a sensor body 6 that holds these components.
[0022]
In the sensor body 6, when the detection target located in the front is in the long distance range R LD outside the predetermined distance D, the light emitted from the light projecting element 2 by the detection target in the long distance range R LD is received by the light receiving element 4. When the detection target located in the front is within the predetermined distance D, the light emitted from the light projecting element 2 at the detection target within the predetermined distance D is outside the light reception range of the light receiving element 4. The set of the light projecting lens 1 and the light projecting element 2 and the set of the light receiving lens 3 and the light receiving element 4 are held apart so as to be reflected (upwardly outside the light receiving range in the figure). In the example of FIG. 1, the distance between the light projecting lens 1 and the light receiving lens 3 is set to BL2 and the distance between the light projecting element 2 and the light receiving element 4 is similar to the conventional reflective photoelectric sensor in FIG. It is set to BLD2.
[0023]
Further, the sensor body 6 receives light emitted from the light projecting element 5 as a detection target in the short distance range R SD (a part of D excluding the near end side in the example of FIG. 1) within the predetermined distance D. The light projecting element 5 is disposed and held between the combination of the light projecting lens 1 and the light projecting element 2 and the group of the light receiving lens 3 and the light receiving element 4 so as to reflect within the light receiving range 4.
[0024]
According to the reflection type photoelectric sensor having the above-described configuration, the set of the light projecting lens 1 and the light projecting element 2 and the set of the light receiving lens 3 and the light receiving element 4 are separated from each other by an appropriate distance so that the object to be detected is a long distance. The displacement length on the light receiving surface of the light receiving element 4 corresponding to the moving distance when moving in the front-rear direction within the range R LD can be arbitrarily set. In the example of FIG. 1, similar to the reflective photoelectric sensor of FIG. 5, which are set to the distance BL2, BLD2, in the far range R LD, from the detection target DO is or located at a position P2 from the position P1 P2 If it is moved to the position P1 by the same distance as in FIG. 5, the displacement length on the light receiving surface of the light receiving element 4 corresponding to the moving distance ΔL is ΔL3 as in FIG.
[0025]
In this case, in the conventional configuration example of FIG. 5, the dead zone range D occurs as described with reference to FIG. 6, but in the reference example , the light projecting element 5 is provided and light emitted from the light projecting element 5 is provided. Is reflected toward the light receiving range of the light receiving element 4 by the detection target in the short distance range R SD within the predetermined distance D, the dead band range D can be reduced by the short distance range R SD. it can. In the example of FIG. 1, most of the dead zone range D is covered by the short distance range R SD .
[0026]
As described above, according to the reference example , the combination of the light projecting lens 1 and the light projecting element 2 and the pair of the light receiving lens 3 and the light receiving element 4 are arbitrarily separated from each other by an appropriate distance, thereby detecting a detection target in a long distance range. The resolution can be increased.
[0027]
The light projecting element 5 is a combination of the light projecting lens 1 and the light projecting element 2 so that the light emitted from the light projecting element 5 on the detection target in the short distance range RSD is reflected within the light receiving range of the light receiving element 4. And the light receiving lens 3 and the set of the light receiving element 4, the dead zone range D can be reduced. In this case, when compared with a conventional reflective photoelectric sensor, only one light projecting element 5 is added, so that it is inexpensive and the size is increased without using it in combination with another reflective photoelectric sensor. The dead zone range D can be reduced.
[0028]
Furthermore, since the short-distance light projecting element 5 is formed of a bullet-shaped LED or chip LED, it is possible to reduce the size and cost as compared with a configuration using a short-distance light projecting element and a light projecting lens. . Moreover, since it is a general part, it is easy to obtain.
[0029]
(Implementation form)
Figure 2 is a block diagram of a reflection type photoelectric sensor implementation form of the present invention, the implementation mode will be described with reference to FIG.
[0030]
Reflective photoelectric sensor implementation embodiment, as shown in FIG. 2, two light emitting element 5, the light projecting lens 1 and a set of set of light emitting element 2 for long range, and the light receiving lens 3 and the light-receiving Two sets of the elements 4 are provided, and a set of the light projecting lens 1 and the light projecting element 2 is arranged between these sets, and the set of the light projecting lens 1 and the light projecting element 2 and the light reception of one set are received. One light projecting element 5 is disposed between the lens 3 and the light receiving element 4, and the other between the pair of the light projecting lens 1 and the light projecting element 2 and the other light receiving lens 3 and the light receiving element 4. A sensor body 6A for arranging and holding the light projecting element 5 is provided.
[0031]
Even in the reflection type photoelectric sensor having such a configuration, one set of the light receiving lens 3 and the light receiving element 4, the combination of the light projecting lens 1 and the light projecting element 2, and the light projecting element 5 provided therebetween are reference. It functions in the same manner as the reflective photoelectric sensor of the example , and the other set of the light receiving lens 3 and the light receiving element 4, the set of the light projecting lens 1 and the light projecting element 2, and the light projecting element 5 provided therebetween. Since it functions in the same way as the reflective photoelectric sensor of the reference example , it can increase the detection resolution for a detection target in a long range without using it with another reflective photoelectric sensor as in the reference example. Can be reduced.
[0032]
【The invention's effect】
As is apparent from the above, the invention described in claim 1 includes a light projecting lens, a long distance light projecting element that emits light forward through the light projecting lens, a light receiving lens, and the light receiving lens. A light-receiving element that receives light coming from the front via, and when the detection target located in the front is in a long distance range outside a predetermined distance, the long distance projection is detected by the detection target in the long distance range. When the light emitted from the optical element is reflected within the light receiving range of the light receiving element and the detection target located in the front is within the predetermined distance, the long distance light projection is performed with the detection target within the predetermined distance. A reflection in which the set of the light projecting lens and the long distance light projecting element and the set of the light receiving lens and the light receiving element are provided so as to reflect light emitted from the element outside the light receiving range of the light receiving element. a type photoelectric sensor, before One set of a light projecting lens and a long distance light projecting element, two sets of the light receiving lens and light receiving element, each further comprising two short distance light projecting elements that emit light forward, A pair of the light projecting lens and a long distance light projecting element is disposed between each pair of the light receiving lens and the light receiving element, and the detection target in the short distance range within the predetermined distance from the short distance light projecting element. For the short distance between the set of the light projecting lens and the long distance light projecting element and the one set of the light receiving lens and the light receiving element so that the emitted light is reflected within the light receiving range of the light receiving element. Since a light projecting element is arranged, and the other short distance light projecting element is disposed between the light projecting lens and the long distance light projecting element and the other light receiving lens and light receiving element , Use with other reflective photoelectric sensors In addition, by separating the combination of the light projecting lens and the light projecting element for a long distance from the light receiving lens and the light receiving element by any suitable distance, the detection resolution for the detection target in the long distance range can be increased. The light projecting element for short distance, the light projecting element for long distance, and the light projecting element for long distance so that the light emitted from the light projecting element for short distance is reflected in the light receiving range of the light receiving element. The range of the dead zone can be reduced by disposing between the pair of the light receiving lens and the light receiving element.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a reflective photoelectric sensor of a reference example related to the present invention.
2 is a block diagram of a reflection type photoelectric sensor implementation according to the present invention.
FIG. 3 is a configuration diagram of a conventional reflective photoelectric sensor.
4 is a diagram illustrating a state in which the detection resolution with respect to a distant detection target deteriorates in the configuration of FIG. 3;
FIG. 5 is a configuration diagram of a reflective photoelectric sensor with improved detection resolution for a detection target farther away than that of FIGS. 3 and 4;
6 is an explanatory diagram of a dead zone in the reflective photoelectric sensor of FIG. 5. FIG.
[Explanation of symbols]
1 Light Emitting Lens 2 Light Emitting Element 3 Light Receiving Lens 4 Light Receiving Element 5 Light Emitting Element 6, 6A Sensor Body

Claims (1)

投光レンズと、この投光レンズを介して前方に光を射出する遠距離用投光素子と、受光レンズと、この受光レンズを介して前方から入来する光を受光する受光素子とを備え、
前方に位置する検出対象が所定距離外の遠距離範囲にある場合、その遠距離範囲にある検出対象で前記遠距離用投光素子から射出された光が前記受光素子の受光範囲内に反射するとともに、前方に位置する検出対象が前記所定距離内にある場合、その所定距離内にある検出対象で前記遠距離用投光素子から射出された光が前記受光素子の受光範囲外に反射するように、前記投光レンズおよび遠距離用投光素子の組みと前記受光レンズおよび受光素子の組みとが離間して設けられる反射型光電センサであって、
前記投光レンズおよび遠距離用投光素子の組みを一組、
前記受光レンズおよび受光素子の組みを二組備え、
それぞれ前方に光を射出する２個の近距離用投光素子をさらに備え、
前記受光レンズおよび受光素子の各組みの間に前記投光レンズおよび遠距離用投光素子の組みを配置するとともに、
前記所定距離内の近距離範囲にある検出対象で前記近距離用投光素子から射出された光が前記受光素子の受光範囲内に反射するように、前記投光レンズおよび遠距離用投光素子の組みと一方の組みの受光レンズおよび受光素子との間に一方の近距離用投光素子を配置し、前記投光レンズおよび遠距離用投光素子の組みと他方の組みの受光レンズおよび受光素子との間に他方の近距離用投光素子を配置してなることを特徴とする反射型光電センサ。 A light projecting lens; a long distance light projecting element that emits light forward through the light projecting lens; a light receiving lens; and a light receiving element that receives light coming from the front through the light receiving lens. ,
When the detection target located in the front is in a long distance range outside a predetermined distance, the light emitted from the long distance light projecting element on the detection target in the long distance range is reflected in the light reception range of the light receiving element. At the same time, when the detection target located in the front is within the predetermined distance, the light emitted from the long-distance light projecting element is reflected outside the light receiving range of the light receiving element. A reflection type photoelectric sensor in which the set of the light projecting lens and the long distance light projecting element and the set of the light receiving lens and the light receiving element are provided apart from each other,
One set of the light projecting lens and the long distance light projecting element,
Comprising two sets of the light receiving lens and light receiving element;
Further comprising two short-distance light projecting elements that each emit light forward,
While disposing a set of the light projecting lens and a long distance light projecting element between each set of the light receiving lens and the light receiving element,
The light projecting lens and the long distance light projecting element so that the light emitted from the short distance light projecting element on the detection target within the short distance range within the predetermined distance is reflected within the light receiving range of the light receiving element. One short distance light projecting element is disposed between the light receiving lens and the light receiving element of one set, and the light projecting lens and long distance light projecting element and the other light receiving lens and light receiving element are disposed. A reflection type photoelectric sensor , wherein the other short-distance light projecting element is disposed between the elements .
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