JPH0736042B2 - Condensing lens for infrared detector - Google Patents
Condensing lens for infrared detectorInfo
- Publication number
- JPH0736042B2 JPH0736042B2 JP1326374A JP32637489A JPH0736042B2 JP H0736042 B2 JPH0736042 B2 JP H0736042B2 JP 1326374 A JP1326374 A JP 1326374A JP 32637489 A JP32637489 A JP 32637489A JP H0736042 B2 JPH0736042 B2 JP H0736042B2
- Authority
- JP
- Japan
- Prior art keywords
- lens
- plane
- angle
- hyperboloid
- condenser lens
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
本発明は赤外線式検知装置、殊に所定検知領域から発せ
られる赤外線を受光検出することによって人体の有無を
検知する受動型検知装置における集光レンズに関するも
のである。The present invention relates to an infrared detection device, and more particularly to a condenser lens in a passive detection device that detects the presence or absence of a human body by receiving and detecting infrared rays emitted from a predetermined detection area.
赤外線式検知装置では、一般に集光レンズの焦点面全面
に赤外線検知素子を配置するのではなく、集光レンズの
焦点位置に赤外線検素子を配設することから、赤外線検
知素子によって検出される赤外線は集光レンズの光軸と
平行に入射するものだけであり、光軸に対して角度をも
った斜め入射光は焦点位置に集光しないために、検知領
域を広げるには、異なる方向に光軸を備える複数の集光
レンズを組み合わせることになる。この時、各集光レン
ズとして、その焦点位置が一致するようにした場合に
は、レンズ全体が半球状となり、曲率が小さくなって製
作が困難となることから、通常、集光レンズにある方向
から斜め入射した光線が赤外線検知素子が配された位置
に焦点を結ぶようにすることで、レンズ全体の曲率を大
きくとることができるようにしている。一例を第９図に
示す。各集光レンズ１はフレネルレンズとして形成され
て、これらが組み合わされた多分割レンズとなってい
る。In an infrared type detection device, generally, the infrared detecting element is not arranged on the entire focal plane of the condenser lens, but the infrared detecting element is arranged at the focal position of the condenser lens. Is incident only parallel to the optical axis of the condenser lens, and obliquely incident light with an angle with respect to the optical axis does not focus at the focal position. A plurality of condenser lenses with axes will be combined. At this time, if the focal positions of the condenser lenses are made to coincide with each other, the entire lens becomes hemispherical, the curvature becomes small, and the manufacturing becomes difficult. By making the light beam obliquely incident on the lens focus on the position where the infrared detecting element is arranged, the curvature of the entire lens can be made large. An example is shown in FIG. Each condenser lens 1 is formed as a Fresnel lens, and is a multi-divided lens in which these are combined.
ところが、上述のように光軸に対して角度をもった斜め
入射光を利用する場合には、集光レンズがもつ収差によ
る「ぼけ」の問題点がつきまとう。これはフレネルレン
ズを用いた場合には、特に顕著となってしまうものであ
り、そして「ぼけ」によって検知ビームが所定の大きさ
以上に広がった場合、赤外線検出素子に入射する赤外線
量が低下するために、感度の低下を招くほか、耐環境性
及び耐外乱性の向上のために赤外線検知素子として２個
のエレメントによる差動出力を用いるツイン素子が使用
されている場合には、２個のエレメントにより生じる２
検知ビームに重なり合う部分で出力が打ち消し合ってし
まうために、感度の低下が更に顕著にあらわれることに
なる。 この点を嫌って集光用光学系として放物面ミラーを組み
合わせた多分割ミラーを用いたものがあるが、この場
合、「ぼけ」による影響は小さく、また反射率が通常90
％以上であるために効率良く集光することができるもの
の、光学系が大きくなってしまうという問題を有してい
る。 本発明はこのような点に鑑み為されたものであり、その
目的とするところは小型で集光効率に優れるとともに検
知領域を広くとることができる赤外線式検知装置用集光
レンズを提供するにある。However, as described above, when the oblique incident light having an angle with respect to the optical axis is used, there is a problem of “blur” due to the aberration of the condenser lens. This is particularly noticeable when a Fresnel lens is used, and when the detection beam spreads beyond a predetermined size due to "blurring", the amount of infrared light that enters the infrared detection element decreases. Therefore, in addition to lowering the sensitivity, if a twin element using a differential output by two elements is used as an infrared detection element for improving the environmental resistance and the disturbance resistance, two elements are used. 2 caused by the element
Since the outputs cancel each other at the portion where the detection beam overlaps, the decrease in sensitivity becomes more remarkable. Some people dislike this point and use a multi-division mirror that combines a parabolic mirror as the condensing optical system, but in this case, the effect of "blur" is small and the reflectance is usually 90%.
%, The light can be condensed efficiently, but there is a problem that the optical system becomes large. The present invention has been made in view of the above circumstances, and an object thereof is to provide a condensing lens for an infrared detection device, which is small in size, excellent in light collection efficiency, and capable of widening a detection area. is there.
しかして本発明は、第一面が平面、第二面が双曲面とさ
れたレンズが組み合わされた多分割レンズであり、各レ
ンズは第二面の双曲面の回転軸が第一面の平面に対して
斜交していることに特徴を有している。 ［作用］ 本発明によれば、フレネル面の各双曲面が共有する回転
軸と平面とがなす角度に応じて、焦点に無収差で集光す
る平行光と平面の法線方向との間に角度を持たせること
ができるために、必要とする方向にレンズを向けなくと
も、この方向からの赤外線の集光を効率よく行うことが
できる。 すなわち、第８図は第一面が平面10、第二面が双曲面20
として形成されているとともに、双曲面20の回転軸Ｃが
第一面の平面10の法線Ｈ方向と一致している通常の無収
差単レンズであり、光軸（この場合、双曲面の回転軸及
び平面の法線と一致）と平行な入射光は無収差で焦点Ｆ
に集光される。このような双曲面20を有する集光レンズ
１において、第７図に示すように、第一面の平面10の法
線Ｈと第二面の双曲面20の回転軸Ｃとが角度θをなすよ
うに第一面の平面10を傾けると、回転軸Ｃに対してある
角度δで入射して集光レンズ１内で双曲面の回転軸Ｃと
平行となる光線が焦点Ｆに無収差で集光することにな
る。尚、ここにおける角度δは、集光レンズ１の屈折率
をＮとする時、スネルの法則 sin（θ＋δ）＝Nsinθ を満足する角度である。 第１図は第一面の平面10を基準に考えた場合を示してお
り、第一面の平面10の法線Ｈに対して角度（θ＋δ）で
入射する平行光が無収差で焦点Ｆに集光する。 角度θを大きくとれば、焦点Ｆに無収差で集光する平行
光が第一面の平面10の法線Ｈとなる角度（θ＋δ）も大
きくなるものであり、そしてある検知領域を設定するに
あたり、第一面の平面10をその検知領域に向けなくと
も、検知領域から出る赤外線を集光レンズ１は無収差で
焦点Ｆ位置に置かれる赤外線検知素子に集光させること
ができるものであり、このような集光レンズ１を組み合
わせた多分割レンズとすることによって、複数方向から
の赤外線を集光することができるものとなる。 ［実施例］ 以下本発明を図示の実施例に基づいて詳述すると、第２
図は本発明の基本となる集光レンズ１の実施例を示して
おり、第一面の平面10の法線Ｈと、第二面の双曲面20の
回転軸Ｃがなす角度θが24.842°、屈折率が1.53、焦点
距離を14.5mm、最大肉厚0.8mmの集光レンズ１を示して
いる。この場合、焦点Ｆに無収差で集光する平行光が第
一面の平面10の法線Ｈとなす角度は40°となる。 このような集光レンズ１の双曲面20側をフレネル面とし
たものを第３図に示す。ここでは第二面の双曲面20を中
央部の第１輪体21とこれを取り囲む第２輪体22、第２輪
体22を更に取り囲む第３輪体23からなるものとするとと
もに、各輪体21,22,23における回転軸が同じで且つ回転
軸との交点における曲率半径が少しずつ異なっている各
双曲面を、夫々最大肉厚が0.8mm、最小肉厚が0.3mmとな
るようにして、第一面の平面10の法線Ｈ方向に重ね合わ
せている。このために、各輪体21,22,23は楕円形となっ
ている。 この種のレンズ素材として一般に用いられるポリエチレ
ンは、安価で加工性が良いものの、厚みが増えると吸収
のために透過率が低くなるので、集光レンズ１の厚みを
できるだけ薄くする必要があるが、フレネルレンズとす
ることで、レンズ面積を小さくすることなく、薄型化を
図ることができるわけである。 本発明は、上記の集光レンズ１を組み合わせた多分割レ
ンズとしたことに特徴を有するものであり、第４図に一
例を示す。ここでは第一面の平面10の法線Ｈと、焦点Ｆ
に無収差で集光する平行光線とのなす角度がα1である
４つのフレネルタイプの集光レンズ１を環状に並べると
ともに、これらの外周に上記角度がα2（α2＞α1）で
ある８つのフレネルタイプの集光レンズ１を環状に並べ
てフラット型多分割レンズを構成した場合を示してい
る。尚、各集光レンズ１の焦点Ｆが同一位置であり且つ
この位置に赤外線検知素子３を配していることはもちろ
んである。 そして赤外線検知素子３として、第５図に示すように、
検知エレメント30を４つ備えたものを用いた場合、上記
の多分割レンズと各検知エレメント30とによって形成さ
れる検知ビームＢは、ある距離を置いたところで、第６
図に示す配置となる。 尚、ここではフラット型となるように組み合わせた多分
割レンズで示したが、円筒形や他の形状に組み合わせた
ものであってもよいのはもちろんである。Therefore, the present invention is a multi-divided lens in which lenses each having a first surface as a flat surface and a second surface as a hyperboloid surface are combined, and each lens has a rotation axis of the hyperbolic surface of the second surface is a flat surface of the first surface. The feature is that it is diagonally crossed with respect to. [Operation] According to the present invention, according to the angle between the rotation axis shared by each hyperboloid of the Fresnel surface and the plane, there is no aberration between the parallel light and the normal direction of the plane. Since the angle can be provided, the infrared rays can be efficiently collected from this direction without directing the lens in the required direction. That is, in FIG. 8, the first surface is the plane 10 and the second surface is the hyperboloid 20.
Is a normal aplanatic single lens in which the rotation axis C of the hyperboloid 20 coincides with the normal H direction of the plane 10 of the first surface, and the optical axis (in this case, rotation of the hyperboloid Incident light parallel to the axis and the normal to the plane) is a focus F without aberration.
Is focused on. In the condenser lens 1 having such a hyperboloid 20, the normal H of the plane 10 of the first surface and the rotation axis C of the hyperboloid 20 of the second surface form an angle θ, as shown in FIG. When the plane 10 of the first surface is tilted as described above, a ray that is incident on the rotation axis C at an angle δ and is parallel to the rotation axis C of the hyperboloid inside the condenser lens 1 is focused on the focus F without aberration. It will shine. Note that the angle δ here is an angle that satisfies Snell's law sin (θ + δ) = N sin θ, where N is the refractive index of the condenser lens 1. FIG. 1 shows a case where the plane 10 of the first surface is considered as a reference, and collimated light incident at an angle (θ + δ) with respect to the normal line H of the plane 10 of the first surface is focused on the focus F without aberration. Collect light. The larger the angle θ, the larger the angle (θ + δ) at which the parallel light condensed at the focal point F without aberration becomes the normal line H of the plane 10 of the first surface, and when setting a certain detection area. Even if the plane 10 of the first surface is not directed to the detection area, the condenser lens 1 can focus the infrared rays emitted from the detection area to the infrared detection element placed at the focal point F position without aberration. By using a multi-divided lens in which such a condenser lens 1 is combined, infrared rays from a plurality of directions can be condensed. [Embodiment] The present invention will be described in detail below with reference to the illustrated embodiment.
The figure shows an embodiment of the condenser lens 1 which is the basis of the present invention, and the angle θ formed by the normal H of the plane 10 of the first surface and the rotation axis C of the hyperboloid 20 of the second surface is 24.842 °. Shows a condenser lens 1 having a refractive index of 1.53, a focal length of 14.5 mm and a maximum wall thickness of 0.8 mm. In this case, the angle formed by the parallel light, which is focused on the focal point F without aberration, with the normal line H of the plane 10 of the first surface is 40 °. FIG. 3 shows such a condenser lens 1 having a Fresnel surface on the hyperboloid 20 side. Here, it is assumed that the hyperboloid 20 of the second surface is composed of the first wheel body 21 in the central portion, the second wheel body 22 surrounding the first wheel body 21, and the third wheel body 23 further surrounding the second wheel body 22 and each wheel. The hyperboloids with the same axis of rotation in the bodies 21, 22, 23 and slightly different radii of curvature at the intersections with the axes of rotation should have a maximum wall thickness of 0.8 mm and a minimum wall thickness of 0.3 mm. And are overlapped in the direction of the normal line H of the plane 10 of the first surface. For this reason, each wheel 21, 22, 23 has an elliptical shape. Polyethylene, which is generally used as a lens material of this type, is inexpensive and has good workability, but since the transmittance decreases due to absorption when the thickness increases, it is necessary to make the thickness of the condenser lens 1 as thin as possible. By using a Fresnel lens, it is possible to reduce the thickness without reducing the lens area. The present invention is characterized in that it is a multi-divided lens in which the above-mentioned condenser lens 1 is combined, and an example is shown in FIG. Here, the normal H of the first plane 10 and the focus F
In addition to arranging four Fresnel type condensing lenses 1 which form an angle of α 1 with a parallel light beam which is condensed with no aberration, in the outer circumference of these, the above-mentioned angle is α 2 (α 2 > α 1 ). A case where a flat multi-segment lens is configured by arranging eight Fresnel type condenser lenses 1 in a ring shape is shown. Needless to say, the focus F of each condenser lens 1 is at the same position and the infrared detecting element 3 is arranged at this position. And as the infrared detecting element 3, as shown in FIG.
In the case of using the one provided with four detection elements 30, the detection beam B formed by the above-mentioned multi-divided lens and each detection element 30 is the sixth beam at a certain distance.
The arrangement is shown in the figure. It should be noted that, although the multi-divided lens combined so as to be a flat type is shown here, it goes without saying that it may be combined into a cylindrical shape or another shape.
以上のように本発明においては、組み合わされる各レン
ズが、双曲面の回転軸と平面とがなす角度に応じて、焦
点に無収差で集光する平行光と平面の法線方向との間に
角度を持たせることができるために、必要とする方向に
レンズを向けなくとも、この方向からの赤外線の集光を
効率よく行うことができるものであり、そしてこのよう
なレンズが組み合わされていることから、小型で集光効
率に優れるとともに検知領域を広くとることができるも
のである。As described above, in the present invention, each lens to be combined is provided between the parallel light that is focused on the focal point without aberration and the normal line direction of the plane according to the angle formed by the rotation axis of the hyperboloid and the plane. Being able to have an angle makes it possible to efficiently collect infrared rays from this direction without having to direct the lens in the required direction, and such lenses are combined. Therefore, it is small in size, excellent in light collection efficiency, and wide in detection area.
第１図及び第２図は本発明に係る集光レンズの基本形の
断面図、第３図（ａ）（ｂ）はフレネルタイプとした場
合の正面図と断面図、第４図（ａ）（ｂ）は本発明一実
施例の正面図と側面図、第５図は同上の赤外線検知素子
の正面図、第６図は同上の検知ビームの配置を示す説明
図、第７図は本発明を説明する断面図、第８図は通常の
双曲面レンズの断面図，第９図は従来例の斜視図であっ
て、１は集光レンズ、10は平面、20は双曲面、Ｈは平面
の法線、Ｃは双曲面の回転軸を示す。1 and 2 are sectional views of a basic form of a condenser lens according to the present invention, FIGS. 3 (a) and 3 (b) are front views and sectional views of a Fresnel type, and FIG. 4 (a) ( b) is a front view and a side view of an embodiment of the present invention, FIG. 5 is a front view of the infrared detecting element of the same, FIG. 6 is an explanatory view showing the arrangement of the detection beam of the same, and FIG. FIG. 8 is a sectional view for explaining, FIG. 8 is a sectional view of an ordinary hyperboloid lens, and FIG. 9 is a perspective view of a conventional example, where 1 is a condenser lens, 10 is a plane, 20 is a hyperboloid, and H is a plane. The normal line, C, indicates the axis of rotation of the hyperboloid.
Claims (1)
ンズが組み合わされた多分割レンズであり、各レンズは
第二面の双曲面の回転軸が第一面の平面に対して斜交し
ていることを特徴とする赤外線式検知装置用集光レン
ズ。1. A multi-divided lens in which lenses each having a first surface which is a flat surface and a second surface which is a hyperboloidal surface are combined, and each lens has a rotation axis of the hyperboloidal surface of the second surface on a flat surface of the first surface. A condensing lens for an infrared detection device, which is characterized by being diagonally intersected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1326374A JPH0736042B2 (en) | 1989-12-15 | 1989-12-15 | Condensing lens for infrared detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1326374A JPH0736042B2 (en) | 1989-12-15 | 1989-12-15 | Condensing lens for infrared detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03186803A JPH03186803A (en) | 1991-08-14 |
| JPH0736042B2 true JPH0736042B2 (en) | 1995-04-19 |
Family
ID=18187089
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1326374A Expired - Lifetime JPH0736042B2 (en) | 1989-12-15 | 1989-12-15 | Condensing lens for infrared detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0736042B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6020979B2 (en) | 2010-09-27 | 2016-11-02 | パナソニックＩｐマネジメント株式会社 | Fresnel lens |
| JP5919530B2 (en) | 2010-12-21 | 2016-05-18 | パナソニックＩｐマネジメント株式会社 | Optical detection device and apparatus using the same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57120902A (en) * | 1981-01-20 | 1982-07-28 | Masao Horiguchi | Solar light condensing member |
| JPH0638128B2 (en) * | 1985-10-07 | 1994-05-18 | 沖電気工業株式会社 | Optical coupling lens |
| JPH0617944B2 (en) * | 1985-10-28 | 1994-03-09 | 東京電子工業株式会社 | Television camera device for in-pipe inspection |
| JP2672492B2 (en) * | 1985-12-06 | 1997-11-05 | オムロン株式会社 | Photoelectric switch |
-
1989
- 1989-12-15 JP JP1326374A patent/JPH0736042B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03186803A (en) | 1991-08-14 |
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