JP4010455B2

JP4010455B2 - Scattered smoke detector

Info

Publication number: JP4010455B2
Application number: JP2003119394A
Authority: JP
Inventors: 哲也長島; 学土肥
Original assignee: Hochiki Corp
Current assignee: Hochiki Corp
Priority date: 2003-04-24
Filing date: 2003-04-24
Publication date: 2007-11-21
Anticipated expiration: 2023-04-24
Also published as: JP2004325211A

Description

【０００１】
【発明の属する技術分野】
本発明は、受光素子に対する散乱特性が異なるように光を発する２個の発光素子を備えた散乱光式煙感知器に関する。
【０００２】
【従来技術】
従来の煙感知器は、火災による煙に限らず、調理の煙やバスルームの湯気等により非火災報を発してしまうことがある。
【０００３】
このような火災以外の原因による非火災報を防止するため、２種類の波長の光を検煙空間に照射し、煙による散乱光について異なる波長の光強度の比を求めて煙の種類を判定する方法や、散乱面に対し垂直な偏光面をもつ光と水平な偏光面を持つ光を照射し、煙による散乱光の各偏光成分の光強度の比を求めて煙の種類を判定する方法が知られている。
【０００４】
【特許文献１】
特開平６−１０９６３１号公報
【特許文献２】
特開平７−１２７２４号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、このような従来の異なる波長の光や偏光面の異なる光を用いて煙の種類を判別する方法にあっては、火災による煙と火災以外の原因による調理の煙やバスルームの湯気等を識別する確度が必ずしも十分とはいえず、さらに高度な煙識別が望まれている。
【０００６】
本発明は、煙識別の確度を高めて非火災報防止を確実なものとする散乱光式煙感知器を提供することを目的とする。
【０００７】
【課題を解決するための手段】
この目的を達成すため本発明は次のように構成する。
【０００８】
本発明は、検煙空間に向け、第１波長を発する第１発光素子と、第１波長とは異なる第２波長を発する第２発光素子と、第１発光素子と第２発光素子から発せられる光を直接受光しない位置に設けられた受光素子とを備えた散乱光式煙感知器に於いて、第１発光素子と受光素子の光軸の交差で構成される第１散乱角θ１に対し、第２発光素子と受光素子の光軸の交差で構成される第２散乱角θ２を大きく構成し、第１発光素子から発せられる第１波長λ１に対し、第２発光素子から発せられる第２波長λ２を短くしたことを特徴とする。
【０００９】
このように本発明は２つの発光素子につき、受光素子に対する散乱角を異ならせることで、煙の種類による散乱特性の相違を作り出し、同時に、２つの発光素子から発する光の波長を異ならせることで、波長に起因した散乱特性の相違を作り出し、この散乱角の相違と波長の相違の相乗効果によって煙の種類による散乱光の光強度に顕著な差をもたせることで、煙の識別確度を高めて調理の湯気などによる非火災報を防止する。
【００１０】
また本発明の別の形態にあっては、検煙空間に向け、所定波長の光を発する第１発光素子と、第２発光素子と、第１発光素子と第２発光素子から発せられる光を直接受光しない位置に設けられた受光素子とを備えた散乱光式煙感知器に於いて、第１発光素子は、自己の光軸と交差する受光素子の光軸とを通る第１散乱面に垂直な偏光面（φ＝９０°）をもつ光を発し、第２発光素子は、自己の光軸と交差する受光素子の光軸とを通る第２散乱面に水平な偏光面（φ＝０°）をもつ光を発し、第１発光素子と受光素子の光軸の交差で構成される第１散乱角θ１に対し、第２発光素子と受光素子での光軸の交差で構成される第２散乱角θを大きく構成したことを特徴とする。
【００１１】
この場合にも、２つの発光素子から発する光の各散乱面に対する偏光面を異ならせることで、光の偏光方向に起因した散乱特性の相違を作り出し、同時に２つの発光素子につき、受光素子に対する散乱角を異ならせることで、煙の種類による散乱特性の相違を作り出し、この偏光方向の相違と散乱角の相違の相乗効果によって煙の種類による散乱光の光強度に顕著な差をもたせることで、煙の識別確度を高めて調理の湯気などによる非火災報を防止する。
【００１２】
本発明の散乱光式煙感知器は、第１発光素子と受光素子で構成する光軸と、第２発光素子と受光素子で構成する光軸が、同一平面上に存在するよう、第1発光素子と第２発光素子及び受光素子を平面角配置としたことを特徴とする。
【００１３】
また散乱光式煙感知器は、第１発光素子と受光素子で構成する光軸と、第２発光素子と受光素子で構成する光軸が、同一平面上に存在しないよう、第1発光素子と第２発光素子及び受光素子を立体角配置としたことを特徴とする。
【００１４】
ここで、第１発光素子による煙の散乱光量と、第２発光素子による煙の散乱光量とを比較することにより、例えば両者の比を取って閾値と比較することで煙の種類を識別し、煙の種類に応じた判断基準により火災判断を行う。
【００１５】
この判断基準は、煙の種類に応じて閾値を変更する。また判断基準は、煙の種類に応じて火災を判断するカウント回数を設定する。
【００１６】
また本発明の散乱光式煙感知器は、通常の監視状態では、第１発光素子のみを駆動し、受光素子から所定の受光出力が得られた際、第２発光素子を駆動することを特徴とする。このため発光素子を２つ設けていても、通常は１つしか駆動されていないため、消費電流の増加を防止する。
【００１７】
ここで散乱角と波長を異ならせた本発明の散乱光式煙感知器は、例えば第１発光素子と受光素子の光軸の交差で構成される第１散乱角を２０°〜５０°の範囲に定め、第２発光素子と受光素子の光軸の交差で構成される第２散乱角を１００°〜１５０°の範囲に定め、また第１発光素子から発せられる第１波長の中心波長を８００ｎｍ以上に定め、第２発光素子から発せられる第２波長の中心波長を５００ｎｍ以下に定めたことを特徴とする。
【００１８】
また偏光方向と散乱角を異ならせた本発明の散乱光式煙感知器は、例えば第１発光素子と受光素子の光軸の交差で構成される第１散乱角θ１を８０°以下に定め、第２発光素子と受光素子の光軸の交差で構成される第２散乱角θ２を１００°以上に定めたことを特徴とする。
【００１９】
【発明の実施の形態】
図１は本発明による散乱光式煙感知器の回路ブロックである。図１において、本発明の散乱光式煙感知器１は、発報回路２、ＣＰＵを用いた信号処理部３、記憶部４、第１発光制御部５、第２発光制御部６、増幅回路７及び検煙部８で構成される。
【００２０】
検煙部８は外部からの光を遮断するために煙の流入が可能な検煙空間を内部に備える。この検煙空間に第１発光素子９、第２発光素子１０及び受光素子１１を設けている。
【００２１】
図２は図１の散乱光式煙感知器１の検煙部８の構造の実施形態を示した説明図である。図２において、検煙部８内には第１発光素子９、第２発光素子１０及び受光素子１１が配置されており、この実施例はそれぞれの光軸９ａ、１０ａ、１１ａが同一平面内に配置された平面角配置の構造としている。
【００２２】
第１発光素子９は、その光軸９ａと受光素子１１の光軸１１ａの交点Ｐに対する第１散乱角θ１を、この実施形態にあってはθ＝３０°に設定している。また第１発光素子９としては近赤外線ＬＥＤを使用しており、第１発光素子９から発せられる光は、中心波長λ１として、この実施形態にあってはλ１＝９００ｎｍ（＝０．９μｍ）を設定している。
【００２３】
このような第１発光素子９に対し、本発明にあっては更に第２発光素子１０を設けている。第２発光素子は、その光軸１０ａと受光素子１１ａとの交点Ｐに対する第２散乱角θ２を、第１発光素子９と受光素子１１の第１散乱角θ１より大きく構成している。この実施形態にあっては第２散乱角θ２はθ２＝１２０°としている。
【００２４】
また第２発光素子１０は可視光ＬＥＤを使用しており、第２発光素子１０から発生される光の中心波長を第２波長λ２とすると、この波長λ２は第１発光素子９の波長λ１より短く設定されており、この実施形態にあってはλ２＝５００ｎｍ（＝０．５μｍ）としている。
【００２５】
図３は図２の検煙部構造において綿灯芯の燃焼煙（白色煙）を対象とした第１発光素子９及び第２発光素子１０からの光による散乱効率Ｉを散乱角θについて示したグラフ図である。
【００２６】
図３において、横軸は散乱角θとしてθ＝０〜１８０°をとり、縦軸に指数関数により散乱効率Ｉをとっている。この図３の綿灯心の煙を対象とした散乱角に対する散乱効率の特性にあっては、図２の第１発光素子９からの第１波長λ１＝９００ｎｍの光による受光素子１１側で受光される散乱効率は特性曲線１３のようになる。一方、図２の第２波長λ２＝５００ｎｍの光を発する第２発光素子１０からの光による煙の散乱効率は特性曲線１４のようになる。
【００２７】
この図３の特性曲線１３、１４について、まず発光素子から発する光の波長について見ると、第１発光素子９の長い波長λ１＝９００ｎｍの特性曲線１３の方が散乱効率が低く、第２波長λ２＝５００ｎｍと波長の短い第２発光素子１０からの光による特性曲線１４の散乱効率の方が高い事がわかる。
【００２８】
一方、第１発光素子９及び第２発光素子１０の各散乱効率の特性曲線１３、１４における散乱角θの変化に対しては、両方とも散乱角θが小さいほど散乱効率が高く、散乱角の増加に従って散乱効率が低下し、１２０°地点で最低値を示すが、その後散乱角の増加に伴って散乱効率が上昇する特性となっている。
【００２９】
本発明にあっては第１発光素子９の散乱角をθ＝３０°に設定しており、従って特性曲線１３におけるＰ１点の散乱効率Ａ１が得られている。一方、第２発光素子１０については第２散乱角θ２をθ＝１２０°に設定しており、このため特性曲線１４におけるＰ２点の散乱効率Ａ２が得られている。
【００３０】
このような第１発光素子９及び第２発光素子１０からの散乱角及び波長の異なる光による散乱効率より得られる受光素子１１の受光量は
（受光量）＝（発光量）×（受光効率）
で与えられるため、図３の散乱効率Iに比例した受光信号量を得ることができる。
【００３１】
本発明にあっては、第１発光素子９と第２発光素子１０からの各光による同じ煙についての散乱光による受光素子１１で得られる受光量の比率Ｒを求める。この受光量の比率Ｒは、散乱効率に比例することから、散乱効率Ａ１、Ａ２につき、
Ｒ＝Ａ１／Ａ２
として求まる。そして、この比率Ｒを予め定めて閾値と比較することで、煙の種類を判断する。
【００３２】
図４は図２の検煙部構造について燃焼物としてケロシンの燃焼煙（黒色煙）に対する第１発光素子９と第２発光素子１０からの光による散乱効率Ｉを散乱角θについて示したグラフ図である。
【００３３】
図４において、第１波長λ１＝９００ｎｍの光を発する第１発光素子９からの光による散乱効率Ｉは特性曲線１５のようになり、一方、第２波長λ２＝５００ｎｍとなる第２発光素子１０から発せられる光による散乱効率Ｉは特性曲線１６のようになる。
【００３４】
この図４のグラフについて、まず波長に着目すると図３の綿灯芯の煙と同様、第１波長λ１＝９００ｎｍの第１発光素子９から発した光による散乱効率の特性曲線１５が低く、これに対し第２波長λ２＝５００ｎｍと波長の短い第２発光素子１０から発した光による散乱効率の特性曲線１６の方が大きい値を示している。
【００３５】
また散乱角θに対する散乱効率の変化は、図３の場合と同様、特性曲線１５、１６共に散乱角が小さいほど散乱効率が高く、散乱角θが１２０°付近で最低値を示した後、散乱角の増加に対し、散乱効率が上昇する特性となっている。
【００３６】
このようなケロシンの燃焼煙について、第１発光素子９の第１散乱角θ１＝３０°を特性曲線１５について見ると、Ｐ３点により散乱効率Ａ１'が与えられる。また第２発光素子１０については第２散乱角θ２＝１２０°であることから特性曲線１６のＰ４点より散乱効率Ａ２'が与えられる。
【００３７】
この散乱効率Ａ１'、Ａ２'は、図３の場合と同様、発光量に受光効率をかけた受光量に比例することから、この場合についても第１発光素子９と第２発光素子１０から発せられた光による受光素子１１の受光量の比Ｒを、散乱効率Ａ１'、Ａ２'を用いて
Ｒ＝Ａ１'／Ａ２'
として求める。
【００３８】
図５は図３及び図４について綿灯芯による燻焼煙とケロシンによる燃焼煙を例にとって第１発光素子９による受光信号量Ａ１、第２発光素子による受光信号量Ａ２、更に各信号量の比率Ｒを一覧表に示している。尚、受光信号量は散乱効率に比例することから図３、図４の散乱効率Ｉの値をそのまま使用している。
【００３９】
この図５の一覧表から明らかなように、綿灯芯を燃焼させた場合の白っぽい煙となる燻焼煙については、第１発光素子９からの光と第２発光素子１０からの光の受光信号量の比率ＲはＲ＝８．０となっている。
【００４０】
これに対しケロシンを燃焼させた時の黒っぽい煙となる燃焼煙については、第１発光素子９と第２発光素子１０からの光による受光信号量の比率がＲ＝２．３となっている。
【００４１】
従って、白っぽい煙となる燻焼煙と黒っぽい煙となる燃焼煙について、第１発光素子９からの光と第２発光素子１０からの光による受光信号量の比率の間には十分な差が生じており、例えば比率Ｒについて煙の種類を判断するための閾値として例えば閾値＝６を設定することで、火災発生時の煙から燻焼煙か燃焼煙かを識別することができる。
【００４２】
一方、水蒸気や湯気などにあっては、煙粒子に比べ粒子径が十分に大きいことから、図３及び図４の散乱角θが小さい場合の散乱効率が火災時の煙に比べ十分に高く、第１散乱角θ１＝３０°となる第１発光素子９からの光による受光信号量が十分に大きく、第２散乱角θ２＝１２０°となる第２発光素子１０からの光による受光信号量との比率Ｒは１０以上の大きな値を持つことになる。
【００４３】
このため第１発光素子９からの光による受光信号量と第２発光素子１０からの光による受光信号量の比率Ｒについて閾値＝１０を設定し、これを上回るような場合には水蒸気や湯気などの非火災と判断することができる。
【００４４】
この点はタバコの煙についても同様であり、比率Ｒに対する閾値を閾値＝１０とすればタバコの煙については比率Ｒが１０以上の大きな値が得られることから同様に非火災と判断することができる。
【００４５】
図６は図２の検煙部を用いた図１の回路ブロックによる本発明の火災感知処理のフローチャートであり、信号処理部３を実現するＣＰＵのプログラム制御により実現される。
【００４６】
この火災感知処理にあっては、通常時は第１発光素子９のみを発光駆動しており、第１発光素子９からの光による受光レベルがプリアラーム的な所定閾値を超えた時に、第２発光素子１０を発光駆動して両方の光による受光信号量の比率から火災を判断するようにしている。
【００４７】
図６において、まずステップＳ１でカウンタｎをｎ＝１にセットする。次にステップＳ２で第１発光素子９をパルス的に発光駆動し、ステップＳ３で第１発光素子９の発光駆動に応じて受光素子１１の受光信号をサンプルホールドとして受光データＡ１を記憶部４に記憶する。
【００４８】
続いてステップＳ４で受光データＡ１が火災のプリアラームを判断する所定の閾値を超えたか否かチェックしており、この閾値が超えた場合にはステップＳ５で第２発光素子１０をパルス的に発光駆動し、これによって受光素子１０から得られる受光信号をサンプルホールドして受光データＡ２として記憶部４に記憶する。
【００４９】
次にステップＳ７で記憶部４に記憶している第１発光素子９からの光による受光データＡ１と第２発光素子１０からの光による受光データＡ２との比率Ｒを算出する。
【００５０】
続いてステップＳ８で比率Ｒを予め定めて非火災を判断するための閾値＝１０と比較する。比率Ｒが閾値＝１０より小さければ火災による煙と判断し、ステップＳ９で燃焼物の種類を判別する閾値＝６と比較する。
【００５１】
この時比率Ｒが閾値＝６以上であれば、ステップＳ１０で白煙火災（燻焼火災）と判断し、ステップＳ１１でカウンタｎをひとつ増加し、ステップＳ１２でカウンタｎがｎ＝３に達しているか否かチェックする。
【００５２】
この場合、カウンタｎ＝２であることからステップＳ２に戻り、ステップＳ２〜Ｓ１１と同じ処理を繰り返し、これによってステップＳ１２でカウンタｎがｎ＝３に達した事が判別されるとステップＳ１４で火災断定とし、火災信号を送出し、その際に必要であれば白煙火災を示す情報を同時に送信する。
【００５３】
一方、ステップＳ９で比率Ｒが閾値＝６未満であった場合にはステップＳ１３に進み、黒煙火災（燃焼火災）と判断し、ステップＳ１４で火災断定を行って受信器側に火災信号を送出し、必要があれば黒煙火災を示す情報を同時に送信する。またステップＳ８で比率Ｒが閾値１０以上であれば、非火災を断定し、ステップＳ１に戻り、カウンタｎをｎ＝１にリセットする。
【００５４】
このように本発明にあっては、図２に示した波長及び散乱角が異なる第１発光素子９と第２発光素子１０からの光による散乱光を受光素子１１で受光して両者の比率を求め、これを所定の閾値と比較して判断することで火災と非火災の判断、さらに火災と判断した場合の白煙火災か黒煙火災かの燃焼物の種類を確実に判断することができる。
【００５５】
ここで図２の検煙部構造にあっては、第１発光素子９として、第１波長λ１＝９００ｎｍ、第１散乱角θ１＝３０°、第２発光素子１０として第２波長λ２＝５００ｎｍ、第２散乱角θ２＝１２０°とした場合を例にとっているが、本発明にあってはこの値を最適値として次の数値的な範囲で同様の効果を実現することができる。
【００５６】
まず第１発光素子９の第１波長λ１としては８００ｎｍ以上の中心波長であれば良い。第１発光素子９の第１散乱角θ１としてはθ１＝２０°〜５０°の範囲に定めれば良い。一方、第２発光素子１０については第２波長λ２としては中心波長５００ｎｍ以下とすれば良く、第２散乱角θ２はθ２＝１００°〜１５０°の範囲に定めれば良い。
【００５７】
より具体的には第１発光素子９の第１波長λ１及び散乱角θ１と、第２発光素子１０の第２波長λ２と散乱角θ２は、図３の綿灯芯の煙、即ち燻焼煙（白色煙）について、それぞれの光による受光量の比率Ｒが燃焼物の種類を識別する閾値＝６より大きく、一方、図４のケロシンの燃焼による燃焼煙（黒色煙）については、第１発光素子９と第２発光素子１０から発した煙による散乱による受光信号量の比率Ｒが閾値＝６より小さくなるように設定すれば良い。
【００５８】
図７は図２の検煙部構造の具体的な配置構造の説明図である。図７において、第１発光素子９、第２発光素子１０及び受光素子１１はそれぞれの光軸９ａ、１０ａ、１１ａが同一平面内に存在する平面角配置とした点が同じであるが、第１発光素子９からの光が直接受光素子１１に入射するのを防ぐために、遮光板１７、１８を第２発光素子１０の配置側に設けている。
【００５９】
また第２発光素子１０からの光は遮光板１７、１８の間を通ってＰ点に向かうように第２発光素子１０を配置している。このため遮光板１７、１８は第１発光素子側からの光の受光素子１１の直接入射を防ぐとともに第２発光素子１０からの不要な成分の光の受光素子１１への入射も防ぐ作用を同時に果たしている。
【００６０】
図８は図２の検煙部についての他の具体的な配置構造の説明図である。図８の配置構造にあっては、受光素子１１と第１発光素子９との配置関係は図７の配置と同じである。第２発光素子１０については受光素子１１の光軸１１ａの反対側に配置している。
【００６１】
この場合、第１発光素子９から受光素子１１へ直接光が入射するのを防ぐため、遮光板１７、１８を配置しているが、第２発光素子１０については遮光板を設ける必要がない。もし第２発光素子１０について想像線で示す遮光板１９を設けると、この遮光板１９に第１発光素子９からの光が当たって受光素子１１に入射することになるため、遮光板１９は不要である。
【００６２】
また遮光版１９がなくても第２発光素子１０の光軸１０ａは受光素子１１から遠ざかる方向に向くように第２散乱角θ２＝１００°〜１５０°の範囲に設定されており、これによって第２発光素子１０の光が受光素子１１へ直接入射することはない。
【００６３】
実際の煙感知器における検煙部の構造は、感知器の設置スペースの必要性から図７の配置構造、もしくは図８の配置構造を必要に応じて選択することができる。
【００６４】
図９は立体角配置をとる図２の検煙部の他の具体的な配置構造の説明図である。図９において、検煙部の一端を構成するチャンバーベース２０の検煙空間側の面には第１発光開口９ｂ、第２発光開口１０ｂ及び受光開口１１ｂが形成され、それぞれの開口の内部に第１発光素子、第２発光素子さらに受光素子を組み込んでいる。
【００６５】
図１０は図９のチャンバーベース２０の裏側から見た説明図であり、チャンバーベース２０の裏側にホルダー２１が一体に形成されており、ホルダー２１の裏側に第１発光収納部９ｃ、第２発光収納部１０ｃさらに受光収納部１１ｃが形成され、第１発光素子、第２発光素子さらに受光素子を組み込んでいる。
【００６６】
図１１は図９、図１０のチャンバーベース２０を用いた立体角配置をとる検煙部全体の配置図である。図１１において、チャンバーベース２０の上部にはチャンバー２４が装着され、チャンバー２４は周囲にラビリンス２３を形成しており、外部からの光の入射を遮断するとともに、煙の流入を可能とし、内部に検煙空間を形成している。
【００６７】
チャンバーベース２０の内部には、この断面図にあっては図９の第１発光開口９ｂと受光開口１１ｂを通る断面であることから、第１発光素子９と受光素子１１が組み込まれ、それぞれの光軸９ａ、１１ａはチャンバー２４内の検煙空間で立体交差している。この点は第２発光開口１０ｂ内に組み込まれている第２発光素子１０についても同様である。
【００６８】
図１２は図１１における発光素子と受光素子の立体角配置の説明図である。図１２（Ａ）は第１発光素子９、第２発光素子１０及び受光素子１１についてその光軸９ａ、１０ａ、１１ａによる立体角配置を示している。
【００６９】
この第１発光素子９、第２発光素子１０及び受光素子１１の光軸９ａ、１０ａ、１１ａが交差するＰ点が図１１のチャンバー２４内の検煙空間に存在しており、これに対し第１発光素子９、第２発光素子１０及び受光素子１１は図１１のチャンバーベース２０の中に配置されている。
【００７０】
図１２（Ｂ）は第１発光素子９のＡ点と受光素子１１のＣ点の間の立体角配置を取り出している。この場合、第１発光素子９のＡ点と受光素子１１のＣ点からの光軸９ａ、１１ａを含む面は三角形ＰＣＡで与えられ、この三角形ＰＣＡを含む面の光軸９ａと光軸１１ａのなす角が第１発光素子９の第１散乱角θ１となる。
【００７１】
図１２（Ｃ）は第２発光素子１０のＢ点と受光素子１１のＣ点との立体角配置を取り出している。この場合、光軸１０ａと１１ａは三角形ＰＣＢを含む面に存在しており、第２発光素子１０と受光素子１１の光軸１０ａ、１１ａのなす散乱角は三角形ＰＣＢを含む面上の光軸１０ａと光軸１１ａのなす場合に散乱角θ２として与えられている。
【００７２】
このような立体角配置をとる検煙部構造によれば、第１発光素子９、第２発光素子１０及び受光素子１１をチャンバーベース２０の内部に組み込み、それぞれの光軸の交点Ｐを検煙空間内となるように配置すればよく、結果的に検煙部の高さを小さくでき感知器の小型化を図ることができる。
【００７３】
図１３は２つの発光素子の散乱角と偏光方向を異ならせた本発明の検煙部構造の他の実施形態を示した説明図である。図１３において、この実施形態の検煙部８にあっては、第１発光素子２５、第２発光素子２９、受光素子３３を配置している。
【００７４】
第1発光素子２５は、その光軸２５ａと受光素子３３の光軸３３ａを通る平面を第1散乱面２７とすると、第1散乱面２７に対し垂直な偏光面を持つ垂直偏光面をもつ光２８を発する。
【００７５】
この例では第１発光素子２５としてＬＥＤを使用しており、したがって第１発光素子２５の前面に偏光フィルタ２６を配置し、第１散乱面２７に垂直な偏光面を持つ光２８を発するようにしている。この第１発光素子２５の第１散乱面２７における光軸２５ａと受光素子３３の光軸３３ａの成す第１散乱角θ１は、例えばθ１＝７０°に設定している。
【００７６】
一方、第２発光素子２９の光軸２９ａと受光素子３３の光軸３３ａを通る平面を第２散乱面３１とすると、第２発光素子２９は第２散乱面３１に平行な偏光面を持つ光３２を発する。また第２発光素子２９の光軸２９ａと受光素子３３の光軸３３ａの第２散乱面３１において成す角となる第２散乱角θ２としては、第１散乱角θ１より大きい例えばθ２＝１２０°に設定している。
【００７７】
第２発光素子２８もＬＥＤを使用していることから、第２発光素子２９の前に偏光フィルター３１を配置して水平偏光面をもつ光３２を発するようにしている。
【００７８】
このように第１発光素子２５からの第１散乱面２７に対し垂直偏光面を持つ光２８と第２発光素子２９からの第２散乱面３１に対し水平偏光面をもつ光３２により、Ｐ点における煙の散乱による受光素子３３に向かう散乱光は、いずれの光についても第２散乱面３１に平行な水平偏光面をもつ光３４として煙粒子に照射されることになる。
【００７９】
図１４は、図１３の検煙部構造において散乱角と偏光角を変えた場合の煙の種類に対する受光信号量の実験的に得られた結果の一覧表である。図１４において、散乱角θとしては７０°、９０°、１２０°をとっており、それぞれの散乱角θについて偏光角φを０°（水平偏光）及び９０°（垂直偏光）とした場合を示している。
【００８０】
また図１３の検煙部構造における本発明の散乱光式煙感知器の回路ブロックは図１の実施形態と同じものを使用しており、その感知器処理の手順は図６のフローチャートに従っており、またステップＳ８の非火災を判断する閾値も、ステップＳ９において白煙火災か黒煙火災かを判断するための閾値も、同じものを使用することができる。
【００８１】
図１４の濾紙、ケロシン、タバコのそれぞれの燃焼煙に対し第１発光素子２５から光を発した場合の受光信号量と第２発光素子２９から光を発した場合の受光信号量を、散乱角θと偏光角φについて見ると次のことがわかる。
【００８２】
まず散乱角θの変化に対しては、第１発光素子２５による垂直偏光及び第２発光素子２９による水平偏光のいずれについても、散乱角が小さいほど受光信号量が大きく、散乱角が大きくなると受光信号量が低下する関係にある。
【００８３】
一方、同じ散乱角θ例えば７０°について見ると、第１発光素子２５による垂直偏光の光による受光信号量の方が、第２発光素子２９による水平偏光の光による受光信号量より大きくなっていることが分かる。
【００８４】
本発明の火災判断にあっては、第１発光素子２５からの光による受光信号量Ａ１と第２発光素子２９からの光による受光信号量Ａ２の比率Ｒを
Ｒ＝Ａ１／Ａ２
として算出して、火災か非火災か、火災であった場合の白煙火災か黒煙火災かを判別する。
【００８５】
ここで比率Ｒを大きくするためには、図１４における散乱角θとして、第１発光素子２５については受光信号量が大きくなる小さい方の散乱角θ１＝７０°を選択し、第２発光素子２９については受光信号量が小さくなる散乱角θ２＝１２０°を選択する。
【００８６】
一方、同じ散乱角における水平偏光と垂直偏光の光では、垂直偏光による光の方が受光信号量が大きく、水平偏光による光の方が受光信号量が小さくなることから、比率Ｒを大きくとるためには、第１発光素子２５について受光信号量を大きくするために偏光角φ１＝９０°となる垂直偏光を選択し、第２発光素子２９については受光信号量が小さくなる偏光角θ２＝０°となる水平偏光を選択する。
【００８７】
この図１４のような散乱角θ及び偏光角φに対する測定結果に基づき、図１３の実施形態にあっては
（１）第１発光素子２５は垂直偏光で第１散乱角θ１＝７０°
（２）第２発光素子２９は水平偏光で第２散乱角θ２＝１２０°
を設定している。
【００８８】
図１５は、（１）（２）のように偏光方向と散乱角を設定した場合の燃焼物の種類に対する第１発光素子２５からの光による受光信号量Ａ１と第２発光素子２９による受光信号量Ａ２を図１４から取り出して一覧表で示し、更に２つの信号量による比率Ｒを算出して示している。
【００８９】
この図１５の一覧表から明らかなように、濾紙やケロシンなどの火災時の燃焼物については比率Ｒは４．４４、５．６０と小さく、これに対し非火災となるタバコについては比率は１６．４７と十分に大きく、したがって図６のフローチャートのように、ステップＳ８で閾値＝１０により比率Ｒを判断することで、火災か非火災かを確実に識別することができる。
【００９０】
また図１５のケロシン及び濾紙の燃焼による煙は黒煙火災に属することから、図６のステップＳ９で閾値＝６を使用することで、ステップＳ１３に進んで黒煙火災（燃焼火災）であることを識別できる。もちろん図５に示した燻焼火災による煙である綿灯芯については、図１５には示されていないが、その比率Ｒとしてケロシンより大きな値が必然的に得られ、したがって図６のステップＳ９で閾値＝６以上の比率Ｒとなって、ステップＳ１０で白煙火災と判断され、カウンタｎによる３カウントで火災が断定される。
【００９１】
ここで図１３の実施形態にあっては、第１発光素子２５の第１散乱角θ１＝７０°とした場合を例にとっているが、実用的にはθ１＝８０°以下の値とすればよい。また第２発光素子２９の第２構成角θ２としてθ２＝１２０°を例にとっているが、実用的な値としてはθ２＝１００°以上とすればよい。
【００９２】
また図１３の実施形態にあっては、第１発光素子２５及び第２発光素子２９としてＬＥＤを使用し、偏光フィルター２６、３０と組み合わせることで垂直偏光面をもつ光２８と水平偏光面をもつ光３２を発するようにしているが、これに代えて偏光された光を出力するレーザダイオードを第１発光素子２５及び第２発光素子２９に使用すれば、偏光フィルータ２６、３０は不要となる。
【００９３】
また図１３の実施形態にあっては、第１発光素子及び第２発光素子の波長を等しくとったが、これを異ならせることで、より煙の識別精度を高めることもできる。
【００９４】
なお図２の２つの発光素子の波長と散乱角を異ならせた検煙部構造の他の実施形態として、第１発光素子９及び第２発光素子１０における波長と散乱角の関係が維持できる構成であれば、２つの発光素子に対し２つの受光素子を設けるようにしてもよい。
【００９５】
また発光素子として白熱球や白色ＬＥＤなどの発光スペクトルの広い発光素子を用いることにより発光素子を１つとし、この発光素子に波長切替用のフィルタを設け、図２の第１発光素子９及び第２発光素子１０の配置位置から光を出すように光路設定を行うことで本発明を実施することができる。
【００９６】
更に図１３の２つの発光素子の散乱角と偏光方向を異ならせた本発明の検煙部構造についても、異なる偏光面をもつ２つの発光素子に対し各々別の受光素子を２ヵ所に設けるようにしてもよい。また２つの発光素子から発する光の偏光面については、図１３における偏光フィルター２６、３０を機械的に回転させたり液晶フィルタを駆動するなどにより偏光面を変化させることで、偏光面の偏光方向を適宜に調整して最適な検出状態を得ることができる。
【００９７】
【発明の効果】
以上説明してきたように本発明によれば、２つの発光素子につき受光素子に対する散乱角を異ならせることで煙の種類による散乱特性の相違を作り出し、同時に２つの発光素子から発する光の波長を異ならせることで波長に起因した散乱特性の相違を作り出し、この散乱角の相違と波長の相違の相乗効果によって煙の種類による散乱光の光強度に顕著な差を持たせることで煙の識別確度を高め、調理の湯気やタバコの煙による非火災報を防止し、更に火災による煙についても黒煙火災と白煙火災といった燃焼物の種類を確実に識別することができる。
【００９８】
また本発明の別の形態にあっては、２つの発光素子から発する光の各散乱面に対する偏光面を異ならせることで光の偏光方向に起因した散乱特性の相違を作り出し、同時に２つの発光素子につき受光素子に対する散乱角を異ならせることで煙の種類による散乱特性の相違を作り出し、この偏光方向の相違と散乱角の相違の相乗効果によって煙の種類による散乱光の光強度に顕著な差を持たせることで煙の識別確度を高め、調理の湯気やタバコの煙などによる非火災報を確実に防止し、また火災時の煙についても黒煙火災と白煙火災を識別して燃焼物の種類を確実に識別することができる。
【図面の簡単な説明】
【図１】本発明による散乱光式煙感知器の回路ブロック図
【図２】２つの発光素子の波長と散乱角を異ならせた本発明の検煙部構造の実施形態を示した説明図
【図３】綿灯芯の燃焼煙における図２の検煙部による散乱角に対する２つの発光素子からの光による散乱効率を示したグラフ図
【図４】ケロシンの燃焼煙における図２の検煙部による散乱角に対する２つの発光素子からの光による散乱効率を示したグラフ図
【図５】図３及び図４において第１発光素子の波長を９００ｎｍ、散乱角θ１を３０°とし、第２発光素子の波長を５００ｎｍ、散乱角θ１を１２０°とした場合の受光信号量とその比率を示した説明図
【図６】図２の検煙部を用いた図１の回路ブロックによる火災感知処理のフローチャート
【図７】図２の検煙部の具体的な配置構造の説明図
【図８】図２の検煙部の他の具体的な配置構造の説明図
【図９】立体角配置をとる図２の検煙部の他の具体的な配置構造の説明図
【図１０】図９のチャンバーベースを裏側から見た説明図
【図１１】図９のチャンバーベースを用いた検煙部全体の断面図
【図１２】図１１における発光素子と受光素子の立体角配置の説明図
【図１３】２つの発光素子の散乱角と偏光方向を異ならせた本発明の検煙部構造の他の実施形態を示した説明図
【図１４】図１３の検煙部構造で散乱角と偏光角を変えた場合の煙の種類に対する受光信号量を示した説明図
【図１５】図１３において第１発光素子の散乱角θ１を７０°、偏向角を９０°（垂直）とし、第２発光素子の散乱角θ１を１２０°、偏向角を０°（水平）としとした場合の受光信号量とその比率を煙の種類について示した説明図
【符号の説明】
１：散乱光式煙感知器
２：発報回路
３：信号処理部
４：記憶部
５：第１発光制御部
６：第２発光制御部
７：増幅回路
８：検煙部
９、２５：第１発光素子
１０、２９：第２発光素子
１１、３３：受光素子
９ａ、１０ａ、１１ａ：光軸
１７、１８、１９：遮光板
２０：チャンバーベース
２１：ホルダー
２２：検煙部
２３：ラビリンス
２４：チャンバー
２６、３０：偏光フィルター
２７：第１散乱面
２８：垂直偏光面をもつ光
３１：第２散乱面
３２、３４：水平偏光面をもつ光[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a scattered light type smoke detector including two light emitting elements that emit light so that scattering characteristics with respect to a light receiving element are different.
[0002]
[Prior art]
Conventional smoke detectors may generate non-fire reports due to cooking smoke, bathroom steam, etc., as well as smoke due to fire.
[0003]
In order to prevent such non-fire reports due to causes other than fire, the smoke detection space is irradiated with light of two different wavelengths, and the type of smoke is determined by determining the ratio of the light intensity of different wavelengths for the scattered light from the smoke And a method of determining the type of smoke by irradiating light having a polarization plane perpendicular to the scattering plane and light having a horizontal polarization plane, and determining the ratio of the light intensity of each polarization component of the scattered light from the smoke It has been known.
[0004]
[Patent Document 1]
JP-A-6-109631
[Patent Document 2]
JP-A-7-12724
[0005]
[Problems to be solved by the invention]
However, in the conventional method of distinguishing the type of smoke using light of different wavelengths or light having different polarization planes, smoke caused by fire, cooking smoke caused by causes other than fire, steam in the bathroom, etc. Is not necessarily sufficient, and more sophisticated smoke identification is desired.
[0006]
It is an object of the present invention to provide a scattered light type smoke detector that enhances the accuracy of smoke identification and ensures non-fire report prevention.
[0007]
[Means for Solving the Problems]
In order to achieve this object, the present invention is configured as follows.
[0008]
The present invention is emitted from a first light emitting element that emits a first wavelength toward a smoke detection space, a second light emitting element that emits a second wavelength different from the first wavelength, and the first light emitting element and the second light emitting element. In a scattered light type smoke detector including a light receiving element provided at a position where light is not directly received, with respect to a first scattering angle θ1 configured by an intersection of optical axes of the first light emitting element and the light receiving element, The second scattering angle θ2 formed by the intersection of the optical axes of the second light emitting element and the light receiving element is configured to be large, and the second wavelength emitted from the second light emitting element with respect to the first wavelength λ1 emitted from the first light emitting element. λ2 is shortened.
[0009]
As described above, the present invention creates a difference in the scattering characteristics depending on the type of smoke by making the scattering angle with respect to the light receiving element different for the two light emitting elements, and at the same time, making the wavelength of light emitted from the two light emitting elements different. The difference in scattering characteristics due to the wavelength is created, and the difference between the scattering angle and the difference in wavelength gives a significant difference in the light intensity of the scattered light due to the type of smoke. Prevent non-fire reports caused by cooking steam.
[0010]
In another embodiment of the present invention, the light emitted from the first light emitting element, the second light emitting element, and the first light emitting element and the second light emitting element that emit light of a predetermined wavelength toward the smoke detection space. In a scattered light type smoke detector provided with a light receiving element provided at a position not directly receiving light, the first light emitting element has a first scattering surface passing through the optical axis of the light receiving element intersecting with its own optical axis. The second light-emitting element emits light having a vertical polarization plane (φ = 90 °), and the second light-emitting element has a polarization plane (φ = 0 horizontal to the second scattering plane passing through the optical axis of the light-receiving element intersecting with its own optical axis. And a first scattering angle θ1 formed by the intersection of the optical axes of the first light-emitting element and the light-receiving element, and a second light-emitting element formed by the intersection of the optical axes of the second light-emitting element and the light-receiving element. It is characterized in that the two scattering angle θ is large.
[0011]
Also in this case, by making the polarization planes of the light emitted from the two light emitting elements different from each other, the difference in the scattering characteristics due to the polarization direction of the light is created, and simultaneously the scattering of the two light emitting elements with respect to the light receiving element. By making the angle different, it creates a difference in the scattering characteristics depending on the type of smoke, and by making a significant difference in the light intensity of the scattered light by the type of smoke by the synergistic effect of this difference in polarization direction and the difference in scattering angle, Increase smoke identification accuracy to prevent non-fire reports from cooking steam.
[0012]
The scattered light type smoke detector of the present invention is configured such that the first light emitting element is configured such that the optical axis composed of the first light emitting element and the light receiving element and the optical axis composed of the second light emitting element and the light receiving element exist on the same plane. The element, the second light emitting element, and the light receiving element are arranged in a plane angle.
[0013]
In addition, the scattered light type smoke detector has the first light emitting element so that the optical axis constituted by the first light emitting element and the light receiving element and the optical axis constituted by the second light emitting element and the light receiving element do not exist on the same plane. The second light emitting element and the light receiving element are arranged in a solid angle.
[0014]
Here, by comparing the amount of smoke scattered by the first light emitting element with the amount of smoke scattered by the second light emitting element, for example, the ratio of the two is taken and compared with a threshold value to identify the type of smoke, The fire is judged according to the judgment standard according to the type of smoke.
[0015]
This criterion changes the threshold according to the type of smoke. In addition, as a judgment criterion, the number of counts for judging a fire according to the type of smoke is set.
[0016]
The scattered light smoke detector of the present invention is characterized in that, in a normal monitoring state, only the first light emitting element is driven, and the second light emitting element is driven when a predetermined light receiving output is obtained from the light receiving element. And For this reason, even if two light emitting elements are provided, since only one is normally driven, an increase in current consumption is prevented.
[0017]
Here, in the scattered light type smoke detector of the present invention in which the scattering angle and the wavelength are different, for example, the first scattering angle formed by the intersection of the optical axes of the first light emitting element and the light receiving element is in the range of 20 ° to 50 °. The second scattering angle formed by the intersection of the optical axes of the second light-emitting element and the light-receiving element is determined in the range of 100 ° to 150 °, and the center wavelength of the first wavelength emitted from the first light-emitting element is 800 nm. As described above, the center wavelength of the second wavelength emitted from the second light emitting element is set to 500 nm or less.
[0018]
The scattered light type smoke detector of the present invention in which the polarization direction and the scattering angle are different from each other, for example, the first scattering angle θ1 formed by the intersection of the optical axes of the first light emitting element and the light receiving element is set to 80 ° or less, The second scattering angle θ2 formed by the intersection of the optical axes of the second light emitting element and the light receiving element is set to 100 ° or more.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit block diagram of a scattered light smoke detector according to the present invention. In FIG. 1, a scattered light smoke detector 1 of the present invention includes an alarm circuit 2, a signal processing unit 3 using a CPU, a storage unit 4, a first light emission control unit 5, a second light emission control unit 6, and an amplifier circuit. 7 and smoke detector 8.
[0020]
The smoke detector 8 includes a smoke detection space in which smoke can flow in to block light from the outside. The first light emitting element 9, the second light emitting element 10, and the light receiving element 11 are provided in the smoke detection space.
[0021]
FIG. 2 is an explanatory diagram showing an embodiment of the structure of the smoke detector 8 of the scattered light smoke detector 1 of FIG. In FIG. 2, a first light emitting element 9, a second light emitting element 10 and a light receiving element 11 are arranged in the smoke detecting section 8. In this embodiment, the respective optical axes 9a, 10a and 11a are in the same plane. It is a structure of the arranged plane angle arrangement.
[0022]
In the first light emitting element 9, the first scattering angle θ1 with respect to the intersection P between the optical axis 9a of the light receiving element 11 and the optical axis 11a of the light receiving element 11 is set to θ = 30 ° in this embodiment. Further, a near-infrared LED is used as the first light emitting element 9, and the light emitted from the first light emitting element 9 has a center wavelength λ1, and in this embodiment, λ1 = 900 nm (= 0.9 μm). It is set.
[0023]
In the present invention, the second light emitting element 10 is further provided for the first light emitting element 9. The second light emitting element is configured such that the second scattering angle θ2 with respect to the intersection P between the optical axis 10a and the light receiving element 11a is larger than the first scattering angle θ1 of the first light emitting element 9 and the light receiving element 11. In this embodiment, the second scattering angle θ2 is θ2 = 120 °.
[0024]
The second light emitting element 10 uses a visible light LED. If the center wavelength of light generated from the second light emitting element 10 is the second wavelength λ2, the wavelength λ2 is greater than the wavelength λ1 of the first light emitting element 9. In this embodiment, λ2 = 500 nm (= 0.5 μm).
[0025]
FIG. 3 is a graph showing the scattering efficiency I of the light from the first light emitting element 9 and the second light emitting element 10 with respect to the scattering angle θ for the combustion smoke (white smoke) of the cotton lantern in the smoke detecting section structure of FIG. FIG.
[0026]
In FIG. 3, the horizontal axis represents the scattering angle θ, θ = 0 to 180 °, and the vertical axis represents the scattering efficiency I by an exponential function. In the characteristic of the scattering efficiency with respect to the scattering angle for the smoke of the cotton wick shown in FIG. 3, the light is received on the light receiving element 11 side by the light having the first wavelength λ1 = 900 nm from the first light emitting element 9 in FIG. The scattering efficiency is as shown by the characteristic curve 13. On the other hand, the smoke scattering efficiency by the light from the second light emitting element 10 that emits light of the second wavelength λ2 = 500 nm in FIG.
[0027]
Regarding the characteristic curves 13 and 14 in FIG. 3, first, regarding the wavelength of light emitted from the light emitting element, the first light emitting element 9 has the following characteristics. long It can be seen that the characteristic curve 13 with the wavelength λ1 = 900 nm has a lower scattering efficiency and the scattering efficiency of the characteristic curve 14 with the light from the second light emitting element 10 having the short wavelength of the second wavelength λ2 = 500 nm is higher.
[0028]
On the other hand, with respect to changes in the scattering angle θ in the characteristic curves 13 and 14 of the respective scattering efficiencies of the first light emitting element 9 and the second light emitting element 10, the scattering efficiency is higher as the scattering angle θ is smaller. The scattering efficiency decreases as the value increases, and shows a minimum value at a 120 ° point. However, the scattering efficiency increases as the scattering angle increases thereafter.
[0029]
In the present invention, the scattering angle of the first light emitting element 9 is set to θ = 30 °, and therefore the scattering efficiency A1 at the point P1 in the characteristic curve 13 is obtained. On the other hand, for the second light emitting element 10, the second scattering angle θ2 is set to θ = 120 °, and therefore, the scattering efficiency A2 at the point P2 in the characteristic curve 14 is obtained.
[0030]
The amount of light received by the light receiving element 11 obtained from the scattering efficiency due to light having different scattering angles and wavelengths from the first light emitting element 9 and the second light emitting element 10 is as follows.
(Amount of received light) = (Amount of emitted light) × (Light receiving efficiency)
Therefore, a received light signal amount proportional to the scattering efficiency I in FIG. 3 can be obtained.
[0031]
In the present invention, the ratio R of the amount of light received by the light receiving element 11 by the scattered light with respect to the same smoke by each light from the first light emitting element 9 and the second light emitting element 10 is obtained. Since the ratio R of the amount of received light is proportional to the scattering efficiency, the scattering efficiency A1, A2
R = A1 / A2
It is obtained as The ratio R is determined in advance and compared with a threshold value to determine the type of smoke.
[0032]
4 is a graph showing the scattering efficiency I of the light from the first light emitting element 9 and the second light emitting element 10 for the burning smoke of kerosene (black smoke) as the combustion substance with respect to the scattering angle structure θ of FIG. It is.
[0033]
In FIG. 4, the scattering efficiency I due to light from the first light emitting element 9 emitting light of the first wavelength λ1 = 900 nm is as shown by the characteristic curve 15, while the second light emitting element 10 having the second wavelength λ2 = 500 nm. The scattering efficiency I due to the light emitted from the light becomes a characteristic curve 16.
[0034]
In the graph of FIG. 4, when focusing on the wavelength, the characteristic curve 15 of the scattering efficiency by the light emitted from the first light emitting element 9 having the first wavelength λ1 = 900 nm is low as in the case of the smoke of the cotton lantern of FIG. On the other hand, the characteristic curve 16 of the scattering efficiency due to the light emitted from the second light emitting element 10 having the short wavelength of the second wavelength λ2 = 500 nm shows a larger value.
[0035]
Similarly to the case of FIG. 3, the change in the scattering efficiency with respect to the scattering angle θ is such that the smaller the scattering angle, the higher the scattering efficiency, and after the scattering angle θ reaches a minimum value near 120 °, The scattering efficiency increases as the angle increases.
[0036]
When the first scattering angle θ1 = 30 ° of the first light emitting element 9 is seen with respect to the characteristic curve 15 for such kerosene combustion smoke, the scattering efficiency A1 ′ is given by the point P3. Further, since the second light emitting element 10 has the second scattering angle θ2 = 120 °, the scattering efficiency A2 ′ is given from the point P4 of the characteristic curve 16.
[0037]
Similar to the case of FIG. 3, the scattering efficiencies A1 ′ and A2 ′ are proportional to the light receiving amount obtained by multiplying the light emitting amount by the light receiving efficiency. Therefore, in this case as well, the first light emitting element 9 and the second light emitting element 10 emit light. The ratio R of the amount of light received by the light receiving element 11 by the emitted light is calculated using the scattering efficiencies A1 ′ and A2 ′.
R = A1 '/ A2'
Asking.
[0038]
5 and FIG. 4 show, for example, smoked smoke from cotton lantern and combustion smoke from kerosene as an example, received light signal amount A1 by the first light emitting element 9, received light signal amount A2 by the second light emitting element, and ratio of each signal amount. R is shown in the list. Since the amount of received light signal is proportional to the scattering efficiency, the value of the scattering efficiency I in FIGS. 3 and 4 is used as it is.
[0039]
As apparent from the list of FIG. 5, the light-receiving signal of the light from the first light emitting element 9 and the light from the second light emitting element 10 for the smoked smoke that becomes whitish smoke when the cotton wick is burned. The quantity ratio R is R = 8.0.
[0040]
On the other hand, for the combustion smoke that becomes blackish smoke when kerosene is burned, the ratio of the amount of light received by the light from the first light emitting element 9 and the second light emitting element 10 is R = 2.3.
[0041]
Therefore, there is a sufficient difference between the ratio of the received light signal amount by the light from the first light emitting element 9 and the light from the second light emitting element 10 for the smoked smoke that becomes whitish smoke and the combustion smoke that becomes blackish smoke. For example, by setting, for example, threshold = 6 as the threshold for determining the type of smoke for the ratio R, it is possible to identify whether smoke is smoke or combustion smoke from the smoke at the time of the fire.
[0042]
On the other hand, in the case of steam or steam, the particle diameter is sufficiently larger than that of smoke particles, so the scattering efficiency when the scattering angle θ of FIG. 3 and FIG. 4 is small is sufficiently high compared to smoke during fire, First scattering angle θ1 = 30 ° The light reception signal amount due to the light from the first light emitting element 9 is sufficiently large, and the ratio R to the light reception signal amount due to the light from the second light emitting element 10 at which the second scattering angle θ2 = 120 ° is as large as 10 or more. Will have a value.
[0043]
For this reason, a threshold value = 10 is set for the ratio R of the received light signal amount by the light from the first light emitting element 9 and the received light signal amount by the light from the second light emitting element 10, and if it exceeds this, water vapor, steam, etc. It can be judged as non-fire.
[0044]
This is the same for tobacco smoke. If the threshold value for the ratio R is set to threshold = 10, a large value of the ratio R of 10 or more can be obtained for tobacco smoke. it can.
[0045]
FIG. 6 is a flowchart of the fire detection process of the present invention by the circuit block of FIG. 1 using the smoke detector of FIG. 2 and is realized by program control of the CPU that implements the signal processor 3.
[0046]
In this fire detection process, only the first light emitting element 9 is normally driven to emit light, and when the level of light received by the light from the first light emitting element 9 exceeds a pre-alarm predetermined threshold, The light emitting element 10 is driven to emit light, and a fire is judged from the ratio of the received light signal amount of both lights.
[0047]
In FIG. 6, first, in step S1, the counter n is set to n = 1. Next, in step S2, the first light emitting element 9 is driven to emit light in pulses. In step S3, the light receiving signal of the light receiving element 11 is sampled and held in accordance with the light emission driving of the first light emitting element 9, and the received light data A1 is stored in the storage unit 4. Remember.
[0048]
Subsequently, in step S4, it is checked whether or not the light reception data A1 exceeds a predetermined threshold value for judging a fire pre-alarm. If this threshold value is exceeded, the second light emitting element 10 is filtered in step S5. Le The light receiving signal obtained from the light receiving element 10 is sampled and held. do it It memorize | stores in the memory | storage part 4 as light reception data A2.
[0049]
Next, in step S7, the ratio R between the light reception data A1 by the light from the first light emitting element 9 and the light reception data A2 by the light from the second light emitting element 10 stored in the storage unit 4 is calculated.
[0050]
Subsequently, in step S8, the ratio R is determined in advance and compared with a threshold value = 10 for determining non-fire. If the ratio R is smaller than the threshold value = 10, it is determined that the smoke is due to fire, and in step S9, it is compared with the threshold value = 6 for determining the type of combustion product.
[0051]
If the ratio R at this time is equal to or greater than the threshold value = 6, it is determined in step S10 that a white smoke fire (fire burning fire) occurs, the counter n is incremented by one in step S11, and the counter n reaches n = 3 in step S12. Check whether it exists.
[0052]
In this case, since the counter n = 2, the process returns to step S2, and the same processing as steps S2 to S11 is repeated. When it is determined in step S12 that the counter n has reached n = 3, the fire is detected in step S14. Assume that a fire signal is sent, and if necessary, information indicating a white smoke fire is sent at the same time.
[0053]
On the other hand, if the ratio R is less than the threshold = 6 in step S9, the process proceeds to step S13, where it is determined that there is a black smoke fire (combustion fire), a fire determination is performed in step S14, and a fire signal is sent to the receiver side. If necessary, information indicating black smoke fire is transmitted at the same time. If the ratio R is greater than or equal to the threshold value 10 in step S8, the non-fire is determined, the process returns to step S1, and the counter n is reset to n = 1.
[0054]
As described above, in the present invention, the light receiving element 11 receives the scattered light from the first light emitting element 9 and the second light emitting element 10 having different wavelengths and scattering angles shown in FIG. By determining and comparing this with a predetermined threshold value, it is possible to reliably determine the type of combustion product, fire or non-fire, and whether it is a white smoke fire or a black smoke fire. .
[0055]
2, the first light emitting element 9 has a first wavelength λ1 = 900 nm, the first scattering angle θ1 = 30 °, the second light emitting element 10 has a second wavelength λ2 = 500 nm, Although the case where the second scattering angle θ2 = 120 ° is taken as an example, the present invention can achieve the same effect in the following numerical range with this value as an optimum value.
[0056]
First, the first wavelength λ1 of the first light emitting element 9 may be a center wavelength of 800 nm or more. The first scattering angle θ1 of the first light emitting element 9 may be set in the range of θ1 = 20 ° to 50 °. On the other hand, for the second light emitting element 10, the center wavelength is 500 nm as the second wavelength λ2. Less than The second scattering angle θ2 may be set in the range of θ2 = 100 ° to 150 °.
[0057]
More specifically, the first wavelength λ1 and the scattering angle θ1 of the first light emitting element 9 and the second wavelength λ2 and the scattering angle θ2 of the second light emitting element 10 are the smoke of the cotton lamp core in FIG. For white smoke), the ratio R of the amount of light received by each light is larger than the threshold value for identifying the type of combustion product = 6, while for combustion smoke (black smoke) due to combustion of kerosene in FIG. 9 and the ratio R of the received light signal amount due to scattering by smoke emitted from the second light emitting element 10 may be set to be smaller than the threshold value = 6.
[0058]
FIG. 7 is an explanatory diagram of a specific arrangement structure of the smoke detector structure of FIG. In FIG. 7, the first light-emitting element 9, the second light-emitting element 10, and the light-receiving element 11 are the same in that the optical axes 9a, 10a, and 11a are arranged in a plane angle with the same plane. In order to prevent light from the light emitting element 9 from directly entering the light receiving element 11, light shielding plates 17 and 18 are provided on the arrangement side of the second light emitting element 10.
[0059]
In addition, the second light emitting element 10 is arranged so that the light from the second light emitting element 10 passes between the light shielding plates 17 and 18 toward the point P. For this reason, the light shielding plates 17 and 18 simultaneously prevent light from entering the light receiving element 11 from the first light emitting element side and also prevent unwanted components of light from the second light emitting element 10 from entering the light receiving element 11 at the same time. Plays.
[0060]
FIG. 8 is an explanatory diagram of another specific arrangement structure for the smoke detector of FIG. In the arrangement structure of FIG. 8, the arrangement relationship between the light receiving element 11 and the first light emitting element 9 is the same as the arrangement of FIG. The second light emitting element 10 is disposed on the opposite side of the light receiving element 11 from the optical axis 11a.
[0061]
In this case, the first light emitting element 9 to the light receiving element 1 Go straight to 1 Although the light shielding plates 17 and 18 are arranged to prevent the incident light from entering, it is not necessary to provide the light shielding plate for the second light emitting element 10. Imagine the second light-emitting element 10 Shielding indicated by a line When the light plate 19 is provided, the light from the first light emitting element 9 strikes the light shielding plate 19 and enters the light receiving element 11, so that the light shielding plate 19 is unnecessary.
[0062]
Even if the light shielding plate 19 is not provided, the optical axis 10a of the second light emitting element 10 is set in the range of the second scattering angle θ2 = 100 ° to 150 ° so as to face away from the light receiving element 11. The light from the two light emitting elements 10 goes to the light receiving element 11 Directly There is no incident.
[0063]
As the structure of the smoke detector in the actual smoke detector, the arrangement structure shown in FIG. 7 or the arrangement structure shown in FIG. 8 can be selected depending on the necessity of the installation space of the detector.
[0064]
FIG. 9 is an explanatory diagram of another specific arrangement structure of the smoke detector shown in FIG. 2 having a solid angle arrangement. In FIG. 9, a first light emitting opening 9b, a second light emitting opening 10b, and a light receiving opening 11b are formed on the surface of the chamber base 20 constituting one end of the smoke detecting section on the side of the smoke detecting space. One light emitting element, a second light emitting element, and a light receiving element are incorporated.
[0065]
FIG. 10 is an explanatory diagram viewed from the back side of the chamber base 20 of FIG. 9, and a holder 21 is integrally formed on the back side of the chamber base 20, and the first light emission storage portion 9 c and the second light emission are provided on the back side of the holder 21. A receiving portion 11c is formed in the receiving portion 10c, and the first light emitting element, the second light emitting element, and the light receiving element are incorporated therein.
[0066]
FIG. 11 is a layout diagram of the entire smoke detector using a solid angle layout using the chamber base 20 of FIGS. 9 and 10. In FIG. 11, a chamber 24 is mounted on the upper portion of the chamber base 20, and the chamber 24 forms a labyrinth 23 around it, which blocks light from the outside and allows inflow of smoke. A smoke detection space is formed.
[0067]
In this cross-sectional view, the first light emitting element 9 and the light receiving element 11 are incorporated in the chamber base 20 because the cross section passes through the first light emitting opening 9b and the light receiving opening 11b in FIG. The optical axes 9 a and 11 a intersect three-dimensionally in the smoke detection space in the chamber 24. This also applies to the second light emitting element 10 incorporated in the second light emitting opening 10b.
[0068]
FIG. 12 is an explanatory diagram of a solid angle arrangement of the light emitting element and the light receiving element in FIG. FIG. 12A shows a solid angle arrangement of the first light emitting element 9, the second light emitting element 10 and the light receiving element 11 by the optical axes 9a, 10a and 11a.
[0069]
A point P where the optical axes 9a, 10a, 11a of the first light emitting element 9, the second light emitting element 10, and the light receiving element 11 intersect is present in the smoke detection space in the chamber 24 of FIG. The first light emitting element 9, the second light emitting element 10, and the light receiving element 11 are disposed in the chamber base 20 of FIG.
[0070]
FIG. 12B shows a solid angle arrangement between point A of the first light emitting element 9 and point C of the light receiving element 11. In this case, the plane including the optical axes 9a and 11a from the point A of the first light emitting element 9 and the point C of the light receiving element 11 is given by a triangle PCA, and the optical axis 9a and the optical axis 11a of the plane including the triangle PCA are provided. The angle formed is the first scattering angle θ1 of the first light emitting element 9.
[0071]
FIG. 12C shows a solid angle arrangement between point B of the second light emitting element 10 and point C of the light receiving element 11. In this case, the optical axes 10a and 11a exist on the plane including the triangular PCB, and the scattering angle formed by the optical axes 10a and 11a of the second light emitting element 10 and the light receiving element 11 is the optical axis 10a on the plane including the triangular PCB. Is given as a scattering angle θ2.
[0072]
According to the smoke detecting section structure having such a solid angle arrangement, the first light emitting element 9, the second light emitting element 10 and the light receiving element 11 are incorporated in the chamber base 20, and the intersection P of the respective optical axes is smoke detected. What is necessary is just to arrange | position so that it may become in space, As a result, the height of a smoke detection part can be made small and the size reduction of a sensor can be achieved.
[0073]
FIG. 13 is an explanatory view showing another embodiment of the smoke detector structure of the present invention in which the scattering angle and the polarization direction of two light emitting elements are different. In FIG. 13, in the smoke detector 8 of this embodiment, a first light emitting element 25, a second light emitting element 29, and a light receiving element 33 are arranged.
[0074]
The first light emitting element 25 is a light having a vertical polarization plane having a polarization plane perpendicular to the first scattering plane 27, where a plane passing through the optical axis 25 a and the optical axis 33 a of the light receiving element 33 is a first scattering plane 27. Issue 28.
[0075]
In this example, an LED is used as the first light emitting element 25. Therefore, a polarizing filter 26 is disposed in front of the first light emitting element 25, and light 28 having a polarization plane perpendicular to the first scattering surface 27 is emitted. ing. The first scattering angle θ1 formed by the optical axis 25a on the first scattering surface 27 of the first light emitting element 25 and the optical axis 33a of the light receiving element 33 is set to θ1 = 70 °, for example.
[0076]
On the other hand, when a plane passing through the optical axis 29 a of the second light emitting element 29 and the optical axis 33 a of the light receiving element 33 is a second scattering surface 31, the second light emitting element 29 is light having a polarization plane parallel to the second scattering surface 31. Issue 32. The second scattering angle θ2, which is an angle formed by the second scattering surface 31 of the optical axis 29a of the second light emitting element 29 and the optical axis 33a of the light receiving element 33, is larger than the first scattering angle θ1, for example, θ2 = 120 °. It is set.
[0077]
Since the second light emitting element 28 also uses an LED, a polarizing filter 31 is disposed in front of the second light emitting element 29 to emit light 32 having a horizontal polarization plane.
[0078]
In this way, the light P having the vertical polarization plane with respect to the first scattering surface 27 from the first light emitting element 25 and the light 32 having the horizontal polarization plane with respect to the second scattering surface 31 from the second light emitting element 29 are Scattered light traveling toward the light receiving element 33 due to smoke scattering is irradiated on the smoke particles as light 34 having a horizontal polarization plane parallel to the second scattering surface 31 for any light.
[0079]
FIG. 14 is a list of experimentally obtained results of the amount of received light signal with respect to the type of smoke when the scattering angle and the polarization angle are changed in the smoke detector structure of FIG. In FIG. 14, the scattering angles θ are 70 °, 90 °, and 120 °, and the case where the polarization angle φ is set to 0 ° (horizontal polarization) and 90 ° (vertical polarization) for each scattering angle θ is shown. ing.
[0080]
Further, the circuit block of the scattered light type smoke detector of the present invention in the smoke detection unit structure of FIG. 13 uses the same circuit block as that of the embodiment of FIG. 1, and the processing procedure of the detector follows the flowchart of FIG. Further, the same threshold can be used as the threshold for determining non-fire in step S8 and the threshold for determining whether white smoke fire or black smoke fire in step S9.
[0081]
The scattering angle is defined as the received light signal amount when light is emitted from the first light emitting element 25 and the light received signal amount when light is emitted from the second light emitting element 29 for each of the filter paper, kerosene, and tobacco smoke of FIG. The following can be seen by looking at θ and the polarization angle φ.
[0082]
First, with respect to the change in the scattering angle θ, the received light signal amount increases as the scattering angle decreases for both the vertically polarized light by the first light emitting element 25 and the horizontally polarized light by the second light emitting element 29. There is a relationship in which the signal amount decreases.
[0083]
On the other hand, when viewed at the same scattering angle θ, for example, 70 °, the amount of received light signal by the vertically polarized light by the first light emitting element 25 is larger than the amount of light received signal by the horizontally polarized light by the second light emitting element 29. I understand that.
[0084]
In the fire determination of the present invention, the ratio R of the received light signal amount A1 due to the light from the first light emitting element 25 and the received light signal amount A2 due to the light from the second light emitting element 29 is determined.
R = A1 / A2
To determine whether it is a fire or a non-fire, or a white smoke fire or a black smoke fire in the case of a fire.
[0085]
Here, in order to increase the ratio R, as the scattering angle θ in FIG. 14, for the first light emitting element 25, the smaller scattering angle θ1 = 70 ° at which the amount of received light signal increases is selected, and the second light emitting element 29 is selected. Is selected such that the scattering angle θ2 = 120 ° at which the amount of received light signal is small.
[0086]
On the other hand, in the case of horizontally polarized light and vertically polarized light at the same scattering angle, the amount of received light signal is larger with light with vertical polarization, and the amount of received light signal is smaller with light with horizontally polarized light. For the first light emitting element 25, vertical polarization with a polarization angle φ1 = 90 ° is selected in order to increase the received light signal amount, and for the second light emitting element 29, the polarization angle θ2 = 0 ° for decreasing the received light signal amount. Select the horizontally polarized light.
[0087]
Based on the measurement results for the scattering angle θ and the polarization angle φ as shown in FIG. 14, the embodiment of FIG.
(1) The first light emitting element 25 is vertically polarized light and has a first scattering angle θ1 = 70 °.
(2) The second light emitting element 29 is horizontally polarized light and the second scattering angle θ2 = 120 °.
Is set.
[0088]
15A and 15B show the received light signal amount A1 by the light from the first light emitting element 25 and the received light signal by the second light emitting element 29 with respect to the kind of the combustion product when the polarization direction and the scattering angle are set as in (1) and (2). The amount A2 is extracted from FIG. 14 and shown in a list, and a ratio R based on two signal amounts is calculated and shown.
[0089]
As is clear from the list of FIG. 15, the ratio R is small as 4.44 and 5.60 for fired combustibles such as filter paper and kerosene, while the ratio is 16 for non-fired tobacco. .47, and therefore, as shown in the flowchart of FIG. 6, it is possible to reliably identify fire or non-fire by determining the ratio R with threshold = 10 in step S8.
[0090]
Moreover, since the smoke resulting from the combustion of kerosene and filter paper in FIG. 15 belongs to a black smoke fire, by using threshold = 6 in step S9 of FIG. 6, the process proceeds to step S13 and is a black smoke fire (combustion fire). Can be identified. Of course, the cotton wick which is the smoke due to the smoldering fire shown in FIG. 5 is not shown in FIG. 15, but a value larger than kerosene is inevitably obtained as the ratio R, and therefore in step S9 of FIG. The ratio R is equal to or greater than the threshold value = 6, and it is determined in step S10 that a white smoke fire has occurred, and the fire is determined by 3 counts by the counter n.
[0091]
Here, in the embodiment of FIG. 13, a case where the first scattering angle θ1 = 70 ° of the first light emitting element 25 is taken as an example, but in practice, a value of θ1 = 80 ° or less may be used. . Further, the second configuration angle θ2 of the second light emitting element 29 is exemplified by θ2 = 120 °, but a practical value may be θ2 = 100 ° or more.
[0092]
Further, in the embodiment of FIG. 13, LEDs are used as the first light emitting element 25 and the second light emitting element 29, and light 28 having a vertical polarization plane and a horizontal polarization plane are combined with the polarization filters 26 and 30. If the laser diode that outputs polarized light is used for the first light emitting element 25 and the second light emitting element 29 instead of the light 32, the polarization filter 26, 30 becomes unnecessary.
[0093]
In the embodiment of FIG. 13, the wavelengths of the first light emitting element and the second light emitting element are set to be equal. However, the smoke identification accuracy can be further improved by making the wavelengths different.
[0094]
As another embodiment of the smoke detector structure in which the wavelengths and scattering angles of the two light emitting elements in FIG. 2 are different, a configuration in which the relationship between the wavelength and the scattering angle in the first light emitting element 9 and the second light emitting element 10 can be maintained. If so, two light receiving elements may be provided for two light emitting elements.
[0095]
Further, by using a light emitting element having a broad emission spectrum such as an incandescent bulb or white LED as the light emitting element, one light emitting element is provided, and a wavelength switching filter is provided on this light emitting element, and the first light emitting element 9 and the first light emitting element in FIG. The present invention can be implemented by setting the optical path so that light is emitted from the arrangement position of the two light emitting elements 10.
[0096]
Further, in the smoke detector structure of the present invention in which the scattering angle and the polarization direction of the two light emitting elements shown in FIG. 13 are different, two different light receiving elements are provided for two light emitting elements having different polarization planes. It may be. The polarization plane of light emitted from the two light emitting elements is changed by changing the plane of polarization by mechanically rotating the polarization filters 26 and 30 in FIG. 13 or driving the liquid crystal filter. The optimum detection state can be obtained by adjusting appropriately.
[0097]
【The invention's effect】
As described above, according to the present invention, the scattering angle with respect to the light receiving element is made different between the two light emitting elements, thereby creating a difference in scattering characteristics depending on the type of smoke, and at the same time, changing the wavelength of light emitted from the two light emitting elements. This creates a difference in the scattering characteristics due to the wavelength, and the synergistic effect of the difference in the scattering angle and the difference in the wavelength gives a noticeable difference in the light intensity of the scattered light depending on the type of smoke. It is possible to prevent non-fire reports due to cooking steam and cigarette smoke, and to reliably identify the types of combustion products such as black smoke fire and white smoke fire.
[0098]
In another embodiment of the present invention, the polarization planes of the light emitted from the two light emitting elements are different from each other to create a difference in scattering characteristics due to the polarization direction of the light, and at the same time, the two light emitting elements. Different scattering angles with respect to the light receiving element create a difference in scattering characteristics depending on the type of smoke, and a synergistic effect of this difference in polarization direction and difference in scattering angle results in a significant difference in the light intensity of scattered light due to the type of smoke. This will increase the accuracy of smoke identification and reliably prevent non-fire reports caused by cooking steam and cigarette smoke, etc. The type can be reliably identified.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of a scattered light smoke detector according to the present invention.
FIG. 2 is an explanatory view showing an embodiment of a smoke detector structure according to the present invention in which the wavelengths and scattering angles of two light emitting elements are made different from each other.
FIG. 3 is a graph showing the scattering efficiency of light from two light emitting elements with respect to the scattering angle of the smoke detection section of FIG.
4 is a graph showing the scattering efficiency of light from two light emitting elements with respect to the scattering angle of the smoke detector of FIG. 2 in kerosene combustion smoke.
5 and FIG. 4 show the received light signal amount when the wavelength of the first light emitting element is 900 nm, the scattering angle θ1 is 30 °, the wavelength of the second light emitting element is 500 nm, and the scattering angle θ1 is 120 °. Explanatory diagram showing the ratio
6 is a flowchart of fire detection processing by the circuit block of FIG. 1 using the smoke detector of FIG.
7 is an explanatory diagram of a specific arrangement structure of the smoke detector section of FIG.
FIG. 8 is an explanatory diagram of another specific arrangement structure of the smoke detector in FIG.
FIG. 9 is an explanatory diagram of another specific arrangement structure of the smoke detector shown in FIG. 2 having a solid angle arrangement;
10 is an explanatory view of the chamber base of FIG. 9 viewed from the back side.
11 is a cross-sectional view of the entire smoke detector using the chamber base of FIG. 9;
12 is an explanatory diagram of a solid angle arrangement of a light emitting element and a light receiving element in FIG.
FIG. 13 is an explanatory view showing another embodiment of the smoke detector structure of the present invention in which the scattering angle and the polarization direction of two light emitting elements are made different from each other.
14 is an explanatory diagram showing the amount of received light signal with respect to the type of smoke when the scattering angle and the polarization angle are changed in the smoke detecting unit structure of FIG. 13;
15 shows that the scattering angle θ1 of the first light emitting element is 70 °, the deflection angle is 90 ° (vertical), the scattering angle θ1 of the second light emitting element is 120 °, and the deflection angle is 0 ° (horizontal). Explanatory diagram showing the amount of received light signal and its ratio for the type of smoke
[Explanation of symbols]
1: Scattered light smoke detector
2: Notification circuit
3: Signal processor
4: Storage unit
5: 1st light emission control part
6: Second light emission control unit
7: Amplifier circuit
8: Smoke detector
9, 25: 1st light emitting element
10, 29: Second light emitting device
11, 33: Light receiving element
9a, 10a, 11a: optical axis
17, 18, 19: Shading plate
20: Chamber base
21: Holder
22: Smoke detector
23: Labyrinth
24: Chamber
26, 30: Polarizing filter
27: First scattering surface
28: Light having a vertical polarization plane
31: Second scattering surface
32, 34: Light having a horizontal polarization plane

Claims

Directly receiving light emitted from the first light-emitting element and the second light-emitting element toward the smoke detection space, the first light-emitting element that emits the first wavelength, the second light-emitting element that emits a second wavelength different from the first wavelength In a scattered light type smoke detector provided with a light receiving element provided at a position where
A second scattering angle constituted by the intersection of the optical axis of the second light emitting element and the light receiving element is made larger than a first scattering angle constituted by the intersection of the optical axis of the first light emitting element and the light receiving element;
A scattered light smoke detector, wherein the second wavelength emitted from the second light emitting element is shortened with respect to the first wavelength emitted from the first light emitting element.

2. The scattered light smoke detector according to claim 1 , wherein an optical axis composed of the first light emitting element and the light receiving element and an optical axis composed of the second light emitting element and the light receiving element exist on the same plane. The scattered light type smoke detector is characterized in that the first light emitting element, the second light emitting element and the light receiving element are arranged in a plane angle.

2. The scattered light smoke detector according to claim 1 , wherein an optical axis composed of the first light emitting element and the light receiving element and an optical axis composed of the second light emitting element and the light receiving element exist on the same plane. The scattered light smoke detector is characterized in that the first light emitting element, the second light emitting element and the light receiving element are arranged in a solid angle.

The scattered light type smoke detector according to claim 1 , wherein the type of smoke is identified by comparing the amount of smoke scattered by the first light emitting element with the amount of smoke scattered by the second light emitting element. Scattered light type smoke detector, characterized in that a fire judgment is made according to a judgment standard according to the type of the light.

5. The scattered light type smoke sensor according to claim 4 , wherein the threshold value is changed according to the type of smoke.

5. The scattered light type smoke detector according to claim 4 , wherein the judgment standard sets a count number for judging a fire according to a kind of smoke.

In claims 2 to 6 light scattering type smoke sensor, wherein, in the normal monitoring state, only the first light emitting element is driven, when the predetermined light receiving output from said light receiving element is obtained, the second light emitting Scattered light type smoke detector characterized by driving element.

In the scattered light type smoke detector according to claim 1,
A first scattering angle constituted by the intersection of the optical axes of the first light emitting element and the light receiving element is set in a range of 20 ° to 50 °, and a second constituted by the intersection of the optical axes of the second light emitting element and the light receiving element. The scattering angle is set in the range of 100 ° to 150 °,
A scattered light smoke detector, characterized in that the center wavelength of the first wavelength emitted from the first light emitting element is set to 800 nm or more, and the center wavelength of the second wavelength emitted from the second light emitting element is set to 500 nm or less .