JP2966541B2 - Photoelectric smoke detector - Google Patents
Photoelectric smoke detectorInfo
- Publication number
- JP2966541B2 JP2966541B2 JP2127891A JP2127891A JP2966541B2 JP 2966541 B2 JP2966541 B2 JP 2966541B2 JP 2127891 A JP2127891 A JP 2127891A JP 2127891 A JP2127891 A JP 2127891A JP 2966541 B2 JP2966541 B2 JP 2966541B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- circuit
- light receiving
- optical axis
- output
- 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
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、建物内外で火災時など
に発生する煙を感知する光電式煙感知器に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric smoke detector for detecting smoke generated in a fire or the like inside or outside a building.
【０００２】[0002]
【従来の技術】従来より、煙感知器として煙粒子による
光の散乱を利用した光電式煙感知器が提供されている
（特開昭５６−１４７２９４号公報、実開昭５８−１７
１５９１号公報、特開昭６０−１０９１８９号公報、実
開昭６０−１３４４９号公報、実開昭６２−２０３５８
号公報等参照）。すなわち、図１２に示すように、投光
素子１と受光素子２とを光軸が交差するように配置し、
投光素子１から監視空間に照射された光の煙粒子Ｐによ
る散乱光を受光素子２で受光するように構成したもので
ある。このように構成された光電式煙感知器では、監視
空間に煙粒子Ｐが存在すれば散乱光が生じることによっ
て受光素子２での受光量が増大するから、受光素子２で
の受光量の大小に応じて煙粒子３の存否を検知できるの
である。2. Description of the Related Art Conventionally, photoelectric smoke detectors utilizing light scattering by smoke particles have been provided as smoke detectors (Japanese Patent Application Laid-Open No. 56-147294, Japanese Utility Model Application Laid-Open No. 58-17).
No. 1591, JP-A-60-109189, JP-A-60-13449, JP-A-62-20358
Reference). That is, as shown in FIG. 12, the light projecting element 1 and the light receiving element 2 are arranged so that the optical axes intersect,
The light receiving element 2 receives light scattered by the smoke particles P of light emitted from the light projecting element 1 to the monitoring space. In the photoelectric smoke detector configured as described above, if smoke particles P exist in the monitoring space, the amount of light received by the light receiving element 2 increases due to the generation of scattered light. , The presence or absence of the smoke particles 3 can be detected.
【０００３】また、本発明者らは図１３に示すように、
１個の投光素子１に対して複数個の受光素子２ａ，２ｂ
を設けたものを提案している。この構成は、散乱光の強
度の角度分布が煙粒子Ｐの粒径に依存するという理論に
基づくものであり、複数の受光素子２ａ，２ｂを設けた
ことによって煙粒子Ｐの粒径を判定し、異なる粒径を有
した微粒子との識別をするものである。この構成では、
図１４に示すように、発光素子１を駆動回路１１によっ
て駆動し、図１５に示すように間欠的に発光させるよう
になっており、各受光素子２ａ，２ｂから出力される受
光信号を受光回路２１ａ，２１ｂで電圧出力に変換した
後、対数増幅回路２２ａ，２２ｂで対数増幅するように
なっている。すなわち、２個の受光素子２ａ，２ｂから
出力される受光信号を対数増幅した後に、減算回路２３
によって両対数増幅回路２２ａ，２２ｂの出力の差を求
めることにより、両受光素子２ａ，２ｂによる受光強度
の比を求めるのである。減算回路２３による演算は、発
光素子１の各発光毎に同期するように、発振回路１２お
よび論理回路１３よりなる発光制御手段によって制御さ
れ、減算回路２３による演算結果は、比較回路２４より
なる判定手段に入力されて受光強度の比が所定値と比較
されるようになっている。このようにして得られた比較
回路２４による判定結果に基づき、信号処理回路２５を
通して出力回路２６を作動させるのである。[0003] Further, as shown in FIG.
A plurality of light receiving elements 2a and 2b for one light emitting element 1
Is proposed. This configuration is based on the theory that the angular distribution of the intensity of the scattered light depends on the particle size of the smoke particles P. By providing a plurality of light receiving elements 2a and 2b, the particle size of the smoke particles P is determined. This is to distinguish the particles from fine particles having different particle diameters. In this configuration,
As shown in FIG. 14, the light emitting element 1 is driven by the driving circuit 11 to emit light intermittently as shown in FIG. 15, and the light receiving signals output from the respective light receiving elements 2a and 2b are received by the light receiving circuit. After conversion into voltage output by 21a and 21b, logarithmic amplification is performed by logarithmic amplifier circuits 22a and 22b. That is, after the light receiving signals output from the two light receiving elements 2a and 2b are logarithmically amplified, the subtraction circuit 23
By calculating the difference between the outputs of the double logarithmic amplifier circuits 22a and 22b, the ratio between the light receiving intensities of the two light receiving elements 2a and 2b is determined. The calculation by the subtraction circuit 23 is controlled by a light emission control unit including the oscillation circuit 12 and the logic circuit 13 so as to synchronize with each light emission of the light emitting element 1. The ratio of the received light intensity inputted to the means is compared with a predetermined value. The output circuit 26 is operated through the signal processing circuit 25 based on the result of the judgment by the comparison circuit 24 obtained in this way.
【０００４】[0004]
【発明が解決しようとする課題】上述した前者の構成で
は、受光素子２による受光量の大小に基づいて煙粒子Ｐ
の存否を判定するものであるから、監視空間に侵入した
虫による反射光や水蒸気等の他の微粒子による散乱光
と、煙粒子による散乱光との識別ができないものであ
り、誤認が生じ易いという問題がある。また感知器の内
部で生じる反射光が受光素子２に常時入射しているもの
であるから、暗雑音が多くなり信号対雑音比を大きくと
ることができず、ノイズマージンが小さいという問題が
ある。In the former configuration, the smoke particles P are determined based on the amount of light received by the light receiving element 2.
It is not possible to distinguish between reflected light from insects that have entered the monitoring space, scattered light from other fine particles such as water vapor, and scattered light from smoke particles, and misidentification is likely to occur. There's a problem. Further, since the reflected light generated inside the sensor is always incident on the light receiving element 2, there is a problem that the background noise increases, the signal-to-noise ratio cannot be increased, and the noise margin is small.
【０００５】これに対して、後者の構成では、煙粒子Ｐ
の粒径を判定しているから、虫による反射光や他の微粒
子による散乱光との識別ができ、しかも、散乱光の強度
の角度分布に基づいて煙粒子Ｐの存否の判定を行うか
ら、暗雑音による影響がほとんどないのであって、前者
の構成の欠点はほぼ解消されることになる。一方、複数
個の受光素子２ａ，２ｂを用いるものであるから、受光
回路２１ａ，２１ｂや対数増幅回路２２ａ，２２ｂも受
光素子２ａ，２ｂと同数必要になるものである。しかし
ながら、受光強度の比を正確に求めるために対数増幅器
２２ａ，２２ｂの温度特性などを揃えるのは非常に困難
であるという問題がある。また、散乱光の受光強度は非
常に小さいものであり、たとえば受光素子２ａ，２ｂと
して一般的なフォトダイオードを用いている場合には、
検知すべき最低量の散乱光に対しては数ｐＡ程度の出力
電流しか得られないものである。すなわち、受光素子２
ａ，２ｂの出力電流は微小であるから、受光回路２１
ａ，２１ｂを低ノイズに設計する必要があり、複数の受
光回路２１ａ，２１ｂを設けるとコスト高につながると
いう問題が生じる。On the other hand, in the latter configuration, the smoke particles P
Since the particle diameter of the particles is determined, it is possible to distinguish the reflected light from insects and the scattered light from other fine particles, and to determine the presence or absence of the smoke particles P based on the angular distribution of the intensity of the scattered light. Since the influence of the background noise is almost negligible, the disadvantage of the former configuration is almost eliminated. On the other hand, since a plurality of light receiving elements 2a and 2b are used, the same number of light receiving circuits 21a and 21b and logarithmic amplifier circuits 22a and 22b are required as the light receiving elements 2a and 2b. However, there is a problem that it is very difficult to make the temperature characteristics of the logarithmic amplifiers 22a and 22b uniform in order to accurately obtain the ratio of the received light intensity. Also, the light receiving intensity of the scattered light is very small. For example, when a general photodiode is used as the light receiving elements 2a and 2b,
With respect to the minimum amount of scattered light to be detected, only an output current of about several pA can be obtained. That is, the light receiving element 2
Since the output currents a and 2b are very small, the light receiving circuit 21
It is necessary to design a and 21b with low noise, and if a plurality of light receiving circuits 21a and 21b are provided, there arises a problem that the cost increases.
【０００６】本発明は上記問題点の解決を目的とするも
のであり、散乱光によって煙粒子の粒径を識別すること
により、水蒸気等の煙以外の微粒子による散乱光や虫等
による反射光での誤検知を防止するとともに、感知器の
内部での反射光による暗雑音の影響を低減してノイズマ
ージンが大きく取れるようにし、しかも、受光手段を１
つにすることによって、温度特性がよく、比較的安価で
ある光電式煙感知器を提供しようとするものである。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem. By identifying the particle size of smoke particles based on scattered light, it is possible to obtain light scattered by fine particles other than smoke such as water vapor or reflected light by insects. Erroneous detection is prevented, the influence of dark noise due to reflected light inside the sensor is reduced, and a large noise margin can be obtained.
The present invention intends to provide a photoelectric smoke detector which has good temperature characteristics and is relatively inexpensive.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するため
に、請求項１では、監視空間に光を照射する複数個の投
光手段と、監視空間内に煙粒子が存在するときに生じる
散乱光を受光する受光手段と、受光手段から出力される
受光信号に基づいて監視空間内の煙粒子の存否を判定す
る受光信号処理手段と、各投光手段から監視空間に対し
て互いに異なる時刻に光が照射されるように各投光手段
の発光タイミングを設定する発光制御手段とを備え、各
投光手段は、光軸が受光手段の光軸に対してそれぞれ所
定の角度をなすように配置され、受光信号処理手段は、
各投光手段から監視空間に照射される光に対する散乱光
の受光手段による受光強度の比を求める比演算部と、求
めた比に基づいて煙粒子の存否を判定する判定部とを備
えているのである。In order to achieve the above object, according to the present invention, a plurality of light projecting means for irradiating light to a monitoring space, and scattering generated when smoke particles are present in the monitoring space. Light receiving means for receiving light; light receiving signal processing means for determining the presence or absence of smoke particles in the monitoring space based on the light receiving signal output from the light receiving means; Light-emission control means for setting the light-emission timing of each light-projection means so that light is emitted, and each light-emission means is arranged such that the optical axis forms a predetermined angle with respect to the optical axis of the light-receiving means. And the received light signal processing means
A ratio calculation unit for calculating a ratio of a received light intensity of the scattered light to a light emitted to the monitoring space from each of the light projecting units; and a determination unit for determining the presence or absence of smoke particles based on the determined ratio. It is.
【０００８】請求項２では、投光手段は２個設けられ、
比演算部は、受光信号を対数増幅する対数増幅回路と、
対数増幅回路の出力を記憶する記憶回路と、対数増幅回
路の出力と記憶回路の記憶値との差を出力する減算回路
と、発光制御手段による各投光手段の発光タイミングに
同期して一方の投光手段の発光時に対数増幅回路の出力
を記憶回路に入力し、他方の投光手段の発光時に対数増
幅回路の出力を減算回路に入力するように切り換えるス
イッチ要素とを備えているのである。According to claim 2, two light projecting means are provided,
The ratio calculation unit includes a logarithmic amplification circuit that logarithmically amplifies the received light signal,
A storage circuit that stores the output of the logarithmic amplifier circuit, a subtraction circuit that outputs the difference between the output of the logarithmic amplifier circuit and the storage value of the storage circuit, and one of the light emission control units in synchronization with the light emission timing of each light emitting unit. There is provided a switch element for inputting the output of the logarithmic amplifier circuit to the storage circuit when the light emitting means emits light and for inputting the output of the logarithmic amplifier circuit to the subtraction circuit when the other light emitting means emits light.
【０００９】請求項３では、各投光手段の光軸と受光手
段の光軸との各交点から各投光手段までの距離が、各投
光手段ごとに異なるように各投光手段を配置しているの
である。請求項４では、各投光手段より監視空間に照射
される光の波長がそれぞれ異なるように設定してある。According to a third aspect of the present invention, each light projecting means is arranged such that the distance from each intersection of the optical axis of each light projecting means and the optical axis of the light receiving means to each light projecting means is different for each light projecting means. It is doing. According to the fourth aspect, the wavelength of the light emitted from each light emitting means to the monitoring space is set to be different from each other.
【００１０】[0010]
【作用】請求項１の構成によれば、煙粒子による散乱光
の強度の角度分布に基づいて煙粒子の粒径を求め、粒径
が所定の範囲以内であるときに煙粒子が存在すると判断
することができるから、散乱光を生じている煙粒子の粒
径が反映されることになり、煙粒子以外の微粒子による
散乱光や他の物体による反射光と、煙粒子による散乱光
とを識別できるようになり、誤検知を防止することがで
きるのである。また、散乱光の強度の角度分布によって
粒径を判定するから、受光強度の比を求めることができ
ればよいのであって、感知器の内部で生じる反射光など
による暗雑音の影響を受けにくく、ノイズマージンが大
きく取れるのである。さらに、受光手段は１つであるか
ら、受光信号の増幅などを行う回路を複数設ける必要が
ないのであって、複数系統の回路の温度特性を揃えた
り、低ノイズの回路を複数用いたりすることによるコス
ト増が抑制されるのである。According to the first aspect of the present invention, the particle size of the smoke particle is determined based on the angular distribution of the intensity of the scattered light by the smoke particle, and it is determined that the smoke particle exists when the particle size is within a predetermined range. Can reflect the particle size of the smoke particles that generate the scattered light, and distinguish between the scattered light by fine particles other than the smoke particles and the reflected light by other objects and the scattered light by the smoke particles It is possible to prevent erroneous detection. Also, since the particle size is determined based on the angular distribution of the intensity of the scattered light, it is only necessary to be able to determine the ratio of the received light intensity, and it is hardly affected by dark noise due to reflected light or the like generated inside the sensor. The margin is large. Furthermore, since there is only one light receiving means, there is no need to provide a plurality of circuits for amplifying the light receiving signal, etc. Therefore, it is necessary to make the temperature characteristics of a plurality of circuits uniform or to use a plurality of low noise circuits. The cost increase due to the above is suppressed.
【００１１】請求項２の構成は、望ましい実施態様であ
って、この構成によれば、対数増幅回路が１つになるか
ら、従来のように複数の対数増幅回路の温度特性を揃え
る必要がなく、設計が容易になるのである。請求項３の
構成では、各投光手段の光軸と受光手段の光軸との交点
までの距離を各投光手段ごとに異なるように設定してい
るのであって、各投光手段から照射された光の散乱光が
受光手段に対してほぼ同じ強度で入射するように距離を
設定しておけば、受光信号処理回路のダイナミックレン
ジを小さくすることができるのであり、設計が容易にな
るのである請求項４の構成では、各投光手段からの照射
光の波長を異ならせているので、各投光手段の光軸と受
光手段の光軸との交差角度を別々に設定することなく、
粒径を判定できることになる。The structure of claim 2 is a desirable embodiment. According to this structure, since only one logarithmic amplifier circuit is used, it is not necessary to make the temperature characteristics of a plurality of logarithmic amplifier circuits uniform as in the related art. , Making the design easier. In the configuration of claim 3, the distance to the intersection of the optical axis of each light projecting means and the optical axis of the light receiving means is set differently for each light projecting means. If the distance is set so that the scattered light of the received light is incident on the light receiving means with almost the same intensity, the dynamic range of the light receiving signal processing circuit can be reduced, and the design becomes easier. In the configuration of certain claim 4, since the wavelength of the irradiation light from each light projecting means is made different, without separately setting the intersection angle between the optical axis of each light projecting means and the optical axis of the light receiving means,
The particle size can be determined.
【００１２】[0012]
【実施例】（原理）構成を具体的に説明する前に、本発
明の原理について説明する。本発明は、微粒子による散
乱光の強度の角度分布が、照射光の波長および微粒子の
粒径に依存するというＭｉｅの散乱理論に基づいてなさ
れている。ここで、パラメータが２個あると扱いにくい
ので、照射光の波長λと、微粒子の粒径Ｄとを折り込ん
だ粒径パラメータαを、α＝πＤ／λと定義して１つの
パラメータで議論できるようにする。DESCRIPTION OF THE PREFERRED EMBODIMENTS (Principle) Before describing the configuration in detail, the principle of the present invention will be described. The present invention is based on Mie's scattering theory that the angular distribution of the intensity of the scattered light by the fine particles depends on the wavelength of the irradiation light and the particle size of the fine particles. Here, since it is difficult to handle if there are two parameters, the particle diameter parameter α obtained by folding the wavelength λ of the irradiation light and the particle diameter D of the fine particles can be defined as α = πD / λ and discussed with one parameter. To do.
【００１３】このようにして定義した粒径パラメータα
を０．３、２、５、１０と設定した場合の散乱光の強度
の角度分布は、それぞれ図３ないし図６のようになる。
ただし、粒子は水であって屈折率を１．３３としてい
る。また、図中の実線は投光手段の光軸と受光手段の光
軸とを含む平面に垂直な方向の偏光成分のみの強度を示
し、破線は上記平面に平行な方向の偏光成分のみの強度
を示したものである。受光手段の前に偏光フィルタのよ
うな偏光成分を抽出する手段を設けない場合には、偏光
方向を考慮する必要がなく、破線と実線との平均値が散
乱光の強度分布になる。The particle diameter parameter α thus defined
Are set to 0.3, 2, 5, and 10, the angular distribution of the intensity of the scattered light is as shown in FIGS.
However, the particles are water and have a refractive index of 1.33. Also, the solid line in the figure indicates the intensity of only the polarization component in the direction perpendicular to the plane including the optical axis of the light projecting means and the optical axis of the light receiving means, and the broken line indicates the intensity of only the polarization component in the direction parallel to the plane. It is shown. When a means for extracting a polarized light component such as a polarizing filter is not provided before the light receiving means, it is not necessary to consider the polarization direction, and the average value of the dashed line and the solid line becomes the intensity distribution of the scattered light.
【００１４】また、偏光方向を考慮しない場合において
投光手段の光軸に対する受光手段の光軸がなす角度が４
５度である位置と１３５度である位置との散乱光の強度
の比と、粒径パラメータとの関係を図７に示す。ここ
に、粒子は水であって屈折率ｍを１．３３としている。
また、屈折率が異なる場合（ｍ＝１．４４、ｍ＝１．５
５）について、ｍ＝１．３３の場合と対比できるよう
に、図８に示している。When the polarization direction is not considered, the angle formed by the optical axis of the light receiving means with respect to the optical axis of the light projecting means is 4 degrees.
FIG. 7 shows the relationship between the ratio of the intensity of the scattered light between the position of 5 degrees and the position of 135 degrees and the particle diameter parameter. Here, the particles are water and the refractive index m is 1.33.
When the refractive indexes are different (m = 1.44, m = 1.5
FIG. 8 shows 5) so that it can be compared with the case where m = 1.33.
【００１５】さらに、図９には、投光手段の光軸に対す
る受光手段の光軸のなす角度が２０度と５０度である場
合の強度の比と、粒径パラメータとの関係を示し、図１
０には、２０度と６０度である場合の強度の比と、粒径
パラメータとの関係を示している。図９および図１０で
は、いろいろな屈折率についての関係を示してあり、屈
折率が変わってもほぼ同じ傾向を示すことがわかる。FIG. 9 shows the relationship between the intensity ratio and the particle diameter parameter when the angle between the optical axis of the light receiving means and the optical axis of the light projecting means is 20 degrees and 50 degrees. 1
0 indicates the relationship between the intensity ratio at 20 degrees and 60 degrees and the particle size parameter. FIGS. 9 and 10 show the relationship between various refractive indexes, and it can be seen that the same tendency is exhibited even when the refractive index changes.
【００１６】いま、粒径パラメータを４とすれば、照射
光の波長が０．９μｍであるときには、粒径パラメータ
の定義式によって、粒径は１．１４μｍになり、また、
光通信分野において近年用いられている波長１．５５μ
ｍの投光素子によって照射光を得るようにすれば、粒径
は１．９７μｍになる。煙粒子の粒径は０．１〜１μｍ
であるから、粒径パラメータを適宜設定し、２箇所で検
知した散乱光の強度の比を求めれば、煙粒子と他の粒子
との識別ができるのである。Assuming that the particle diameter parameter is 4, when the wavelength of the irradiation light is 0.9 μm, the particle diameter becomes 1.14 μm according to the definition formula of the particle diameter parameter.
1.55 μm wavelength recently used in the optical communication field
When the irradiation light is obtained by the m light projecting elements, the particle diameter becomes 1.97 μm. Smoke particle size is 0.1-1μm
Therefore, if the particle size parameter is appropriately set and the ratio of the intensity of the scattered light detected at two locations is determined, the smoke particles can be distinguished from other particles.
【００１７】（実施例１）図１（Ａ）に本実施例の光学
系の構成を示す。投光手段は２個設けられ、それぞれ投
光素子１ａ，１ｂと投光レンズ３ａ，３ｂとにより構成
される。投光素子１ａ，１ｂには、発光ダイオード、半
導体レーザ、キセノンランプ等が用いられる。投光レン
ズ３ａ，３ｂは集光レンズであって、投光素子１ａ，１
ｂからの照射光を煙粒子Ｐが導入される監視空間に導
く。監視空間に存在する煙粒子Ｐによって生じる散乱光
は受光手段に入射する。受光手段は、集光レンズである
受光レンズ４と受光素子２とからなる。受光素子２に
は、フォトトランジスタ、フォトダイオード、フォトダ
イオードと受光信号処理回路が一体化された集積回路等
が用いられる。ここに、各投光手段の光軸Ｘ1 ，Ｘ2 と
受光手段の光軸Ｘ0 とは所定の角度をなすように配置さ
れる。(Embodiment 1) FIG. 1A shows the configuration of an optical system according to this embodiment. Two light projecting means are provided, each including light projecting elements 1a and 1b and light projecting lenses 3a and 3b. Light emitting diodes, semiconductor lasers, xenon lamps and the like are used for the light emitting elements 1a and 1b. The light projecting lenses 3a and 3b are condensing lenses,
The irradiation light from b is guided to the monitoring space where the smoke particles P are introduced. The scattered light generated by the smoke particles P existing in the monitoring space enters the light receiving means. The light receiving means includes a light receiving lens 4 as a condenser lens and a light receiving element 2. As the light receiving element 2, a phototransistor, a photodiode, an integrated circuit in which the photodiode and a light receiving signal processing circuit are integrated, or the like is used. Here, the optical axes X 1 and X 2 of the light projecting means and the optical axis X 0 of the light receiving means are arranged at a predetermined angle.
【００１８】各投光素子１ａ，１ｂは、それぞれ図２に
示すように、間欠的に発光するように発光タイミングが
設定されている（ａは投光素子１ａの発光タイミング、
ｂは投光素子１ｂの発光タイミングを示す）。すなわ
ち、図１（Ｂ）に示すように、発振回路１２より出力さ
れるパルスを論理回路１３に入力して図２のような２系
統のタイミングパルスを生成するのであって、発振回路
１２と論理回路１３とにより発光タイミング制御手段が
構成される。各タイミングパルスは、駆動回路１１ａ，
１１ｂを通してそれぞれ投光素子１ａ，１ｂに入力され
る。As shown in FIG. 2, each of the light emitting elements 1a and 1b is set to emit light intermittently (a is the light emitting timing of the light emitting element 1a,
b indicates the light emission timing of the light emitting element 1b). That is, as shown in FIG. 1B, a pulse output from the oscillation circuit 12 is input to a logic circuit 13 to generate two timing pulses as shown in FIG. The circuit 13 constitutes a light emission timing control unit. Each timing pulse is supplied to the drive circuit 11a,
The light is input to the light projecting elements 1a and 1b through the light emitting element 11b.
【００１９】一方、受光素子２から出力される受光信号
は、受光信号処理手段によって処理される。受光信号処
理手段では、受光信号を受光回路２１において受光量に
対応した電圧出力に変換した後、対数増幅回路２２によ
って対数増幅する。対数増幅回路２２の出力は、論理回
路１３より出力されるタイミングパルスによって制御さ
れるスイッチ要素２７を通して減算回路２３と記憶回路
２８とに選択的に入力される。たとえば、投光素子１ａ
が点灯しているときには、対数増幅回路２２の出力を記
憶回路２８に入力して記憶保持するようにし、投光素子
１ｂが点灯しているときには、対数増幅回路２２の出力
を減算回路２３に入力するのである。減算回路２３で
は、対数増幅回路２２の出力が入力されている期間に、
記憶回路２８の記憶値との差を演算して出力する。ま
た、記憶回路２８では次の値が入力されると、前の値は
消去されるようになっている。このようにして得られた
減算回路２３の出力値は、各投光素子１ａ，１ｂが点灯
していたときの受光素子２での受光強度の比の対数にな
る。すなわち、対数増幅回路２２、減算回路２３、スイ
ッチ要素２７、記憶回路２８により、受光量の比を求め
る比演算部が構成されるのである。ここにおいて、スイ
ッチ要素２７は、投光素子１ａ，１ｂの点灯期間に生じ
る散乱光のみが受光側で処理されるようにすることによ
って、外乱光による雑音成分を除去するようにしてあ
る。On the other hand, the light receiving signal output from the light receiving element 2 is processed by the light receiving signal processing means. In the light receiving signal processing unit, the light receiving signal is converted into a voltage output corresponding to the amount of received light in the light receiving circuit 21 and then logarithmically amplified by the logarithmic amplifier 22. The output of the logarithmic amplification circuit 22 is selectively input to a subtraction circuit 23 and a storage circuit 28 through a switch element 27 controlled by a timing pulse output from the logic circuit 13. For example, the light emitting element 1a
When is turned on, the output of the logarithmic amplifier 22 is input to the storage circuit 28 to be stored and stored. When the light emitting element 1b is turned on, the output of the logarithmic amplifier 22 is input to the subtraction circuit 23. You do it. In the subtraction circuit 23, while the output of the logarithmic amplifier circuit 22 is being input,
The difference from the value stored in the storage circuit 28 is calculated and output. When the next value is input to the storage circuit 28, the previous value is deleted. The output value of the subtraction circuit 23 obtained in this way is the logarithm of the ratio of the received light intensity at the light receiving element 2 when each of the light emitting elements 1a and 1b is lit. That is, the logarithmic amplification circuit 22, the subtraction circuit 23, the switch element 27, and the storage circuit 28 constitute a ratio calculation unit for calculating the ratio of the amount of received light. Here, the switch element 27 removes noise components due to disturbance light by processing only the scattered light generated during the lighting period of the light emitting elements 1a and 1b on the light receiving side.
【００２０】減算回路２３の出力は、比較回路２４に入
力され、減算回路２３の出力値が、あらかじめ設定され
ている所定の範囲内であるかどうかが判定される。所定
の範囲内であるときには信号処理回路２５を介して出力
回路２６を作動させる。すなわち、比較回路２４は監視
空間における煙粒子の存否を判定する判定部として機能
するのである。ここに、比較回路２４の設定値は可変抵
抗ＶＲにより調節可能となっている。The output of the subtraction circuit 23 is input to the comparison circuit 24, and it is determined whether or not the output value of the subtraction circuit 23 is within a predetermined range. When it is within the predetermined range, the output circuit 26 is operated via the signal processing circuit 25. That is, the comparison circuit 24 functions as a determination unit that determines the presence or absence of smoke particles in the monitoring space. Here, the set value of the comparison circuit 24 can be adjusted by the variable resistor VR.
【００２１】（実施例２）実施例１の構成では、投光手
段の光軸Ｘ1,Ｘ2 と、受光手段の光軸Ｘ0 とが１点で交
差するようにし、この交点から各投光手段までの距離を
等しく設定していたが、図３ないし図６によって明らか
なように、光軸Ｘ1,Ｘ2 と光軸Ｘ0 との交差角度が小さ
いほど、受光手段での受光強度が大きくなる傾向があ
る。２つの交差角度の関係や粒子の粒径にもよるが、粒
径パラメータが４であれば、交差角度が２０度と５０度
とのときには、図９に示したように、受光量がほぼ１桁
異なることになる。したがって、受光回路２１、対数増
幅器２２などには、広いダイナミックレンジが要求され
る。(Embodiment 2) In the configuration of Embodiment 1, the optical axes X 1 , X 2 of the light projecting means and the optical axis X 0 of the light receiving means intersect at one point, and each of the projections starts from this intersection. Although the distance to the light means was set equal, as is apparent from FIGS. 3 to 6, the smaller the intersection angle between the optical axes X 1 , X 2 and the light axis X 0 , the more the light receiving intensity at the light receiving means. Tends to be large. Although depending on the relationship between the two intersection angles and the particle size of the particles, if the particle size parameter is 4, when the intersection angles are 20 degrees and 50 degrees, as shown in FIG. Will be orders of magnitude different. Therefore, a wide dynamic range is required for the light receiving circuit 21, the logarithmic amplifier 22, and the like.
【００２２】そこで、図１１に示すように、光軸Ｘ1,Ｘ
2 と光軸Ｘ0 との交差角度の小さい方、この例では受光
手段の光軸Ｘ0 に対する交差角度が２０度の投光手段１
ａを交差角度が５０度の投光手段１ｂよりも交点から例
えば２倍の距離に遠ざける。このようにすれば、交差角
度が２０度の投光手段１ａに対応する受光素子２での受
光量は遠ざける前に比べて１／４に減少する。すなわ
ち、各投光素子１ａ，１ｂからの照射光に対する散乱光
の受光手段による受光強度がほぼ等しくなるから、受光
回路２１、対数増幅回路２２に対して広いダイナミック
レンジが要求されなくなり、回路設計が容易になるので
ある。Therefore, as shown in FIG. 11, the optical axes X 1 , X
The light projecting means 1 having a smaller intersection angle between the optical axis 2 and the optical axis X 0 , in this example, the intersection angle of the light receiving means with respect to the optical axis X 0 is 20 degrees.
The distance a is, for example, twice as far from the intersection as the light projecting means 1b whose intersection angle is 50 degrees. In this way, the amount of light received by the light receiving element 2 corresponding to the light projecting means 1a having an intersection angle of 20 degrees is reduced to 1/4 of that before the distance. That is, since the light receiving intensity of the scattered light with respect to the irradiation light from each of the light projecting elements 1a and 1b by the light receiving means becomes substantially equal, a wide dynamic range is not required for the light receiving circuit 21 and the logarithmic amplifier circuit 22, and the circuit design is reduced It will be easier.
【００２３】（実施例３）本実施例は、各投光素子１
ａ，１ｂからの照射光の波長を異ならせたものであっ
て、両投光手段の光軸Ｘ1,Ｘ2 が受光手段の光軸Ｘ0 に
対して異なる角度で配置されていない場合でも、粒子の
粒径を求めることが可能になるものである。なお、上記
各実施例において、投光手段の光軸Ｘ1,Ｘ2 と受光手段
の光軸Ｘ0とを同一平面上に配置しているが、必ずしも
同一平面に配置する必要はない。(Embodiment 3) In this embodiment, each light emitting element 1
a, 1b, the wavelengths of the irradiating lights are different, and even if the optical axes X 1 , X 2 of both light projecting means are not arranged at different angles with respect to the optical axis X 0 of the light receiving means. , It is possible to determine the particle size of the particles. In each of the above embodiments, the optical axes X 1 and X 2 of the light projecting means and the optical axis X 0 of the light receiving means are arranged on the same plane, but they need not always be arranged on the same plane.
【００２４】[0024]
【発明の効果】本発明は上述のように、煙粒子による散
乱光の強度の角度分布に基づいて煙粒子の粒径を求め、
粒径が所定の範囲以内であるときに煙粒子が存在すると
判断することができるから、散乱光を生じている煙粒子
の粒径が反映されることになり、煙粒子以外の微粒子に
よる散乱光や他の物体による反射光と、煙粒子による散
乱光とを識別できるようになり、誤検知を防止すること
ができるという利点を有する。また、散乱光の強度の角
度分布によって粒径を判定するから、受光強度の比を求
めることができればよいのであって、感知器の内部で生
じる反射光などによる暗雑音の影響を受けにくく、ノイ
ズマージンが大きく取れるのである。さらに、受光手段
は１つであるから、受光信号の増幅などを行う回路を複
数設ける必要がないのであって、複数系統の回路の温度
特性を揃えたり、低ノイズの回路を複数用いたりするこ
とによるコスト増が抑制されるという利点がある。According to the present invention, as described above, the particle size of smoke particles is determined based on the angular distribution of the intensity of scattered light by the smoke particles.
Since it can be determined that smoke particles are present when the particle size is within a predetermined range, the particle size of the smoke particles causing the scattered light is reflected, and the scattered light by fine particles other than the smoke particles is reflected. This makes it possible to discriminate between light reflected by other objects and light scattered by smoke particles, thereby preventing erroneous detection. Also, since the particle size is determined based on the angular distribution of the intensity of the scattered light, it is only necessary to be able to determine the ratio of the received light intensity, and it is hardly affected by dark noise due to reflected light or the like generated inside the sensor. The margin is large. Furthermore, since there is only one light receiving means, there is no need to provide a plurality of circuits for amplifying the light receiving signal, etc. Therefore, it is necessary to make the temperature characteristics of a plurality of circuits uniform or to use a plurality of low noise circuits. Therefore, there is an advantage that cost increase due to is suppressed.
【００２５】また、請求項２の構成によれば、対数増幅
回路が１つになるから、従来のように複数の対数増幅回
路の温度特性を揃える必要がなく、設計が容易になると
いう利点がある。請求項３の構成では、各投光手段の光
軸と受光手段の光軸との交点までの距離を各投光手段ご
とに異なるように設定しているのであって、各投光手段
から照射された光の散乱光が受光手段に対してほぼ同じ
強度で入射するように距離を設定しておけば、受光信号
処理回路のダイナミックレンジを小さくすることができ
るのであり、設計が容易になるのである請求項４の構成
では、各投光手段からの照射光の波長を異ならせている
ので、各投光手段の光軸と受光手段の光軸との交差角度
を別々に設定することなく、粒径を判定できることにな
る。According to the second aspect of the present invention, since only one logarithmic amplifier circuit is used, it is not necessary to make the temperature characteristics of a plurality of logarithmic amplifier circuits uniform as in the prior art, and the design is facilitated. is there. In the configuration of claim 3, the distance to the intersection of the optical axis of each light projecting means and the optical axis of the light receiving means is set differently for each light projecting means. If the distance is set so that the scattered light of the received light is incident on the light receiving means with almost the same intensity, the dynamic range of the light receiving signal processing circuit can be reduced, and the design becomes easier. In the configuration of certain claim 4, since the wavelength of the irradiation light from each light projecting means is made different, without separately setting the intersection angle between the optical axis of each light projecting means and the optical axis of the light receiving means, The particle size can be determined.
【図１】実施例１を示し、（Ａ）は光学系の構成図、
（Ｂ）はブロック図である。FIG. 1 shows a first embodiment, in which (A) is a configuration diagram of an optical system,
(B) is a block diagram.
【図２】実施例１の動作説明図である。FIG. 2 is an operation explanatory diagram of the first embodiment.
【図３】本発明の原理説明図である。FIG. 3 is a diagram illustrating the principle of the present invention.
【図４】本発明の原理説明図である。FIG. 4 is a diagram illustrating the principle of the present invention.
【図５】本発明の原理説明図である。FIG. 5 is a diagram illustrating the principle of the present invention.
【図６】本発明の原理説明図である。FIG. 6 is a diagram illustrating the principle of the present invention.
【図７】本発明の原理説明図である。FIG. 7 is a diagram illustrating the principle of the present invention.
【図８】本発明の原理説明図である。FIG. 8 is a diagram illustrating the principle of the present invention.
【図９】本発明の原理説明図である。FIG. 9 is a diagram illustrating the principle of the present invention.
【図１０】本発明の原理説明図である。FIG. 10 is a diagram illustrating the principle of the present invention.
【図１１】実施例２の光学系の構成図である。FIG. 11 is a configuration diagram of an optical system according to a second embodiment.
【図１２】従来例を示す要部断面図である。FIG. 12 is a sectional view of a main part showing a conventional example.
【図１３】他の従来例を示す光学系の構成図である。FIG. 13 is a configuration diagram of an optical system showing another conventional example.
【図１４】図１３に示した従来例のブロック図である。14 is a block diagram of the conventional example shown in FIG.
【図１５】図１３に示した従来例の動作説明図である。FIG. 15 is an operation explanatory diagram of the conventional example shown in FIG.
１ａ 投光素子 １ｂ 投光素子 ２ 受光素子 １２ 発振回路 １３ 論理回路 ２１ 受光回路 ２２ 対数増幅回路 ２３ 減算回路 ２４ 比較回路 ２７ スイッチ要素 ２８ 記憶回路 Ｐ 煙粒子 1a light emitting element 1b light emitting element 2 light receiving element 12 oscillation circuit 13 logic circuit 21 light receiving circuit 22 logarithmic amplifier circuit 23 subtraction circuit 24 comparison circuit 27 switch element 28 storage circuit P smoke particle
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) G08B 17/02 - 17/12 G01N 21/53 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) G08B 17/02-17/12 G01N 21/53
Claims (4)
段と、監視空間内に煙粒子が存在するときに生じる散乱
光を受光する受光手段と、受光手段から出力される受光
信号に基づいて監視空間内の煙粒子の存否を判定する受
光信号処理手段と、各投光手段から監視空間に対して互
いに異なる時刻に光が照射されるように各投光手段の発
光タイミングを設定する発光制御手段とを備え、各投光
手段は、光軸が受光手段の光軸に対してそれぞれ所定の
角度をなすように配置され、受光信号処理手段は、各投
光手段から監視空間に照射される光に対する散乱光の受
光手段による受光強度の比を求める比演算部と、求めた
比に基づいて煙粒子の存否を判定する判定部とを備えて
成ることを特徴とする光電式煙感知器。1. A plurality of light projecting means for irradiating light to a monitored space, a light receiving means for receiving scattered light generated when smoke particles are present in the monitored space, and a light receiving signal output from the light receiving means. A light-receiving signal processing unit that determines the presence or absence of smoke particles in the monitoring space based on the light-receiving timing; and a light-emitting timing of each light-emitting unit such that light is emitted from the light-emitting unit to the monitoring space at different times. Light emission control means, wherein each light projection means is arranged so that an optical axis forms a predetermined angle with respect to the optical axis of the light reception means, and the light reception signal processing means irradiates the monitoring space from each light emission means. And a determination unit for determining the ratio of the intensity of the scattered light to the received light by the light receiving means, and a determination unit for determining the presence or absence of smoke particles based on the determined ratio. vessel.
受光信号を対数増幅する対数増幅回路と、対数増幅回路
の出力を記憶する記憶回路と、対数増幅回路の出力と記
憶回路の記憶値との差を出力する減算回路と、発光制御
手段による各投光手段の発光タイミングに同期して一方
の投光手段の発光時に対数増幅回路の出力を記憶回路に
入力し、他方の投光手段の発光時に対数増幅回路の出力
を減算回路に入力するように切り換えるスイッチ要素と
を備えて成ることを特徴とする請求項１記載の光電式煙
感知器。2. A light emitting device comprising: two light projecting means;
A logarithmic amplifier circuit for logarithmically amplifying the received light signal, a storage circuit for storing the output of the logarithmic amplifier circuit, a subtraction circuit for outputting the difference between the output of the logarithmic amplifier circuit and the storage value of the storage circuit, The output of the logarithmic amplifier circuit is input to the storage circuit when one light emitting means emits light, and the output of the logarithmic amplifier circuit is input to the subtraction circuit when the other light emitting means emits light in synchronization with the light emitting timing of the light means. The photoelectric smoke detector according to claim 1, further comprising a switch element for switching.
各交点から各投光手段までの距離が、各投光手段ごとに
異なるように各投光手段を配置して成ることを特徴とす
る請求項１または請求項２記載の光電式煙感知器。3. The light projecting means is arranged such that the distance from each intersection of the optical axis of each light projecting means and the optical axis of the light receiving means to each light projecting means is different for each light projecting means. The photoelectric smoke detector according to claim 1 or 2, wherein:
の波長がそれぞれ異なることを特徴とする請求項１ない
し請求項３のいずれかに記載の光電式煙感知器。4. The photoelectric smoke detector according to claim 1, wherein wavelengths of light emitted from each light emitting means to the monitoring space are different from each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2127891A JP2966541B2 (en) | 1991-02-15 | 1991-02-15 | Photoelectric smoke detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2127891A JP2966541B2 (en) | 1991-02-15 | 1991-02-15 | Photoelectric smoke detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04260197A JPH04260197A (en) | 1992-09-16 |
| JP2966541B2 true JP2966541B2 (en) | 1999-10-25 |
Family
ID=12050669
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2127891A Expired - Lifetime JP2966541B2 (en) | 1991-02-15 | 1991-02-15 | Photoelectric smoke detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2966541B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4414166C1 (en) * | 1994-04-22 | 1995-12-07 | Lorenz Mesgeraetebau | Method and device for measuring light scattering on particles |
| US7746239B2 (en) | 2003-11-17 | 2010-06-29 | Hochiki Corporation | Light scattering type smoke detector |
| CN100463006C (en) * | 2003-11-17 | 2009-02-18 | 报知机股份有限公司 | Smoke sensor using scattering light |
| DE102004001699A1 (en) | 2004-01-13 | 2005-08-04 | Robert Bosch Gmbh | fire alarm |
| JP2008250851A (en) * | 2007-03-30 | 2008-10-16 | Nohmi Bosai Ltd | Photoelectric smoke detector |
| JP7203500B2 (en) * | 2018-03-13 | 2023-01-13 | 古河電気工業株式会社 | fire smoke detector |
-
1991
- 1991-02-15 JP JP2127891A patent/JP2966541B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04260197A (en) | 1992-09-16 |
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