JP2902491B2 - Suspended particulate detector - Google Patents
Suspended particulate detectorInfo
- Publication number
- JP2902491B2 JP2902491B2 JP3021274A JP2127491A JP2902491B2 JP 2902491 B2 JP2902491 B2 JP 2902491B2 JP 3021274 A JP3021274 A JP 3021274A JP 2127491 A JP2127491 A JP 2127491A JP 2902491 B2 JP2902491 B2 JP 2902491B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- output
- circuit
- light emitting
- temperature
- 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 - Fee Related
Links
- 238000001514 detection method Methods 0.000 claims description 40
- 239000010419 fine particle Substances 0.000 claims description 20
- 239000000428 dust Substances 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 14
- 239000000779 smoke Substances 0.000 claims description 14
- 230000003287 optical effect Effects 0.000 claims description 12
- 239000013618 particulate matter Substances 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 20
- 230000010355 oscillation Effects 0.000 description 8
- 230000035945 sensitivity Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 4
- 230000003321 amplification Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 241000208125 Nicotiana Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
- Fire-Detection Mechanisms (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、火災発生時の煙を検知
したりあるいは粉塵や煙草の煙等を検知したりする用途
に用いられる浮遊微粒子検出装置に関するものである。The present invention relates to relates to a floating遊微particle detector that is used in applications or detect smoke or the like of the detection or or dust and tobacco smoke during a fire.
【０００２】[0002]
【従来の技術】浮遊微粒子検出装置としては、煙や粉塵
などの微粒子による発光素子からの光の拡散光を受光素
子で受光することにより浮遊微粒子を検出するものがあ
る。この種の浮遊微粒子検出装置の従来の投光部は図９
（ａ）に示すように構成してあり、発光素子としての発
光ダイオードＬＤに直列に接続されたトランジスタＱ1
を発振回路１２の出力でオン，オフさせて、発光ダイオ
ードＬＤを間欠的に発光させ、駆動電流を限流抵抗Ｒ1
により設定していた。ここで、発振回路１２の出力は図
１０に示すようにオンデューティが小さくなるように設
定してある。2. Description of the Related Art As an apparatus for detecting suspended particulates, there is an apparatus for detecting suspended particulates by receiving, by a light receiving element, diffused light of light emitted from a light emitting element due to particulates such as smoke and dust. FIG. 9 shows a conventional light emitting unit of this type of suspended particulate detection device.
(A), a transistor Q 1 connected in series to a light emitting diode LD as a light emitting element
Are turned on and off by the output of the oscillation circuit 12, the light emitting diode LD emits light intermittently, and the driving current is reduced by the current limiting resistor R 1.
Was set by Here, the output of the oscillation circuit 12 is set so that the on-duty becomes small as shown in FIG.
【０００３】ところで、上述の構成の投光部の発光ダイ
オードＬＤの駆動電流を一定にした場合、発光ダイオー
ドＬＤの光出力はおよそ１℃あたり−１％の割合で変化
する。図１１（ａ）は発光ダイオードＬＤの駆動電流を
一定にして温度を０℃から５０℃まで変化させた場合の
発光ダイオードＬＤの光出力の変化を示す。従って、こ
のような投光部であると、高温状態で微粒子に対する検
出感度が低下する問題があった。図１１（ｂ）は発光ダ
イオードＬＤの駆動電流を一定とし、微粒子が一定量存
在する場合における受光部の検出出力を示し、上記発光
ダイオードＬＤの光出力変化の影響がそのまま検出感度
として現れる。When the driving current of the light emitting diode LD of the light emitting section having the above-mentioned configuration is kept constant, the light output of the light emitting diode LD changes at a rate of about -1% per 1 ° C. FIG. 11A shows a change in light output of the light emitting diode LD when the driving current of the light emitting diode LD is kept constant and the temperature is changed from 0 ° C. to 50 ° C. Therefore, such a light projecting unit has a problem that the detection sensitivity to fine particles in a high temperature state is reduced. FIG. 11B shows the detection output of the light receiving unit when the driving current of the light emitting diode LD is constant and a certain amount of fine particles are present. The effect of the light output change of the light emitting diode LD directly appears as the detection sensitivity.
【０００４】そこで、この点を改善する方法として、図
１１（ｃ）に示すように温度に応じて駆動電流を変化さ
せて、発光ダイオードＬＤの光出力の温度変化を打ち消
すことが考えられる。この場合、図９（ｂ）に示すよう
に限流抵抗Ｒ1 に並列にサーミスタ等の感温素子Ｔｈを
接続するか、あるいは同図（ｃ）に示すように２個の感
温素子Ｔｈ1 ，Ｔｈ2 を夫々限流抵抗Ｒ1 に並列及び直
列に接続すればよい。つまり、図９（ｂ），（ｃ）の場
合には、図１１（ｃ）に示すように、発光ダイオードＬ
Ｄの駆動電流を低温側では小さく、高温側で大きくす
る。なお、代表的な感温素子Ｔｈであるサーミスタの抵
抗値の温度特性を図１２に示す。同図におけるＲ25／Ｒ
ｔは、周囲温度ｔのときの抵抗値の２５℃のときの抵抗
値に対する比の逆数を示し、図中の１５００，３００
０，５０００はＢ定数（サーミスタ定数）を示す。Therefore, as a method of improving this point, as shown in FIG. 11C, it is conceivable to change the driving current according to the temperature to cancel the temperature change of the light output of the light emitting diode LD. In this case, 9 the current limiting resistor R 1 as shown in (b) Connect the thermosensitive element Th, such as a thermistor, in parallel, or figure 2 of the temperature sensing element as shown in (c) Th 1 it may be connected in parallel and in series Th 2 respectively current limit resistor R 1. That is, in the case of FIGS. 9B and 9C, as shown in FIG.
The driving current of D is small on the low temperature side and is large on the high temperature side. FIG. 12 shows the temperature characteristics of the resistance value of the thermistor, which is a typical temperature sensing element Th. R 25 / R in FIG.
t represents the reciprocal of the ratio of the resistance value at the ambient temperature t to the resistance value at 25 ° C.
0,5000 indicates a B constant (thermistor constant).
【０００５】[0005]
【発明が解決しようとする課題】上述のような拡散式の
浮遊微粒子検出装置の場合、検出感度を高くするには、
受光出力を大きくする必要があり、駆動電流として１Ａ
程度にする必要がある。ところが、省電力機器や電池駆
動機器などに用いられた場合、電源電圧が低くなり、駆
動電流を１Ａとするためには、感温素子Ｔｈの抵抗値を
小さくしなければならない。例えば、感温素子Ｔｈとし
てサーミスタを用い、電源電圧が６Ｖである場合に、１
Ａの電流を流すためには、サーミスタの抵抗値は数Ωと
しなければならず、このような小さい抵抗値のサーミス
タはないために、複数個のサーミスタを並列接続しなけ
ればならない。しかも、サーミスタに大きな電流を流す
と、自己発熱のために抵抗値が低下し、抵抗値の設定や
Ｂ定数の設定が困難になるという問題があった。SUMMARY OF THE INVENTION In the case of the above-mentioned diffusion type suspended particle detecting apparatus, the detection sensitivity can be increased by:
It is necessary to increase the light receiving output, and the driving current is 1 A
Need to be on the order. However, when used in power-saving equipment or battery-powered equipment, the power supply voltage decreases, and in order to reduce the drive current to 1 A, the resistance of the temperature-sensitive element Th must be reduced. For example, when a thermistor is used as the temperature sensing element Th and the power supply voltage is 6 V, 1
In order for the current A to flow, the resistance of the thermistor must be several Ω, and since there is no thermistor having such a small resistance, a plurality of thermistors must be connected in parallel. In addition, when a large current is passed through the thermistor, the resistance value decreases due to self-heating, and there is a problem that it is difficult to set the resistance value and the B constant.
【０００６】本発明は上述の点に鑑みて為されたもので
あり、その目的とするところは、発光素子の温度特性に
よる出力信号の温度特性を確実且つ容易に補償すること
ができる浮遊微粒子検出装置を提供することにある。[0006] The present invention has been made in view of the above points, and an object thereof is to improve the temperature characteristics of a light emitting element.
It is an object of the present invention to provide a floating particle detecting device capable of reliably and easily compensating for the temperature characteristic of an output signal .
【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の発明では、発光素子を間欠的に発光し
て、煙や粉塵などの微粒子による散乱光を受光素子で受
光し、この受光素子の受光出力を発光素子の発光周期に
同期して検波し、この検波出力を積分するサンプルホー
ルド回路を備える浮遊微粒子検出装置において、上記サ
ンプルホールド回路にゲインを持たせ、そのゲインに発
光素子の光出力の温度変化を打ち消す温度特性を持たせ
てある。In order to achieve the above object, according to the first aspect of the present invention, the light emitting element emits light intermittently, and the light receiving element receives light scattered by fine particles such as smoke and dust. In a floating particle detecting apparatus including a sample-and-hold circuit that detects a light-receiving output of the light-receiving element in synchronization with a light-emitting cycle of a light-emitting element and integrates the detection output, the sample-and-hold circuit has a gain, and the gain emits light. The device has a temperature characteristic for canceling the temperature change of the optical output of the element.
【０００８】また、請求項２の発明では、発光素子を発
光し、煙や粉塵などの微粒子による散乱光を受光素子で
受光して微粒子を検出し、上記受光素子の受光出力から
ノイズなどによる不要周波数成分を除去するフィルタ回
路を備える浮遊微粒子検出装置において、上記フィルタ
回路をアクティブフィルタで構成し、アクティブフィル
タにゲインを持たせ、そのゲインに発光素子の光出力の
温度変化を打ち消す温度特性を持たせて、上記目的を達
成してある。According to the second aspect of the present invention, the light emitting element emits light, and scattered light due to fine particles such as smoke and dust is received by the light receiving element to detect the fine particles. In a floating particle detection device including a filter circuit for removing a frequency component, the filter circuit is configured by an active filter, the active filter has a gain, and the gain has a temperature characteristic of canceling a temperature change of a light output of a light emitting element. Thus, the above object has been achieved.
【０００９】さらに、請求項３の発明では、発光素子を
発光し、煙や粉塵などの微粒子による散乱光を受光素子
で受光して微粒子を検出し、上記受光素子の受光出力を
電圧信号に変換するＩ／Ｖ変換回路を備える浮遊微粒子
検出装置において、Ｉ／Ｖ変換回路の出力を分圧して入
力に帰還する分圧帰還型に形成し、上記Ｉ／Ｖ変換回路
の出力側の分圧部に発光素子の光出力の温度変化を打ち
消す温度特性を持たせて、上記目的を達成している。Further, according to the third aspect of the present invention, the light emitting element emits light, and scattered light due to fine particles such as smoke or dust is received by the light receiving element to detect the fine particles, and the light receiving output of the light receiving element is converted into a voltage signal. A floating particle detecting device provided with an I / V conversion circuit, wherein the output of the I / V conversion circuit is divided and formed into a voltage division feedback type for feeding back to an input.
The above-mentioned object is achieved by providing the output-side voltage dividing section with a temperature characteristic for canceling the temperature change of the light output of the light emitting element.
【００１０】[0010]
【作用】請求項１乃至３の夫々の発明においては、夫々
受光部側の構成回路に発光素子の光出力の温度特性を打
ち消す温度特性を持たせて、検出出力が発光素子の光出
力の変化により高温時に感度が低下することを防止した
ものである。しかも、このように受光部側で温度補償を
行えば、発光素子側で温度補償を行う場合のように、感
温素子に大きな電流が流れることがなく、よって温度補
償特性を確実且つ容易に設定できる。According to the first to third aspects of the present invention, each of the constituent circuits on the light receiving section side has a temperature characteristic for canceling the temperature characteristic of the light output of the light emitting element, and the detection output changes in the light output of the light emitting element. This prevents the sensitivity from decreasing at high temperatures. Moreover, if the temperature compensation is performed on the light receiving unit side as in the case where the temperature compensation is performed on the light emitting element side, a large current does not flow through the temperature sensitive element, so that the temperature compensation characteristics can be set reliably and easily. it can.
【００１１】[0011]
【実施例】（実施例１）図１乃至図５に発明の一実施例
を示す。まず、本発明が適用される浮遊微粒子検出装置
の一例を図３に示す。この浮遊微粒子検出装置では、中
空の直方状のケース１により光学室２を形成し、上記ケ
ース１内の一端面の上方に光軸を他端面の下方方向に向
けて発光素子としての発光ダイオードＬＤを配置すると
共に、他端面の上方に光軸を一端面の下方に向けてフォ
トダイオードＰＤとしてのフォトダイオードＰＤを配置
してある。ここで、発光ダイオードＬＤはケース１に一
体形成されたアパーチャ６によって投光領域を制限して
あり、またフォトダイオードＰＤはケース１に一体形成
されたフード９により受光領域を制限してある。なお、
フード９の内面には複数の光トラップ８を設けてある。
ここで、受光効率を上げてフォトダイオードＰＤの出力
を受けて信号処理を行う処理回路の負担を軽くするため
にフード９内に受光レンズを設けてもよい。さらに、電
気ノイズの影響を少なくするためにシールド部材でフォ
トダイオードＰＤの受光面を除く外面を覆ってもよい。
上記ケース１は、第３図（ｂ）に示すように、一側面が
開口された矩形箱状で光学室２の一側壁となる面の外面
にフォトダイオードＰＤの出力に応じて適宜信号処理を
行う処理回路を構成するプリント基板４が装着されたベ
ース１ａと、このベース１ａの開口に被着されるカバー
１ｂとで形成してある。(Embodiment 1) FIGS. 1 to 5 show an embodiment of the present invention. First, FIG. 3 shows an example of a suspended particulate detection device to which the present invention is applied. In this device for detecting suspended particulates, an optical chamber 2 is formed by a hollow rectangular case 1, and a light emitting diode LD as a light emitting element is formed with an optical axis directed downward above one end face in the case 1 and below the other end face. And a photodiode PD as a photodiode PD is arranged above the other end face with the optical axis directed downward below the one end face. Here, the light emitting region of the light emitting diode LD is limited by an aperture 6 formed integrally with the case 1, and the light receiving region of the photodiode PD is limited by a hood 9 formed integrally with the case 1. In addition,
A plurality of optical traps 8 are provided on the inner surface of the hood 9.
Here, a light receiving lens may be provided in the hood 9 in order to increase the light receiving efficiency and reduce the load on a processing circuit that receives the output of the photodiode PD and performs signal processing. Further, in order to reduce the influence of electric noise, the outer surface of the photodiode PD except for the light receiving surface may be covered with a shield member.
As shown in FIG. 3 (b), the case 1 has a rectangular box shape with one side opened, and performs an appropriate signal processing on the outer surface of a surface serving as one side wall of the optical chamber 2 in accordance with the output of the photodiode PD. It is formed of a base 1a on which a printed circuit board 4 constituting a processing circuit to be mounted is mounted, and a cover 1b attached to an opening of the base 1a.
【００１２】検知領域は発光ダイオードＬＤの投光領域
とフォトダイオードＰＤの受光領域とが重なる領域とな
り、この検知領域に一致させて煙や粉塵などの浮遊微粒
子（図３（ｂ）中のＣで示す）を流入させる流入口３を
ケース１に形成してある。この浮遊微粒子検出装置で
は、検知領域における煙や粉塵などの浮遊微粒子による
発光ダイオードＬＤからの光の散乱光をフォトダイオー
ドＰＤにて受光することにより浮遊微粒子を検出する。The detection area is an area where the light emitting area of the light emitting diode LD and the light receiving area of the photodiode PD overlap. In accordance with the detection area, floating particulates such as smoke and dust (C in FIG. 3B). 1) is formed in the case 1. In this floating particle detection device, floating particles are detected by receiving, with a photodiode PD, light scattered from the light emitting diode LD due to floating particles such as smoke and dust in a detection area.
【００１３】ところで、本実施例においては検知領域の
発光ダイオードＬＤ及びフォトダイオードＰＤが配置さ
れた側( 図３（ａ）中の検知領域の上方) における投光
領域及び受光領域に共に入らない近傍に遮光壁１０ａを
設けると共に、検知領域の発光ダイオードＬＤ及びフォ
トダイオードＰＤが配置された側とは反対側( 図３中の
検知領域の下方) で投光領域と受光領域とが重なり合う
検知領域の境界部に先端が臨み光学室２の下部を発光ダ
イオードＬＤ及びフォトダイオードＰＤ側に分離する遮
光壁１０ｂを設けてある。これら遮光壁１０ａ，１０ｂ
はケース１に一体に形成してある。ここで、本実施例の
遮光壁１０ａは略台形状で底部を三角形状に凹設してあ
り、遮光壁１０ｂの先端は尖らせてあり、遮光壁１０ａ
の下部のエッジや遮光壁１０ｂの先端に結露を生じにく
くしてある。By the way, in this embodiment, the vicinity of the detection area on the side where the light emitting diode LD and the photodiode PD are arranged (above the detection area in FIG. 3A), which does not enter both the light projecting area and the light receiving area. The light-shielding wall 10a is provided on the side of the light-emitting diode LD and the photodiode PD in the detection area (the lower side of the detection area in FIG. 3). A light-shielding wall 10b whose front end faces the boundary portion and separates the lower part of the optical chamber 2 toward the light emitting diode LD and the photodiode PD is provided. These light shielding walls 10a, 10b
Are formed integrally with the case 1. Here, the light-shielding wall 10a of the present embodiment has a substantially trapezoidal shape, a bottom portion is concavely formed in a triangular shape, and a tip of the light-shielding wall 10b is sharpened.
The lower edge and the tip of the light shielding wall 10b are hardly dewed.
【００１４】このように遮光壁１０ａ及び遮光壁１０ｂ
を形成することにより、本実施例では発光ダイオードＬ
Ｄから投光された光が光学室２の壁面などで少なくとも
１０回反射してもフォトダイオードＰＤに入射されない
ようになっている。そして、ケース１は黒色のＡＢＳ樹
脂などで形成してあるため反射率が小さく、反射率を多
めに見ても１０回反射すれば、投光パワーに対する迷光
パワーの比率（迷光パワー／投光パワー) が極めて小さ
くなり、Ｓ／Ｎ比を十分に確保できるようにしてある。As described above, the light shielding walls 10a and 10b
In this embodiment, the light emitting diode L
Even if the light projected from D is reflected at least ten times on the wall surface of the optical chamber 2 or the like, the light does not enter the photodiode PD. Since the case 1 is made of black ABS resin or the like, the reflectance is small. If the reflectance is increased 10 times even if the reflectance is relatively large, the ratio of the stray light power to the light projection power (stray light power / light projection power) ) Becomes extremely small so that a sufficient S / N ratio can be secured.
【００１５】ところで、この種の浮遊微粒子検出装置に
おいては、光学室２の内壁面に埃などが付着すると迷光
が増大する。ここで、迷光を増大させる最大の要因とな
るのは、フォトダイオードＰＤの受光領域の前方に望む
光学室２の一端壁１ｄに埃が付着する場合であり、次に
発光ダイオードＬＤの投光領域の前方に望む他端壁１ｃ
に埃が付着する場合である。そこで、これら端壁面１
ｃ，１ｄを夫々下方に向く面に形成する（いわゆるオー
バーハングさせる）と、埃の付着を少なくすることがで
きて迷光の増大を阻止できる。なお、この浮遊微粒子検
出装置の場合には、横置きあるいは縦置きのいずれでも
使用されることを考慮し、上記端壁面１ｃ，１ｄが常に
下方を向くように形成してある。さらに、このような面
に上記端壁面１ｃ，１ｄを形成すると、発光ダイオード
ＬＤからの光を両側方に反射させることができ、さらに
発光ダイオードＬＤの迷光となる光の反射回数を増加さ
せることが望め、さらにＳ／Ｎ比を改善することを期待
できる。さらにまた、端壁面１ｃ，１ｄは曲面に形成し
てもよい。In this type of suspended particulate detection device, stray light increases when dust or the like adheres to the inner wall surface of the optical chamber 2. Here, the largest factor for increasing stray light is when dust adheres to one end wall 1d of the optical chamber 2 which is desired in front of the light receiving area of the photodiode PD, and then the light emitting area of the light emitting diode LD. End wall 1c looking forward of
This is the case where dust adheres to the surface. Therefore, these end wall surfaces 1
If c and 1d are formed on the respective surfaces facing downward (so-called overhang), the adhesion of dust can be reduced and the increase of stray light can be prevented. In addition, in the case of the suspended particulate detection device, the end wall surfaces 1c and 1d are formed so as to always face downward in consideration that the device is used either horizontally or vertically. Further, when the end wall surfaces 1c and 1d are formed on such a surface, light from the light emitting diode LD can be reflected to both sides, and the number of times of reflection of stray light of the light emitting diode LD can be increased. It can be expected that the S / N ratio is further improved. Furthermore, the end wall surfaces 1c and 1d may be formed as curved surfaces.
【００１６】図２は浮遊微粒子検出装置の回路構成を示
すブロック図であり、その具体回路は図１（ａ）に示
す。なお、以下の説明では本実施例の特徴とする構成が
明確となるように、まず図２と、図８に示す従来の具体
回路に基づいて全体構成の説明を行う。投光部Ａは、発
光素子としての発光ダイオードＬＤと、電源電圧を定電
圧化する定電圧回路１１と、図１０に示すパルス信号を
発生する発振回路１２と、発振回路１２の出力に応じて
発光ダイオードＬＤを駆動する駆動回路１３とからな
り、発振回路１２は定電圧回路１１から供給される定電
圧を電源として動作し、図８に示すようにトランジスタ
Ｑ1 で構成された駆動回路１３により発光ダイオードＬ
Ｄを間欠的に発光させる。FIG. 2 is a block diagram showing a circuit configuration of the apparatus for detecting suspended particulates, and a specific circuit thereof is shown in FIG. In the following description, the overall configuration will be first described based on the conventional specific circuit shown in FIG. 2 and FIG. 8 so that the configuration characteristic of the present embodiment is clear. The light projecting unit A includes a light emitting diode LD as a light emitting element, a constant voltage circuit 11 for converting a power supply voltage to a constant voltage, an oscillation circuit 12 for generating a pulse signal shown in FIG. consists driving circuit 13 for driving the light emitting diode LD, the oscillation circuit 12 is a constant voltage supplied from the constant voltage circuit 11 operates as a power source, a driving circuit 13 constituted by transistors Q 1 as shown in FIG. 8 Light emitting diode L
D emits light intermittently.
【００１７】受光部Ｂは、微粒子による拡散光を受光す
る受光素子としてのフォトダイオードＰＤと、このフォ
トダイオードＰＤの受光出力を電圧信号に変換するＩ／
Ｖ変換回路１４と、ノイズなどの不要な周波数成分を除
去するハイパスフィルタ（ＨＰＦ）１５，ローパスフィ
ルタ（ＬＰＦ）１６と、ローパスフィルタ１６出力を検
波する検波回路１７と、検波出力をサンプルホールドす
るサンプルホールド回路１８と、サンプルホールド出力
のレベルを可変するレベルシフト回路１９と、レベルシ
フト出力を直流増幅するＤＣ増幅回路２０と、Ｉ／Ｖ変
換回路１４からサンプルホールド回路１８までの回路動
作のための基準電圧を発生する基準電圧発生回路２１と
からなる。ここで、図８に示す具体回路では、ローパス
フィルタ１６としてアクティブフィルタで形成してあ
り、検波回路１７とサンプルホールド回路１８はアナロ
グスイッチとしてのＦＥＴＱ2 を共通に用いて、投光部
Ａの発振回路１２から与えられる信号に応じてローパス
フィルタ１６出力を検波して積分するいわゆる同期積分
型のサンプルホールド回路としてある。The light receiving section B includes a photodiode PD as a light receiving element for receiving light diffused by the fine particles, and an I / O for converting a light receiving output of the photodiode PD into a voltage signal.
V conversion circuit 14, high-pass filter (HPF) 15 and low-pass filter (LPF) 16 for removing unnecessary frequency components such as noise, detection circuit 17 for detecting the output of low-pass filter 16, and sample for sampling and holding the detection output A hold circuit 18, a level shift circuit 19 for varying the level of the sample hold output, a DC amplifying circuit 20 for amplifying the level shift output with direct current, and circuit operations from the I / V conversion circuit 14 to the sample hold circuit 18 A reference voltage generating circuit 21 for generating a reference voltage. Here, in the specific circuit shown in FIG. 8, Yes formed in the active filter as a low-pass filter 16, detector circuit 17 and a sample-and-hold circuit 18 is used in common FETs Q 2 as an analog switch, the oscillation of the light projecting unit A This is a so-called synchronous integration type sample-and-hold circuit that detects and integrates the output of the low-pass filter 16 according to the signal supplied from the circuit 12.
【００１８】この受光部Ｂは次のように動作する。フォ
トダイオードＰＤの受光出力は、Ｉ／Ｖ変換回路１４に
より電圧信号に変換され（Ｉ／Ｖ変換され）、フィルタ
１５，１６によりノイズ等の不要な周波数成分が除去さ
れる。なお、本実施例のフィルタ１５，１６では５０Ｈ
ｚ以下と１０ＫＨｚ以上の周波数成分を除去するように
してある。不要周波数成分が除去された信号は、検波回
路１７により検波される。ここで、この検波回路１７は
例えばＦＥＴ等を用いたアナログスイッチで構成してあ
り、投光部Ａの発振回路１７の発振周期に同期して、つ
まりは発光ダイオードＬＤの発光周期に同期して信号成
分だけを検波する。この検波出力はサンプルホールド回
路１８で同期積分される。ここで、上記した各回路は基
準電圧発生回路２１から与えられる基準電圧を基準にし
て信号処理を行っている。ところで、このサンプルホー
ルド回路１８の出力には上述した構造的な改善を図って
あっても、図５（ａ）に示すように迷光分（図中矢印で
示す）が含まれる。そこで、レベルシフト回路１９では
サンプルホールド回路１８の出力から上記基準電圧発生
回路２１から与えられていた基準電圧を除去するため、
図５（ｂ）に示すようにＤＣ増幅回路２０の基準電位ま
で引き下げる。これにより、迷光分をキャンセルする。
また、このようにレベルシフトすることで、出力のダイ
ナミックレンジが広げられる。ＤＣ増幅回路２０では、
上記レベルシフトされた出力である信号成分を直流増幅
して、図５（ｃ）に示すように出力が微粒子の濃度に応
じてＤＣ増幅回路２０の基準電位から電源電圧付近まで
変化する出力特性を得る。The light receiving section B operates as follows. The light receiving output of the photodiode PD is converted into a voltage signal (I / V conversion) by the I / V conversion circuit 14, and unnecessary frequency components such as noise are removed by the filters 15 and 16. Note that the filters 15 and 16 of this embodiment use 50H.
Frequency components below z and above 10 KHz are removed. The signal from which unnecessary frequency components have been removed is detected by the detection circuit 17. Here, the detection circuit 17 is configured by an analog switch using, for example, an FET, and is synchronized with the oscillation cycle of the oscillation circuit 17 of the light emitting unit A, that is, in synchronization with the light emission cycle of the light emitting diode LD. Detects only signal components. This detection output is synchronously integrated by the sample and hold circuit 18. Here, each of the above-described circuits performs signal processing with reference to a reference voltage provided from the reference voltage generation circuit 21. By the way, the output of the sample-and-hold circuit 18 includes a stray light component (indicated by an arrow in the figure) as shown in FIG. Therefore, the level shift circuit 19 removes the reference voltage given from the reference voltage generation circuit 21 from the output of the sample hold circuit 18,
As shown in FIG. 5B, the potential is lowered to the reference potential of the DC amplifier circuit 20. This cancels the stray light component.
Further, by performing the level shift in this manner, the dynamic range of the output is expanded. In the DC amplification circuit 20,
The signal component as the level-shifted output is DC-amplified, and the output characteristic varies from the reference potential of the DC amplification circuit 20 to the vicinity of the power supply voltage according to the concentration of the fine particles as shown in FIG. obtain.
【００１９】以下に、本実施例の特徴とする点について
説明する。本実施例では、従来の問題点であった発光ダ
イオードＬＤの温度特性に応じて温度に応じて検出出力
が変化し、高温時に検出感度が低下する点を改善するた
め、サンプルホールド回路１８に上記投光部Ａにおける
温度特性を打ち消す温度特性を持たせてある。ここで、
従来のサンプルホールド回路１８のままであると、温度
特性を持たせることができない。そこで、本実施例では
図１（ａ）に示すようにサンプルホールド回路１８の出
力に設けられたバッファの代わりにアンプ２２を用い、
このアンプ２２に発光ダイオードＬＤの温度特性を相殺
する温度特性、つまりは高温時にゲインが増加する温度
特性を持たせてある。Hereinafter, features of the present embodiment will be described. In the present embodiment, in order to improve the point that the detection output changes according to the temperature in accordance with the temperature characteristic of the light emitting diode LD, which is a conventional problem, and the detection sensitivity decreases at high temperature, A temperature characteristic for canceling the temperature characteristic in the light projecting section A is provided. here,
If the conventional sample-and-hold circuit 18 is left as it is, it cannot have temperature characteristics. Therefore, in this embodiment, an amplifier 22 is used instead of a buffer provided at the output of the sample and hold circuit 18 as shown in FIG.
The amplifier 22 has a temperature characteristic that cancels out the temperature characteristic of the light emitting diode LD, that is, a temperature characteristic in which the gain increases at a high temperature.
【００２０】具体的には、従来ではバッファとして用い
ていたオペアンプＯＰ1 でアンプ２２を構成してあり、
ゲインを決定する抵抗Ｒ3 に並列にサーミスタＲ5 を接
続してある。従って、上記アンプ２２のゲインに高温と
なってサーミスタＲ5 の抵抗値が低下した場合に増加
し、逆に低温になると低下する図４中の実線で示す温度
特性を持たせてある。ここで、このアンプ２２のゲイン
の温度特性を投光部Ａの発光ダイオードＬＤにおける温
度特性を打ち消すように設定すれば、検出感度が高温で
低下することを防止でき、図４に破線で示すように検出
出力が温度で変化することを防止できる。しかも、本実
施例のようにサンプルホールド回路１８にて温度補償を
行えば、感温素子として用いてあるサーミスタＲ5 に大
きな電流が流れず、よって抵抗値が大きなもので済み、
複数個のサーミスタを並列接続するということを不要と
でき、また自己発熱も少なくできるので、抵抗値やＢ定
数の選定が容易となり、投光部Ａ側で発光ダイオードＬ
Ｄの温度補償を行う場合よりも確実且つ容易に温度補償
を行うことができる。Specifically, the amplifier 22 is constituted by the operational amplifier OP 1 which has been conventionally used as a buffer.
The resistor R 3 to determine the gain is connected to the thermistor R 5 in parallel. Thus, increases if the resistance value of the thermistor R 5 is lowered by a high temperature in the gain of the amplifier 22, are to have a temperature characteristic indicated by the solid line in FIG. 4 to be reduced as the temperature becomes lower conversely. Here, if the temperature characteristic of the gain of the amplifier 22 is set so as to cancel the temperature characteristic of the light emitting diode LD of the light emitting unit A, the detection sensitivity can be prevented from lowering at a high temperature, and as shown by a broken line in FIG. Thus, the detection output can be prevented from changing with temperature. Moreover, by performing temperature compensation at the sample hold circuit 18 as in this embodiment, no large current flows through the thermistor R 5 that is used as a temperature sensing element, thus the resistance value requires at large,
It is not necessary to connect a plurality of thermistors in parallel, and self-heating can be reduced, so that the resistance value and the B constant can be easily selected.
Temperature compensation can be performed more reliably and easily than when temperature compensation of D is performed.
【００２１】なお、アンプ２２のゲインをさらに精度良
く発光ダイオードＬＤの温度特性を打ち消すように設定
したい場合には、図１（ｂ）に示すように抵抗Ｒ3 と直
列にサーミスタＲ6 を挿入すればよい。 （実施例２）図６（ａ）は本発明の他の実施例を示すも
ので、本実施例ではアクティブフィルタで構成されたロ
ーパスフィルタ１６により発光ダイオードＬＤの温度特
性を打ち消すものである。構成的にはローパスフィルタ
１６のオペアンプＯＰ2 で形成されたアンプにゲインを
持たせ、このアンプのゲインを設定する抵抗Ｒ7 にサー
ミスタＲ9 を並列に接続して、上記アンプに実施例１と
同様に図４に実線で示す温度特性を持たせ、発光ダイオ
ードＬＤの温度特性による高温時の検出感度の低下を補
償するようにしたものである。なお、本実施例の場合に
も、図６（ｂ）に示すように抵抗Ｒ7 に直列にサーミス
タＲ10を接続してもよい。If it is desired to set the gain of the amplifier 22 so as to more accurately cancel the temperature characteristic of the light emitting diode LD, a thermistor R 6 is inserted in series with the resistor R 3 as shown in FIG. I just need. (Embodiment 2) FIG. 6A shows another embodiment of the present invention. In this embodiment, the temperature characteristic of the light emitting diode LD is canceled by a low-pass filter 16 constituted by an active filter. Constitutive To to have a gain in the amplifier formed by the operational amplifier OP 2 in the low-pass filter 16, a resistor R 7 to set the gain of the amplifier by connecting the thermistor R 9 in parallel, as in Example 1 above amplifier Similarly, a temperature characteristic indicated by a solid line in FIG. 4 is provided to compensate for a decrease in detection sensitivity at a high temperature due to the temperature characteristic of the light emitting diode LD. Incidentally, in the case of this embodiment, it may be connected to the thermistor R 10 in series with a resistor R 7 as shown in Figure 6 (b).
【００２２】（実施例３）図７（ａ）は本発明のさらに
他の実施例であり、本実施例ではＩ／Ｖ変換回路１４と
して出力を抵抗Ｒ11，Ｒ12で分圧した電圧を高抵抗値の
抵抗Ｒ14を介して入力に帰還する構成にし、分圧抵抗Ｒ
12にサーミスタＲ13を並列に接続することにより、上記
各実施例と同様に図４の実線で示す温度特性をＩ／Ｖ変
換回路１４に持たせてあり、本実施例の場合には図７
（ｂ）に示すように抵抗Ｒ12に直列にサーミスタＲ15を
接続してもよい。本実施例の場合にも上記実施例と同様
の効果が得られる。[0022] The still more another embodiment, the voltage in the present embodiment divided by resistors R 11, R 12 and output as the I / V conversion circuit 14 (Example 3) FIG. 7 (a) the invention via the resistor R 14 of high resistance value to a configuration in which fed back to the input voltage dividing resistors R
By connecting a thermistor R 13 in parallel to the 12, the temperature characteristics shown by the solid line in FIG. 4 similarly to the above-described embodiments function features the I / V conversion circuit 14, in the case of the embodiment 7
A resistor R 12 as shown in (b) may be connected to the thermistor R 15 in series. In the case of this embodiment, the same effect as in the above embodiment can be obtained.
【００２３】[0023]
【発明の効果】本発明は上述のように、請求項１の発明
では、発光素子を間欠的に発光して、煙や粉塵などの微
粒子による散乱光を受光素子で受光し、この受光素子の
受光出力を発光素子の発光周期に同期して検波し、この
検波出力を積分するサンプルホールド回路を備える浮遊
微粒子検出装置において、上記サンプルホールド回路に
ゲインを持たせ、そのゲインに発光素子の光出力の温度
変化を打ち消す温度特性を持たせてあるので、サンプル
ホールド回路で検出出力が発光素子の光出力の変化によ
り高温時に感度が低下することを防止でき、しかも受光
部側で温度補償を行えば、発光素子側で温度補償を行う
場合のように、感温素子に大きな電流が流れることがな
く、よって温度補償特性を確実且つ容易に設定できる。As described above, according to the first aspect of the present invention, the light emitting element emits light intermittently and scattered light due to fine particles such as smoke and dust is received by the light receiving element. In a floating particle detecting apparatus having a sample-and-hold circuit for detecting a light-receiving output in synchronization with a light-emitting period of a light-emitting element and integrating the detected output, a gain is provided to the sample-and-hold circuit, and the gain is applied to the light output of the light-emitting element. It has a temperature characteristic that cancels out the temperature change, so that the detection output of the sample-and-hold circuit can be prevented from deteriorating at high temperatures due to the change in the light output of the light-emitting element at high temperatures. Unlike the case where temperature compensation is performed on the light emitting element side, a large current does not flow through the temperature sensitive element, and thus the temperature compensation characteristics can be set reliably and easily.
【００２４】また、請求項２の発明では、発光素子を発
光し、煙や粉塵などの微粒子による散乱光を受光素子で
受光して微粒子を検出し、受光素子の受光出力からノイ
ズなどによる不要周波数成分を除去するフィルタ回路を
備える浮遊微粒子検出装置において、上記フィルタ回路
をアクティブフィルタで構成し、アクティブフィルタに
ゲインを持たせ、そのゲインに発光素子の光出力の温度
変化を打ち消す温度特性を持たせてあるので、フィルタ
回路で検出出力が発光素子の光出力の変化により高温時
に感度が低下することを防止でき、しかも感温素子に大
きな電流が流れれないので、上記請求項１の発明と同様
に温度補償特性を確実且つ容易に設定できる。According to the second aspect of the present invention, the light emitting element emits light, scattered light due to fine particles such as smoke and dust is received by the light receiving element to detect the fine particles, and an unnecessary frequency due to noise or the like is detected from the light receiving output of the light receiving element. In the apparatus for detecting suspended particulates having a filter circuit for removing components, the filter circuit is constituted by an active filter, the active filter is provided with a gain, and the gain is provided with a temperature characteristic for canceling a temperature change of the light output of the light emitting element. Since the detection output of the filter circuit can be prevented from lowering at a high temperature due to a change in the light output of the light emitting element, a large current does not flow through the temperature sensitive element. The temperature compensation characteristics can be set reliably and easily.
【００２５】さらに請求項３の発明では、発光素子を発
光し、煙や粉塵などの微粒子による散乱光を受光素子で
受光して微粒子を検出し、受光素子の受光出力を電圧信
号に変換するＩ／Ｖ変換回路を備える浮遊微粒子検出装
置において、Ｉ／Ｖ変換回路の出力を分圧して入力に帰
還する分圧帰還型に形成し、上記Ｉ／Ｖ変換回路の出力
側の分圧部に発光素子の光出力の温度変化を打ち消す温
度特性を持たせてあるので、Ｉ／Ｖ変換回路で検出出力
が発光素子の光出力の変化により高温時に感度が低下す
ることを防止でき、上述の発明と同様に温度補償特性を
確実且つ容易に設定できる。Further, according to the third aspect of the present invention, the light emitting element emits light, the light scattered by the fine particles such as smoke and dust is received by the light receiving element to detect the fine particles, and the light receiving output of the light receiving element is converted into a voltage signal. In the floating particle detection device provided with the / V conversion circuit, the output of the I / V conversion circuit is formed into a voltage division feedback type which divides the output and feeds back to the input.
The voltage divider on the side has a temperature characteristic to cancel the temperature change of the light output of the light emitting element, so that the detection output of the I / V conversion circuit is reduced at high temperature due to the change of the light output of the light emitting element. The temperature compensation characteristics can be set reliably and easily as in the above-described invention.
【図１】（ａ）は本発明の一実施例の具体回路図であ
る。 （ｂ）は別構成の要部の回路図である。FIG. 1A is a specific circuit diagram of one embodiment of the present invention. (B) is a circuit diagram of a main part of another configuration.
【図２】同上の概略構成を示すブロック図である。FIG. 2 is a block diagram showing a schematic configuration of the above.
【図３】（ａ）は浮遊微粒子検出装置の構造を示す平面
図である。 （ｂ）は同上の側面断面図である。FIG. 3A is a plan view showing the structure of a suspended particulate detection device. (B) is a side sectional view of the same.
【図４】同上における温度補償用のゲイン特性及び温度
補償を行った場合の検出出力の温度特性を示す説明図で
ある。FIG. 4 is an explanatory diagram showing gain characteristics for temperature compensation and temperature characteristics of a detection output when temperature compensation is performed in the above.
【図５】（ａ）はサンプルホールド回路の微粒子濃度に
対する出力特性の説明図である。 （ｂ）はレベルシフト回路の微粒子濃度に対する出力特
性の説明図である。 （ｃ）はＤＣ増幅回路の微粒子濃度に対する出力特性の
説明図である。FIG. 5A is an explanatory diagram of an output characteristic with respect to a particle concentration of a sample and hold circuit. FIG. 3B is an explanatory diagram of output characteristics of the level shift circuit with respect to the concentration of fine particles. (C) is an explanatory diagram of the output characteristics with respect to the particle concentration of the DC amplifier circuit.
【図６】（ａ）は他の実施例の回路図である。 （ｂ）は別構成の要部の回路図である。FIG. 6A is a circuit diagram of another embodiment. (B) is a circuit diagram of a main part of another configuration.
【図７】（ａ）はさらに他の実施例の回路図である。 （ｂ）は別構成の要部の回路図である。FIG. 7A is a circuit diagram of still another embodiment. (B) is a circuit diagram of a main part of another configuration.
【図８】従来例の具体的な回路図である。FIG. 8 is a specific circuit diagram of a conventional example.
【図９】（ａ）は基本的な投光部の構成を示す回路図で
ある。 （ｂ）は発光ダイオードの温度補償を行う場合の回路図
である。 （ｃ）は発光ダイオードの温度補償を行う場合の他の構
成の回路図である。FIG. 9A is a circuit diagram illustrating a basic configuration of a light emitting unit. (B) is a circuit diagram in the case where temperature compensation of the light emitting diode is performed. (C) is a circuit diagram of another configuration when temperature compensation of the light emitting diode is performed.
【図１０】発振回路の出力波形図である。FIG. 10 is an output waveform diagram of the oscillation circuit.
【図１１】（ａ）は発光ダイオードの光出力の温度特性
を示す説明図である。 （ｂ）は検出出力の温度特性を示す説明図である。 （ｃ）は発光ダイオードの光出力の温度補償を行う場合
の駆動電流の温度特性を示す説明図である。FIG. 11A is an explanatory diagram showing a temperature characteristic of an optical output of a light emitting diode. (B) is an explanatory view showing a temperature characteristic of a detection output. FIG. 3C is an explanatory diagram showing a temperature characteristic of a driving current when temperature compensation of the light output of the light emitting diode is performed.
【図１２】代表的なサーミスタの温度特性の説明図であ
る。FIG. 12 is an explanatory diagram of a temperature characteristic of a typical thermistor.
ＬＤ 発光ダイオード ＰＤ フォトダイオード Ｒ5 サーミスタ １４ Ｉ／Ｖ変換回路 １６ フィルタ回路 １８ サンプルホールド回路LD Light-emitting diode PD Photodiode R 5 Thermistor 14 I / V conversion circuit 16 Filter circuit 18 Sample hold circuit
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭55−117943（ＪＰ，Ａ) 実開 平２−123691（ＪＰ，Ｕ) 実開 平２−71255（ＪＰ，Ｕ) 実開 平２−108193（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.6，ＤＢ名) G01N 15/06 G01N 15/14 G01N 21/00 - 21/01 G01N 21/17 - 21/61 G08B 17/02 - 17/12 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-117943 (JP, A) JP-A-2-123691 (JP, U) JP-A-2-71255 (JP, U) JP-A-2-117 108193 (JP, U) (58) Fields investigated (Int. Cl. 6 , DB name) G01N 15/06 G01N 15/14 G01N 21/00-21/01 G01N 21/17-21/61 G08B 17/02 -17/12
Claims (3)
などの微粒子による散乱光を受光素子で受光し、この受
光素子の受光出力を発光素子の発光周期に同期して検波
し、この検波出力を積分するサンプルホールド回路を備
える浮遊微粒子検出装置において、上記サンプルホール
ド回路にゲインを持たせ、そのゲインに発光素子の光出
力の温度変化を打ち消す温度特性を持たせて成ることを
特徴とする浮遊微粒子検出装置。1. A light-emitting element intermittently emits light, scattered light due to fine particles such as smoke and dust is received by a light-receiving element, and a light-receiving output of the light-receiving element is detected in synchronization with a light-emitting cycle of the light-emitting element. In the apparatus for detecting suspended particulates having a sample-and-hold circuit for integrating the detection output, the sample-and-hold circuit has a gain, and the gain has a temperature characteristic to cancel a temperature change of the light output of the light emitting element. Suspended particulate detector.
子による散乱光を受光素子で受光して微粒子を検出し、
受光素子の受光出力からノイズなどによる不要周波数成
分を除去するフィルタ回路を備える浮遊微粒子検出装置
において、上記フィルタ回路をアクティブフィルタで構
成し、アクティブフィルタにゲインを持たせ、そのゲイ
ンに発光素子の光出力の温度変化を打ち消す温度特性を
持たせて成ることを特徴とする浮遊微粒子検出装置。2. A light emitting element emits light, and scattered light due to fine particles such as smoke and dust is received by a light receiving element to detect fine particles.
In a floating particle detection device including a filter circuit for removing unnecessary frequency components due to noise or the like from a light receiving output of a light receiving element, the filter circuit is configured by an active filter, and the active filter has a gain. A floating particulate matter detection device characterized by having a temperature characteristic for canceling a change in output temperature.
子による散乱光を受光素子で受光して微粒子を検出し、
受光素子の受光出力を電圧信号に変換するＩ／Ｖ変換回
路を備える浮遊微粒子検出装置において、Ｉ／Ｖ変換回
路の出力を分圧して入力に帰還する分圧帰還型に形成
し、上記Ｉ／Ｖ変換回路の出力側の分圧部に発光素子の
光出力の温度変化を打ち消す温度特性を持たせて成るこ
とを特徴とする浮遊微粒子検出装置。3. A light emitting element emits light, and scattered light due to fine particles such as smoke and dust is received by a light receiving element to detect the fine particles.
In airborne particle detector device comprising a I / V conversion circuit for converting a voltage signal to the light receiving output of the light receiving element, formed on the partial pressure feedback to feedback to divide an output of the I / V conversion circuit, the I / An apparatus for detecting suspended particulates, wherein a voltage divider on the output side of a V conversion circuit has a temperature characteristic for canceling a temperature change of an optical output of a light emitting element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3021274A JP2902491B2 (en) | 1991-02-15 | 1991-02-15 | Suspended particulate detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3021274A JP2902491B2 (en) | 1991-02-15 | 1991-02-15 | Suspended particulate detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04259845A JPH04259845A (en) | 1992-09-16 |
| JP2902491B2 true JP2902491B2 (en) | 1999-06-07 |
Family
ID=12050545
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3021274A Expired - Fee Related JP2902491B2 (en) | 1991-02-15 | 1991-02-15 | Suspended particulate detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2902491B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9885602B2 (en) | 2015-12-28 | 2018-02-06 | Panasonic Intellectual Property Management Co., Ltd. | Particle sensor |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08233737A (en) * | 1995-02-28 | 1996-09-13 | Yua Tec:Kk | Capillary photodetector, photometric apparatus and method for measuring microparticles in suspension using it |
| US8907802B2 (en) | 2012-04-29 | 2014-12-09 | Valor Fire Safety, Llc | Smoke detector with external sampling volume and ambient light rejection |
| US9140646B2 (en) | 2012-04-29 | 2015-09-22 | Valor Fire Safety, Llc | Smoke detector with external sampling volume using two different wavelengths and ambient light detection for measurement correction |
| US8952821B2 (en) | 2012-04-29 | 2015-02-10 | Valor Fire Safety, Llc | Smoke detector utilizing ambient-light sensor, external sampling volume, and internally reflected light |
| WO2015065965A1 (en) | 2013-10-30 | 2015-05-07 | Valor Fire Safety, Llc | Smoke detector with external sampling volume and ambient light rejection |
| JP2016156696A (en) * | 2015-02-24 | 2016-09-01 | アズビル株式会社 | Particle detection device |
| JP2019027842A (en) * | 2017-07-27 | 2019-02-21 | 株式会社デンソー | Particle sensor |
| WO2019044251A1 (en) * | 2017-08-29 | 2019-03-07 | パナソニックＩｐマネジメント株式会社 | Particle detection system and particle detection method |
| CN112326895B (en) * | 2020-12-04 | 2021-10-01 | 深圳市安室智能有限公司 | Sensitivity compensation method and related product |
-
1991
- 1991-02-15 JP JP3021274A patent/JP2902491B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9885602B2 (en) | 2015-12-28 | 2018-02-06 | Panasonic Intellectual Property Management Co., Ltd. | Particle sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04259845A (en) | 1992-09-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2902491B2 (en) | Suspended particulate detector | |
| JPH05327450A (en) | Light emitting diode drive circuit | |
| JP2007121145A (en) | Photoelectric type dust sensor device, air cleaner and air conditioner | |
| US7388479B2 (en) | Human sensing back-up alarm device | |
| US5900960A (en) | Circuit arrangement for receiving light signals | |
| US4570075A (en) | Optical end-of-tape detection device | |
| US5155353A (en) | High dynamic range integrated opto-electronic sensor and MOSFET amplifiers for pulsed light | |
| JP3056798B2 (en) | Floating particle detector | |
| JP2004340708A (en) | Signal detecting circuit for rain sensor and signal detecting method | |
| JPS62269374A (en) | Semiconductor laser device | |
| JPS5821800B2 (en) | Light intensity integration circuit for automatic light control flash device | |
| JP2809549B2 (en) | Amplifier | |
| JP2649973B2 (en) | Concentration measuring device | |
| JP4180714B2 (en) | Photoelectric switch | |
| SU1458716A1 (en) | Photoelectric transducer | |
| JPH08122252A (en) | Dust sensor | |
| JPH0779143A (en) | Base line regeneration circuit | |
| JP3046977B2 (en) | Signal current detection circuit | |
| JP2585630B2 (en) | AGC circuit | |
| JPH08128953A (en) | Oil deterioration degree detecting device | |
| KR940007799Y1 (en) | Amending circuit for brightness-change | |
| JP3267184B2 (en) | Photoelectric smoke detector | |
| JP3232132B2 (en) | Optical displacement meter | |
| JP2605128B2 (en) | Detection circuit | |
| JP3467243B2 (en) | Photoelectric smoke detector |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 19990309 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080319 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090319 Year of fee payment: 10 |
|
| LAPS | Cancellation because of no payment of annual fees |