JPH0330097A - Photoelectric smoke sensor - Google Patents
Photoelectric smoke sensorInfo
- Publication number
- JPH0330097A JPH0330097A JP16632689A JP16632689A JPH0330097A JP H0330097 A JPH0330097 A JP H0330097A JP 16632689 A JP16632689 A JP 16632689A JP 16632689 A JP16632689 A JP 16632689A JP H0330097 A JPH0330097 A JP H0330097A
- Authority
- JP
- Japan
- Prior art keywords
- light
- signal
- output
- amplifier
- circuit
- 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.)
- Pending
Links
- 239000000779 smoke Substances 0.000 title claims abstract description 33
- 239000003990 capacitor Substances 0.000 claims abstract description 22
- 230000010355 oscillation Effects 0.000 claims description 9
- 230000002457 bidirectional effect Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 7
- 239000004065 semiconductor Substances 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
Landscapes
- Fire-Detection Mechanisms (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野１
本発明は、煙による光の散乱を検出する光電式煙感知器
に関するものである．
［従来の技術］
第３図は光電式の煙感知器の従来例を示すブロック図で
ある。発光素子１は発振回ＦＩ＠１０により間欠的に光
信号を発生する。発光素子１からの光の放射方向と、受
光素子２による光の受光方向とは異なり、煙感知器内に
煙が存在しないときには、受光素子２は光をほとんど受
光しない．一方、煙感知器内に煙が存在するときには、
発光素子１からの光は煙によって散乱されるので、受光
素子２は煙による散乱光を受光する．この散乱光は極め
て微弱なものであるので、受光アンプ２０にて増幅した
後、比較回路２１にて所定の基準レベルと比較する．比
較回路２１の出力は信号処理回路２２にて信号処理され
、信頼性のある検出信号が得られたときには、発報回路
２３にて煙感知信号を発報する．比較回路２１は煙濃度
が所定濃度以上であるか否かを判定しており、信号処理
回路２２は電磁ノイズなどによる誤動作を防ぐための信
号処理を行っている。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a photoelectric smoke detector that detects light scattering due to smoke. [Prior Art] FIG. 3 is a block diagram showing a conventional example of a photoelectric smoke detector. The light emitting element 1 intermittently generates optical signals by the oscillation circuit FI@10. The direction in which light is emitted from the light emitting element 1 is different from the direction in which light is received by the light receiving element 2, and when there is no smoke within the smoke detector, the light receiving element 2 receives almost no light. On the other hand, when smoke is present in the smoke detector,
Since the light from the light emitting element 1 is scattered by the smoke, the light receiving element 2 receives the light scattered by the smoke. Since this scattered light is extremely weak, it is amplified by a light receiving amplifier 20 and then compared with a predetermined reference level by a comparison circuit 21. The output of the comparison circuit 21 is processed by the signal processing circuit 22, and when a reliable detection signal is obtained, the alarm circuit 23 issues a smoke detection signal. The comparison circuit 21 determines whether the smoke density is higher than a predetermined concentration, and the signal processing circuit 22 performs signal processing to prevent malfunctions due to electromagnetic noise or the like.
第４図は受光アンプ２０と比較回路２１の具体回路例を
示している。受光アンプ２０はオペアンプＡ １， Ａ
２を縦続接続したものであり、オペアンプＡ１は帰還
インピーダンスとしてコンデンサＣと抵抗Ｒ１を接続さ
れ、受光素子２からの光電流を電圧信号に変換する。コ
ンデンサＣ１は高域カット用であり、抵抗Ｒ１は電流一
電圧変換係数設定用である。オペアンブＡ２は入力抵抗
Ｒ２と帰還抵抗Ｒ３とを有し、オペアンプＡ，の出力電
圧を増幅する。増幅率は（−Ｒ，／Ｒ２）となる。オペ
アンプＡ２の出力電圧には、各オペアンブＡ ＋ ，
Ａ ２のオフセットや受光素子２の暗電流の成分が含ま
れ、これらは周囲温度によって大きく変動する。そこで
、コンデンサＣ２によって直流成分を除去し、発光素子
ｌの発光時に生じた散乱光による変動戒分のみを比較回
路２１にて検出している．比較回路２１の負入力端子に
は、電源電圧を抵抗Ｒ．，Ｒ．にて分圧した電圧が基準
レベルとして印加されており、正入力端子の電圧が上記
基準レベルを越えたときに、比較回路２１の出力が゛’
Ｈｉｇｈ”レベルとなる。一端をコンデンサＣ２に接続
された抵抗Ｒ，の他端には基準電圧Ｖｒｅｆが印加され
ており、散乱光による入力信号が無いときには、コンデ
ンサＣ２と抵抗Ｒ４との接続点の電圧は、基準電圧Ｖｒ
ｅｆに等しくなる。この基準電圧Ｖｒｅｆは比較回路２
１の負入力端子に印加された基準レベルよりも低く設定
されている。FIG. 4 shows a specific circuit example of the light receiving amplifier 20 and the comparison circuit 21. The light receiving amplifier 20 is an operational amplifier A1, A
The operational amplifier A1 is connected with a capacitor C and a resistor R1 as a feedback impedance, and converts the photocurrent from the light receiving element 2 into a voltage signal. The capacitor C1 is for high frequency cut, and the resistor R1 is for setting the current-voltage conversion coefficient. Operational amplifier A2 has an input resistor R2 and a feedback resistor R3, and amplifies the output voltage of operational amplifier A. The amplification factor is (-R, /R2). The output voltage of operational amplifier A2 includes each operational amplifier A + ,
This includes the offset of A2 and the dark current component of the light receiving element 2, and these vary greatly depending on the ambient temperature. Therefore, the DC component is removed by the capacitor C2, and the comparison circuit 21 detects only the fluctuations caused by the scattered light generated when the light emitting element 1 emits light. A power supply voltage is connected to the negative input terminal of the comparison circuit 21 through a resistor R. ,R. The voltage divided by is applied as a reference level, and when the voltage at the positive input terminal exceeds the reference level, the output of the comparator circuit 21 becomes ``''.
The resistor R is connected to the capacitor C2 at one end, and the reference voltage Vref is applied to the other end.When there is no input signal due to scattered light, the connection point between the capacitor C2 and the resistor R4 is applied. The voltage is the reference voltage Vr
It becomes equal to ef. This reference voltage Vref is
The reference level applied to the negative input terminal of No. 1 is set lower than the reference level applied to the negative input terminal of No. 1.
［発明が解決しようとする課題］
上述の従来技術において、オペアンプＡ ＋ ， Ａ
２にオフセットが無ければ、ゼロ入力時のオペアンブＡ
２の出力は電圧ＶＢに等しくなるが、現実にはオペアン
プＡ ＋ ， Ａ ２にオフセツｌ・が存在するので、
そのオフセット電圧を各々ＶＯＳ．，ＶＯ！３２とする
と、オペアンブＡ２の出力は、ゼロ入力時の電圧ＶＢに
比べてΔＶの誤差電圧を生じる。[Problem to be solved by the invention] In the above-mentioned conventional technology, operational amplifiers A + , A
If there is no offset in 2, operational amplifier A at zero input
The output of A2 is equal to the voltage VB, but in reality there is an offset l in the operational amplifiers A + and A2, so
The offset voltage is set to VOS. , VO! 32, the output of the operational amplifier A2 produces an error voltage of ΔV compared to the voltage VB at zero input.
ΔＶ＝ （Ｒ３／Ｒ．２）（ＶＯＳＩ−Ｖｏｓ２）例
えば、Ｖ ０９＋ ＝ １ ｍＶ、ＶＯＳ２＝ ３ｎ
Ｖ．Ｒｌ／ Ｒ ２ ＝ ３ ０とすると、ΔＶ−−３
０（１＋３）１２０ｍＶとなる。ΔV= (R3/R.2) (VOSI-Vos2) For example, V 09+ = 1 mV, VOS2 = 3n
V. If Rl/R2 = 30, ΔV--3
0(1+3)120mV.
今、煙による散乱光に起因する受光電流を１０ｎＡ，Ｒ
，＝ｌＭΩ、Ｒ ３ ／ Ｒ ２ ＝ ３ ０とすると
、煙による受光アンプ２０の出力信号Ｖｓは、Ｖｓ＝１
０ｎＡＸ ＩＭΩＸ３０＝３００ｍＶとなる。この出
力信号Ｖｓに比べて、誤差電圧ΔＶが比較的大きいため
、オペアンプＡ２の出力を比較回路２ｌにそのまま入力
すると、発報すべき煙濃度で発報しなかったり、逆に低
い煙濃度で発報するという不都合が生じてしまう。受光
素子２の暗電流が大きくなっても同じようなことが起こ
る。そこで、従来の回路ではコンデンサＣ２と抵抗Ｒ４
によりハイパスフィルタを構成し、直流戒分をカットし
ている。ハイパスフィルタの低域遮断周波数は、Ｃ ２
＝ １ ０ ０ ｎＦ ， Ｒ４−１ ０ ＫΩとすれ
ば、ｆｃ＝１／２πＣｚＲ＜＃１６０Ｈｚとなる。Now, the light receiving current caused by light scattered by smoke is 10nA, R.
, = lMΩ, R 3 / R 2 = 30, the output signal Vs of the light receiving amplifier 20 due to smoke is Vs = 1
0nAX IMΩX30=300mV. Since the error voltage ΔV is relatively large compared to this output signal Vs, if the output of the operational amplifier A2 is directly input to the comparator circuit 2l, an alarm may not be issued at the smoke concentration that should be issued, or conversely, it may not be issued at a low smoke density. This creates the inconvenience of having to report the situation. A similar situation occurs even when the dark current of the light receiving element 2 becomes large. Therefore, in the conventional circuit, capacitor C2 and resistor R4
This constitutes a high-pass filter and cuts out the direct current. The low cutoff frequency of the high-pass filter is C2
= 100 nF, R4-10 KΩ, then fc=1/2πCzR<#160Hz.
ところが、第４図に示す回路を集積回路化してコストダ
ウンと小型軽量化を図ろうとした場合には、半導体集積
回路では大容量のコンデンサや高抵抗は実現困難となる
という問題が生じる。半導体集積回路で実現できるコン
デンサの容量の上限値は実用的にはｓｏｐｐ程度であり
、抵抗の上限値は５０ＫΩ程度である。したがって、こ
れらの値でハイバスフィルタを横戒しても、低域遮断周
波数はｆｃξ６４ＫＨｚとなり、実用的な使用周波数帯
域〈ｌ〜２０Ｋ８２程度）を大きく越えてしまい、直流
カットの目的を果たせない。However, if an attempt is made to reduce cost, size, and weight by integrating the circuit shown in FIG. 4, a problem arises in that it is difficult to realize large-capacity capacitors and high resistance in semiconductor integrated circuits. Practically speaking, the upper limit of capacitance that can be realized in a semiconductor integrated circuit is about sopp, and the upper limit of resistance is about 50KΩ. Therefore, even if the high-pass filter is used with these values, the low cutoff frequency will be fcξ64KHz, which greatly exceeds the practical frequency band (approximately 1 to 20K82), and the purpose of DC cut cannot be achieved.
本発明はこのような点に鑑みてなされたものであり、そ
の目的とするところは、受光素子の暗電流や増幅器のド
リフトによる誤差電圧の影響を除去できるようにした光
電式煙感知器を半導体集積回路化に適した楕戒で提供す
ることにある。The present invention has been made in view of the above points, and its purpose is to provide a photoelectric smoke detector using a semiconductor device that can eliminate the influence of dark current of the light receiving element and error voltage due to drift of the amplifier. The goal is to provide an elliptical format suitable for integrated circuits.
［課題を解決するための手段］
本発明にあっては、上記の課題を解決するために、第３
図に示すように、間欠的に発光信号を発生する発振回路
１０と、発振回路１０から出力される発光信号に応じて
間欠的に光信号を発生する発光素子１と、発光素子１か
ら放射された光信号が感知器内部に侵入した煙により散
乱された光を受光する受光素子２と、受光素子２の受光
出力を増幅する受光アンプ２０と、受光アンプ２０の出
力信号から煙濃度が所定値以上か否かを刊定する比較回
路２１とを備える光電式煙感知器において、第１図に示
すように、受光アンプ２０と比較回路２１の間に反転増
幅器Ａ，を備え、受光アンプ２０の出力と反転増幅器Ａ
，の反転入力との間に第１のコンデンサＣ２を接続し、
反転増幅器Ａ３の反転入力と出力との間に前記発光信号
の発生前にオン・オフされるスイッチ回路Ｑと第２のコ
ンデンサＣ３を並列接続したことを特徴とするものであ
る。[Means for Solving the Problems] In the present invention, in order to solve the above problems, the third
As shown in the figure, an oscillation circuit 10 that intermittently generates a light emission signal, a light emitting element 1 that intermittently generates an optical signal in response to the light emission signal output from the oscillation circuit 10, and a light emitting element 1 that emits light from the light emitting element 1. A light receiving element 2 receives the light scattered by the smoke that entered the sensor, a light receiving amplifier 20 amplifies the light receiving output of the light receiving element 2, and a smoke density is determined from the output signal of the light receiving amplifier 20 to a predetermined value. In a photoelectric smoke detector equipped with a comparison circuit 21 that determines whether or not the Output and inverting amplifier A
, a first capacitor C2 is connected between the inverting input of ,
This device is characterized in that a switch circuit Q, which is turned on and off before the generation of the light emission signal, and a second capacitor C3 are connected in parallel between the inverting input and output of the inverting amplifier A3.
［作用］
本発明にあっては、このように、受光アンプ２０と比較
回路２１の間に反転増幅器Ａ，を備え、受光アンプ２０
の出力と反転増幅器Ａ，の反転入力との間に第１のコン
デンサＣ２を接続し、反転増幅器Ａ，の反転入力と出力
との間に前記発光信号の発生前にオン・オフされるスイ
ッチ回路Ｑと第２のコンデンサＣ３を並列接続したので
、受光アンプ２０のオフセット電圧や受光素子２の暗電
流により受光アンプ２０の出力に誤差電圧Δ■があっで
も、発光信号の発生前に、スイッチ回路Ｑがオン・オフ
されることにより反転増幅器Ａ，の出力電圧が所定の基
準電圧Ｖｒｅｆに設定され、誤差電圧ΔＶは比較回路２
１には入力されない。したがって、受光アンブ２０の出
力のうち、煙による散乱光に起因する微弱な出力信号Ｖ
ｓのみを正確に検出することができる。[Function] In the present invention, as described above, the inverting amplifier A is provided between the light receiving amplifier 20 and the comparison circuit 21, and the light receiving amplifier 20
A first capacitor C2 is connected between the output of the inverting amplifier A and the inverting input of the inverting amplifier A, and the switch circuit is turned on and off between the inverting input and the output of the inverting amplifier A. Q and the second capacitor C3 are connected in parallel, so even if there is an error voltage Δ■ in the output of the light-receiving amplifier 20 due to the offset voltage of the light-receiving amplifier 20 or the dark current of the light-receiving element 2, the switch circuit is connected before the light emission signal is generated. By turning Q on and off, the output voltage of the inverting amplifier A is set to a predetermined reference voltage Vref, and the error voltage ΔV is set to the comparator circuit 2.
1 is not entered. Therefore, among the outputs of the light receiving amplifier 20, a weak output signal V caused by light scattered by smoke
Only s can be detected accurately.
［実施例］
第１図は本発明の一実施例の回路図である。本実施例に
おいて、上述の従来例と対応する部分には同一の符号を
付して重複する説明は省略する。[Embodiment] FIG. 1 is a circuit diagram of an embodiment of the present invention. In this embodiment, parts corresponding to those in the conventional example described above are given the same reference numerals and redundant explanations will be omitted.
第１図に示す回路では、受光アンプ２０と比較回路２１
の間に、反転増幅器Ａ３を備えている。この反転増幅器
Ａ，は一般的なオペアンプよりなる。In the circuit shown in FIG.
In between, an inverting amplifier A3 is provided. This inverting amplifier A consists of a general operational amplifier.
受光アンプ２０の出力と反転増幅器Ａ，の反転入力との
間には、コンデンサＣ２が接続されている。A capacitor C2 is connected between the output of the light receiving amplifier 20 and the inverting input of the inverting amplifier A.
また、反転増幅器Ａ３の反転入力と出力との間には、ス
イッチ回路ＱとコンデンサＣ，が並列接続されている．
スイッチ回路Ｑはアナログスイッチような双方向性のス
イッチ素子よりなり、ゲート信号φにより開閉制御され
る。このゲート信号は上述の発振回路１０から発光素子
１に与えられる発光信号よりも先行して発生する。Further, a switch circuit Q and a capacitor C are connected in parallel between the inverting input and output of the inverting amplifier A3.
The switch circuit Q is composed of a bidirectional switching element such as an analog switch, and is controlled to open and close by a gate signal φ. This gate signal is generated prior to the light emission signal applied to the light emitting element 1 from the oscillation circuit 10 described above.
第２図は本実施例の動作波形図である。ゲー１・信号φ
が“”Ｈｉｇｈ”レベルになると、スイッチ回路Ｑがオ
ンとなり、反転増幅器Ａ，の出力電圧は基準電圧Ｖｒｅ
ｆに設定される。ゲート信号φは暫時”Ｈｉｇｈ”レベ
ルに保持されて、その後、”ＬＯＷ”レベルとなる。本
実施例では、比較回路２１として、入力段のトランジス
タがＪＦＥＴ又はＭＯＳトランジスタよりなる高入力イ
ンピーダンスのタイプを用いており、その入力バイアス
電流は数ｒ＋Ａ〜１００ｐＡ程度と極めて小さい．した
がって、例えば、コンデンサＣ ２ ， Ｃ ３の容量
が１０ｐＦ程度の小さな容量であっても、反転増幅器Ａ
３の出力端子の電圧は、スイッチ回路Ｑをオフした後、
数１＋１Ｓｅｅの間はほとんど基準電圧Ｖｒｅｆに保持
される。ゲート信号φが立ち下がってから、発振回路１
０の発光信号により発光素子１が発光すると、受光アン
プ２０は出力信号Ｖｓを発生する。このとき、スイッチ
回路Ｑがオフされているので、反転増幅器Ａ，はゲイン
が（−Ｃ２／Ｃ３）の反転増幅器として作用する。例え
ば、Ｃ２＝Ｃ．であれば、受光アンプ２０の出力信号Ｖ
ｓを同じ振幅で反転した信号が反転増幅器Ａ，から出力
される。このとき、受光アンプ２０の出力信号に直流的
にΔＶの誤差電圧が生じていたとしても、反転増幅器Ａ
３の出力においては、この誤差電圧Δ■が除去されて、
受光アンプ２０の出力信号Ｖｓを反転した信号だけが出
力される．この入力電圧の変化が所定値以上であれば、
比較回路２１により煙感知信号が得られる。FIG. 2 is an operational waveform diagram of this embodiment. Game 1/Signal φ
When becomes “High” level, the switch circuit Q is turned on and the output voltage of the inverting amplifier A becomes the reference voltage Vre.
f. The gate signal φ is held at the "High" level for a while, and then becomes the "LOW" level. In this embodiment, the comparison circuit 21 uses a high input impedance type in which the input stage transistor is a JFET or MOS transistor, and its input bias current is extremely small, on the order of several r+A to 100 pA. Therefore, for example, even if the capacitors C 2 and C 3 have a small capacitance of about 10 pF, the inverting amplifier A
After turning off the switch circuit Q, the voltage at the output terminal of No. 3 is
The reference voltage Vref is maintained for most of the period of 1+1See. After the gate signal φ falls, the oscillation circuit 1
When the light emitting element 1 emits light in response to a light emission signal of 0, the light receiving amplifier 20 generates an output signal Vs. At this time, since the switch circuit Q is turned off, the inverting amplifier A acts as an inverting amplifier with a gain of (-C2/C3). For example, C2=C. If so, the output signal V of the light receiving amplifier 20
A signal obtained by inverting s with the same amplitude is output from the inverting amplifier A. At this time, even if an error voltage of ΔV occurs in the output signal of the light receiving amplifier 20, the inverting amplifier A
At the output of No. 3, this error voltage Δ■ is removed, and
Only a signal obtained by inverting the output signal Vs of the light receiving amplifier 20 is output. If this change in input voltage is greater than a predetermined value,
A comparison circuit 21 provides a smoke detection signal.
なお、反転増幅器Ａ，の非反転入力に与える基準電圧は
、受光アンブ２０に与える基準電圧Ｖｒｅｒとは異なる
電圧であっても構わない。Note that the reference voltage applied to the non-inverting input of the inverting amplifier A may be a voltage different from the reference voltage Vrer applied to the light receiving amplifier 20.
［発明の効果］
本発明にあっては、上述のように、発振回路の出力によ
り発光素子から間欠的に光信号を発生し、感知器内部に
侵入した煙による散乱光を受光する受光素子の受光出力
を受光アンプにより増幅し、比較回路により煙濃度が所
定値以上か否かを判定するようにした光電式煙感知器に
おいて、受光アンプと比較回路の間に反転増幅器を備え
、受光アンプの出力と反転増幅器の反転入力との間に第
１のコンデンサを接続し、反転増幅器の反転入力と出力
との間に前記発光信号の発生前にオン・オフされるスイ
ッチ回路と第２のコンデンサを並列接続したから、受光
アンプのオフセットや受光素子の温度依存或分等による
ドリフトの影響を受けることなく、煙濃度を判定できる
という効果があり、また、スイッチ回路にて反転増幅器
の出力電圧を設定するようにしたので、大容量のコンデ
ンサや高抵抗を設ける必要がなく、半導体集積回路化し
たときに外付け部品が不要になるので、低コスト化、小
型軽量化の効果が十分に発揮されるものである。[Effects of the Invention] As described above, the present invention includes a light-receiving element that intermittently generates an optical signal from a light-emitting element using the output of an oscillation circuit, and receives scattered light from smoke that has entered the sensor. In a photoelectric smoke detector in which the light receiving output is amplified by a light receiving amplifier and a comparing circuit determines whether the smoke concentration is above a predetermined value, an inverting amplifier is provided between the light receiving amplifier and the comparing circuit, and the light receiving amplifier is amplified. A first capacitor is connected between the output and the inverting input of the inverting amplifier, and a switch circuit that is turned on and off before the emission signal is generated and a second capacitor are connected between the inverting input and the output of the inverting amplifier. Because they are connected in parallel, the smoke density can be determined without being affected by drift due to the offset of the light receiving amplifier or the temperature dependence of the light receiving element, and the output voltage of the inverting amplifier can be set using the switch circuit. This eliminates the need for large-capacity capacitors and high resistance, and eliminates the need for external components when integrated into a semiconductor circuit, which fully realizes the effects of lower costs, smaller size, and lighter weight. It is something.
第１図は本発明の一実施例の回路図、第２図は同上の動
作波形図、第３図は従来の光電式煙感知器のブロック図
、第４図は同上の要部回路図である。
１は発光素子、２は受光素子、１０は発振回路、２０は
受光アンプ、２ｌは比較回路、Ａ，は反転増幅器、Ｃ
２ ． Ｃ ３はコンデンサ、Ｑはスイッチ回路である
。Figure 1 is a circuit diagram of an embodiment of the present invention, Figure 2 is an operational waveform diagram of the same as above, Figure 3 is a block diagram of a conventional photoelectric smoke detector, and Figure 4 is a circuit diagram of the main parts of the same as above. be. 1 is a light emitting element, 2 is a light receiving element, 10 is an oscillation circuit, 20 is a light receiving amplifier, 2l is a comparison circuit, A is an inverting amplifier, C
2. C3 is a capacitor, and Q is a switch circuit.
Claims (1)
路から出力される発光信号に応じて間欠的に光信号を発
生する発光素子と、発光素子から放射された光信号が感
知器内部に侵入した煙により散乱された光を受光する受
光素子と、受光素子の受光出力を増幅する受光アンプと
、受光アンプの出力信号から煙濃度が所定値以上か否か
を判定する比較回路とを備える光電式煙感知器において
、受光アンプと比較回路の間に反転増幅器を備え、受光
アンプの出力と反転増幅器の反転入力との間に第１のコ
ンデンサを接続し、反転増幅器の反転入力と出力との間
に前記発光信号の発生前にオン・オフされるスイッチ回
路と第２のコンデンサを並列接続したことを特徴とする
光電式煙感知器。(1) An oscillation circuit that intermittently generates a light emission signal, a light emitting element that intermittently generates a light signal in response to the light emission signal output from the oscillation circuit, and a light signal emitted from the light emitting element inside the sensor. a light-receiving element that receives light scattered by smoke that has entered the room, a light-receiving amplifier that amplifies the light-receiving output of the light-receiving element, and a comparison circuit that determines whether the smoke concentration is equal to or higher than a predetermined value from the output signal of the light-receiving amplifier. In the photoelectric smoke detector, an inverting amplifier is provided between the light receiving amplifier and the comparison circuit, a first capacitor is connected between the output of the light receiving amplifier and the inverting input of the inverting amplifier, and the first capacitor is connected between the inverting input and the output of the inverting amplifier. A photoelectric smoke detector characterized in that a switch circuit that is turned on and off before the generation of the light emission signal and a second capacitor are connected in parallel between the light emission signal and the light emission signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16632689A JPH0330097A (en) | 1989-06-27 | 1989-06-27 | Photoelectric smoke sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16632689A JPH0330097A (en) | 1989-06-27 | 1989-06-27 | Photoelectric smoke sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0330097A true JPH0330097A (en) | 1991-02-08 |
Family
ID=15829286
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16632689A Pending JPH0330097A (en) | 1989-06-27 | 1989-06-27 | Photoelectric smoke sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0330097A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005269610A (en) * | 2004-03-17 | 2005-09-29 | Microsoft Corp | System and method for encoding features distributed disorderedly inside object |
| JP2009244106A (en) * | 2008-03-31 | 2009-10-22 | Tokyo Gas Co Ltd | Stable isotope-labeled resin |
| WO2009131119A1 (en) * | 2008-04-24 | 2009-10-29 | パナソニック電工株式会社 | Smoke sensor |
| JP2009282955A (en) * | 2008-04-24 | 2009-12-03 | Panasonic Electric Works Co Ltd | Smoke sensor |
| JP2010122995A (en) * | 2008-11-20 | 2010-06-03 | Panasonic Electric Works Co Ltd | Smoke sensor |
| JP2010146402A (en) * | 2008-12-19 | 2010-07-01 | Panasonic Electric Works Co Ltd | Smoke sensor |
-
1989
- 1989-06-27 JP JP16632689A patent/JPH0330097A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005269610A (en) * | 2004-03-17 | 2005-09-29 | Microsoft Corp | System and method for encoding features distributed disorderedly inside object |
| JP2009244106A (en) * | 2008-03-31 | 2009-10-22 | Tokyo Gas Co Ltd | Stable isotope-labeled resin |
| WO2009131119A1 (en) * | 2008-04-24 | 2009-10-29 | パナソニック電工株式会社 | Smoke sensor |
| JP2009282955A (en) * | 2008-04-24 | 2009-12-03 | Panasonic Electric Works Co Ltd | Smoke sensor |
| AU2009239074B2 (en) * | 2008-04-24 | 2013-03-21 | Panasonic Corporation | Smoke sensor |
| US8552355B2 (en) | 2008-04-24 | 2013-10-08 | Panasonic Corporation | Smoke sensor including a current to voltage circuit having a low frequency correction means to produce a correction current |
| JP2010122995A (en) * | 2008-11-20 | 2010-06-03 | Panasonic Electric Works Co Ltd | Smoke sensor |
| JP2010146402A (en) * | 2008-12-19 | 2010-07-01 | Panasonic Electric Works Co Ltd | Smoke sensor |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7352107B2 (en) | Transconductance circuit for piezoelectric transducer | |
| US7129487B2 (en) | Infrared detecting circuit and an infrared detector | |
| JPH10511453A (en) | Ultra low noise optical receiver | |
| DE69631142D1 (en) | Condition monitoring of a gas detector | |
| US6952005B2 (en) | Optical receiver circuit | |
| JPH0330097A (en) | Photoelectric smoke sensor | |
| JP3203363B2 (en) | Peak detector | |
| KR950003136B1 (en) | Power amplifier | |
| US5929759A (en) | Proximity detector with rapid reception amplification | |
| JP2674110B2 (en) | Temperature compensation circuit for avalanche photodiode bias circuit | |
| US6188278B1 (en) | Amplification circuits | |
| JP2562830B2 (en) | Received light signal detection circuit of photoelectric smoke detector | |
| JP2688895B2 (en) | Photoelectric analog smoke detector | |
| JP4060597B2 (en) | Pulse width detection circuit and reception circuit | |
| JPH01226205A (en) | Amplifier with output swing limit | |
| JP3267184B2 (en) | Photoelectric smoke detector | |
| JPH05340807A (en) | Infrared detector | |
| JPH0514096A (en) | Light receiving amplifier circuit for photoelectric sensor | |
| JPH03179816A (en) | Electronic switch | |
| JPH10154285A (en) | Photoelectric smoke sensor | |
| JPH0267933A (en) | Detecting circuit for pyroelectric infrared-ray sensor | |
| JPH0628322B2 (en) | Current / voltage conversion circuit | |
| KR0120585B1 (en) | Sp/lp mode detection circuit | |
| JPS636480A (en) | Pulse photocurrent amplifier circuit with tracking hold circuit | |
| JPH04259105A (en) | Amplifier circuit |