JPH0460276B2 - - Google Patents
Info
- Publication number
- JPH0460276B2 JPH0460276B2 JP1500286A JP1500286A JPH0460276B2 JP H0460276 B2 JPH0460276 B2 JP H0460276B2 JP 1500286 A JP1500286 A JP 1500286A JP 1500286 A JP1500286 A JP 1500286A JP H0460276 B2 JPH0460276 B2 JP H0460276B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- circuit
- smoke
- output
- switch element
- 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
Links
- 239000000779 smoke Substances 0.000 claims description 37
- 230000007423 decrease Effects 0.000 claims description 15
- 230000035945 sensitivity Effects 0.000 claims description 15
- 230000003321 amplification Effects 0.000 claims description 12
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 12
- 239000003990 capacitor Substances 0.000 claims description 8
- 238000012544 monitoring process Methods 0.000 claims description 5
- 230000010355 oscillation Effects 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 230000002265 prevention Effects 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
Landscapes
- Fire-Detection Mechanisms (AREA)
Description
【発明の詳細な説明】
〔技術分野〕
本発明は、光電式煙感知器の感度が鈍感になり
煙を感知できなくなつて失報することを防止する
失報防止回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a mis-alarm prevention circuit that prevents a photoelectric smoke detector from becoming insensitive and unable to detect smoke, resulting in mis-alarms.
従来、光電式煙感知器には失報警報機能、即
ち、感度が鈍感になつて万一の火災時に煙を感知
できなくなつたことを知らせる機能はなく、単に
煙がある濃度を越えれば警報信号を出力するもの
であつた。したがつて、感度の点検を頻繁に行な
わなければならず、又、点検の間にひどく汚れて
煙を感知する光学系が劣化し、万一の火災時に動
作しない危険性を有していた。
Conventionally, photoelectric smoke detectors do not have a false alarm function, that is, a function that alerts them that their sensitivity has become insensitive and they are no longer able to detect smoke in the event of a fire; they simply issue an alarm when smoke exceeds a certain concentration. It outputs a signal. Therefore, the sensitivity has to be checked frequently, and there is a risk that the optical system for detecting smoke will become so dirty during the inspection that it will deteriorate and become inoperable in the event of a fire.
一般に、光電式煙感知器の内部回路は第４図の
ように構成しており、発振回路１は第５図ａのよ
うに周期約３秒で一瞬発光素子２を発光させる。
受光素子３は発光素子２が発光すれば、その光を
受光して微少電流を発生し、増巾回路４で増巾さ
れて第５図ｂのように電圧Vsとして出力される。
光学系５は散乱式であるため、通常は光学系５の
壁面等で反射された光のみが受光素子３に入光す
るが、第５図の時刻toで煙が入ると煙粒子で反射
した光も受光素子３に入光するため、電圧Vsは
煙濃度の増加につれて大きくなる。電圧Vsの波
高値と煙濃度との関係は第６図のようになり、従
来の光電式煙感知器は増巾回路４の出力を次段の
トラジスタのベース、エミツタ間に直接入力し、
トランジスタがオンすれば煙あり、オフのときは
煙なしとしていたので、しきい値は約0.6Vとな
る。したがつて、第６図の実線で示す正常なとき
は煙濃度ａ％／ｍで動作するが、破線のように失
報側に感度がずれるとｂ％／ｍに変化する。又、
煙ないときの電圧VsはＡ又はＢであるから、従
来例ではどちらの場合にもトランジスタはオフで
あり、失報側の検出は不可能であつた。 Generally, the internal circuit of a photoelectric smoke detector is constructed as shown in FIG. 4, and the oscillation circuit 1 causes the light emitting element 2 to momentarily emit light at a period of about 3 seconds as shown in FIG. 5a.
When the light emitting element 2 emits light, the light receiving element 3 receives the light and generates a small current, which is amplified by the amplifying circuit 4 and output as a voltage Vs as shown in FIG. 5b.
Since the optical system 5 is of a scattering type, normally only the light reflected from the wall of the optical system 5 enters the light receiving element 3, but when smoke enters at time t in Fig. 5, it is reflected by smoke particles. Since light also enters the light receiving element 3, the voltage Vs increases as the smoke density increases. The relationship between the peak value of the voltage Vs and the smoke density is as shown in Figure 6. In the conventional photoelectric smoke detector, the output of the amplification circuit 4 is input directly between the base and emitter of the next stage transistor.
Since there was smoke when the transistor was on and no smoke when it was off, the threshold value was approximately 0.6V. Therefore, during normal operation as shown by the solid line in FIG. 6, the smoke density operates at a%/m, but when the sensitivity deviates to the side of failure as shown by the broken line, it changes to b%/m. or,
Since the voltage Vs when there is no smoke is A or B, in the conventional example, the transistor is off in either case, making it impossible to detect a false alarm.
本発明の目的とするところは、煙感知器の感度
劣化を自動的に検知し、警報信号を出力すること
により万一の火災時の失報を防止し、更に、定期
的な感度点検を少なくし、しかも、回路電圧が低
下したときにも確実に動作するようにすることに
ある。
The purpose of the present invention is to automatically detect deterioration in the sensitivity of smoke detectors and output an alarm signal to prevent false alarms in the event of a fire, and to reduce the need for periodic sensitivity checks. Moreover, the purpose is to ensure reliable operation even when the circuit voltage drops.
実施例
光電式煙感知器は第１図のように構成されてお
り、電源端子T1、T2間に電源を接続して定電圧
回路６、定電流回路７を介して発振回路１、発光
素子２、受光素子３および増巾回路４に電源を供
給するとともに信号処理回路８に電源を供給に、
信号処理回路８の出力により出力スイツチング回
路９を動作させる。信号処理回路８は第２図の主
スイツチ要素であるトランジスタTr1その他で形
成され、増巾回路４の出力電圧Vsが入力されて
従来と同様に煙濃度があるレベルになると出力ス
イツチング回路９が動作し、警報を発する。失報
防止回路は第２図のように構成し、電圧Vsは２
個のFET（FET1、FET2）で構成された電圧比較
回路としての差動増巾回路１０に入力され、基準
電圧V1と比較されてVs＞V1であればFET1がオ
ンして差動増巾回路１０より出力を出す。ここ
で、差動増巾回路１０の基準電圧V1はツエナー
ダイオードZDにより定電圧化している。また、
基準電圧V1は煙監視空間に煙粒子が存在しない
ときに煙監視空間の壁面での反射などによつて得
られる増巾回路４の出力電圧を判別するように設
定されるのであつて、発光素子２の発光時に得ら
れる増巾回路４の出力電圧の正常時の電圧よりは
低く、失報側への感度の低下時の電圧よりは高く
なるように設定されている。ここに差動増巾回路
１０にFETに使用したのは、電圧Vsの値が0.6V
以下という低い値であるため、トランジスタでは
構成できないためであり、FETであれば電圧Vs
が0.1V程度でもオンさせることができる。又、
可変抵抗VRで電圧V1を調整するのは光学系の特
性のばらつきにより電圧Vsがばらつくためであ
る。差動増巾回路１０の出力はAND回路１１に
入力し、差動増巾回路１０の出力と発光素子２を
駆動する発振回路１の出力との両方がAND回路
１１に入力したとき、AND回路１１より出力を
出し、放電回路１２を形成する。第１のスイツチ
要素であるトランジスタTr4をオンにする。即
ち、発光素子２が第３図ａの信号により発光し、
電圧Vsが第３図ｂに示す波形のとき、t1−t2間、
t5−t6間およびt7−t8間ではトランジスタTr2、
Tr3共にオンになるためトランジスタTr4がオン
になるが、電圧Vsがt3−t4間のようにノイズであ
る場合には、トランジスタTr3がオンしないた
め、トランジスタTr4はオンしない。いいかえれ
ば、ノイズによる電圧Vsの変化でFET1がオンし
たとしもその時間帯が発光期間外であれば何ら影
響は受けない。スイツチング回路１３はCR時定
数回路１４及び第２のスイツチ要素であるPUT
を有し、コンデンサＣの電圧が一定電圧以上にな
つたとき、スイツチング動作をし、コンデンサＣ
は放電回路１２が動作したとき放電されるように
する。第２図の電源端子a0、a1は第１図の端子
a0、a1に接続する。
Embodiment A photoelectric smoke detector is constructed as shown in Fig. 1. A power supply is connected between power terminals T 1 and T 2 and the oscillation circuit 1 and light emitting circuit are connected via a constant voltage circuit 6 and a constant current circuit 7. For supplying power to the element 2, the light receiving element 3, and the amplification circuit 4, and to supply power to the signal processing circuit 8,
The output switching circuit 9 is operated by the output of the signal processing circuit 8. The signal processing circuit 8 is formed by the transistor Tr 1 , which is the main switching element shown in FIG. operates and issues an alarm. The false alarm prevention circuit is configured as shown in Figure 2, and the voltage Vs is 2.
The voltage is input to the differential amplification circuit 10 as a voltage comparison circuit composed of FETs (FET 1 , FET 2 ), and is compared with the reference voltage V 1. If Vs>V 1 , FET 1 is turned on. An output is output from the differential amplification circuit 10. Here, the reference voltage V1 of the differential amplifier circuit 10 is made constant by a Zener diode ZD. Also,
The reference voltage V 1 is set to determine the output voltage of the amplification circuit 4 obtained by reflection on the wall of the smoke monitoring space when there are no smoke particles in the smoke monitoring space. The output voltage of the amplifying circuit 4 obtained when the element 2 emits light is set to be lower than the voltage during normal operation, but higher than the voltage when the sensitivity to the side of failure is decreased. Here, the voltage Vs value used for the FET in the differential amplifier circuit 10 is 0.6V.
This is because it cannot be configured with a transistor because it is a low value below, and if it is a FET, the voltage Vs
It can be turned on even when the voltage is around 0.1V. or,
The reason why the voltage V 1 is adjusted by the variable resistor VR is that the voltage Vs varies due to variations in the characteristics of the optical system. The output of the differential amplification circuit 10 is input to the AND circuit 11, and when both the output of the differential amplification circuit 10 and the output of the oscillation circuit 1 that drives the light emitting element 2 are input to the AND circuit 11, the AND circuit is input. An output is output from 11 to form a discharge circuit 12. The first switch element, transistor Tr 4 , is turned on. That is, the light emitting element 2 emits light according to the signal shown in FIG. 3a,
When the voltage Vs has the waveform shown in Figure 3b, between t1 and t2 ,
Between t5 and t6 and between t7 and t8 , the transistor Tr2 ,
Since both Tr 3 are turned on, the transistor Tr 4 is turned on, but if the voltage Vs is noise, such as between t 3 and t 4 , the transistor Tr 3 is not turned on, so the transistor Tr 4 is not turned on. In other words, even if FET 1 is turned on due to a change in voltage Vs due to noise, it will not be affected at all as long as the time period is outside the light emission period. The switching circuit 13 includes a CR time constant circuit 14 and a second switching element PUT.
When the voltage of capacitor C exceeds a certain voltage, it performs a switching operation and capacitor C
is made to be discharged when the discharge circuit 12 is operated. The power terminals a 0 and a 1 in Figure 2 are the terminals in Figure 1.
Connect to a 0 and a 1 .
動 作
光学系が正常なときは、電圧Vsは差動増巾回
路１０に入力され、電圧V1と比較されてVs＞V1
であればFET1がオンし、同時にトランジスタ
Tr2もオンし、このときトランジスタTr3がオン
であればトランジスタTr4もオンしてコンデンサ
Ｃに充電されている電荷が放電する。したがつ
て、電圧V2は第３図ｃのように電圧V3を上回る
ことがなく、スイツチング回路１３のPUTはオ
ンしない。Operation When the optical system is normal, the voltage Vs is input to the differential amplifier circuit 10, and compared with the voltage V1 , Vs> V1.
If so, FET 1 turns on and at the same time transistor
Tr 2 is also turned on, and if the transistor Tr 3 is on at this time, the transistor Tr 4 is also turned on and the charge stored in the capacitor C is discharged. Therefore, the voltage V 2 does not exceed the voltage V 3 as shown in FIG. 3c, and the PUT of the switching circuit 13 is not turned on.
つぎに、光学系の汚れ等で煙がないときの電圧
Vsの値が低くなつたとき、即ち、感度が失報側
にずれた場合に、電圧Vsが電圧V1を越えなくな
ると、FET1がオンすることがなくなり、トラン
ジスタTr2、Tr4もオンせず、コンデンサＣは時
定数R7×Ｃで充電され、電圧V2がV3を上回つた
時点でPUTがオンする。PUTがオンすれば警報
を発するようにすれば失報警報が実現できる。失
報警報は火災警報程急ぐ必要はないから、時定数
R7×Ｃは大きくし、電圧VsがV1を下回つてから
１〜５分でも充分であり、時定数を大きくするこ
とにより失報警報の誤報を減少できる。 Next, consider the voltage when there is no smoke due to dirt in the optical system, etc.
When the value of Vs becomes low, that is, when the sensitivity shifts to the side of false alarm, when the voltage Vs no longer exceeds the voltage V1 , FET 1 is no longer turned on, and transistors Tr 2 and Tr 4 are also turned on. Instead, capacitor C is charged with a time constant R 7 ×C, and PUT is turned on when voltage V 2 exceeds V 3 . A missed alarm can be realized by issuing an alarm when PUT is turned on. Missed alarms do not need to be as urgent as fire alarms, so the time constant
It is sufficient to increase R 7 ×C and 1 to 5 minutes after the voltage Vs falls below V 1 , and by increasing the time constant, false alarms can be reduced.
更に、部品故障により、端子a0、a1間の電圧
V0が低下した場合には、発光素子２に流れる電
流が減少し、電圧Vsが低下する。しかるに、差
動増巾回路１０の基準電圧V1はツエナーダイオ
ードZDによりその電圧レベルを安定にしている
ので、電圧V0がツエナーダイオードZDのツエナ
ー電圧以下にならない限り、基準電圧V1のレベ
ルは変らない。通常、電圧V0は約10V、電圧Vs
は0.6程度であるから、ツエナーダイオードZDの
ツエナー電圧は約2Vで充分である。したがつて、
電圧V0が10Vより2Vまで低下しても電圧V1は変
らないことになり、電圧V0の低下に起因する電
圧Vsの低下により失報も検出できる。 Furthermore, due to component failure, the voltage between terminals a 0 and a 1
When V 0 decreases, the current flowing through the light emitting element 2 decreases, and the voltage Vs decreases. However, since the voltage level of the reference voltage V 1 of the differential amplifier circuit 10 is stabilized by the Zener diode ZD, the level of the reference voltage V 1 remains unchanged unless the voltage V 0 becomes lower than the Zener voltage of the Zener diode ZD. It doesn't change. Usually voltage V 0 is about 10V, voltage Vs
is about 0.6, so a Zener voltage of about 2V for the Zener diode ZD is sufficient. Therefore,
Even if the voltage V 0 decreases from 10 V to 2 V, the voltage V 1 will not change, and a false alarm can also be detected due to the decrease in the voltage Vs caused by the decrease in the voltage V 0 .
本発明は上述の構成を有するものであるから、
光学系の汚れなどによつて煙を検知する感度が失
報側に低下したときに、発光素子の発光時におけ
る増巾回路の出力電圧が基準電圧よりも低くなる
ことを利用することによつて、感度の低下を検出
することができるのであり、このときには電圧比
較回路の出力が反転せず第１のスイツチ要素がオ
ンにならないからコンデンサの端子電圧が上昇し
て第２のスイツチ要素がオンになり、失報警報を
発することができるのである。すなわち、感度の
低下を自動的に検知して第２のスイツチ要素がオ
ンになることによつて感度の低下を報知できると
いう効果を奏する。その結果、万一の火災時には
失報を防止できる上、定期的な感度点検の回数を
削減できるのである。また、基準電源は一定電圧
に設定されているから回路電圧が低下しても基準
電圧は一定に保たれるのであつて、回路電圧が低
下したときに増巾回路の出力が低下すれば、光学
系の機能が低下した場合と同様に報知できること
になる。すなわち、回路電圧の低下による感度の
低下も報知できるという利点がある。
Since the present invention has the above configuration,
By utilizing the fact that the output voltage of the amplifier circuit becomes lower than the reference voltage when the light emitting element emits light when the smoke detection sensitivity decreases to the side of false alarm due to dirt in the optical system, etc. In this case, the output of the voltage comparator circuit is not inverted and the first switch element is not turned on, so the terminal voltage of the capacitor increases and the second switch element is turned on. Therefore, a missed alarm can be issued. In other words, the present invention has the effect that a decrease in sensitivity can be notified by automatically detecting a decrease in sensitivity and turning on the second switch element. As a result, not only can false alarms be prevented in the event of a fire, but the number of periodic sensitivity checks can also be reduced. In addition, since the reference power source is set to a constant voltage, the reference voltage will remain constant even if the circuit voltage decreases. This means that notification can be made in the same way as when the system's functionality deteriorates. That is, there is an advantage that a decrease in sensitivity due to a decrease in circuit voltage can also be reported.
第１図は光電式煙感知器のブロツク回路図、第
２図は本発明の一実施例の回路図、第３図は同上
の要部電圧、電流波形図、第４図は一般の光電式
煙感知器の要部ブロツク回路図、第５図は同上の
要部電圧、電流波形図、第６図は同上の特性図で
ある。
１……発振回路、２……発光素子、３……受光
素子、４……増巾回路、１０……差動増巾回路、
１１……AND回路、１２……放電回路、１３…
…スイツチング回路、１４……CR時定数回路、
ZD……ツエナーダイオード、Ｃ……コンデンサ。
Figure 1 is a block circuit diagram of a photoelectric smoke detector, Figure 2 is a circuit diagram of an embodiment of the present invention, Figure 3 is a voltage and current waveform diagram of the same main parts, and Figure 4 is a general photoelectric smoke detector. FIG. 5 is a block circuit diagram of the main parts of the smoke detector, FIG. 5 is a voltage and current waveform diagram of the main parts of the same, and FIG. 6 is a characteristic diagram of the same. DESCRIPTION OF SYMBOLS 1... Oscillation circuit, 2... Light emitting element, 3... Light receiving element, 4... Amplification circuit, 10... Differential amplification circuit,
11...AND circuit, 12...discharge circuit, 13...
...switching circuit, 14...CR time constant circuit,
ZD... Zener diode, C... Capacitor.
Claims (1)
的に光を照射する発光素子と、煙監視空間の煙粒
子による散乱光を受光する受光素子と、受光素子
の出力を増巾する増巾回路、増巾回路の出力電圧
が所定電圧以下であるときにオンになる主スイツ
チ要素と主スイツチ要素のオン・オフに基づいて
煙濃度が所定レベル以上になつたと判断されると
警報を発する出力スイツチング回路とを備えた光
電式煙感知器における煙の検知感度の低下を検知
する失報防止回路であつて、一定の基準電圧を発
生する基準電源と、増巾回路の出力電圧を基準電
圧と比較し出力電圧が基準電圧以上になると出力
を反転させる電圧比較回路と、電圧比較回路の出
力が反転するとオンになる第１のスイツチ要素
と、所定の抵抗を介して常時充電され第１のスイ
ツチ要素がオンになると放電されるコンデンサ
と、コンデンサの端子電圧が所定電圧以上になる
とオンになつて煙の検知感度の低下を報知する失
報警報を発する第２のスイツチ要素とを備え、上
記基準電圧は、煙監視空間に煙粒子が存在しない
ときの発光素子の発光時の増巾回路の出力電圧の
正常時の電圧よりも低く、煙の検知感度の低下時
の電圧よりも高く設定されたことを特徴とする光
電式煙感知器の失報防止回路。1. A light emitting element that is driven by an oscillation circuit and intermittently irradiates light into the smoke monitoring space, a light receiving element that receives light scattered by smoke particles in the smoke monitoring space, and an amplification circuit that amplifies the output of the light receiving element. A main switch element that turns on when the output voltage of the amplification circuit is below a predetermined voltage, and an output switching circuit that issues an alarm when it is determined that the smoke density has exceeded a predetermined level based on the on/off of the main switch element. This is a false alarm prevention circuit that detects a decrease in smoke detection sensitivity in a photoelectric smoke detector equipped with A voltage comparator circuit that inverts the output when the output voltage exceeds a reference voltage, a first switch element that turns on when the output of the voltage comparator circuit inverts, and a first switch element that is constantly charged through a predetermined resistor. It is equipped with a capacitor that is discharged when it is turned on, and a second switch element that is turned on when the terminal voltage of the capacitor exceeds a predetermined voltage and issues a false alarm that indicates a decrease in smoke detection sensitivity, and the reference voltage is , the output voltage of the amplification circuit when the light emitting element emits light when there are no smoke particles in the smoke monitoring space is set lower than the normal voltage and higher than the voltage when smoke detection sensitivity decreases. Features a photoelectric smoke detector false alarm prevention circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1500286A JPS62173595A (en) | 1986-01-27 | 1986-01-27 | Misalarm prevention circuit for photoelectric type smoke sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1500286A JPS62173595A (en) | 1986-01-27 | 1986-01-27 | Misalarm prevention circuit for photoelectric type smoke sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62173595A JPS62173595A (en) | 1987-07-30 |
| JPH0460276B2 true JPH0460276B2 (en) | 1992-09-25 |
Family
ID=11876693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1500286A Granted JPS62173595A (en) | 1986-01-27 | 1986-01-27 | Misalarm prevention circuit for photoelectric type smoke sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62173595A (en) |
-
1986
- 1986-01-27 JP JP1500286A patent/JPS62173595A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62173595A (en) | 1987-07-30 |
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