JPH03111998A - Ionization type smoke sensor - Google Patents
Ionization type smoke sensorInfo
- Publication number
- JPH03111998A JPH03111998A JP25024689A JP25024689A JPH03111998A JP H03111998 A JPH03111998 A JP H03111998A JP 25024689 A JP25024689 A JP 25024689A JP 25024689 A JP25024689 A JP 25024689A JP H03111998 A JPH03111998 A JP H03111998A
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- ion chamber
- voltage
- ion
- smoke
- 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 26
- 230000010355 oscillation Effects 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 239000000428 dust Substances 0.000 abstract description 14
- 239000003990 capacitor Substances 0.000 abstract description 11
- 230000005855 radiation Effects 0.000 abstract description 5
- 230000035945 sensitivity Effects 0.000 abstract description 4
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 13
- 206010069201 Smoke sensitivity Diseases 0.000 description 6
- 230000003321 amplification Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 238000009825 accumulation Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- -1 etc. Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
Landscapes
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Fire-Detection Mechanisms (AREA)
Abstract
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、イオン化式煙感知器に関するものである。[Detailed description of the invention] [Industrial application field] The present invention relates to an ionization type smoke detector.
イオン化式煙感知器は一般にイオン室を2つ具備する2
チヤンバ一方式と、第4図に示すようなイオン室2を1
つ有する1チヤンバ一方式とがあり、いずれも既に商品
化されている。後者の場合の作動原理は、放射線源8を
有するイオン室2に電圧を加えておき、検出すべき煙が
存在していない時は、イオン電流が略一定量流れており
、前記イオン室2に煙が流入するとイオン電流が流れに
くくなり、電流値が減少し、これを電圧に変換し、増幅
等を経て、スイッチング回路6を作動させ、受信機に信
号を送出するものである。この原理を応用した実際の回
路構成は、例えば特公昭62−42319号公報等に開
示しているが、前記第4図乃至第6図のような回路構成
及び波形図を有するものである。この回路の具体的な検
知動作は、イオン室2にパルス電圧が印加されており、
印加している期間T1には、イオン電流■1が流れ、抵
抗ROの両端にROXII (V)の電圧が発生する
。またイオン室2に電流を印加していない期間T2にイ
オン室2に流れる電流を12 (通常はl2=0であ
る)とすると、抵抗ROの両端にROXI2 (V)
の電圧が発生する。これら両時点の電圧差(変化分)
VS −(ROX II −RO×工2)を増幅回路3
で交流増幅した後、後段に接続した閾値回路5で判別し
てスイッチングするようにしている。これら両時点の電
圧差■Sは、煙の濃度が増加するにつれてイオン電流1
1が小さくなり、これにともない電圧差vSが小さくな
ることにより、前記閾値回路5の閾値以下となり作動す
るのである。Ionization smoke detectors generally have two ion chambers.
One chamber type and one ion chamber 2 as shown in Figure 4.
There is a one-chamber type with two types, and both have already been commercialized. The operating principle in the latter case is that a voltage is applied to the ion chamber 2 containing the radiation source 8, and when there is no smoke to be detected, an approximately constant amount of ion current flows through the ion chamber 2. When smoke flows in, the ion current becomes difficult to flow, the current value decreases, this is converted into voltage, and through amplification etc., the switching circuit 6 is activated and a signal is sent to the receiver. An actual circuit configuration to which this principle is applied is disclosed, for example, in Japanese Patent Publication No. 62-42319, and has the circuit configuration and waveform diagrams shown in FIGS. 4 to 6. The specific detection operation of this circuit is that a pulse voltage is applied to the ion chamber 2,
During the application period T1, an ion current 1 flows, and a voltage of ROXII (V) is generated across the resistor RO. Furthermore, if the current flowing through the ion chamber 2 during the period T2 when no current is applied to the ion chamber 2 is 12 (normally l2=0), ROXI2 (V) is applied to both ends of the resistor RO.
voltage is generated. Voltage difference (change) between these two points
VS - (ROX II - RO x Engineering 2) to amplifier circuit 3
After alternating current amplification is performed, a threshold circuit 5 connected at a subsequent stage performs discrimination and switching. The voltage difference between these two points S is the ionic current 1 as the smoke concentration increases.
1 becomes smaller, and as a result, the voltage difference vS becomes smaller, so that it becomes less than the threshold of the threshold circuit 5 and operates.
さて、前記のようなイオン化式煙感知器を長期間使用し
たり、粉塵等の多い悪環境化に設置すると、第7図に示
すように、イオン室2内にはこり9が堆積することがあ
る。このほこり9が電気的に導体であれば、イオン電流
に影響は及ぼさないが、糸くず、砂等であると電気的に
は絶縁体であり、誘電体すなわちコンデンサとして機能
することが確認されており、イオン室内の電流に影響を
及ぼす。今、第8図(イ)、(ロ)に示すように、はこ
り9を等価的に抵抗RXとコンデンサCXの並列回路と
考え、印加電圧Vpを第9図に示したパルス電圧とする
と、コンデンサCXの両端電圧は、第9図下段に示すよ
うに、0〜10(印加電圧)■の間のある値で一定とな
る。その理由は、はこり9の等価抵抗RXとイオン室2
全体の抵抗RIが非常に大きく、コンデンサCXの充放
電時定数は印加している期間T1及びしていない期間T
2に比べて、非常に大きい値となっているためである。Now, if the ionization type smoke detector as described above is used for a long period of time or installed in a bad environment with a lot of dust, etc., dust 9 may accumulate in the ion chamber 2, as shown in Fig. 7. be. If this dust 9 is an electrical conductor, it will not affect the ionic current, but if it is lint, sand, etc., it is electrically insulating and has been confirmed to function as a dielectric, that is, a capacitor. This affects the current in the ion chamber. Now, as shown in FIGS. 8(a) and 8(b), if we consider the bump 9 to be equivalently a parallel circuit of a resistor RX and a capacitor CX, and the applied voltage Vp is the pulse voltage shown in FIG. 9, The voltage across the capacitor CX is constant at a certain value between 0 and 10 (applied voltage) (as shown in the lower part of FIG. 9). The reason is the equivalent resistance RX of the lump 9 and the ion chamber 2.
The overall resistance RI is very large, and the charging/discharging time constant of the capacitor CX is the period T1 when the voltage is applied and the period T when it is not applied.
This is because it is a very large value compared to 2.
このほこり9による一定電圧の増加分をVCXとする。Let VCX be the increase in constant voltage due to this dust 9.
このようにはこり9が堆積した状態で、期間TI及び期
間T2にイオン室2空間に加わる電圧はVTI =
10−VCX
VT2= −VCX
となる。従って電圧差VSは
■5
=ROX (VTIの のI−VT2の のI)となる
。第1O図の電圧−電流特性の実測値によると、この関
係は直線にはならないので、前記式のアングラインの値
は、はこりによるVCXO値に依存して異なる。そして
VCXが0のときに最小となる。With the lumps 9 deposited in this manner, the voltage applied to the ion chamber 2 space during periods TI and T2 is VTI =
10-VCX VT2=-VCX. Therefore, the voltage difference VS is 5=ROX (I of VTI - I of VT2). According to the measured values of the voltage-current characteristics shown in FIG. 1O, this relationship is not a straight line, so the value of Angline in the above equation varies depending on the VCXO value due to the bulge. And it becomes minimum when VCX is 0.
以上の点を要約すると、
■イオン室内にほこりが堆積すると、イオン室の空間に
加わる電圧が変化し、その結果イオン電流も変化し、電
圧差VSも変化する。To summarize the above points: (1) When dust accumulates in the ion chamber, the voltage applied to the space of the ion chamber changes, and as a result, the ion current changes, and the voltage difference VS also changes.
■上記変化の方向はほこりによるvCxの値にばらつき
があっても常に電圧差VSは大きくなる方向であり、煙
感度としては、感度が鈍くなる方向である。(2) The direction of the change is such that the voltage difference VS always increases even if there are variations in the value of vCx due to dust, and the smoke sensitivity becomes less sensitive.
前記の如く、はこりの堆積により、煙感度が鈍くなるこ
とは、火災感知器としての基本機能に係わる問題であり
、早急な解決が望まれる。As mentioned above, the decrease in smoke sensitivity due to the accumulation of dust is a problem related to the basic function of a fire detector, and an immediate solution is desired.
この発明は、前記のような実状に着目して案出されたも
ので、その目的とするところは、イオン化式煙感知器の
イオン室内にほこりが堆積しても、煙感度が変化しない
イオン化式煙感知器を得ることにある。This invention was devised by paying attention to the above-mentioned actual situation, and its purpose is to provide an ionization type smoke detector in which the smoke sensitivity does not change even if dust accumulates in the ion chamber of the ionization type smoke detector. The point is to get a smoke detector.
二の発明では、上記目的を達成するために、次の手段を
講じた。In the second invention, the following measures were taken to achieve the above object.
すなわち、この発明にかかるイオン化式煙感知器は、定
電圧回路を有する電源回路と、発振回路と、該発振回路
の出力パルスが加えられるイオン室と、前記イオン室の
基準点の電圧が、煙の存在により、基準電圧を越える時
に感知器動作をなすべく出力する閾値回路とから成るイ
オン化式煙感知器において、前記イオン室に印加される
前記発振回路の出力パルスをアース電位を基準にして略
等しい絶対値で正、負に変化させる変換回路を設けたこ
とを特徴とするにして等しい絶対値で正、負に変化させ
たた構成としている。That is, the ionization type smoke sensor according to the present invention includes a power supply circuit having a constant voltage circuit, an oscillation circuit, an ion chamber to which an output pulse of the oscillation circuit is applied, and a voltage at a reference point of the ion chamber that In an ionization type smoke detector consisting of a threshold circuit that outputs an output to operate the sensor when a reference voltage is exceeded, the output pulse of the oscillation circuit applied to the ion chamber is approximately The structure is characterized in that it includes a conversion circuit that changes the polarity between positive and negative values with equal absolute values.
本発明では、イオン室に正、負に等しい波高値のパルス
電圧が印加し、イオン室内のコンデンサ成分を有するほ
こりにも前記のパルス電圧が印加するが、正、負のパル
スが交互に印加することによりほこりのコンデンサ成分
に蓄電することがなくイオン室の電界に変化が生じない
こととなり、ほこりの堆積による経年変化による感度鈍
化がなくなるのである。In the present invention, a pulse voltage having equal positive and negative peak values is applied to the ion chamber, and the pulse voltage is also applied to dust having a capacitor component in the ion chamber, but positive and negative pulses are applied alternately. As a result, there is no accumulation of electricity in the capacitor component of dust, and no change occurs in the electric field in the ion chamber, eliminating sensitivity deterioration due to aging due to dust accumulation.
以下、この発明の実施例を図面に基づいて説明する。 Embodiments of the present invention will be described below based on the drawings.
イオン化式煙感知器Aの構造は第7図のものと同様であ
り、ボディbの内部に回路部を搭載したプリント基板p
に、アノード電極aと、このアノード電11iaに囲ま
れて、カソード電極kが設けられ、イオン室2を構成し
ている。カソード電極kには放射線源8が取りつけであ
る。ボディbとアノード電極aには煙が流入する孔が設
けである。The structure of the ionization type smoke detector A is similar to that shown in Fig. 7, and includes a printed circuit board p with a circuit section mounted inside the body b.
An anode electrode a and a cathode electrode k surrounded by the anode electrode 11ia are provided to constitute an ion chamber 2. A radiation source 8 is attached to the cathode electrode k. The body b and the anode electrode a are provided with holes through which smoke flows.
一方、全体回路は、従来例の第4図と略同様であり、要
部のみ前記第1図に変換したもので実現できる。ここで
第4図の回路を説明すると、1は無安定マルチ、フリッ
プフロップ等からなる発振回路、2はセンサとしてのイ
オン室、3はFET、オペアンプ等からなるイオン電流
の交流(変化)分の増幅回路、4はコンデンサ、抵抗、
アナログスイッチ等からなる信号整流回路、5は信号電
圧と基準電圧とを比較するコンパレータ等を有する閾値
回路、7は定電圧回路、ダイオードブリッジ等を含む電
源回路である。On the other hand, the overall circuit is substantially the same as that of the conventional example shown in FIG. 4, and can be realized by converting only the main parts to that shown in FIG. 1. To explain the circuit shown in Fig. 4, 1 is an oscillation circuit consisting of an astable multi-channel, flip-flop, etc., 2 is an ion chamber as a sensor, and 3 is an AC (change) component of the ion current consisting of FET, operational amplifier, etc. Amplification circuit, 4 is a capacitor, a resistor,
A signal rectifier circuit including an analog switch, etc.; 5 a threshold circuit having a comparator for comparing the signal voltage with a reference voltage; and 7 a power supply circuit including a constant voltage circuit, a diode bridge, etc.
第1図は、要部の回路図を示し、発振回路1にコンデン
サC1と抵抗R1の回路を構成し、パルス周期TL =
T2とし、CI XRIを周期T1より充分大きくすれ
ば、コンデンサC1はVC1=10/2=5Vに充電さ
れ、イオン室2に印加される電圧は第2図(ロ)のよう
になる。上記の構成によると、充電、放電条件が全く対
称であるため、はこりによるコンデンサ成分CXに充電
される電荷はほとんどなくなり、第3図に示すように、
■CXの値はほぼOvを維持し、イオン化式煙感知器の
感度を鈍くする弊害がなくなる。FIG. 1 shows a circuit diagram of the main part, in which an oscillation circuit 1 includes a capacitor C1 and a resistor R1, and the pulse period TL =
If the period T2 is set and CI According to the above configuration, since the charging and discharging conditions are completely symmetrical, almost no charge is charged to the capacitor component CX due to the lump, and as shown in FIG.
■The CX value is maintained at approximately Ov, eliminating the negative effect of dulling the sensitivity of ionization smoke detectors.
この発明によれば、定電圧回路を有する電源回路と、発
振回路と、該発振回路の出力パルスが加えられるイオン
室と、前記イオン室の基準点の電圧が、煙の存在により
、基準電圧を越える時に感知器動作をなすべく出力する
閾値回路とから成るイオン化式煙感知器において、前記
イオン室に印加される前記発振回路の出力パルスをアー
ス電位を基準にして略等しい絶対値で正、負に変化させ
る変換回路を設けたので、誘電体のほこりがイオン室に
堆積しても、イオン室内の電界を変化させることがない
ため、煙感度は変化せずに当初の煙感度を維持できる。According to the present invention, a power supply circuit having a constant voltage circuit, an oscillation circuit, an ion chamber to which an output pulse of the oscillation circuit is applied, and a voltage at a reference point of the ion chamber lower than the reference voltage due to the presence of smoke. In an ionization type smoke detector, the output pulse of the oscillation circuit applied to the ion chamber is set to a positive or negative value with substantially the same absolute value with respect to the ground potential. Since a conversion circuit is provided to change the smoke sensitivity, even if dielectric dust accumulates in the ion chamber, the electric field inside the ion chamber does not change, so the smoke sensitivity remains unchanged and the original smoke sensitivity can be maintained.
第1図乃至第3図はこの発明の実施例を示し、第1図は
イオン化式煙感知器の要部回路図、第2図は回路の波形
図、第3図は波形図とCX電圧の関係図である。
第4図乃至第10図は、従来例を示し、第4図はイオン
化式煙感知器の回路図、第5図は要部回路図、第6図は
波形図、第7図はイオン化式煙感知器の断面図、第8図
は等価回路、第9図は波形図とCX電圧の関係図、第1
0図は電圧−電流関係図である。
1・・・発振回路1.2・・・イオン室、3・・・増幅
回路、4・・・信号整流回路、5・・・閾値回路、6・
・・スイッチング回路、7・・・電源回路、8・・・放
射線源、9・・・はこり。Figures 1 to 3 show embodiments of the present invention. Figure 1 is a circuit diagram of the main part of an ionization smoke detector, Figure 2 is a waveform diagram of the circuit, and Figure 3 is a waveform diagram and CX voltage diagram. It is a relationship diagram. Figures 4 to 10 show conventional examples, Figure 4 is a circuit diagram of an ionization type smoke detector, Figure 5 is a main circuit diagram, Figure 6 is a waveform diagram, and Figure 7 is an ionization type smoke detector. A cross-sectional view of the sensor, Fig. 8 is an equivalent circuit, Fig. 9 is a waveform diagram and a relationship diagram of CX voltage, Fig. 1
Figure 0 is a voltage-current relationship diagram. DESCRIPTION OF SYMBOLS 1... Oscillation circuit 1.2... Ion chamber, 3... Amplification circuit, 4... Signal rectification circuit, 5... Threshold circuit, 6...
...Switching circuit, 7...Power supply circuit, 8...Radiation source, 9...Fluff.
Claims (1)
発振回路の出力パルスが加えられるイオン室と、前記イ
オン室の基準点の電圧が、煙の存在により、基準電圧を
越える時に感知器動作をなすべく出力する閾値回路とか
ら成るイオン化式煙感知器において、 前記イオン室に印加される前記発振回路の出力パルスを
アース電位を基準にして略等しい絶対値で正、負に変化
させる変換回路を設けたことを特徴とするイオン化式煙
感知器。(1) A power supply circuit having a constant voltage circuit, an oscillation circuit, an ion chamber to which the output pulse of the oscillation circuit is applied, and a voltage detected when the voltage at the reference point of the ion chamber exceeds the reference voltage due to the presence of smoke. In the ionization type smoke detector, the output pulse of the oscillation circuit applied to the ion chamber is changed to positive or negative by approximately equal absolute values with respect to the ground potential. An ionization type smoke detector characterized by being equipped with a conversion circuit.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25024689A JPH03111998A (en) | 1989-09-26 | 1989-09-26 | Ionization type smoke sensor |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25024689A JPH03111998A (en) | 1989-09-26 | 1989-09-26 | Ionization type smoke sensor |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH03111998A true JPH03111998A (en) | 1991-05-13 |
Family
ID=17205019
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP25024689A Pending JPH03111998A (en) | 1989-09-26 | 1989-09-26 | Ionization type smoke sensor |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH03111998A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2014534422A (en) * | 2011-10-06 | 2014-12-18 | マイクロチップ テクノロジー インコーポレイテッドMicrochip Technology Incorporated | Differential current measurement to determine ionic current in the presence of leakage current |
EP2757573A4 (en) * | 2011-09-15 | 2015-06-17 | Tokyo Metro Ind Tech Res Inst | Ionized gas detector and ionized gas detection method |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS54153697A (en) * | 1978-05-24 | 1979-12-04 | Matsushita Electric Works Ltd | Ionization type smoke detector |
-
1989
- 1989-09-26 JP JP25024689A patent/JPH03111998A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS54153697A (en) * | 1978-05-24 | 1979-12-04 | Matsushita Electric Works Ltd | Ionization type smoke detector |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2757573A4 (en) * | 2011-09-15 | 2015-06-17 | Tokyo Metro Ind Tech Res Inst | Ionized gas detector and ionized gas detection method |
US9645113B2 (en) | 2011-09-15 | 2017-05-09 | Tokyo Metropolitan Industrial Technology Research Institute | Ionized gas detector and ionized gas detecting method |
JP2014534422A (en) * | 2011-10-06 | 2014-12-18 | マイクロチップ テクノロジー インコーポレイテッドMicrochip Technology Incorporated | Differential current measurement to determine ionic current in the presence of leakage current |
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