JP4781146B2 - Fire detector - Google Patents

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JP4781146B2
JP4781146B2 JP2006095590A JP2006095590A JP4781146B2 JP 4781146 B2 JP4781146 B2 JP 4781146B2 JP 2006095590 A JP2006095590 A JP 2006095590A JP 2006095590 A JP2006095590 A JP 2006095590A JP 4781146 B2 JP4781146 B2 JP 4781146B2
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貴俊 山岸
英聖 森田
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Nohmi Bosai Ltd
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本発明は、例えば、炎の赤外線を感知して火災を判別する火災感知器に関するものである。   The present invention relates to a fire detector that senses a fire by detecting infrared rays of a flame, for example.

従来の感知器として、煙濃度が低くなるとセンサ（散乱光式煙感知器）の感度を上げ、煙濃度が高くなるとその感度を下げるようにしたものがある。例えば、各感度で設定された範囲において煙濃度が変化し、その感度では後段側のＡ／Ｄ変換器などのダイナミックレンジを超える場合、これを閾値で判別し、次の感度設定データに切り替えることで、ダイナミックレンジを再び利用するようにしている。また、この感知器の他の例として、増幅器の帰還抵抗を変えて増幅率を変化させるものがある（例えば、特許文献１参照）。   As a conventional sensor, there is a sensor that increases the sensitivity of a sensor (scattered light type smoke detector) when the smoke concentration is low and decreases the sensitivity when the smoke concentration is high. For example, if the smoke density changes within the range set for each sensitivity, and that sensitivity exceeds the dynamic range of the A / D converter on the rear stage side, etc., this is discriminated by a threshold value and switched to the next sensitivity setting data The dynamic range is used again. Another example of this sensor is one that changes the amplification factor by changing the feedback resistance of the amplifier (see, for example, Patent Document 1).

増幅器の帰還抵抗を変えて増幅率を変化させる回路として例えば図２に示すものがある。この図は赤外線を感知するセンサ１１を備えた火災感知器の回路図で、そのセンサ１１が炎の赤外線を感知し、赤外線量に基づく感知信号を出力すると、感知信号に含まれる１Ｈｚ〜１０Ｈｚの赤外線の信号がＨＰＦ１２、ＬＰＦ１４及びＨＰＦ１５によって選択されると共に、前段のアンプ１３により増幅され、次段のアンプ１６に出力される。アンプ１６に入力された増幅信号は、帰還抵抗Ｒ１側に接続された切替スイッチＳ１とＨＰＦ１７の抵抗Ｒ９側に接続された切替スイッチＳ２とのオン／オフの組合せに応じた増幅度で増幅され、後段のアンプ１９によりさらに増幅されて出力される。このアンプ１９から出力される増幅信号は、ＨＰＦ１７、ＨＰＦ１８及びＬＰＦ２０の各フィルタによって、増幅された赤外線の信号が選択されたものである。   An example of a circuit that changes the amplification factor by changing the feedback resistance of the amplifier is shown in FIG. This figure is a circuit diagram of a fire detector having a sensor 11 for detecting infrared rays. When the sensor 11 senses infrared rays of a flame and outputs a detection signal based on the amount of infrared rays, the detection signal includes 1 Hz to 10 Hz. An infrared signal is selected by the HPF 12, LPF 14, and HPF 15, amplified by the preceding amplifier 13, and output to the subsequent amplifier 16. The amplified signal input to the amplifier 16 is amplified with an amplification degree according to the combination of ON / OFF of the changeover switch S1 connected to the feedback resistor R1 side and the changeover switch S2 connected to the resistor R9 side of the HPF 17, The signal is further amplified by the subsequent amplifier 19 and output. The amplified signal output from the amplifier 19 is obtained by selecting an infrared signal amplified by the HPF 17, HPF 18, and LPF 20 filters.

特公平５−１０７１８号公報（第３頁−第４頁、第１図−第３図）Japanese Examined Patent Publication No. 5-10718 (pages 3 to 4, FIGS. 1 to 3)

従来は、Ａ／Ｄ変換器などのダイナミックレンジを効率よく利用するようにした場合、感度を切り替えた後、信号が飽和していないか、また信号が小さ過ぎないかの状態を確認しなければならず、問題があれば感度を元に戻すなどの複雑な判断が必要となっていた。また、切替スイッチＳ１、Ｓ２の切り替えによるアンプ１６の過渡応答が安定してから、その増幅信号を読み込まなければならず、その間、火災判断ができなかった。   Conventionally, when the dynamic range such as an A / D converter is used efficiently, it is necessary to confirm whether the signal is not saturated or the signal is not too small after switching the sensitivity. In other words, if there was a problem, complicated judgments such as returning the sensitivity to the original level were necessary. Further, after the transient response of the amplifier 16 due to the changeover of the changeover switches S1 and S2 is stabilized, the amplified signal must be read, and during that time, a fire determination cannot be made.

本発明は、前述のような課題を解決するためになされたもので、感度を切り替えた後の状態を確認することなく、また、センサからの増幅信号の増幅度切替前後で増幅信号を連続的に処理し、正確に火災判別ができる火災感知器を提供することを目的とする。   The present invention has been made in order to solve the above-described problems. The amplified signal is continuously transmitted before and after switching the sensitivity of the amplified signal from the sensor without checking the state after switching the sensitivity. The purpose is to provide a fire detector that can process and accurately determine fire.

本発明に係る火災感知器は、火災を感知し、その感知に基づく感知信号を出力するセンサと、センサの感知信号から所定の周波数成分の信号を選択して増幅する第１の増幅部と、切替スイッチを有し、第１の増幅部からの増幅信号を所定の増幅度で増幅し、切替スイッチの接続状態が切り替えられたとき、所定の増幅度よりも低い増幅度で増幅信号を増幅する第２の増幅部と、第２の増幅部からの増幅信号に基づいて火災の有無を判別し、その増幅信号が所定のレベル幅内に入っていないときは、切替スイッチの接続状態を切り替える火災判別部とを有する火災感知器において、第１の増幅部は、センサの感知信号から所定の周波数成分の信号を選択する複数の第１のフィルタと、この第１のフィルタによって選択された所定の周波数成分の信号を増幅する第１のアンプと、第１のアンプにより増幅された所定の周波数成分の増幅信号を通過させる複数の第２のフィルタとで構成され、第２の増幅部は、リアクタンス成分を含んでいない。
また、本発明に係る火災感知器は、切替スイッチを切り替えたときの過渡応答時間が火災判別部のサンプリング間隔よりも短くなっている。 A fire detector according to the present invention detects a fire, outputs a detection signal based on the detection, a first amplification unit that selects and amplifies a signal having a predetermined frequency component from the detection signal of the sensor, Having a changeover switch, amplifying the amplified signal from the first amplification unit with a predetermined amplification degree, and amplifying the amplified signal with an amplification degree lower than the predetermined amplification degree when the connection state of the changeover switch is switched Fire that determines the presence or absence of a fire based on the second amplification unit and the amplified signal from the second amplification unit, and switches the connection state of the changeover switch when the amplified signal is not within a predetermined level width In the fire detector having the determination unit, the first amplifying unit includes a plurality of first filters for selecting a signal having a predetermined frequency component from the sensor detection signal, and a predetermined filter selected by the first filter. Of frequency components A first amplifier for amplifying an issue, is composed of a plurality of second filter which passes the amplified signal of a predetermined frequency component amplified by the first amplifier, the second amplifier unit contains a reactance component Not .
In the fire detector according to the present invention, the transient response time when the changeover switch is switched is shorter than the sampling interval of the fire discrimination unit.

本発明においては、センサの感知信号から所定の周波数成分の信号を選択して増幅する第１の増幅部と、切替スイッチを有し、第１の増幅部からの増幅信号を所定の増幅度で増幅し、切替スイッチの接続状態が切り替えられたとき、所定の増幅度よりも低い増幅度で増幅信号を増幅する第２の増幅部と、第２の増幅部からの増幅信号に基づいて火災の有無を判別し、その増幅信号が所定のレベル幅内に入っていないときは、切替スイッチの接続状態を切り替える火災判別部とを有する火災感知器において、第１の増幅部を、センサの感知信号から所定の周波数成分の信号を選択する複数の第１のフィルタと、この第１のフィルタによって選択された所定の周波数成分の信号を増幅する第１のアンプと、第１のアンプにより増幅された所定の周波数成分の増幅信号を通過させる複数の第２のフィルタとで構成し、第２の増幅部をリアクタンス成分を含んでいない構成としたので、増幅度の切替前後において増幅信号を連続的に処理でき、火災か否かの判断ができない期間をなくすことが可能になる。
In the present invention, a first amplifying unit that selects and amplifies a signal having a predetermined frequency component from the sensor detection signal and a changeover switch, and the amplified signal from the first amplifying unit has a predetermined amplification degree. When the amplification switch is switched and the connection state of the change-over switch is switched, a second amplification unit that amplifies the amplified signal with an amplification degree lower than a predetermined amplification degree, and a fire based on the amplification signal from the second amplification part In a fire detector having a fire discriminating unit that switches the connection state of the changeover switch when the presence / absence is discriminated and the amplified signal is not within the predetermined level width, the first amplifying unit is connected to the sensor sensing signal. A plurality of first filters for selecting a signal of a predetermined frequency component from the first amplifier, a first amplifier for amplifying a signal of a predetermined frequency component selected by the first filter, and the first amplifier Predetermined lap Constituted by a plurality of second filter for passing amplified signal of several components, the second amplifying portion since the configuration does not contain a reactive component, it can continuously process the amplified signal before and after switching of the amplification degree It becomes possible to eliminate the period during which it is not possible to determine whether or not a fire has occurred.

図１は本発明の実施の形態に係る火災感知器の構成を示す回路図である。
図１に示す火災感知器は、赤外線を感知するセンサ１、回路全体のバイアス電圧を供給する電源２、センサ１の感知信号から所定の周波数成分（赤外線の周波数）を選択して増幅する第１の増幅部３、増幅度を切り替える切替スイッチＳ１を有する第２の増幅部４、及び第２の増幅部４の出力から火災の有無を判別する制御回路部５を備えている。センサ１は、例えば炭酸ガス共鳴帯のセンサからなり、予め設定された警戒区域内で出火すると、その炎の赤外線を感知し、赤外線量に基づく感知信号を出力する。センサ１によって感知される赤外線は、炎のちらつきによって主に周波数が１Ｈｚ〜１０Ｈｚの範囲内で変化する。 FIG. 1 is a circuit diagram showing a configuration of a fire detector according to an embodiment of the present invention.
The fire detector shown in FIG. 1 includes a sensor 1 that senses infrared light, a power source 2 that supplies a bias voltage for the entire circuit, and a first frequency component (infrared frequency) that is selected and amplified from the sensing signal of the sensor 1. , The second amplifying unit 4 having a changeover switch S1 for switching the amplification degree, and the control circuit unit 5 for determining the presence or absence of a fire from the output of the second amplifying unit 4. The sensor 1 is composed of, for example, a sensor in a carbon dioxide resonance band. When a fire breaks out in a preset alert area, the sensor 1 senses the infrared rays of the flame and outputs a sensing signal based on the amount of infrared rays. Infrared rays detected by the sensor 1 mainly change within a frequency range of 1 Hz to 10 Hz due to flickering of flame.

第１の増幅部３は、センサ１の出力端に設けられたハイパスフィルタ（Ｃ４，Ｒ６）３１（以下、「ＨＰＦ３１」とする）、非反転端子（＋）がＨＰＦ３１の出力端と接続された第１のアンプ３２、第１のアンプ３２の出力端（ＯＵＴ）と反転端子（−）との間に設けられたローパスフィルタ（Ｃ１，Ｒ３）３３（以下、「ＬＰＦ３３」とする）、第１のアンプ３２の反転端子と電源２の出力端との間に設けられたＨＰＦ（Ｒ７，Ｃ５）３４、第１のアンプ３２の出力端とアース側との間に設けられたＬＰＦ（Ｒ８，Ｃ６）３５、このＬＰＦ３５の出力端とアース側との間に設けられたＨＰＦ（Ｃ３，Ｒ１０）３６、ＨＰＦ３６の出力端に設けられたＨＰＦ（Ｃ２，Ｒ９）３７を備えている。   The first amplifying unit 3 includes a high-pass filter (C4, R6) 31 (hereinafter referred to as “HPF 31”) provided at the output end of the sensor 1 and a non-inverting terminal (+) connected to the output end of the HPF 31. The first amplifier 32, a low-pass filter (C1, R3) 33 (hereinafter referred to as “LPF 33”) provided between the output terminal (OUT) of the first amplifier 32 and the inverting terminal (−), first HPF (R7, C5) 34 provided between the inverting terminal of the amplifier 32 and the output terminal of the power source 2, and LPF (R8, C6) provided between the output terminal of the first amplifier 32 and the ground side. 35) HPF (C3, R10) 36 provided between the output end of the LPF 35 and the ground side, and HPF (C2, R9) 37 provided at the output end of the HPF 36.

ＨＰＦ３１、ＬＰＦ３３及びＨＰＦ３４によって第１のバンドパスフィルタが構成され、各フィルタ及び第１のアンプ３２によってセンサ１の感知信号に含まれる１Ｈｚ〜１０Ｈｚの赤外線の信号が選択されて増幅される。また、第１のアンプ３２の出力端側に設けられたＬＰＦ３５、ＨＰＦ３６及びＨＰＦ３７によって第２のバンドパスフィルタが構成され、各フィルタにより、増幅された赤外線の信号（増幅信号）のみが通過する。第１のアンプ３２の増幅度は例えば２０倍に設定されている。   The HPF 31, LPF 33, and HPF 34 constitute a first band pass filter, and each filter and the first amplifier 32 select and amplify an infrared signal of 1 Hz to 10 Hz included in the sensing signal of the sensor 1. The LPF 35, HPF 36, and HPF 37 provided on the output end side of the first amplifier 32 constitute a second band pass filter, and only the amplified infrared signal (amplified signal) passes through each filter. The amplification factor of the first amplifier 32 is set to 20 times, for example.

第２の増幅部４は、反転端子がＨＰＦ３７の出力端と接続され、非反転端子（＋）が電源２の出力端と接続された第２のアンプ４１、この第２のアンプ４１の出力端と反転端子との間に設けられた並列接続の帰還抵抗Ｒ１，Ｒ２、帰還抵抗Ｒ１と第２のアンプ４１の出力端との間に挿入された切替スイッチＳ１、反転端子が抵抗Ｒ５を介して第２のアンプ４１の出力端と接続され、非反転端子が電源２の出力端と接続され、さらに、出力端と反転端子との間に帰還抵抗Ｒ４が接続された第３のアンプ４２を備えている。前記の切替スイッチＳ１は、通常オフ状態で、後述する切替信号が入力されたときにオンする。   The second amplifier 4 includes a second amplifier 41 having an inverting terminal connected to the output terminal of the HPF 37 and a non-inverting terminal (+) connected to the output terminal of the power supply 2, and an output terminal of the second amplifier 41. Feedback resistors R1 and R2 connected in parallel between the inverting terminal and the inverting terminal, a changeover switch S1 inserted between the feedback resistor R1 and the output terminal of the second amplifier 41, and the inverting terminal via the resistor R5. The third amplifier 42 is connected to the output terminal of the second amplifier 41, the non-inverting terminal is connected to the output terminal of the power supply 2, and the feedback resistor R4 is connected between the output terminal and the inverting terminal. ing. The change-over switch S1 is normally turned off and is turned on when a change-over signal described later is input.

第２のアンプ４１は、例えば、切替スイッチＳ１がオフ状態のとき高増幅度（例えば１６倍）となり、第１アンプ３２によって２０倍に増幅された増幅信号（赤外線の信号）を１６倍して３２０倍に増幅し、切替スイッチＳ１がオンされたときは低増幅度（例えば１倍）となり、第１のアンプ３２からの増幅信号（２０倍）をそのまま出力する。第３のアンプ４２は、増幅度が例えば１６倍に設定されており、第２のアンプ４１の増幅信号が第１のアンプ３２との合計で３２０倍のときは５１２０倍（３２０×１６）に増幅し、第の２アンプ４１の増幅信号が１倍のときは３２０倍（２０×１６）に増幅する。切替スイッチＳ１の切り替えによる増幅信号の過渡応答時間は、ＬＰＦ、ＨＰＦを構成しているリアクタンス成分に影響を与えないために極めて短い。これにより、後述の所定間隔でのサンプリング時間内で過渡応答が終了し、連続したサンプリングを行うことができる。   For example, the second amplifier 41 has a high amplification degree (for example, 16 times) when the changeover switch S1 is in an OFF state, and 16 times the amplified signal (infrared signal) amplified by 20 times by the first amplifier 32. When amplification is performed 320 times and the changeover switch S1 is turned on, the amplification degree is low (for example, 1 time), and the amplified signal (20 times) from the first amplifier 32 is output as it is. The amplification factor of the third amplifier 42 is set to 16 times, for example, and when the amplified signal of the second amplifier 41 is 320 times in total with the first amplifier 32, the amplification factor is 5120 times (320 × 16). When the amplified signal of the second second amplifier 41 is 1, the signal is amplified 320 times (20 × 16). The transient response time of the amplified signal due to the changeover of the changeover switch S1 is extremely short because it does not affect the reactance components constituting the LPF and HPF. Thereby, the transient response is completed within a sampling time at a predetermined interval described later, and continuous sampling can be performed.

制御回路部５は、例えば、第３アンプ４２の出力端と接続されたＡ／Ｄ変換器５１、及び火災判別部機能を有するマイコン５２を備えている。このマイコン５２は、Ａ／Ｄ変換器５１に第３のアンプ４２の増幅信号（５１２０倍）が入力されると、その増幅信号のデジタル値（例えば電圧）を所定間隔（２０ｍＳ〜１００ｍＳ）毎にサンプリングし、デジタル値が所定のレベル幅内に入っているか否かを判定する。増幅信号のデジタル値が所定のレベル幅内にないときは切替信号を切替スイッチＳ１に出力してオフ状態からオンにする。その切替スイッチＳ１のオンにより、３２０倍の増幅信号がＡ／Ｄ変換器５１に入力されると、前記と同様にその増幅信号のデジタル値を所定間隔毎にサンプリングし、デジタル値が所定のレベル幅内に入っているか否かを判定する。   The control circuit unit 5 includes, for example, an A / D converter 51 connected to the output terminal of the third amplifier 42 and a microcomputer 52 having a fire determination unit function. When the amplified signal (5120 times) of the third amplifier 42 is input to the A / D converter 51, the microcomputer 52 sets the digital value (for example, voltage) of the amplified signal at predetermined intervals (20 mS to 100 mS). Sampling is performed to determine whether the digital value is within a predetermined level range. When the digital value of the amplified signal is not within the predetermined level width, a change signal is output to the changeover switch S1 and turned on from the off state. When the changeover switch S1 is turned on and an amplified signal of 320 times is input to the A / D converter 51, the digital value of the amplified signal is sampled at predetermined intervals as described above, and the digital value is set to a predetermined level. Determine whether it is within the width.

５１２０倍の増幅信号又は３２０倍の増幅信号のデジタル値が所定のレベルを超えて、その状態が所定時間継続しているときは火災発生と判断して、その旨を受信機（図示せず）に通知する。増幅信号を５１２０倍から３２０倍に切り替えているのは、炎の赤外線量の増加によって飽和状態になったときであり、また逆に３２０倍から５１２０倍に切り替えるときは、赤外線量の減少によって炎と判別しにくくなったときである。これは、炎のちらつきによる赤外線の強弱を連続的に認識するためである。   When the digital value of the 5120-fold amplified signal or 320-fold amplified signal exceeds a predetermined level and the state continues for a predetermined time, it is determined that a fire has occurred, and a receiver (not shown) to that effect Notify The amplification signal is switched from 5120 times to 320 times when it becomes saturated due to the increase in the amount of infrared rays of the flame, and conversely when it is switched from 320 times to 5120 times, the flame amount is reduced due to the decrease in the amount of infrared rays. When it becomes difficult to distinguish. This is for continuously recognizing the intensity of infrared rays caused by flickering of flame.

次に、前記のように構成された火災感知器の動作を説明する。
予め設定された警戒区域内で出火すると、センサ１がその炎の赤外線を感知し、赤外線量に基づく感知信号を第１の増幅部３に出力する。この時、感知信号に含まれる１Ｈｚ〜１０Ｈｚの赤外線の信号がＨＰＦ３１、ＬＰＦ３３及びＨＰＦ３４によって選択されると共に、第１のアンプ３２により２０倍に増幅され、第２のバンドパスフィルタを構成するＬＰＦ３５→ＨＰＦ３６→ＨＰＦ３７を順に通過して第２の増幅部４の第２のアンプ４１に至る。この第２のアンプ４１は、切替スイッチＳ１がオフ状態であるため、第１のアンプ３２からの増幅信号（赤外線の信号）を１６倍して３２０倍に増幅し、第３のアンプ４２に出力する。第３のアンプ４２は、第２のアンプ４１の増幅信号が入力されると、さらに１６倍して５１２０倍に増幅し、制御回路部５のＡ／Ｄ変換器５１に出力する。 Next, the operation of the fire detector configured as described above will be described.
When a fire breaks out in a preset alert area, the sensor 1 senses the infrared rays of the flame and outputs a sensing signal based on the amount of infrared rays to the first amplifying unit 3. At this time, an infrared signal of 1 Hz to 10 Hz included in the sensing signal is selected by the HPF 31, LPF 33, and HPF 34, and amplified by 20 times by the first amplifier 32, and the LPF 35 constituting the second band pass filter → HPF 36 → HPF 37 are sequentially passed to reach the second amplifier 41 of the second amplifying unit 4. Since the second switch 41 is in the OFF state, the second amplifier 41 amplifies the amplified signal (infrared signal) from the first amplifier 32 by 16 times and outputs the amplified signal to the third amplifier 42. To do. When the amplified signal of the second amplifier 41 is input, the third amplifier 42 further amplifies the signal by 16 times to 5120 times and outputs the amplified signal to the A / D converter 51 of the control circuit unit 5.

一方、マイコン５２は、Ａ／Ｄ変換器５１に５１２０倍に増幅された増幅信号が入力されると、増幅信号のデジタル値（例えば電圧）を所定間隔毎にサンプリングし、デジタル値が所定のレベル幅内に入っているか否かを判定する。デジタル値が所定のレベルを超えているときは、所定時間経過したどうかを判定し、その状態が所定時間継続されたときは、火災発生と判断してその旨を受信機に通知する。また、サンプリングした増幅信号（５１２０倍）のデジタル値が所定のレベル幅内にないときは、飽和状態になっていると判断して、切替信号を切替スイッチＳ１に出力し、オフ状態からオンに切り替える。その切替スイッチＳ１がオンになってから、リアクタンス成分を含まない第２のアンプ４１が安定するまでの時間は、次のサンプリング時間よりも短いので、サンプリングの抜けが発生せず、連続的なデータ取得ができる。   On the other hand, when the amplified signal amplified 5120 times is input to the A / D converter 51, the microcomputer 52 samples the digital value (for example, voltage) of the amplified signal at predetermined intervals, and the digital value is at a predetermined level. Determine whether it is within the width. When the digital value exceeds a predetermined level, it is determined whether or not a predetermined time has elapsed, and when the state continues for a predetermined time, it is determined that a fire has occurred and a notification to that effect is given to the receiver. When the digital value of the sampled amplified signal (5120 times) is not within the predetermined level width, it is determined that the signal is saturated, and the changeover signal is output to the changeover switch S1 and turned on from the off state. Switch. Since the time from when the change-over switch S1 is turned on to the stabilization of the second amplifier 41 that does not include the reactance component is shorter than the next sampling time, sampling loss does not occur and continuous data You can get it.

この時、第２のアンプ４１は、増幅度が１６倍から１倍と低くなり、第１のアンプ３２からの増幅信号（２０倍）をそのままの状態で第３アンプ４２に出力する。第３のアンプ４２は、第２のアンプ４１からの増幅信号が入力されると、その増幅信号を１６倍して３２０倍に増幅し、Ａ／Ｄ変換器５１に出力する。マイコン５２は、Ａ／Ｄ変換器５１に３２０倍に増幅された増幅信号が入力されると、前記と同様に、増幅信号のデジタル値（例えば電圧）を所定間隔毎にサンプリングし、デジタル値が前述した所定のレベル幅内に入っているか否かを判定する。デジタル値が所定のレベルを超えているときは、所定時間経過したどうかを判定し、その状態が所定時間継続されたときは、火災発生と判断してその旨を受信機に通知する。また、サンプリングした増幅信号（３２０倍）のデジタル値が所定のレベル幅内にないときは、その増幅度では炎と判別しにくくなっていると判断して、切替信号を切替スイッチＳ１に出力し、オン状態からオフに切り替える。   At this time, the second amplifier 41 has an amplification degree reduced from 16 times to 1 time, and outputs the amplified signal (20 times) from the first amplifier 32 to the third amplifier 42 as it is. When the amplified signal from the second amplifier 41 is input, the third amplifier 42 amplifies the amplified signal by 16 times and outputs the amplified signal to the A / D converter 51. When the amplified signal amplified by 320 times is input to the A / D converter 51, the microcomputer 52 samples the digital value (for example, voltage) of the amplified signal at predetermined intervals, and the digital value is It is determined whether or not it falls within the predetermined level range described above. When the digital value exceeds a predetermined level, it is determined whether or not a predetermined time has elapsed, and when the state continues for a predetermined time, it is determined that a fire has occurred and a notification to that effect is given to the receiver. When the digital value of the sampled amplified signal (320 times) is not within the predetermined level width, it is determined that it is difficult to discriminate flame from the amplification level, and a changeover signal is output to the changeover switch S1. , Switch from on to off.

以上のように実施の形態によれば、第１の増幅部３側にハイパスフィルタ（ＨＰＦ）及びローパスフィルタ（ＬＰＦ）を組合せてなる第１及び第２のバンドパスフィルタを設け、第２の増幅部４側に第２のアンプ４１の増幅度を切り替える切替スイッチＳ１を設けて、増幅度の異なる増幅信号を選択できるようにしたので、第２の増幅部４側の過渡応答時間をサンプリング間隔よりも短くすることが可能になり、このため、増幅度の切替前後において増幅信号を連続的に処理でき、火災か否かの判断ができない期間をなくすことが可能になる。   As described above, according to the embodiment, the first amplification unit 3 is provided with the first and second band-pass filters formed by combining the high-pass filter (HPF) and the low-pass filter (LPF), and the second amplification. Since the changeover switch S1 for switching the amplification degree of the second amplifier 41 is provided on the side of the unit 4 so that amplified signals having different amplification levels can be selected, the transient response time on the second amplification unit 4 side is determined from the sampling interval. Therefore, the amplified signal can be continuously processed before and after switching of the amplification degree, and it is possible to eliminate a period during which it is not possible to determine whether or not there is a fire.

本発明の実施の形態に係る火災感知器の構成を示す回路図である。It is a circuit diagram which shows the structure of the fire detector which concerns on embodiment of this invention. 従来の火災感知器の構成を示す回路図である。It is a circuit diagram which shows the structure of the conventional fire detector.

符号の説明Explanation of symbols

１ センサ、２ 電源、３ 第１の増幅部、３１ ＨＰＦ、３２ 第１のアンプ、３３ ＬＰＦ、３４ ＨＰＦ、３５ ＬＰＦ、３６ ＨＰＦ、３７ ＨＰＦ、４ 第２の増幅部、４１ 第２のアンプ、４２ 第３のアンプ、Ｓ１ 切替スイッチ、５ 制御回路部、５１ Ａ／Ｄ変換器、５２ マイコン。
DESCRIPTION OF SYMBOLS 1 Sensor, 2 Power supply, 3 1st amplifier, 31 HPF, 32 1st amplifier, 33 LPF, 34 HPF, 35 LPF, 36 HPF, 37 HPF, 4 2nd amplifier, 41 2nd amplifier, 42 3rd amplifier, S1 changeover switch, 5 control circuit part, 51 A / D converter, 52 microcomputer.

Claims (2)

火災を感知し、その感知に基づく感知信号を出力するセンサと、
該センサの感知信号から所定の周波数成分の信号を選択して増幅する第１の増幅部と、
切替スイッチを有し、前記第１の増幅部からの増幅信号を所定の増幅度で増幅し、前記切替スイッチの接続状態が切り替えられたとき、前記所定の増幅度よりも低い増幅度で前記増幅信号を増幅する第２の増幅部と、
該第２の増幅部からの増幅信号に基づいて火災の有無を判別し、その増幅信号が所定のレベル幅内に入っていないときは、前記切替スイッチの接続状態を切り替える火災判別部とを有する火災感知器において、
前記第１の増幅部は、前記センサの感知信号から所定の周波数成分の信号を選択する複数の第１のフィルタと、該第１のフィルタによって選択された所定の周波数成分の信号を増幅する第１のアンプと、該第１のアンプにより増幅された所定の周波数成分の増幅信号を通過させる複数の第２のフィルタとで構成され、
前記第２の増幅部は、リアクタンス成分を含んでいないことを特徴とする火災感知器。 A sensor for detecting a fire and outputting a detection signal based on the detection;
A first amplifying unit that selects and amplifies a signal having a predetermined frequency component from the sensing signal of the sensor;
Having a changeover switch, amplifying the amplified signal from the first amplification unit with a predetermined amplification degree, and when the connection state of the changeover switch is switched, the amplification with a lower amplification degree than the predetermined amplification degree A second amplifier for amplifying the signal;
A fire discriminating unit that discriminates the presence or absence of a fire based on the amplified signal from the second amplifying unit, and switches the connection state of the changeover switch when the amplified signal is not within a predetermined level width; In the fire detector,
The first amplifying unit a plurality of first filters for selecting a signal having a predetermined frequency component from the sensing signal of the sensor, and a first filter for amplifying the signal having a predetermined frequency component selected by the first filter. 1 amplifier and a plurality of second filters that pass the amplified signal of a predetermined frequency component amplified by the first amplifier,
The fire detector, wherein the second amplifying unit does not include a reactance component . 前記切替スイッチを切り替えたときの過渡応答時間が前記火災判別部のサンプリング間隔よりも短いことを特徴とする請求項１記載の火災感知器。   The fire detector according to claim 1, wherein a transient response time when the changeover switch is switched is shorter than a sampling interval of the fire discriminating unit.
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