JPH06347333A - Circuit for pyroelectric sensor - Google Patents
Circuit for pyroelectric sensorInfo
- Publication number
- JPH06347333A JPH06347333A JP5157871A JP15787193A JPH06347333A JP H06347333 A JPH06347333 A JP H06347333A JP 5157871 A JP5157871 A JP 5157871A JP 15787193 A JP15787193 A JP 15787193A JP H06347333 A JPH06347333 A JP H06347333A
- Authority
- JP
- Japan
- Prior art keywords
- operational amplifier
- resistance value
- input terminal
- pyroelectric
- resistor
- Prior art date
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、電流モード型の焦電セ
ンサ用回路に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for a current mode type pyroelectric sensor.
【０００２】[0002]
【従来の技術】最近、応答速度の高い赤外線検出が要望
されており、これに応えるために電流モード型の焦電セ
ンサ用回路の開発が望まれている。この種の焦電センサ
用回路として、従来より図２に示すようなものが知られ
ている。同図に示すものは、オペアンプ４の反転入力端
子に焦電素子Ｓ１の一端側が接続されるとともに、オペ
アンプ４の出力端と反転入力端子間には帰還抵抗体３が
接続されている。焦電素子Ｓ１の他端側とオペアンプ４
の非反転入力端子側には、電源ＶCCとＶSSによりバイア
ス電圧が抵抗体Ｒa ，Ｒb を介して加えられている。同
図において、焦電素子Ｓ１は赤外線受光量に応じて自発
分極し、焦電電流を発生する。この焦電素子Ｓ１に発生
する焦電電流は帰還抵抗体Ｒf により電圧に変換されて
焦電圧としてオペアンプ１の反転入力端子に加わり、オ
ペアンプ１は電圧を増幅して赤外線の検出信号を出力す
る。このときのオペアンプ１の増幅率は、帰還抵抗体３
の抵抗値Ｒf を焦電素子Ｓ１の内部抵抗値ｒで除した値
Ｒf ／ｒで与えられる。2. Description of the Related Art Recently, infrared ray detection with high response speed has been demanded, and in order to meet this demand, development of a circuit for a current mode type pyroelectric sensor is desired. As a circuit for this type of pyroelectric sensor, a circuit as shown in FIG. 2 has been conventionally known. In the structure shown in the figure, one end of the pyroelectric element S1 is connected to the inverting input terminal of the operational amplifier 4, and the feedback resistor 3 is connected between the output terminal of the operational amplifier 4 and the inverting input terminal. The other end of the pyroelectric element S1 and the operational amplifier 4
The non-inverting input terminal side of the bias voltage resistor R a, are added via a R b by the power supply V CC and V SS. In the figure, the pyroelectric element S1 spontaneously polarizes according to the amount of received infrared rays, and generates a pyroelectric current. The pyroelectric current generated in the pyroelectric element S1 is converted into a voltage by the feedback resistor R f and applied to the inverting input terminal of the operational amplifier 1 as a focal voltage, and the operational amplifier 1 amplifies the voltage and outputs an infrared detection signal. . At this time, the amplification factor of the operational amplifier 1 is the feedback resistor 3
The resistance value R f is divided by the internal resistance value r of the pyroelectric element S1 to obtain a value R f / r.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、焦電素
子Ｓ１の内部抵抗値ｒは極めて大きく、例えば、通常10
9 〜1010Ω程度であり、焦電素子Ｓ１に発生する焦電電
流は微小な値となるので、オペアンプ４から出力する電
圧を後段の信号処理に差し支えない大きさにし、かつ、
オペアンプ４の増幅率Ｒf ／ｒを高くするには、帰還抵
抗体３の抵抗値Ｒf を109 〜1011Ωと大抵抗値に設定し
なければならなかった。一方、このような大抵抗値の抵
抗体を精度よく作製するのは大変難しく、その抵抗値に
対し、±20％程度の誤差が生じていた。したがって、オ
ペアンプ４の増幅率Ｒf ／ｒが設計通りに設定できず、
焦電センサ毎に増幅率がばらつき、また、焦電素子Ｓ１
の内部抵抗値ｒに規制されて増幅率を自由に設定できな
いという問題があった。However, the internal resistance value r of the pyroelectric element S1 is extremely large.
Since it is about 9 to 10 10 Ω, and the pyroelectric current generated in the pyroelectric element S1 has a very small value, the voltage output from the operational amplifier 4 is set to a magnitude that does not interfere with signal processing in the subsequent stage, and
In order to increase the amplification factor R f / r of the operational amplifier 4, it is necessary to set the resistance value R f of the feedback resistor 3 to a large resistance value of 10 9 to 10 11 Ω. On the other hand, it is very difficult to accurately manufacture such a resistor having a large resistance value, and an error of about ± 20% occurs with respect to the resistance value. Therefore, the amplification factor R f / r of the operational amplifier 4 cannot be set as designed,
The amplification factor varies from pyroelectric sensor to pyroelectric element S1.
There is a problem in that the amplification factor cannot be freely set because the internal resistance value r is restricted.
【０００４】また、焦電センサの感度は帰還抵抗体３の
抵抗値の大きさに比例しており、その一方で、焦電セン
サの応答速度は帰還抵抗体３の抵抗値の大きさに逆比例
するので、焦電センサの感度を上げれば応答速度は遅く
なるというように、焦電センサの感度と応答速度を両方
満足する焦電センサ用回路を提供することが非常に困難
であった。The sensitivity of the pyroelectric sensor is proportional to the resistance value of the feedback resistor 3, while the response speed of the pyroelectric sensor is inverse to the resistance value of the feedback resistor 3. Since it is proportional, it is very difficult to provide a circuit for a pyroelectric sensor that satisfies both the sensitivity and the response speed of the pyroelectric sensor, such that the response speed becomes slower if the sensitivity of the pyroelectric sensor is increased.
【０００５】本発明は上記従来の課題を解決するために
なされたものであり、その目的は、帰還抵抗体の抵抗値
を小さくでき、オペアンプの増幅率が自由に、正確に設
定でき、また、応答速度が速く、感度の良い焦電センサ
用回路を提供することにある。The present invention has been made to solve the above-mentioned conventional problems, and the purpose thereof is to make it possible to reduce the resistance value of the feedback resistor, to freely and accurately set the amplification factor of the operational amplifier, and It is to provide a circuit for a pyroelectric sensor having a high response speed and high sensitivity.
【０００６】[0006]
【課題を解決するための手段】本発明は上記目的を達成
するために、次のように構成されている。すなわち、本
発明は、焦電素子の出力電流信号を電圧信号に変換しオ
ペアンプにより増幅して出力する電流モード型の焦電セ
ンサ用回路において、前記オペアンプの反転入力端子に
は外付け抵抗体が接続されるとともにオペアンプの出力
端と反転入力端子間には帰還抵抗体が接続されており、
焦電素子の出力端はオペアンプの非反転入力端子に接続
され、焦電素子の出力端とオペアンプの非反転入力端子
との間には焦電素子の出力電流信号を電圧信号に変換す
る電圧変換抵抗体の一端側が接続されていることを特徴
として構成されている。In order to achieve the above object, the present invention is constructed as follows. That is, the present invention is a circuit for a current mode type pyroelectric sensor which converts an output current signal of a pyroelectric element into a voltage signal, amplifies and outputs the voltage signal by an operational amplifier, wherein an external resistor is provided at an inverting input terminal of the operational amplifier. A feedback resistor is connected between the output terminal and the inverting input terminal of the operational amplifier,
The output terminal of the pyroelectric element is connected to the non-inverting input terminal of the operational amplifier, and the voltage conversion that converts the output current signal of the pyroelectric element into a voltage signal is provided between the output terminal of the pyroelectric element and the non-inverting input terminal of the operational amplifier. It is configured such that one end side of the resistor is connected.
【０００７】[0007]
【作用】赤外線を受光して分極する焦電素子から発生す
る出力電流信号は電圧変換抵抗体により電圧に変換さ
れ、変換電圧としてオペアンプの非反転入力端子側に加
わる。この変換電圧はオペアンプの増幅率、すなわち帰
還抵抗体の抵抗値を外付け抵抗体の抵抗値で除した値を
もって増幅されて、オペアンプの出力端より出力する。The output current signal generated from the pyroelectric element that receives and polarizes infrared rays is converted into a voltage by the voltage conversion resistor and applied as a converted voltage to the non-inverting input terminal side of the operational amplifier. This converted voltage is amplified by the amplification factor of the operational amplifier, that is, the value obtained by dividing the resistance value of the feedback resistor by the resistance value of the external resistor, and output from the output terminal of the operational amplifier.
【０００８】このように、オペアンプの増幅率は外付け
抵抗体と帰還抵抗体の各抵抗値によってのみ決定され、
焦電素子の内部抵抗には依存しないので、帰還抵抗体の
抵抗値を低く抑えられ、また、オペアンプの増幅率を自
由に設定できる。As described above, the amplification factor of the operational amplifier is determined only by the resistance values of the external resistor and the feedback resistor,
Since it does not depend on the internal resistance of the pyroelectric element, the resistance value of the feedback resistor can be suppressed low, and the amplification factor of the operational amplifier can be freely set.
【０００９】さらに、焦電センサの応答速度は電圧変換
抵抗体の抵抗値にのみ依存して、前記帰還抵抗体の抵抗
値には依存することはないので、応答速度を速める方向
に、かつ、オペアンプからの出力が後段の信号処理に差
し支えない大きさの電圧に変換するように電圧変換抵抗
体の抵抗値が設定される。Further, since the response speed of the pyroelectric sensor depends only on the resistance value of the voltage conversion resistor and not on the resistance value of the feedback resistor, the response speed is increased, and The resistance value of the voltage conversion resistor is set so that the output from the operational amplifier is converted into a voltage of a magnitude that does not interfere with signal processing in the subsequent stage.
【００１０】[0010]
【実施例】以下、本発明の実施例を図面に基づいて説明
する。図１には、本発明に係る焦電センサ用回路の一実
施例の回路構成が示されている。同図において、オペア
ンプ４の反転入力端子側には外付け抵抗体１の出力端が
接続され、オペアンプ４の出力端と反転入力端子間には
帰還抵抗体３が接続されている。オペアンプ４の非反転
入力端子側には焦電素子Ｓ１の出力端が接続され、焦電
素子Ｓ１の出力端とオペアンプ４の非反転入力端子との
間には焦電素子Ｓ１の発生する出力電流信号としての焦
電電流を電圧に変換する電圧変換抵抗体２の一端側が接
続され、電圧変換抵抗体２の他端側はグランド側に接続
されている。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit configuration of an embodiment of a pyroelectric sensor circuit according to the present invention. In the figure, the output terminal of the external resistor 1 is connected to the inverting input terminal side of the operational amplifier 4, and the feedback resistor 3 is connected between the output terminal of the operational amplifier 4 and the inverting input terminal. The output terminal of the pyroelectric element S1 is connected to the non-inverting input terminal side of the operational amplifier 4, and the output current generated by the pyroelectric element S1 is between the output terminal of the pyroelectric element S1 and the non-inverting input terminal of the operational amplifier 4. One end of the voltage conversion resistor 2 that converts the pyroelectric current as a signal into a voltage is connected, and the other end of the voltage conversion resistor 2 is connected to the ground side.
【００１１】外付け抵抗体１の入力側はコンデンサＣ１
を介して、また、焦電素子Ｓ１の入力側はコンデンサＣ
２を介して、抵抗体Ｒa とＲb との接続部５に接続され
ている。これらコンデンサＣ１とＣ２は、オペアンプ４
の入力オフセット電圧による回路の直流電圧を除くよう
機能している。抵抗体Ｒa とＲb とからなる直列接続体
の両端側には、オペアンプ４に必要なバイアス電圧を加
える電源ＶCC，ＶSSが接続されて焦電センサ用回路が構
成されている。The input side of the external resistor 1 is a capacitor C1.
And the input side of the pyroelectric element S1 is a capacitor C
It is connected to the connecting portion 5 between the resistors R a and R b via 2. These capacitors C1 and C2 are operational amplifiers 4
It functions to remove the DC voltage of the circuit due to the input offset voltage of. The pyroelectric sensor circuit is configured by connecting power supplies V CC and V SS for applying a bias voltage required for the operational amplifier 4 to both ends of a series connection body including resistors R a and R b .
【００１２】次に、以上のように構成される焦電センサ
用回路の回路動作を説明する。オペアンプ４には電源Ｖ
CCとＶSSから必要なバイアス電圧が抵抗体Ｒa ，Ｒb に
よって設定されて加えられている。被検出体から発せら
れる赤外線が焦電素子Ｓ１に入射すると、焦電素子Ｓ１
は分極して焦電電流を発生し、この焦電電流は電圧変換
抵抗体２により電圧に変換されて変換電圧としてオペア
ンプ４の非反転入力端子側に加わる。この変換電圧は外
付け抵抗体１の抵抗値Ｒ1 と、帰還抵抗体３の抵抗値Ｒ
f によって決定されるオペアンプ４の増幅率Ｒf ／Ｒ1
をもって増幅されて、オペアンプ４の出力端より出力さ
れる。Next, the circuit operation of the pyroelectric sensor circuit configured as described above will be described. The operational amplifier 4 has a power supply V
The required bias voltage from CC and V SS is set and applied by the resistors R a and R b . When infrared rays emitted from the object to be detected enter the pyroelectric element S1, the pyroelectric element S1
Is polarized to generate a pyroelectric current, which is converted into a voltage by the voltage conversion resistor 2 and applied as a converted voltage to the non-inverting input terminal side of the operational amplifier 4. This converted voltage is the resistance value R 1 of the external resistor 1 and the resistance value R of the feedback resistor 3.
amplification factor of the operational amplifier 4 which is determined by f R f / R 1
Is amplified and output from the output terminal of the operational amplifier 4.
【００１３】本実施例によれば、オペアンプ４の増幅率
Ｒf ／Ｒ1 は、従来のように焦電素子Ｓ１の大きな内部
抵抗値ｒに依存することはなく、帰還抵抗体３と外付け
抵抗体１との各抵抗値の比によってのみ決定されるの
で、オペアンプ４の増幅率Ｒf／Ｒ1 を大きな値に自由
に設定することができ、また、帰還抵抗体３の抵抗値も
105 Ω程度に低く抑えることができる。このような汎用
の抵抗値をもつ帰還抵抗体３は抵抗値に対し、±0.1 ％
の範囲内に精度よく作製されるため、オペアンプ４の増
幅率をセンサ毎のばらつきなく、一定の値にすることが
できる。According to the present embodiment, the amplification factor R f / R 1 of the operational amplifier 4 does not depend on the large internal resistance value r of the pyroelectric element S1 as in the conventional case, but rather the feedback resistor 3 and the externally attached element. Since it is determined only by the ratio of each resistance value to the resistor 1, the amplification factor R f / R 1 of the operational amplifier 4 can be freely set to a large value, and the resistance value of the feedback resistor 3 is also set.
It can be kept as low as 10 5 Ω. The feedback resistor 3 having such a general-purpose resistance value is ± 0.1% of the resistance value.
Since it is manufactured with high accuracy within the range, the amplification factor of the operational amplifier 4 can be set to a constant value without variation among the sensors.
【００１４】また、焦電センサの感度は帰還抵抗体３に
依存するが、帰還抵抗体３を従来例よりも格段に低抵抗
値にしても、オペアンプ４の増幅率を大きくできるか
ら、オペアンプ４から高い電圧を出力することによりセ
ンサの感度を上げることができる。Further, the sensitivity of the pyroelectric sensor depends on the feedback resistor 3, but the amplification factor of the operational amplifier 4 can be increased even if the feedback resistor 3 has a much lower resistance value than the conventional example. It is possible to increase the sensitivity of the sensor by outputting a high voltage.
【００１５】さらに、焦電センサの応答速度は従来で
は、大抵抗値の帰還抵抗体３に依存していたので、応答
速度の速いものを提供できなかったが、本実施例では、
応答速度は電圧変換抵抗体２の抵抗値によって規制され
るので、電圧変換抵抗体２をオペアンプ４からの出力が
後段の信号処理に差し支えない程度に低く設定すること
により応答速度を速めることができる。Further, since the response speed of the pyroelectric sensor has hitherto been dependent on the feedback resistor 3 having a large resistance value, it was not possible to provide the one having a high response speed, but in this embodiment,
Since the response speed is regulated by the resistance value of the voltage conversion resistor 2, the response speed can be increased by setting the voltage conversion resistor 2 so low that the output from the operational amplifier 4 does not interfere with signal processing in the subsequent stage. .
【００１６】なお、本発明は上記実施例に限定されるこ
とはなく、様々な実施の態様を採り得る。例えば、上記
実施例では、コンデンサＣ１とＣ２を２つ設けたが、ど
ちらか一方のみでもよい。また、オペアンプ４のオフセ
ット電圧が十分小さなものであればコンデンサを省略し
てもよい。The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, although two capacitors C1 and C2 are provided in the above embodiment, only one of them may be provided. The capacitor may be omitted if the offset voltage of the operational amplifier 4 is sufficiently small.
【００１７】[0017]
【発明の効果】本発明は、オペアンプの反転入力端子に
外付け抵抗体を接続し、オペアンプの出力端と反転入力
端子間に帰還抵抗体を接続したので、オペアンプの増幅
率は帰還抵抗体の抵抗値を外付け抵抗体の抵抗値で除し
た値となり、従来のように焦電素子の大きな内部抵抗に
よって規制されることなく、焦電素子とは無関係にオペ
アンプの増幅率を自由に設定できる。According to the present invention, since the external resistor is connected to the inverting input terminal of the operational amplifier and the feedback resistor is connected between the output terminal of the operational amplifier and the inverting input terminal, the amplification factor of the operational amplifier is equal to that of the feedback resistor. It is the value obtained by dividing the resistance value by the resistance value of the external resistor, and the amplification factor of the operational amplifier can be set freely regardless of the pyroelectric element, without being restricted by the large internal resistance of the pyroelectric element as in the past. .
【００１８】また、従来では、オペアンプの増幅率は帰
還抵抗体の抵抗値を焦電素子の大きな内部抵抗で除した
値で得られるため、帰還抵抗体の抵抗値を109 〜1011Ω
と大きく設定しなければならなかったが、本発明ではオ
ペアンプの増幅率は焦電素子でない外付け抵抗体と帰還
抵抗体の比によって決まるため、帰還抵抗体の抵抗値を
従来のように大きな抵抗値に設定する必要はなく、帰還
抵抗体の抵抗値を低い汎用的な値に設定できることによ
り、帰還抵抗体を精度よく作製できることとなり、オペ
アンプの増幅率も正確に、かつ、自由に設定でき、セン
サ毎のばらつきもなくなる。Further, conventionally, the amplification factor of the operational amplifier is obtained by dividing the resistance value of the feedback resistor by the large internal resistance of the pyroelectric element, so that the resistance value of the feedback resistor is 10 9 to 10 11 Ω.
However, in the present invention, the amplification factor of the operational amplifier is determined by the ratio of the external resistor that is not the pyroelectric element and the feedback resistor. It is not necessary to set the value to a value, and by setting the resistance value of the feedback resistor to a low general value, the feedback resistor can be manufactured with high precision, and the amplification factor of the operational amplifier can be set accurately and freely. Variations among sensors are also eliminated.
【００１９】さらに、焦電素子の出力電流信号を電圧変
換抵抗体により電圧に変換してオペアンプの非反転入力
端子に加わるようにしているので、オペアンプからの出
力が後段の信号処理に差し支えない程度に電圧変換抵抗
体の抵抗値を低く設定することにより応答速度を速める
ことができる。Furthermore, since the output current signal of the pyroelectric element is converted into a voltage by the voltage conversion resistor and applied to the non-inverting input terminal of the operational amplifier, the output from the operational amplifier does not interfere with signal processing in the subsequent stage. By setting the resistance value of the voltage conversion resistor to be low, the response speed can be increased.
【図１】本発明に係る焦電センサ用回路の回路構成図で
ある。FIG. 1 is a circuit configuration diagram of a circuit for a pyroelectric sensor according to the present invention.
【図２】従来の電流モード型焦電センサ用回路の説明図
である。FIG. 2 is an explanatory diagram of a conventional current mode type pyroelectric sensor circuit.
１ 外付け抵抗体 ２ 電圧変換抵抗体 ３ 帰還抵抗体 ４ オペアンプ Ｓ１ 焦電素子 1 External resistor 2 Voltage conversion resistor 3 Feedback resistor 4 Operational amplifier S1 Pyroelectric element
Claims (1)
換しオペアンプにより増幅して出力する電流モード型の
焦電センサ用回路において、前記オペアンプの反転入力
端子には外付け抵抗体が接続されるとともにオペアンプ
の出力端と反転入力端子間には帰還抵抗体が接続されて
おり、焦電素子の出力端はオペアンプの非反転入力端子
に接続され、焦電素子の出力端とオペアンプの非反転入
力端子との間には焦電素子の出力電流信号を電圧信号に
変換する電圧変換抵抗体の一端側が接続されていること
を特徴とする焦電センサ用回路。1. A current mode type pyroelectric sensor circuit for converting an output current signal of a pyroelectric element into a voltage signal, amplifying the voltage signal by an operational amplifier and outputting the voltage signal, wherein an external resistor is connected to an inverting input terminal of the operational amplifier. A feedback resistor is connected between the output terminal of the operational amplifier and the inverting input terminal, and the output terminal of the pyroelectric element is connected to the non-inverting input terminal of the operational amplifier. A circuit for a pyroelectric sensor, characterized in that one end side of a voltage conversion resistor for converting an output current signal of the pyroelectric element into a voltage signal is connected between the inverting input terminal and the inverting input terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5157871A JPH06347333A (en) | 1993-06-03 | 1993-06-03 | Circuit for pyroelectric sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5157871A JPH06347333A (en) | 1993-06-03 | 1993-06-03 | Circuit for pyroelectric sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06347333A true JPH06347333A (en) | 1994-12-22 |
Family
ID=15659232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5157871A Pending JPH06347333A (en) | 1993-06-03 | 1993-06-03 | Circuit for pyroelectric sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06347333A (en) |
-
1993
- 1993-06-03 JP JP5157871A patent/JPH06347333A/en active Pending
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