JPS632453B2 - - Google Patents
Info
- Publication number
- JPS632453B2 JPS632453B2 JP56073738A JP7373881A JPS632453B2 JP S632453 B2 JPS632453 B2 JP S632453B2 JP 56073738 A JP56073738 A JP 56073738A JP 7373881 A JP7373881 A JP 7373881A JP S632453 B2 JPS632453 B2 JP S632453B2
- Authority
- JP
- Japan
- Prior art keywords
- operational amplifier
- circuit
- input terminal
- inverting input
- zero
- 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
- 239000003990 capacitor Substances 0.000 claims description 4
- 238000005259 measurement Methods 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- 230000010354 integration Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000005375 photometry Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 239000011669 selenium Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Description
【発明の詳細な説明】
本発明は、シリコン光電池等の光電変換素子を
用いて閃光あるいは定常光の測定を行なう場合の
光電流積分回路よりなるオートゼロ測光回路に関
するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auto-zero photometry circuit comprising a photocurrent integration circuit when measuring flash light or steady light using a photoelectric conversion element such as a silicon photovoltaic cell.
シリコン光電池やセレン光電池等の光電変換素
子を用いて測光を行なう場合、光電流出力の直線
性を保つため、素子の出力電圧を０〔Ｖ〕付近に
保持しながら出力電流を取り出す必要があり、一
般には演算増幅器を用いて電流−電圧変換を行な
い、特に閃光を測定する場合は演算増幅器で積分
器を構成して光量の測定を行なうのが通例であ
る。 When performing photometry using a photoelectric conversion element such as a silicon photovoltaic cell or a selenium photovoltaic cell, in order to maintain the linearity of the photocurrent output, it is necessary to extract the output current while maintaining the output voltage of the element near 0 [V]. Generally, an operational amplifier is used to perform current-to-voltage conversion, and particularly when measuring flash light, it is customary to construct an integrator using the operational amplifier to measure the amount of light.
演算増幅器を測光に用いる場合、測定誤差を生
ずる一因としてゼロ点ドリフトの問題がある。シ
リコン光電池のように光起電力形の光電変換素子
を上述のようにゼロバイアスで使用する場合は素
子自身の暗電流をゼロとみなすことができるの
で、演算増幅器が生ずるゼロ点ドリフトを除去で
きればゼロ調整の必要のない高安定な回路が実現
できる。 When an operational amplifier is used for photometry, one of the causes of measurement errors is the problem of zero point drift. When using a photovoltaic photoelectric conversion element such as a silicon photovoltaic cell with zero bias as mentioned above, the dark current of the element itself can be considered zero, so if the zero point drift caused by the operational amplifier can be removed, the dark current can be zero. A highly stable circuit that does not require adjustment can be realized.
演算増幅器のゼロ点ドリフトは、オフセツト電
圧と入力バイアス電流の変動によつて生ずるもの
であり、微弱光を測定する場合は両方の特性が大
きく影響する。しかしながら、この両方の特性を
充分満足するような演算増幅器を得ることはきわ
めて困難であり、ここに本発明の必要性がある。 The zero point drift of an operational amplifier is caused by variations in the offset voltage and input bias current, and both characteristics have a large effect when measuring weak light. However, it is extremely difficult to obtain an operational amplifier that fully satisfies both of these characteristics, and this is where the need for the present invention lies.
一般に、ゼロ点ドリフトの補正方法としては、
測定前に入力を切り離してゼロ調整回路の可変抵
抗を調節する方法、あるいは、ドリフト分をあら
かじめ測定しておき、後で測定値から差し引く方
法などがよく採用されている。しかしながら、こ
れらの方法では、多チヤンネル同時測定や多数の
サンプルの測定においては非常に繁雑な操作とな
り、ややもすると操作ミス等で測定誤差を生ずる
恐れもある。また、最近では、スイツチ素子（ス
イツチ、リレー、アナログスイツチ回路など）を
用いてゼロドリフト（オフセツト電圧）を補正す
る回路が考案されているが、これらはいずれもス
イツチ回路を複数個用いたものであり、回路が複
雑になるのみならず、各スイツチ回路の切換タイ
ミングのずれ等による測定誤差を生ずる要因があ
つた。 Generally, the zero point drift correction method is as follows:
Commonly used methods include disconnecting the input before measurement and adjusting the variable resistance of the zero adjustment circuit, or measuring the drift amount in advance and subtracting it from the measured value later. However, these methods require very complicated operations in simultaneous multi-channel measurement or measurement of a large number of samples, and there is a risk that measurement errors may occur due to operational errors or the like. In addition, recently, circuits have been devised to correct zero drift (offset voltage) using switch elements (switches, relays, analog switch circuits, etc.), but all of these circuits use multiple switch circuits. This not only complicates the circuit, but also causes measurement errors due to shifts in switching timing of each switch circuit.
本発明は、このような従来の問題を解決し、ス
イツチ素子により１回路のみの切り換えを行な
い、自動的にゼロドリフト（オフセツト電圧）を
補正して、閃光および定常光の測定ができる測光
回路を提供するものである。 The present invention solves these conventional problems and provides a photometry circuit that can measure flashing light and steady light by switching only one circuit using a switch element and automatically correcting zero drift (offset voltage). This is what we provide.
以下、本発明を添付図面により、その実施例に
ついて詳述する。第１図において、１はシリコン
光電池、２は演算増幅器、３はリレー、４はサン
プルホールド回路であり、シリコン光電池１から
の光電流を演算増幅器２に入力し、積分コンデン
サC1により入力電流の積分を行なうよう構成さ
れている。オフセツト電圧補正の動作は次のとお
りである。まず、リレー３の接点は測定前にはa1
に接続されている。この状態の等価回路は第２図
のａに示すとおりで、演算増幅器２の出力端子に
はオフセツト電圧が発生しており、C1とC2には
このオフセツト電圧がR1、R2を通して充電され
る。この電圧の極性が図に示したとおりであると
仮定する。このときシリコン光電池１が演算増幅
器２の出力端子に接続された形となるが、光電流
はすべて演算増幅器２に吸収されるので問題とな
らない。 Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In Fig. 1, 1 is a silicon photocell, 2 is an operational amplifier, 3 is a relay, and 4 is a sample and hold circuit.The photocurrent from the silicon photovoltaic cell 1 is input to the operational amplifier 2, and the input current is controlled by an integrating capacitor C1 . It is configured to perform integration. The operation of offset voltage correction is as follows. First, the contact point of relay 3 is a 1 before measurement.
It is connected to the. The equivalent circuit in this state is shown in Figure 2a. An offset voltage is generated at the output terminal of operational amplifier 2, and this offset voltage charges C1 and C2 through R1 and R2. be done. Assume that the polarity of this voltage is as shown in the figure. At this time, the silicon photovoltaic cell 1 is connected to the output terminal of the operational amplifier 2, but this does not pose a problem since all the photocurrent is absorbed by the operational amplifier 2.
さて、次にリレー３の接点がa2に接続されると
第２図のｂに示すような等価回路となり、積分コ
ンデンサC1による積分器が構成される。R1はこ
の時は負荷抵抗として働く。ここで、先程C1に
充電されたオフセツト電圧の極性を調べると、第
２図のｂに示したとおりであり、−入力端子から
オフセツト電圧と逆極性の電圧が出力端子との間
に生じることになり、出力端子ではオフセツト電
圧が相殺されてゼロになる。一方、光電池１の出
力は、演算増幅器２の−入力端子に接続されて光
電流の積分動作が開始される。ここで、閃光を発
光させるかあるいは定常光を一定時間積分した
後、サンプルホールド回路４により積分値を保持
し、μ−CPUに取り込む等の処理をした後リレ
ー３をもとの状態にもどす。このようにして、オ
フセツト電圧を完全に補正した積分動作が可能と
なる。ただし、入力バイアス電流による誤差は補
正されず、積分時間に比例して現われるので、特
に長い積分時間をとる場合は入力バイアス電流の
小さい演算増幅器を使用する必要がある。ここ
で、R1はC1が放電する時過大電流が流れるのを
防止する。R2とC2は、リレー３の接点がa1〜a2
の間を移動する瞬間に演算増幅器が開ループとな
つて動作不安定になるのを防ぐためのものであ
る。 Next, when the contact point of relay 3 is connected to a2 , an equivalent circuit as shown in FIG . R 1 works as a load resistance at this time. Now, when we examine the polarity of the offset voltage charged to C1 earlier, we find that it is as shown in Figure 2b, and a voltage with the opposite polarity to the offset voltage is generated between the - input terminal and the output terminal. The offset voltage is canceled out and becomes zero at the output terminal. On the other hand, the output of the photovoltaic cell 1 is connected to the negative input terminal of the operational amplifier 2, and the integration operation of the photocurrent is started. Here, after emitting a flash light or integrating the steady light for a certain period of time, the integrated value is held by the sample hold circuit 4, and after processing such as importing it into the μ-CPU, the relay 3 is returned to its original state. In this way, an integral operation with completely corrected offset voltage is possible. However, since errors due to the input bias current are not corrected and appear in proportion to the integration time, it is necessary to use an operational amplifier with a small input bias current when a particularly long integration time is required. Here, R1 prevents excessive current from flowing when C1 discharges. R 2 and C 2 are the contacts of relay 3 between a 1 and a 2
This is to prevent the operational amplifier from becoming open loop and becoming unstable at the moment of movement between the two.
さらに、入力バイアス電流の充分小さい演算増
幅器を用いれば、第３図に示すように、光電池の
出力と演算増幅器の入力の間に新たなスイツチ回
路５を設けることにより、演算増幅器２にホール
ド機能を持たせてサンプルホールド４を省略する
こともできる。 Furthermore, if an operational amplifier with a sufficiently small input bias current is used, a hold function can be added to the operational amplifier 2 by providing a new switch circuit 5 between the output of the photovoltaic cell and the input of the operational amplifier, as shown in FIG. It is also possible to omit the sample hold 4.
このように、本発明による測光回路を使用する
ことにより、比較的安価な演算増幅器を用いなが
らゼロドリフト誤差のきわめて小さな測光回路を
実現することができる。本発明による測光回路
は、測定精度の向上、測定装置の操作性の向上の
面で大きな効果が期待できる。 As described above, by using the photometric circuit according to the present invention, it is possible to realize a photometric circuit with extremely small zero-drift error while using a relatively inexpensive operational amplifier. The photometric circuit according to the present invention can be expected to have great effects in terms of improving measurement accuracy and improving the operability of the measuring device.
添付の図面は、本発明の実施例を示すもので、
第１図はその基本回路図を示す。第２図のａはリ
レー３の接点をa1に接続した時の等価回路を示
し、ｂはリレー３の接点をa2に接続した時の等価
回路を示す。第３図は、本発明の別の実施例にお
ける基本回路図を示す。
１……シリコン光電池、２……演算増幅器、３
……リレー、４……サンプルホールド回路。
The accompanying drawings illustrate embodiments of the invention, and
FIG. 1 shows its basic circuit diagram. In FIG. 2, a shows an equivalent circuit when the contact of relay 3 is connected to a1 , and b shows an equivalent circuit when the contact of relay 3 is connected to a2 . FIG. 3 shows a basic circuit diagram in another embodiment of the invention. 1... Silicon photovoltaic cell, 2... Operational amplifier, 3
...Relay, 4...Sample and hold circuit.
Claims (1)
号入力端子とした演算増幅器と、前記演算増幅器
の反転入力端子に一端を接続した積分コンデンサ
と、前記演算増幅器の出力端子を、反転入力端子
かまたは前記積分コンデンサの他方の端子のどち
らかに接続するように回路を切り換えるスイツチ
素子と、前記積分コンデンサの前記スイツチ側の
端子と接地との間に接続した抵抗より構成される
ことを特徴とするオートゼロ測光回路。1 An operational amplifier whose non-inverting input terminal is grounded and whose inverting input terminal is a signal input terminal, an integrating capacitor whose one end is connected to the inverting input terminal of the operational amplifier, and whose output terminal is connected to the inverting input terminal. Alternatively, it is characterized by comprising a switch element that switches the circuit to be connected to one of the other terminals of the integrating capacitor, and a resistor connected between the switch side terminal of the integrating capacitor and ground. Auto zero metering circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7373881A JPS57189028A (en) | 1981-05-15 | 1981-05-15 | Auto zero photometric circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7373881A JPS57189028A (en) | 1981-05-15 | 1981-05-15 | Auto zero photometric circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57189028A JPS57189028A (en) | 1982-11-20 |
| JPS632453B2 true JPS632453B2 (en) | 1988-01-19 |
Family
ID=13526872
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7373881A Granted JPS57189028A (en) | 1981-05-15 | 1981-05-15 | Auto zero photometric circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57189028A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02186591A (en) * | 1989-01-13 | 1990-07-20 | Hitachi Ltd | High-frequency heating device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55116226A (en) * | 1979-03-03 | 1980-09-06 | Hitachi Ltd | Discharging current integration-type photodetector |
-
1981
- 1981-05-15 JP JP7373881A patent/JPS57189028A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55116226A (en) * | 1979-03-03 | 1980-09-06 | Hitachi Ltd | Discharging current integration-type photodetector |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57189028A (en) | 1982-11-20 |
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