JPH0367134A - Photoelectric converter - Google Patents
Photoelectric converterInfo
- Publication number
- JPH0367134A JPH0367134A JP1202544A JP20254489A JPH0367134A JP H0367134 A JPH0367134 A JP H0367134A JP 1202544 A JP1202544 A JP 1202544A JP 20254489 A JP20254489 A JP 20254489A JP H0367134 A JPH0367134 A JP H0367134A
- Authority
- JP
- Japan
- Prior art keywords
- photoelectric conversion
- current
- leakage current
- light
- photodiode
- 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
- 238000006243 chemical reaction Methods 0.000 claims description 33
- 238000009825 accumulation Methods 0.000 abstract description 8
- 230000035945 sensitivity Effects 0.000 abstract description 4
- 239000003990 capacitor Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 230000005669 field effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000005685 electric field effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
- H04N25/62—Detection or reduction of noise due to excess charges produced by the exposure, e.g. smear, blooming, ghost image, crosstalk or leakage between pixels
- H04N25/621—Detection or reduction of noise due to excess charges produced by the exposure, e.g. smear, blooming, ghost image, crosstalk or leakage between pixels for the control of blooming
- H04N25/623—Detection or reduction of noise due to excess charges produced by the exposure, e.g. smear, blooming, ghost image, crosstalk or leakage between pixels for the control of blooming by evacuation via the output or reset lines
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は光電変換装置、特に、極めて微弱な光を抽らえ
て感度よく電気信号に変換する光電変換装置に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoelectric conversion device, and particularly to a photoelectric conversion device that extracts extremely weak light and converts it into an electrical signal with high sensitivity.
従来から光電変換素子と電荷蓄積手段とを基本要素とす
る光電変換装置がある。この装置は、光電変換素子の光
電流によって電荷蓄積手段に電荷を蓄え、その蓄積電荷
の変化に１ｆう電圧変化を電気信号として取り出すもの
である。2. Description of the Related Art Conventionally, there have been photoelectric conversion devices whose basic elements are a photoelectric conversion element and a charge storage means. This device stores electric charge in a charge storage means using a photocurrent of a photoelectric conversion element, and extracts a voltage change of 1f in response to a change in the accumulated electric charge as an electric signal.
〔発明が解決しようとする課題）
ところで、微弱な光を電気信号に変換しようとする場合
には、光電流による電荷蓄積の時間を長くしてＳ／Ｎ比
を上げる必要がある。しかし、光電変換素子には必ず洩
れ電流が存在するため、光を全く受けなくとも電荷蓄積
手段に電荷が徐々に蓄積され、最後には蓄積不能状態に
至ってしまう。[Problems to be Solved by the Invention] By the way, when attempting to convert weak light into an electrical signal, it is necessary to increase the S/N ratio by increasing the time for charge accumulation by photocurrent. However, since a leakage current always exists in a photoelectric conversion element, charge is gradually accumulated in the charge storage means even when no light is received, and eventually a state in which storage is impossible is reached.
そのために、蓄積時間を十分に長くとることができず、
したがって、感度の良い光電変換装置を得ることかでき
なかった。なお、光電変換素子を液体窒素温度程度まで
冷却すれば、洩れ電流を無視できる程度に小さくするこ
とができるが、冷却装置を含めると非常に大掛かりな装
置とならざるを得ない。Therefore, the storage time cannot be kept long enough,
Therefore, it was not possible to obtain a photoelectric conversion device with good sensitivity. Note that if the photoelectric conversion element is cooled to about the temperature of liquid nitrogen, the leakage current can be reduced to a negligible level, but if a cooling device is included, the device must be very large-scale.
本発明の課題は、このような問題点を解消することにあ
る。An object of the present invention is to solve these problems.
上記課題を解決するために、本発明の光電変換装置は、
光電変換素子の洩れ電流とほぼ等しい電流をその光電変
換素子に供給する洩れ電流補償手段を備えたものである
。なお、洩れ電流補償手段は、前記光電変換素子と同−
横這の光電変換素子であって受光部が遮蔽されたもので
あることが望ましい。In order to solve the above problems, the photoelectric conversion device of the present invention includes:
This device includes leakage current compensating means for supplying a current approximately equal to the leakage current of the photoelectric conversion element to the photoelectric conversion element. Note that the leakage current compensation means is the same as the photoelectric conversion element.
It is preferable that the photoelectric conversion element be a horizontal photoelectric conversion element with a shielded light receiving part.
光電変換素子の洩れ電流と等しい電流が洩れ電流補償手
段から常時供給されているため、洩れ電流に基づいて電
荷蓄積手段に電荷が蓄積されることがない。したがって
、洩れ電流によって電荷蓄積手段が蓄積限界に達してし
まうことがない。Since a current equal to the leakage current of the photoelectric conversion element is constantly supplied from the leakage current compensation means, charges are not accumulated in the charge storage means based on the leakage current. Therefore, the charge storage means does not reach its storage limit due to leakage current.
また、洩れ電流補償手段に光電変換素子と同−横這の光
電変換素子を用いれば、温度特性を初めとする種々の特
性が一致しているため、洩れ電流補償手段は過不足なく
光電変換素子の洩れ電流を補償することができる。In addition, if the same photoelectric conversion element as the photoelectric conversion element is used as the leakage current compensation means, since various characteristics including temperature characteristics are the same, the leakage current compensation means can be used as a photoelectric conversion element without excess or deficiency. leakage current can be compensated for.
第１図は本発明の一実施例を示す回路図である。 FIG. 1 is a circuit diagram showing an embodiment of the present invention.
光電変換素子であるフォトダイオード１は微弱光検出用
のものであり、数１１ｍ角の広い受光面を持っている。The photodiode 1, which is a photoelectric conversion element, is for detecting weak light and has a wide light-receiving surface of several 11 meters square.
フォトダイオード１のアノードは接地され、カソードは
別のフォトダイオード２のアノードに接続されている。The anode of photodiode 1 is grounded, and the cathode is connected to the anode of another photodiode 2.
フォトダイオード２は、フォトダイオード１と形状およ
び大きさのいずれにおいても同じであり、遮光手段３と
共に洩れ電流補償手段４を構成している。フォトダイオ
ード２のカソードは５ｖの定電圧が印加される端子１１
に接続されている。The photodiode 2 has the same shape and size as the photodiode 1, and together with the light shielding means 3 constitutes a leakage current compensating means 4. The cathode of the photodiode 2 is a terminal 11 to which a constant voltage of 5V is applied.
It is connected to the.
電荷蓄積手段５は、容量手段６とスイッチング手段であ
るＭＯＳ電界電界効果フラノジスタフ構成されている。The charge storage means 5 is composed of a capacitance means 6 and a MOS electric field effect flanozystaff which is a switching means.
トランジスタ７のドレインは２．５Ｖの定電圧が印加さ
れる端子１２に接続され、ゲートは振幅電圧をＯｖ〜５
ｖとする制御用電圧が印加される端子１３に接続されて
いる。容量手段６は一端が接地され、他端はトランジス
タ７のソース、フォトダイオードｌのカソードおよび後
述するソースホロワトランジスタ９のゲートにそれぞれ
接続されている。容量手段６は、その容量値がむしろ小
さいほうが望ましいので、コンデンサを積極的に付加す
る必要はない。すなわち、容量手段６は配線容量および
トランジスタ９のゲート容量だけで構成されている。The drain of the transistor 7 is connected to the terminal 12 to which a constant voltage of 2.5V is applied, and the gate has an amplitude voltage of Ov~5.
It is connected to a terminal 13 to which a control voltage v is applied. One end of the capacitive means 6 is grounded, and the other end is connected to the source of the transistor 7, the cathode of the photodiode 1, and the gate of a source follower transistor 9, which will be described later. Since it is preferable for the capacitor means 6 to have a small capacitance value, there is no need to actively add a capacitor. That is, the capacitor means 6 is composed only of the wiring capacitor and the gate capacitor of the transistor 9.
インピーダンス変換手段８は、ソースホロワ電界効果ト
ランジスタつと定電流源としての電界効果トランジスタ
１０による直列回路で構成さている。トランジスタ９の
ドレインは５ｖの定電圧が印加される端子１４に接続さ
れ、ソースはトランジスタ１０のドレインに接続されて
いる。トランジスタ１０のソースは接地され、そのゲー
トはＩＶの定電圧が印加される端子１５に接続されてい
る。トランジスタ９および１０の接続点１８は、この光
電変換装置の出力端子である。The impedance conversion means 8 is constituted by a series circuit including a source follower field effect transistor and a field effect transistor 10 as a constant current source. The drain of the transistor 9 is connected to a terminal 14 to which a constant voltage of 5V is applied, and the source is connected to the drain of the transistor 10. The source of the transistor 10 is grounded, and the gate thereof is connected to a terminal 15 to which a constant voltage of IV is applied. A connection point 18 between transistors 9 and 10 is an output terminal of this photoelectric conversion device.
つぎに本実施例の動作を説明する。端子１１．１２．１
４．１５にはそれぞれ上述した所定の定心圧が印加され
ており、端子１３にはＯＶが印加されているものとする
。端子１３に印加される制ａｔ＝号は、ハイレベルを５
Ｖ、ｏ−レベル０■とする２ＥＩｉ信号であり、ローレ
ベルを基準状態とし、ｌＪｍｓの幅をＮｊつハイレベル
のパルスをリセット信号とする。リセット信号の周明は
、例えば１０分程度である。Next, the operation of this embodiment will be explained. Terminal 11.12.1
It is assumed that the above-described predetermined constant pressure is applied to each terminal 4.15, and OV is applied to the terminal 13. The control at= signal applied to the terminal 13 has a high level of 5
It is a 2EIi signal with a V, o level of 0■, with a low level as a reference state and a high level pulse with a width of 1Jms of Nj as a reset signal. The period of time for the reset signal is, for example, about 10 minutes.
トランジスタ７は通常オフ状態となっており、そのゲー
トにリセット信号が与えられると導通ずる。トランジス
タ７が導通すると、端子１２に２．５Ｖが印加されてい
るため、容量手段６の端子ＩＨＪ電圧は２．５■に初期
設定（リセット）される。リセット後は、つぎのりセッ
ト信号が与えられるまで、すなわち、信号蓄積期間中ト
ランジスタ７はオフ状態を維持する。Transistor 7 is normally in an off state, and becomes conductive when a reset signal is applied to its gate. When the transistor 7 becomes conductive, since 2.5V is applied to the terminal 12, the terminal IHJ voltage of the capacitor means 6 is initialized (reset) to 2.5. After resetting, the transistor 7 remains off until the next set signal is applied, that is, during the signal accumulation period.
ｆ１号蓄積期間中にフォトダイオード１の受光部に光２
０か照１４されると、受光量に応じた充電流Ｃ３が流れ
、容量手段６に初期設定で充電された電ｆ１：７が放電
する。一方、フォトダイオード１には、充電流Ｃ３とは
別に、受光量に無関係に洩れ電流Ｃが常時流れている。During the f1 accumulation period, light 2 is applied to the light receiving part of photodiode 1.
When the light is illuminated 14, a charging current C3 flows according to the amount of light received, and the electric current f1:7 charged in the capacitive means 6 in the initial setting is discharged. On the other hand, in addition to the charging current C3, a leakage current C constantly flows through the photodiode 1, regardless of the amount of received light.
しかし、洩れ電流ＣＩはフォトダイオード２に流れる洩
れ電流Ｃ２によって相殺されるため、容量手段６の蓄積
電Ｎｊに全く影響を与えない。However, since the leakage current CI is canceled out by the leakage current C2 flowing through the photodiode 2, it does not affect the accumulated current Nj of the capacitor means 6 at all.
このように、容量手段６の蓄積電荷は充電流Ｃ３によっ
てのみ放電し、この放電によって点１７の電位が徐々に
低下する。したがって、つぎにリセットされる直前の点
１７の電位は、当該信号拮積期間中にフォトダイオード
１が受光した光量に対応した値となる。なお、本発明は
非常に微弱な光を検出しようするものであり、その電位
変化はたとえば数百ｍＶ程度である。点１７の電位はト
ランジスタ９のゲートに与えられており、ソース・ゲー
ト間で一定の電圧だけレベルシフトされ、かつ、インピ
ーダンス変換されて接続点１８から出力される。つぎの
りセット信号人力では、再び容量手段６の電圧は２．５
Ｖに初期設定され、以後同様の動作が繰り返される。In this way, the accumulated charge in the capacitor means 6 is discharged only by the charging current C3, and the potential at point 17 gradually decreases due to this discharge. Therefore, the potential at point 17 immediately before being reset next has a value corresponding to the amount of light received by photodiode 1 during the signal accumulation period. Note that the present invention is intended to detect very weak light, and the potential change is, for example, about several hundred mV. The potential at point 17 is applied to the gate of transistor 9, level-shifted by a constant voltage between the source and gate, impedance converted, and output from connection point 18. In the next setting signal manually, the voltage of the capacitive means 6 is 2.5 again.
It is initialized to V, and the same operation is repeated thereafter.
なお、本大施列では洩れ電流補償手段として、フォトダ
イオード〕と同じ形で受光部が連蔽されているフォトダ
イオードが用いられているが、本発明はこれに限定され
るものではない。たとえば、光感応性のないダイオード
で洩れ電流特性かフォトダイオード１と類似しているし
のを用いれば遮光手段３は不要である。しかし、洩れ電
流補償手段を本実施例のように構成すれば、フォトダイ
オード１の洩れ電流Ｃ１を常に過不足なく補償すること
ができ、極めて正確な光電変換を行うことができる。Note that in this large array, a photodiode whose light-receiving portions are connected in the same manner as the photodiode is used as the leakage current compensating means, but the present invention is not limited to this. For example, if a non-photosensitive diode having leakage current characteristics similar to the photodiode 1 is used, the light shielding means 3 is not necessary. However, if the leakage current compensating means is configured as in this embodiment, the leakage current C1 of the photodiode 1 can always be compensated for in excess or deficiency, and extremely accurate photoelectric conversion can be performed.
以上説明したように、本発明の光電変換装置によれば、
洩れ電流によって重荷蓄積手段が蓄積眼光に達してしま
うことがない。そのため、微弱光を高いＳ／Ｎ比で検出
するために蓄枯１．１７間を長くとることかできる。ま
た、洩れ電流の影響を全く受けていないので、受光量と
＜ｌｆｆ１圧値の関係は蓄積時間の長駆にかかわらす同
じである。したがって、感度が高く、使い勝手のよい光
電変換装置としてｆり川することができる。As explained above, according to the photoelectric conversion device of the present invention,
The leakage current will not cause the heavy storage means to reach the storage eye. Therefore, in order to detect weak light with a high S/N ratio, it is possible to take a long period of 1.17 seconds. Furthermore, since there is no influence of leakage current, the relationship between the amount of received light and the <lff1 pressure value remains the same regardless of the length of the accumulation time. Therefore, it can be used as a photoelectric conversion device with high sensitivity and ease of use.
４ 、 図ｉｈ＋ ノｉ７ｈ ’ｌｉ す説明第１園は
本発明の一大施向を示す回路図である。4. Figure Ih+Noi7h'li Explanation The first diagram is a circuit diagram showing a major feature of the present invention.
１．２・・・フォトダイオード、３・・・遮光手段１．
４・・・洩れ？Ｊｉ流抽償手段、５・・・電６：ｊ蓄積
手段、６・・・容量手段、７・・・スイッチング用トラ
ンジスタ、８・・インピーダンス変換手段、９・・・ソ
ースホロワトランジスタ、１０・・・定電流源用トラン
ジスタ。1.2... Photodiode, 3... Light shielding means 1.
4...Leak? Ji current extraction means, 5... Electricity 6: j accumulation means, 6... Capacitance means, 7... Switching transistor, 8... Impedance conversion means, 9... Source follower transistor, 10. ...Transistor for constant current source.
５■ ２．５■ ｏｒ５Ｖ Ｖ5■ 2.5 ■ or5V V
Claims (1)
光電流による電荷を蓄積し蓄積電荷に応じた電圧を出力
する電荷蓄積手段とを備えた光電変換装置において、前
記光電変換素子の洩れ電流とほぼ等しい電流を当該光電
変換素子に供給する洩れ電流補償手段を備えたことを特
徴とする光電変換装置。 ２、洩れ電流補償手段は、前記光電変換素子と同一構造
の光電変換素子であって受光部が遮蔽されたものである
ことを特徴とする請求項１記載の光電変換装置。[Scope of Claims] 1. A photoelectric conversion device comprising a photoelectric conversion element that flows a photocurrent according to the amount of received light, and a charge storage means that stores the charge caused by the photocurrent and outputs a voltage according to the accumulated charge. . A photoelectric conversion device comprising leakage current compensating means for supplying a current substantially equal to the leakage current of the photoelectric conversion element to the photoelectric conversion element. 2. The photoelectric conversion device according to claim 1, wherein the leakage current compensating means is a photoelectric conversion element having the same structure as the photoelectric conversion element, and a light receiving part thereof is shielded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1202544A JPH0367134A (en) | 1989-08-04 | 1989-08-04 | Photoelectric converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1202544A JPH0367134A (en) | 1989-08-04 | 1989-08-04 | Photoelectric converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0367134A true JPH0367134A (en) | 1991-03-22 |
Family
ID=16459264
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1202544A Pending JPH0367134A (en) | 1989-08-04 | 1989-08-04 | Photoelectric converter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0367134A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100404389B1 (en) * | 2001-04-07 | 2003-11-12 | 박규식 | Home Hydro-Cultivater |
-
1989
- 1989-08-04 JP JP1202544A patent/JPH0367134A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100404389B1 (en) * | 2001-04-07 | 2003-11-12 | 박규식 | Home Hydro-Cultivater |
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