JPS6238380Y2 - - Google Patents
Info
- Publication number
- JPS6238380Y2 JPS6238380Y2 JP1981103481U JP10348181U JPS6238380Y2 JP S6238380 Y2 JPS6238380 Y2 JP S6238380Y2 JP 1981103481 U JP1981103481 U JP 1981103481U JP 10348181 U JP10348181 U JP 10348181U JP S6238380 Y2 JPS6238380 Y2 JP S6238380Y2
- Authority
- JP
- Japan
- Prior art keywords
- diaphragm
- circuit
- braking
- aperture
- opening
- 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
- 230000003321 amplification Effects 0.000 claims description 5
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 5
- 238000001514 detection method Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
Landscapes
- Exposure Control For Cameras (AREA)
- Diaphragms For Cameras (AREA)
Description
【考案の詳細な説明】
この考案は、監視用等に用いられる自動絞り機
構付レンズを使用したビデオカメラの自動絞り装
置に関する。[Detailed Description of the Invention] This invention relates to an automatic diaphragm device for a video camera using a lens with an automatic diaphragm mechanism used for monitoring purposes and the like.
この考案の対象とするビデオカメラの自動絞り
装置の概略構成を第１図に示す。 FIG. 1 shows a schematic configuration of an automatic aperture device for a video camera, which is the subject of this invention.
これを簡単に説明すると、図示しない撮像管か
らのビデオ信号を輝度検出回路１に入力して被写
体輝度の応じた信号を出力させ、レベル調整回路
２で設定されたレベルに応じてレベル調整して、
絞りを駆動すべき方向に応じた極性の電圧信号を
駆動回路３へ入力し、絞り開閉装置４の駆動コイ
ルに電流を流して絞り羽根を開閉作動させるよう
になつている。 To explain this simply, a video signal from an image pickup tube (not shown) is input to the brightness detection circuit 1, which outputs a signal according to the subject brightness, and the level is adjusted according to the level set by the level adjustment circuit 2. ,
A voltage signal with a polarity corresponding to the direction in which the diaphragm is to be driven is input to the drive circuit 3, and current is passed through the drive coil of the diaphragm opening/closing device 4 to open and close the diaphragm blades.
この時、絞り羽根のハンチングを防止するため
に、絞り開閉装置４には速度検出コイルを備えて
おり、絞り羽根の作動方向及び速度に応じた極性
及び大きさの電圧信号を発生させ、その電圧信号
を制動回路５を介して増幅して駆動回路３にフイ
ードバツクし（レベル調整回路２からの電圧信号
と制動回路５からの電圧信号は逆極性となる）、
絞り羽根に制動をかけて絞りの開閉速度を制御す
る。 At this time, in order to prevent hunting of the aperture blades, the aperture opening/closing device 4 is equipped with a speed detection coil, which generates a voltage signal whose polarity and magnitude correspond to the operating direction and speed of the aperture blades. The signal is amplified via the braking circuit 5 and fed back to the drive circuit 3 (the voltage signal from the level adjustment circuit 2 and the voltage signal from the braking circuit 5 have opposite polarities),
It applies brakes to the aperture blades to control the opening and closing speed of the aperture.
ところで、従来このようなビデオカメラの自動
絞り装置では、絞りが閉じる方向に作動する時も
開く方向に作動する時も同様な制動作用が働き、
絞りの作動速度は同じであつた。 By the way, in conventional automatic aperture devices for video cameras, the same braking action works when the aperture operates in the closing direction and in the opening direction.
The operating speed of the aperture was the same.
しかしながら、このようなビデオカメラからの
ビデオ信号によりCRT上に映出される画面は、
被写体が暗い状態から急に明るくなると、一瞬真
白になつて像が見えなくなり、その後絞りが閉じ
るに従つて徐々に像が見えてくる。 However, the screen displayed on the CRT using the video signal from such a video camera is
When a subject suddenly becomes bright from a dark state, it becomes completely white for a moment and the image becomes invisible, and then as the aperture closes, the image gradually becomes visible.
一方、被写体が明るい状態から急に暗くなつた
場合には、画面は急に暗くなるが少しは像が見
え、その後絞りが開くに従つて像が明瞭になつて
くる。 On the other hand, if the subject suddenly becomes dark from a bright state, the screen will suddenly become dark, but the image will be visible for a while, and then the image will become clearer as the aperture opens.
すなわち、絞りの作動速度が同じであつても、
見かけ上は絞りが閉じる方向に動く時には開く方
向に動く時よりも遅いように見えるので見苦しか
つた。 In other words, even if the operating speed of the aperture is the same,
It was unsightly because the diaphragm seemed to move slower in the closing direction than in the opening direction.
この考案は、このような問題を解消するために
なされたもので、前述のようなビデオカメラの自
動絞り装置において、制動回路を入力電圧の極性
によつて増幅度が変わる増幅回路によつて構成
し、絞りが開く方向に動く時と閉じる方向に動く
時とで制動量を異ならせ、それによつて絞りの作
動速度を異ならせ、被写体の明るさが急に明るく
なつた時と急に暗くなつた時の画面の変化が同様
に見えるようにしたものである。 This idea was made to solve this problem, and in the automatic aperture device of the video camera mentioned above, the braking circuit is constructed with an amplifier circuit whose amplification degree changes depending on the polarity of the input voltage. However, the amount of braking is different when the aperture moves in the direction of opening and when it moves in the direction of closing, and the operating speed of the aperture is thereby made different, so that the brightness of the subject suddenly becomes brighter and the brightness of the subject suddenly becomes darker. The changes in the screen when the screen changes are shown in the same way.
以下、添付図面の第２図及び第３図によつてこ
の考案の実施例を説明する。 Embodiments of this invention will be described below with reference to FIGS. 2 and 3 of the accompanying drawings.
第２図は、この考案によるビデオカメラの自動
絞り装置のブロツク図であり、第１図と同一部分
には同一符号を付してあり、その部分の説明は省
略する。 FIG. 2 is a block diagram of an automatic aperture device for a video camera according to this invention, in which the same parts as in FIG.
制動回路５′が従来の制動回路と異なり、入力
電圧の極性によつて増幅度が変わる増幅回路によ
つて構成している。すなわち、オペアンプOPの
反転入力端子と出力端子との間に、抵抗R1とダ
イオードD1の直列回路と、抵抗R2とダイオード
D2の直列回路とを並列に接続し、ダイオードD1
とダイオードD2の向きを逆にして、オペアンプ
OPの出力V0が正の時にはダイオードD1が導通
し、オペアンプOPの出力が負の時にはダイオー
ドD2が導通するようにしてある。 The braking circuit 5' differs from conventional braking circuits in that it is constituted by an amplifier circuit whose amplification degree changes depending on the polarity of the input voltage. That is, between the inverting input terminal and the output terminal of the operational amplifier OP, there is a series circuit of a resistor R 1 and a diode D 1 , and a series circuit of a resistor R 2 and a diode.
Connect the diode D 1 in parallel with the series circuit of D 2
By reversing the direction of diode D2 and the op amp
When the output V 0 of the operational amplifier OP is positive, the diode D 1 is conductive, and when the output of the operational amplifier OP is negative, the diode D 2 is conductive.
そして、このオペアンプOPの反転入力端子を
抵抗R3を介して接地し、非反転入力端子に絞り
開閉装置４に備えた速度検出コイルＬによつて発
生する絞りの作動方向及び速度に応じた極性及び
大きさの電圧信号Viを入力する。 The inverting input terminal of this operational amplifier OP is grounded via a resistor R3 , and the non-inverting input terminal is connected to a polarity corresponding to the operating direction and speed of the diaphragm generated by the speed detection coil L provided in the diaphragm opening/closing device 4. Input the voltage signal Vi of the magnitude and magnitude.
なお、抵抗RoとコンデンサCoは発振防止用に
接続してある。 Note that the resistor Ro and capacitor Co are connected to prevent oscillation.
ここで、絞り開閉装置４において、絞り羽根が
閉じる方向に動いた時（駆動回路３への入力信号
が負）、速度検出コイルＬに発生する起電圧Viが
正の電圧となるようにしておくと、この時オペア
ンプOPの出力Voは正になるから、ダイオードD1
が導通し、抵抗R1を通して帰還電流が流れる。 Here, in the aperture opening/closing device 4, when the aperture blades move in the closing direction (the input signal to the drive circuit 3 is negative), the electromotive force Vi generated in the speed detection coil L is made to be a positive voltage. At this time, the output Vo of the operational amplifier OP becomes positive, so the diode D1
conducts, and a feedback current flows through resistor R1 .
したがつて、その時の出力Voは、
Vo＝Ｒ１／Ｒ３Vi＋d1 ……(1)
となる。（但し、d1はダイオードD1の順方向電圧
降下）
一方、絞り羽根が開く方向に動いた時（駆動回
路３への入力信号が正）には、速度検出コイルＬ
に発生する起電圧Viが負の電圧になり、この時
オペアンプOPの出力Voが負になるから、ダイオ
ードD2が導通し、抵抗R2を通して帰還電流が流
れる。 Therefore, the output Vo at that time is Vo=R 1 /R 3 Vi+d 1 (1). (However, d 1 is the forward voltage drop of diode D 1. ) On the other hand, when the aperture blades move in the direction of opening (the input signal to the drive circuit 3 is positive), the speed detection coil L
The electromotive voltage Vi generated in the diode becomes negative, and at this time the output Vo of the operational amplifier OP becomes negative, so the diode D2 becomes conductive and a feedback current flows through the resistor R2 .
したがつて、その時の出力Voは、
Vo＝Ｒ２／Ｒ３Vi−d2 ……(2)
となる。（但し、d2はダイオードD2の順方向電圧
降下）
(1)式及び(2)式によるViとVoの関係を図に示す
と第３図のようになり、抵抗R1とR2の抵抗値を
R2＞R1に選んでおけば、Viが正の時の勾配R1／
R3よりもViが負の時の勾配R2／R3の方が大きく
なる。d1，d2は非常に小さいので、この勾配R1／
R2及びR2／R3がこの増幅回路の増幅度をほぼ表
わし、この場合、入力電圧Viが負の時より正の
時の方が増幅度が大きくなる。 Therefore, the output Vo at that time is Vo=R 2 /R 3 Vi−d 2 (2). (However, d 2 is the forward voltage drop of diode D 2. ) The relationship between Vi and Vo based on equations (1) and (2) is shown in Figure 3, and the relationship between resistances R 1 and R 2 is resistance value
If R 2 > R 1 is selected, the gradient R 1 /
When Vi is negative, the slope R 2 /R 3 becomes larger than R 3 . Since d 1 and d 2 are very small, this gradient R 1 /
R 2 and R 2 /R 3 approximately represent the amplification degree of this amplifier circuit, and in this case, the amplification degree is greater when the input voltage Vi is positive than when it is negative.
このようにすれば、速度検出コイルＬに発生す
る起電圧の絶対値が同じであつても、その極性に
よつて制動回路５′の出力電圧Voの大きさが異な
り、駆動回路３へのフイードバツク量すなわち制
動量が変わることになる。 In this way, even if the absolute value of the electromotive force generated in the speed detection coil L is the same, the magnitude of the output voltage Vo of the braking circuit 5' will differ depending on its polarity, and feedback to the drive circuit 3 will be reduced. The amount, that is, the amount of braking will change.
したがつて、絞りが開く方向に作動する時と閉
じる方向に作動する時とで絞りの作動速度を異な
らせることができ、上述の実施例のように、絞り
が閉じる時には制動量を小さくして作動速度を速
くし、絞りが開くときには制動量を大きくして作
動速度を遅くすれば、CRT画面上での画像の変
化がいずれの場合も同じように感じて見易くな
る。 Therefore, the operating speed of the diaphragm can be made different when the diaphragm operates in the opening direction and when it operates in the closing direction, and as in the above embodiment, when the diaphragm closes, the amount of braking is reduced. By increasing the operating speed and slowing the operating speed by increasing the amount of braking when the aperture opens, changes in the image on the CRT screen will feel the same and be easier to see in either case.
また、場合によてはオペアンプOPの反転入力
と非反転入力を逆にしてもよいし、オペアンプ以
外の増幅器等を使つてもよい。 In some cases, the inverting input and non-inverting input of the operational amplifier OP may be reversed, or an amplifier other than the operational amplifier may be used.
以上、実施例について説明したように、この考
案によるビデオカメラの自動絞り装置は、絞りの
作動方向によつて制動量を異ならせることができ
るので、絞りが開く方向に作動する時と閉じる方
向に作動する時とでその作動速度を異ならせ、
CRT画面上での画像の変化がいずれの場合にも
同様に見えるようにすることができる。また、場
合によつては故意に開き方向と閉じ方向の絞り作
動速度を大幅に変えることもできる。 As described above with respect to the embodiments, the automatic diaphragm device for a video camera according to this invention can vary the amount of braking depending on the operating direction of the diaphragm. The operating speed is different depending on when it operates,
Changes in the image on the CRT screen can be made to look the same in both cases. Further, depending on the case, the throttle operation speed in the opening direction and the closing direction can be intentionally changed significantly.
第１図は、この考案の対象とする従来のビデオ
カメラの自動絞り装置のブロツク図、第２図は、
この考案の一実施例を示すブロツク図、第３図
は、第２図における制動回路５′としての増幅回
路の入出力特性の一例を示す線図である。
１……輝度検出回路、２……レベル調整回路、
３……駆動回路、４……絞り開閉装置、５，５′
……制動回路、Ｌ……速度検出コイル。
Figure 1 is a block diagram of a conventional automatic aperture device for a video camera, which is the subject of this invention, and Figure 2 is
FIG. 3, a block diagram showing an embodiment of this invention, is a diagram showing an example of the input/output characteristics of the amplifier circuit as the braking circuit 5' in FIG. 2. 1... Brightness detection circuit, 2... Level adjustment circuit,
3... Drive circuit, 4... Throttle opening/closing device, 5, 5'
...Brake circuit, L...Speed detection coil.
Claims (1)
的に絞りを開閉駆動し、速度検出コイルによつて
絞りの作動方向及び速度に応じた極性及び大きさ
の電圧信号を発生させ、その電圧信号を制動回路
によつて増幅して駆動回路にフイードバツクし、
絞りの開閉速度を制御するようにしたビデオカメ
ラの自動絞り装置において、 前記制動回路を入力電圧の極性によつて増幅度
が変わる増幅回路によつて構成し、絞りが開く方
向に動く時と閉じる方向に動く時とで制動量を異
ならせるようにしたことを特徴とするビデオカメ
ラの自動絞り装置。[Claims for Utility Model Registration] The brightness of the subject is detected using a video signal and the diaphragm is automatically driven to open and close. The voltage signal is amplified by a braking circuit and fed back to the drive circuit,
In an automatic diaphragm device for a video camera that controls the opening and closing speed of the diaphragm, the braking circuit is configured with an amplifier circuit whose amplification degree changes depending on the polarity of the input voltage, and when the diaphragm moves in the direction of opening and closing. An automatic aperture device for a video camera, characterized in that the amount of braking is different depending on the direction of movement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1981103481U JPS5811370U (en) | 1981-07-14 | 1981-07-14 | Video camera automatic aperture device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1981103481U JPS5811370U (en) | 1981-07-14 | 1981-07-14 | Video camera automatic aperture device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5811370U JPS5811370U (en) | 1983-01-25 |
| JPS6238380Y2 true JPS6238380Y2 (en) | 1987-09-30 |
Family
ID=29898096
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1981103481U Granted JPS5811370U (en) | 1981-07-14 | 1981-07-14 | Video camera automatic aperture device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5811370U (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2879569B2 (en) * | 1989-03-30 | 1999-04-05 | キヤノン株式会社 | Imaging device |
-
1981
- 1981-07-14 JP JP1981103481U patent/JPS5811370U/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5811370U (en) | 1983-01-25 |
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