JPH036068Y2 - - Google Patents
Info
- Publication number
- JPH036068Y2 JPH036068Y2 JP19728883U JP19728883U JPH036068Y2 JP H036068 Y2 JPH036068 Y2 JP H036068Y2 JP 19728883 U JP19728883 U JP 19728883U JP 19728883 U JP19728883 U JP 19728883U JP H036068 Y2 JPH036068 Y2 JP H036068Y2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- resistor
- circuit
- potentiometer
- operational amplifier
- 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
- 238000001514 detection method Methods 0.000 claims description 6
- 230000000087 stabilizing effect Effects 0.000 claims description 5
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Description
【考案の詳細な説明】
技術分野
この考案は、監視用のCCTVカメラ等に用いら
れるテレビカメラ用レンズの自動絞り制御回路に
関する。[Detailed Description of the Invention] Technical Field This invention relates to an automatic aperture control circuit for a television camera lens used in CCTV cameras for monitoring purposes.
従来技術
この考案を適用するテレビカメラ用レンズの自
動絞り制御回路の概略構成を第1図に示す。Prior Art FIG. 1 shows a schematic configuration of an automatic aperture control circuit for a television camera lens to which this invention is applied.
これを簡単に説明すると、図示しない撮像管を
含むテレビカメラ本体側からのビデオ信号を輝度
検出回路1に入力し、整流・平滑化した輝度検出
信号VSをレベル調整回路2に入力し、目標絞り
値に応じて設定される基準レベルと比較してレベ
ル調整し、絞りを駆動するための電圧信号を駆動
回路3へ入力する。 To explain this simply, a video signal from the TV camera body including an image pickup tube (not shown) is input to the brightness detection circuit 1, a rectified and smoothed brightness detection signal VS is input to the level adjustment circuit 2, and a target aperture is input to the brightness detection circuit 1. The level is adjusted by comparing it with a reference level set according to the value, and a voltage signal for driving the aperture is input to the drive circuit 3.
その信号に応じて駆動回路3が開閉装置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。その際、絞り羽根の開閉速度を検出して制動
回路5を介してフイードバツクをかけ、ハンチン
グを防止する。 In response to the signal, the drive circuit 3 applies current to the drive coil of the switching device 4 to open and close the aperture blades. At this time, the opening/closing speed of the aperture blades is detected and feedback is applied via the braking circuit 5 to prevent hunting.
このようなテレビカメラ用レンズの自動絞り制
御回路において、特にレンズ交換式のテレビカメ
ラでは、カメラ本体側からレンズ側への供給電圧
がまちまちである。 In such automatic aperture control circuits for television camera lenses, especially in interchangeable lens television cameras, the voltage supplied from the camera body side to the lens side varies.
一方、第1図におけるレベル調整回路2で、絞
りの目標値に応じた基準レベルを設定するため
に、一般的に抵抗と電位差計(可変抵抗器)によ
つて電源電圧を分圧する回路が用いられるが、そ
のような回路では、電源電圧が変化するとそれに
追従して基準レベルが変動してしまうので、絞り
値が設定値と違つてしまう欠点がある。 On the other hand, in the level adjustment circuit 2 in Fig. 1, a circuit that divides the power supply voltage using a resistor and a potentiometer (variable resistor) is generally used to set the reference level according to the target value of the aperture. However, in such a circuit, when the power supply voltage changes, the reference level fluctuates in response to the change, so the aperture value has the disadvantage of being different from the set value.
そこで、ダイオードの順方向電圧又はツエナー
ダイオードのツエナー電圧によつて対アース電圧
を規制する供給電圧安定化回路を設け、その出力
電圧を電位差計によつて分圧して基準レベルを得
るようにして、電源電圧の変化による影響をなく
すようにしたものも提案されている。 Therefore, a supply voltage stabilization circuit is provided that regulates the voltage to ground by the forward voltage of the diode or the Zener voltage of the Zener diode, and the output voltage is divided by a potentiometer to obtain a reference level. There have also been proposals that eliminate the effects of changes in power supply voltage.
しかしながら、そのようにしても、比較器とし
て演算増幅器を使用する回路構成の場合、オフセ
ツト調整等の補償回路を別に設けないと、レベル
調整の範囲により調整不能になる場合があるとい
う問題があつた。 However, even if this is done, in the case of a circuit configuration that uses an operational amplifier as a comparator, there is a problem that adjustment may become impossible depending on the level adjustment range unless a compensation circuit such as offset adjustment is provided separately. .
目 的
この考案は、上記の問題に着目してなされたも
ので、電源電圧が変化しても影響されにくく、演
算増幅器を使用したレベル調整回路で広いレベル
調整範囲を得ることができ、しかもオフセツト調
整回路等を別に設ける必要のないテレビカメラ用
レンズの自動絞り制御回路を提供することを目的
とする。Purpose This invention was created with a focus on the above problems.It is not easily affected by changes in the power supply voltage, can obtain a wide level adjustment range with a level adjustment circuit using an operational amplifier, and has a low offset. An object of the present invention is to provide an automatic aperture control circuit for a television camera lens that does not require a separate adjustment circuit or the like.
構 成
そこで、この考案によるテレビカメラ用レンズ
の自動絞り制御回路は、対アース電圧にこだわら
ず、電源電圧を2個の抵抗とツエナーダイオード
によつて分圧して得たツエナー電圧を、目標絞り
値に応じて可調整される電位差計と別の抵抗で分
圧し、その電位差計の分圧出力を輝度検出信号を
一方の入力とする第1の演算増幅器の他方の入力
とし、その出力端子と、電源電圧を2個の抵抗で
分圧した電圧を入力するボルテージホロワとして
の第2の演算増幅器の出力端子との間に得られる
出力電圧信号によつて、レンズの絞りを駆動する
ようにしたものである。Configuration Therefore, the automatic aperture control circuit for a television camera lens devised according to this invention uses the Zener voltage obtained by dividing the power supply voltage by two resistors and a Zener diode, without worrying about the voltage with respect to ground, to set the target aperture value. The voltage is divided by a potentiometer that can be adjusted according to the voltage and another resistor, and the divided voltage output of the potentiometer is used as the other input of a first operational amplifier that receives the luminance detection signal as one input, and its output terminal and The aperture of the lens is driven by the output voltage signal obtained between the output terminal of the second operational amplifier as a voltage follower that inputs the voltage obtained by dividing the power supply voltage by two resistors. It is something.
実施例
この考案の実施例を添付図面の第2図によつて
説明する。Embodiment An embodiment of this invention will be explained with reference to FIG. 2 of the accompanying drawings.
この実施例において、テレビカメラからの電源
電圧供給端子10,11間に、第1の抵抗R1と
第2の抵抗R2との間にツエナーダイオードZDを
介挿して直列に接続して電圧安定化回路を形成
し、そのツエナーダイオードZDに並列に、目標
絞り値に応じて可調整される電位差計(可変抵抗
器)VRと第3の抵抗R3との直列回路を接続して
いる。 In this embodiment, a Zener diode ZD is inserted between the power supply voltage supply terminals 10 and 11 from the television camera and between the first resistor R 1 and the second resistor R 2 and connected in series to stabilize the voltage. A series circuit consisting of a potentiometer (variable resistor) VR and a third resistor R3 that can be adjusted according to the target aperture value is connected in parallel to the Zener diode ZD.
そして、輝度検出信号VSを一方の入力とする
比較器としての第1の演算増幅器OP1の他方の入
力、すなわち基準電圧Vrとして電位差計VRから
の分圧出力を印加する。 Then, the divided voltage output from the potentiometer VR is applied to the other input of the first operational amplifier OP1 as a comparator, which receives the luminance detection signal VS as one input, that is, as the reference voltage Vr.
また、上述の電圧安定化回路に並列に第4の抵
抗R4と第5の抵抗R5との直列回路により電源電
圧V0を分圧し、その分圧出力V5を入力とするボ
ルテージホロワとしての第2の演算増幅器OP2を
設け、この第2の演算増幅器OP2と第1の演算増
幅器OP1の各出力端子12,13間に得られる出
力電圧信号Voutによつてレンズの絞りを駆動す
る。 In addition, a voltage follower that divides the power supply voltage V 0 by a series circuit of a fourth resistor R 4 and a fifth resistor R 5 in parallel with the voltage stabilizing circuit described above, and receives the divided voltage output V 5 as an input. A second operational amplifier OP 2 is provided, and the aperture of the lens is controlled by the output voltage signal Vout obtained between the output terminals 12 and 13 of the second operational amplifier OP 2 and the first operational amplifier OP 1 . Drive.
ここで、第1〜第5の抵抗R1〜R5及び電位差
計VRの抵抗値を、それぞれR1,R2,R3,R4,
R5,VRとすると、
R2×R4=R1×R5
となるように、且つR1+R2に比べてVR+R3の抵
抗値が大きくなるように、各抵抗値を設定する。 Here, the resistance values of the first to fifth resistors R 1 to R 5 and the potentiometer VR are respectively R 1 , R 2 , R 3 , R 4 ,
Assuming R 5 and VR, each resistance value is set so that R 2 ×R 4 =R 1 ×R 5 and the resistance value of VR + R 3 is larger than that of R 1 +R 2 .
そして、電源電圧をV0、ツエナーダイオード
のカソード側の電圧をV1、アノード側の電圧を
V2、ツエナー電圧をVZD、出力電圧をVoutとし
て、VS=0の時の出力電圧Voutの電位差計VR
による調整範囲を求めると、次のようになる。 Then, the power supply voltage is V 0 , the voltage on the cathode side of the Zener diode is V 1 , and the voltage on the anode side is
V 2 , Zener voltage is VZD, output voltage is Vout, potentiometer VR of output voltage Vout when VS = 0
The adjustment range is calculated as follows.
Vout=(V1−V0×R5/R4+R5)〜(V2+VZD×R3/VR
+R3−V0×R5/R4+R5)=〔VZD+(V0−VZDQ
×R2/R1+R2−V0×R5/R4+R5〕〜〔(V0−VZD)
×R2/R1+R2+VZD×R3/VR+R3−V0×R5R4+R5〕
ここで、R1=nR2,R4=nR5とすると、
Vout=〔VZD+(V0−VZD)×R2/(n+1)R2−V0×
R5/(n+1)R5〕〜〔(V0−VZD)
×R2/(n+1)R2+VZD×R3/VR+R3−V0×R5/
(n+1)R5〕=(n×VZD/n+1)〜(VZD×R3/VR
+R3−VZD/n+1)
となり、出力電圧Voutの可変範囲は、電源電圧
V0の変化係わらず一定になる。 Vout=(V 1 −V 0 ×R 5 /R 4 +R 5 ) ~ (V 2 +VZD×R 3 /VR
+R 3 −V 0 ×R 5 /R 4 +R 5 ) = [VZD+(V 0 −VZDQ ×R 2 /R 1 +R 2 −V 0 ×R 5 /R 4 +R 5 )] ~ [(V 0 −VZD)
×R 2 /R 1 +R 2 +VZD×R 3 /VR+R 3 −V 0 ×R 5 R 4 +R 5 ] Here, if R 1 = nR 2 , R 4 = nR 5 , then Vout = −VZD)×R 2 /(n+1)R 2 −V 0 ×
R 5 / (n+1) R 5 ] ~ [(V 0 −VZD) ×R 2 / (n+1) R 2 +VZD×R 3 /VR+R 3 −V 0 ×R 5 /
(n+1)R 5 ] = (n×VZD/n+1) ~ (VZD×R 3 /VR
+R 3 -VZD/n+1), and the variable range of the output voltage Vout is the power supply voltage.
It remains constant regardless of changes in V 0 .
たとえば、n=1(R1=R2,R4=R5),VR=
2×R3とすると、
Vout=(VZD/2)〜(−VZD/6)
となり、ツエナー電圧の1/2から−1/6まで変化
し、−VZD/6よりオフセツト調整分をとること
ができる。 For example, n=1 (R 1 = R 2 , R 4 = R 5 ), VR=
If 2×R 3 , Vout = (VZD/2) to (-VZD/6), which varies from 1/2 to -1/6 of the Zener voltage, and it is possible to take the offset adjustment from -VZD/6. can.
なお、ここで正負の極性はV0/2を基準点
(0レベル)としている。 Note that the positive and negative polarities here have V 0 /2 as the reference point (0 level).
第3図は、この考案の応用例を示し、第2図の
実施例を一部変更したもので、電位差計VRのア
ース側を第3の抵抗R3を介して電源のアース側
端子11に接続し、この電位差計VRと第3の抵
抗R3との接続点と第2の演算増幅OP2の出力端子
13との間にダイオードDを順方向に接続してい
る。 FIG . 3 shows an example of application of this invention, which is a partially modified version of the embodiment shown in FIG. A diode D is connected in the forward direction between the connection point between the potentiometer VR and the third resistor R3 and the output terminal 13 of the second operational amplifier OP2 .
そして、この例では、第2図の実施例における
各抵抗及び電位差計の抵抗値に関する条件に加え
て、第2の抵抗R3に比べて電位差計VRは抵抗値
の大きいものを使う。 In this example, in addition to the conditions regarding the resistance values of each resistor and potentiometer in the embodiment of FIG. 2, a potentiometer VR having a larger resistance value than the second resistor R3 is used.
そして、ダイオードDの順方向電圧をVDと
し、前述の場合と同様にVS=0の時の出力電圧
Voutの調整範囲を求めると、次のようになる。 Then, let the forward voltage of diode D be VD, and as in the previous case, the output voltage when VS = 0
The adjustment range for Vout is determined as follows.
Vout=(V1−V0×R5/R4+R5)〜〔(V0×R5/R4+R5
−VD)−V0×R5/R4+R5〕
=〔VZD+(V0−VZD)×R2/R1+R2−V0×R5/R4+
R5〕〜(−VD)
ここで、R1=nR2,R4=nR5とすると、
Vout= 〔VZD+(V0−VZD)×1/(n+1)−V0/
(n+1)〕〜(−VD) =(nVZD/n+1)〜(−VD
)
となり、Voutの可変範囲は電源電圧V0の変化に
係わらず一定になる。また、−VDによりオフセ
ツト調整分をとることができる。 Vout=(V 1 −V 0 ×R 5 /R 4 +R 5 ) ~ [(V 0 ×R 5 /R 4 +R 5
−VD) −V 0 ×R 5 /R 4 +R 5 ] = [VZD + (V 0 −VZD) × R 2 /R 1 +R 2 −V 0 ×R 5 /R 4 +
R 5 ] ~ (-VD) Here, if R 1 = nR 2 , R 4 = nR 5 , Vout = [VZD + (V 0 - VZD) x 1/(n+1) - V 0 /
(n+1)] ~ (-VD) = (nVZD/n+1) ~ (-VD
), and the variable range of Vout remains constant regardless of changes in the power supply voltage V0 . Also, -VD can be used to compensate for offset adjustment.
なお、これらの計算は近似計算であるが、実際
の使用において、その誤差は無視できる程度であ
る。 Note that although these calculations are approximate calculations, the errors thereof are negligible in actual use.
効 果
以上説明してきたように、この考案によるテレ
ビカメラ用レンズの自動絞り制御回路は、絞り制
御用信号のレベル調整範囲が電源電圧の変動に係
わらず一定になるので、常に設定した目標絞り値
になるように正確に制御することができ、しか
も、その調整範囲が広く、演算増幅器に対するオ
フセツト調整をも兼ねることができるので、回路
構成が簡単で安価に供給できる。Effects As explained above, in the automatic aperture control circuit for television camera lenses according to this invention, the level adjustment range of the aperture control signal remains constant regardless of fluctuations in the power supply voltage, so the set target aperture value is always maintained. It can be accurately controlled so as to have a wide adjustment range, and can also be used as offset adjustment for the operational amplifier, so the circuit configuration is simple and can be supplied at low cost.
第1図は、この考案を適用するテレビ用カメラ
の自動絞り制御回路の概略構成図、第2図は、こ
の考案の実施例を示す回路図、第3図は、この考
案の応用例を示す回路である。
10,11……電源電圧供給端子、12,13
……出力端子、R1……第1の抵抗、R2……第2
の抵抗、R3……第3の抵抗、R4……第4の抵抗、
R5……第5の抵抗、VR……電位差計、ZD……
ツエナーダイオード、OP1……第1の演算増幅
器、OP2……第2の演算増幅器。
Fig. 1 is a schematic configuration diagram of an automatic aperture control circuit for a television camera to which this invention is applied, Fig. 2 is a circuit diagram showing an embodiment of this invention, and Fig. 3 is an example of application of this invention. It is a circuit. 10, 11... Power supply voltage supply terminal, 12, 13
...output terminal, R1 ...first resistor, R2 ...second
resistance, R 3 ... third resistance, R 4 ... fourth resistance,
R 5 ...Fifth resistor, VR...Potentiometer, ZD...
Zener diode, OP1 ...first operational amplifier, OP2 ...second operational amplifier.
Claims (1)
の抵抗と第2の抵抗との間にツエナーダイオード
を介挿して直列に接続した電圧安定化回路と、該
電圧安定化回路のツエナーダイオードに並列に接
続した目標絞り値に応じて可調整される電位差計
と第3の抵抗との直列回路と、テレビカメラから
のビデオ信号に基く輝度検出信号を一方の入力と
し、前記電位差計からの分圧出力をもう一方の入
力とする比較器としての第1の演算増幅器と、前
記電圧安定化回路に並列に接続した第4の抵抗と
第5の抵抗との直列回路と、この第4の抵抗と第
5の抵抗の接続点の電圧を入力するボルテージホ
ロワとしての第2の演算増幅器と、この第2の演
算増幅器の出力端子と前記第1の演算増幅器の出
力端子との間に得られる出力電圧信号によつてレ
ンズの絞りを駆動制御するようにすると共に、前
記第2、第4の抵抗の抵抗値の積と第1、第5の
抵抗の抵抗値の積が等しく、且つ前記第1、第2
の抵抗の抵抗値の和より前記電位差計と第3の抵
抗の抵抗値の和の方が大きくなるように前記各抵
抗及び電位差計の抵抗値を設定したことを特徴と
するテレビカメラ用レンズの自動絞り制御回路。 Connect the first terminal between the power supply voltage supply terminals from the TV camera.
A voltage stabilizing circuit is connected in series with a Zener diode inserted between the resistor and the second resistor, and the voltage stabilizing circuit is connected in parallel to the Zener diode of the voltage stabilizing circuit and is adjustable according to the target aperture value. A series circuit of a potentiometer and a third resistor, and a comparator having one input as a luminance detection signal based on a video signal from a television camera and the other input as a divided voltage output from the potentiometer. 1 operational amplifier, a series circuit of a fourth resistor and a fifth resistor connected in parallel to the voltage stabilizing circuit, and a voltage for inputting the voltage at the connection point of the fourth resistor and the fifth resistor. A second operational amplifier as a follower, and an output voltage signal obtained between the output terminal of the second operational amplifier and the output terminal of the first operational amplifier to drive and control the aperture of the lens. and the product of the resistance values of the second and fourth resistors is equal to the product of the resistance values of the first and fifth resistors, and
A television camera lens characterized in that the resistance values of each of the resistors and the potentiometer are set so that the sum of the resistance values of the potentiometer and the third resistor is greater than the sum of the resistance values of the resistors. Automatic aperture control circuit.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19728883U JPS60108071U (en) | 1983-12-23 | 1983-12-23 | Automatic aperture control circuit for TV camera lenses |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19728883U JPS60108071U (en) | 1983-12-23 | 1983-12-23 | Automatic aperture control circuit for TV camera lenses |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS60108071U JPS60108071U (en) | 1985-07-23 |
JPH036068Y2 true JPH036068Y2 (en) | 1991-02-15 |
Family
ID=30755493
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP19728883U Granted JPS60108071U (en) | 1983-12-23 | 1983-12-23 | Automatic aperture control circuit for TV camera lenses |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS60108071U (en) |
-
1983
- 1983-12-23 JP JP19728883U patent/JPS60108071U/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS60108071U (en) | 1985-07-23 |
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