JPH0619492B2 - Automatic focusing device - Google Patents

Automatic focusing device

Info

Publication number
JPH0619492B2
JPH0619492B2 JP58235348A JP23534883A JPH0619492B2 JP H0619492 B2 JPH0619492 B2 JP H0619492B2 JP 58235348 A JP58235348 A JP 58235348A JP 23534883 A JP23534883 A JP 23534883A JP H0619492 B2 JPH0619492 B2 JP H0619492B2
Authority
JP
Japan
Prior art keywords
frequency component
lens
detection circuit
frequency
maximum
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 - Lifetime
Application number
JP58235348A
Other languages
Japanese (ja)
Other versions
JPS60126612A (en
Inventor
秀夫 豊田
正己 大西
好徳 北村
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP58235348A priority Critical patent/JPH0619492B2/en
Publication of JPS60126612A publication Critical patent/JPS60126612A/en
Publication of JPH0619492B2 publication Critical patent/JPH0619492B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/28—Systems for automatic generation of focusing signals
    • G02B7/36—Systems for automatic generation of focusing signals using image sharpness techniques, e.g. image processing techniques for generating autofocus signals

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Automatic Focus Adjustment (AREA)

Description

【発明の詳細な説明】 産業上の利用分野 本発明はビデオカメラの撮像素子より得た電気信号の高
域周波数成分を検出し、前記高域周波数成分の振幅が最
大になる様にレンズの焦点整合装置を駆動する自動焦点
整合装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a high frequency component of an electric signal obtained from an image sensor of a video camera, and focuses a lens so that the amplitude of the high frequency component is maximized. The present invention relates to an automatic focus alignment device that drives an alignment device.

従来例の構成とその問題点 近年、ビデオカメラはポータブルビデオテープレコーダ
ーと伴にその需要が急速に伸びている。自動焦点整合装
置はビデオカメラの取扱いを簡便にし、より一層の普及
に貢献するものである。Configuration of Conventional Example and its Problems In recent years, the demand for video cameras has been rapidly increasing along with portable video tape recorders. The automatic focusing device facilitates the handling of the video camera and contributes to its further spread.

従来の自動焦点整合装置の一例として赤外線を被写体に
受けて発射し、被写体より反射した赤外線を受光し、前
記受光角度より被写体までの距離を測定し、前記測定距
離に応じてレンズの焦点整合装置を所定の位置に駆動す
るものがある。前記方式は、被写体までの距離を正確に
測定し、前記測定結果に応じてレンズの焦点整合装置を
所定の位置に駆動するためには高い組立精度が必要であ
った。また被写体に発射し反射した赤外線を受光するた
めに、遠い被写体は不得手であり、また消費電力も少な
くなかった。As an example of a conventional automatic focus adjusting device, infrared rays are received by a subject and emitted, and infrared rays reflected from the subject are received, and the distance to the subject is measured from the light receiving angle, and a focus adjusting device for a lens according to the measured distance. There are those that drive the to a predetermined position. The above method requires high assembly accuracy in order to accurately measure the distance to the subject and drive the lens focus matching device to a predetermined position according to the measurement result. In addition, since it receives infrared rays that are emitted to and reflected from a subject, it is not good for distant subjects, and power consumption is not small.

自動焦点整合装置の他の方式として、撮像素子の撮像面
に受光している被写体像を、周期的光学的にボカし、前
記ボケを検出し、前記ボケの振幅と位相により撮像素子
より得られる信号の高域周波数成分が最大になる様に、
レンズの焦点整合装置を駆動するものがある。前記方式
は、撮像素子より得られる信号そのものを利用し、レン
ズの焦点整合装置を含めてクローズドループを形成して
おり、高い組立精度を必要とせず、被写体までの距離を
影響を受けることなく、また消費電力も少ない。As another method of the automatic focusing device, the subject image received on the image pickup surface of the image pickup device is periodically optically blurred, the blur is detected, and the image is obtained from the image pickup device by the amplitude and phase of the blur. To maximize the high frequency components of the signal,
Some drive the lens focus matching device. The method uses the signal itself obtained from the image sensor, forms a closed loop including the lens focus matching device, does not require high assembly accuracy, and is not affected by the distance to the subject, It also consumes less power.

以下に従来の前述した方式の自動焦点整合装置について
説明する。The conventional automatic focusing device of the above-mentioned method will be described below.

第１図は従来の自動焦点整合装置のブロック図の一例を
示すものであり、１はレンズ、２は撮像面に結像してい
る被写体の光学情報を電気信号に変換する撮像素子、３
は撮像素子２より得た電気信号を増幅する前置増幅器、
４は前置増幅器の出力信号に種々の処理を加え、テレビ
ジョン信号にするプロセス回路、５はプロセス回路４や
撮像素子駆動回路６に同期信号やブランキング信号等を
供給する同期信号発生器である。７は撮像素子より得た
電気信号の高域周波数成分を検出する高域周波数成分検
出回路で、例えば中心周波数１ＭHzのバンドパスフィル
タである。８は前記高域周波数成分より基準周波数成分
を検出する基準周波数成分検出回路である。９は基準周
波数発生器で、基準周波数を同期検波回路１０に供給す
るとともに、モータ駆動回路１１に供給し、レンズ１の
焦点整合装置をモータ１２で基準周波数で微変動させ、
レンズ１のフォーカスを目に検知できない程度に変化さ
せ、前記変化によって高域周波数成分に含まれる基準周
波数成分を高域周波数検出回路７、基準周波数成分検出
回路８で検出し、前記基準周波数成分の振幅と位相を基
準周波数によって同期検波回路１０で検出し、前記検出
信号をモータ駆動回路１１に加え、撮像素子２より得ら
れる電気信号の高域周波数成分が最大になる様にモータ
１２を駆動する。FIG. 1 shows an example of a block diagram of a conventional automatic focusing device, in which 1 is a lens, 2 is an image pickup device for converting optical information of a subject imaged on an image pickup surface into an electric signal, 3
Is a preamplifier for amplifying the electric signal obtained from the image pickup device 2,
Reference numeral 4 is a process circuit for adding various processing to the output signal of the preamplifier to convert it into a television signal, and 5 is a synchronization signal generator for supplying a synchronization signal, a blanking signal, etc. to the process circuit 4 and the image pickup element drive circuit 6. is there. Reference numeral 7 is a high-frequency component detecting circuit for detecting a high-frequency component of an electric signal obtained from the image pickup device, which is, for example, a bandpass filter having a center frequency of 1 MHz. Reference numeral 8 is a reference frequency component detection circuit for detecting a reference frequency component from the high frequency component. Reference numeral 9 is a reference frequency generator, which supplies the reference frequency to the synchronous detection circuit 10 and the motor drive circuit 11, and causes the motor 12 to finely change the focus matching device of the lens 1 at the reference frequency.
The focus of the lens 1 is changed to such an extent that it cannot be detected by the eyes, and the reference frequency component included in the high frequency component is detected by the high frequency detection circuit 7 and the reference frequency component detection circuit 8 by the change, and the reference frequency component The amplitude and the phase are detected by the synchronous detection circuit 10 by the reference frequency, the detection signal is added to the motor drive circuit 11, and the motor 12 is driven so that the high frequency component of the electric signal obtained from the image pickup device 2 is maximized. .

以上のように構成された従来の自動焦点整合装置につい
て、以下その動作について第２図を用いて説明する。The operation of the conventional automatic focus adjusting device configured as described above will be described below with reference to FIG.

第２図において横軸はレンズ１の焦点整合装置の位置を
示しており、近は近距離の被写体に焦点が合う位置であ
り、遠は遠距離の被写体に焦点が合う位置である。縦軸
は高域周波数成分を示している。いま、被写体までの距
離がＤとする。レンズ１の焦点整合装置が前記距離Ｄに
対応した位置Ｄ１にある時、焦点が整合し撮像素子２よ
り得られる電気信号の高域周波数成分は最大となり、前
記位置Ｄ１より近距離側、遠距離側のいずれにずれても
減少する山型特性となり第２図に示す様になる。ａ１，
ａ２はモータの基準周波数での微変動により焦点整合装
置の動きを示している。ａ１はレンズの焦点整合装置が
Ｄ１より近距離側にある場合のモータの微変動を示して
おり、この時高域周波数成分は前記微変動によるフォー
カス変化によってｂ１のような振幅変調を受ける。ａ２
はＤ１より遠距離側にある場合で、この時高域周波数成
分はｂ２のような振幅変調を受ける。前記ｂ１，ｂ２の
振幅変調は第２図から明らかな様にレンズ１の焦点整合
位置が合焦点より近距離側にあるか遠距離側にあるかに
よって位相が反転する。従ってｂ１の信号を基準周波数
信号で同期検波し、前記同期検波した信号でモータ１２
を矢印Ｃ１の方向に駆動するなら、ｂ２の信号では矢印
ｃ２の方向に駆動されることになり、常に高域周波数成
分が最大になる点で安定することになる。In FIG. 2, the horizontal axis indicates the position of the focus matching device of the lens 1, where the near is the position where a short-distance subject is focused, and the far is the position where a long-distance subject is focused. The vertical axis represents the high frequency components. Now, assume that the distance to the subject is D. When the focus matching device of the lens 1 is at the position D 1 corresponding to the distance D, the focus is matched and the high frequency component of the electric signal obtained from the image pickup element 2 becomes the maximum, and the short distance side from the position D 1 . As shown in FIG. 2, the mountain-shaped characteristic is reduced even if the distance is shifted to the far side. a 1 ,
Reference symbol a 2 indicates the movement of the focusing device due to a slight change in the reference frequency of the motor. a 1 indicates a slight fluctuation of the motor when the focus adjusting device of the lens is located closer to the lens than D 1. At this time, the high frequency component is amplitude-modulated like b 1 by the focus change due to the slight fluctuation. receive. a 2
Is on the far side of D 1 , and the high frequency component is subjected to amplitude modulation like b 2 at this time. As is clear from FIG. 2, the amplitude modulation of b 1 and b 2 is inverted in phase depending on whether the focus matching position of the lens 1 is on the near distance side or the far distance side of the in-focus point. Therefore, the signal of b 1 is synchronously detected by the reference frequency signal, and the motor 12 is synchronously detected by the synchronously detected signal.
If is driven in the direction of arrow C 1 , the signal of b 2 is driven in the direction of arrow c 2 , and it is stable in that the high frequency component always becomes maximum.

しかしながら上記のような構成では、レンズの焦点整合
装置を含めてクローズドループを形成でき焦点整合装置
の精度を要求しないなどの特徴を有するが、次の様な問
題点を有していた。However, the above-mentioned configuration has a feature that a closed loop can be formed including the focus adjusting device of the lens and the accuracy of the focus adjusting device is not required, but it has the following problems.

いま、光学レンズの焦点整合状態と空間周波数レスポン
スの関係について考える。点光源より発せられた光はレ
ンズによって焦点面で一点に集められるが、焦点面と撮
像素子の撮像面がずれている場合、第３図に示すように
等照度の半径ｒの円すなわち円形アパーチャが撮像面上
にできる。前記円形アパーチャを撮像素子によって第３
図に示す方向の一次元走査を行なった時に得られる空間
周波数に対するレスポンスは第４図のようになる。この
様に光学レンズは空間周波数に対するローパスフィルタ
となり、円形アパーチャの半径ｒに反比例して帯域幅が
変化する。しかしながら、そのレスポンスは、空間周波
数に対して一様に減少するものでなく、いくつかの零点
をもっている。一方、前述したように、光学レンズ系は
一種のローパスフィルタと考えられ、焦点整合状態によ
って一定距離の被写体に対してその帯域幅が変化するか
ら、しゃ断周波数付近の撮像素子２より得られる電気信
号の高域周波数成分の振幅が変化する。本実施例の方式
は、レンズの焦点整合装置をモータ１２で基準周波数で
微変動させることにより、円形アパーチャの半径を変化
させ、前述した高域周波数成分の変化を高域周波数成分
検出回路７、基準周波数成分検出回路８で得て、焦点整
合動作させている。ところが、前述した様に光学レンズ
系のアパーチャレスポンスは単調減少でなく、いくつか
の零点をもっている。従って、例えば高域周波数成分検
出回路７のバンドパスフィルタのレスポンス(1)の様な
場合、高域周波数成分検出回路７より得た信号振幅は、
第５図ａに示す様に円形アパーチャの半径の減少（ｒ１
−ｒ２）に対して単調に増加するが、レスポンス(2)の
場合、単調に変化せず、合焦点とは別の所に極大点また
は極小点をもつことになる。よって、極大点を境にし
て、第５図に示すようにモータの微変動による高域周波
数成分の変化の位相が、合焦点を境にした場合と同じ様
に位相が反転し、焦点整合装置は前記極大点で安定して
しまい、完全な誤動作を起こすという問題点を有してい
た。前記円形アパーチャレスポンスの零点は、円形アパ
ーチャ半径ｒによって移動し、バンドパスフィルタの中
心周波数がどの位置にあっても同様な誤動作を引起こす
ものである。Now, let us consider the relationship between the focus matching state of the optical lens and the spatial frequency response. The light emitted from the point light source is collected at one point on the focal plane by the lens. However, when the focal plane and the image pickup surface of the image pickup device are deviated, as shown in FIG. Can be on the imaging surface. The circular aperture is thirdly
The response to the spatial frequency obtained when the one-dimensional scanning in the direction shown in the figure is performed is as shown in FIG. In this way, the optical lens functions as a low-pass filter for the spatial frequency, and the bandwidth changes in inverse proportion to the radius r of the circular aperture. However, the response does not decrease uniformly with respect to the spatial frequency and has some zeros. On the other hand, as described above, the optical lens system is considered as a kind of low-pass filter, and its bandwidth changes for a subject at a certain distance depending on the focus matching state. Therefore, an electric signal obtained from the image sensor 2 near the cutoff frequency is obtained. The amplitude of the high frequency component of changes. In the method of this embodiment, the radius of the circular aperture is changed by finely changing the lens focus matching device by the motor 12 at the reference frequency, and the above-mentioned change of the high frequency component is detected by the high frequency component detecting circuit 7. It is obtained by the reference frequency component detection circuit 8 and the focus matching operation is performed. However, as described above, the aperture response of the optical lens system does not monotonically decrease, but has some zero points. Therefore, for example, in the case of the response (1) of the bandpass filter of the high frequency component detecting circuit 7, the signal amplitude obtained from the high frequency component detecting circuit 7 is
As shown in FIG. 5a, the radius of the circular aperture is reduced (r 1
It increases monotonically with respect to −r 2 ) but in the case of response (2), it does not monotonically change, and has a maximum point or a minimum point at a place different from the focal point. Therefore, as shown in FIG. 5, the phase of the change of the high frequency component due to the slight change of the motor is inverted at the maximum point as a boundary, and the phase is inverted in the same manner as when the in-focus point is set as a boundary, and the focus matching device is provided. Has a problem that it becomes stable at the maximum point and causes a complete malfunction. The zero point of the circular aperture response moves due to the circular aperture radius r, and causes the same malfunction regardless of the position of the center frequency of the bandpass filter.

発明の目的 本発明は上記従来の問題点を解消するもので、ビデオカ
メラの撮像素子より得た電気信号の高域周波数成分を検
出し、前記高域周波数成分の振幅が最大になる様にレン
ズの焦点整合装置を駆動するシステムにおいて、前述し
た光学系レンズのもつレスポンスによる誤動作をしない
自動焦点整合装置を提供することを目的とする。An object of the present invention is to solve the above-mentioned conventional problems, and to detect a high frequency component of an electric signal obtained from an image pickup device of a video camera, a lens so that the amplitude of the high frequency component becomes maximum. It is an object of the present invention to provide an automatic focus matching device that does not malfunction due to the response of the above-mentioned optical system lens in the system for driving the focus matching device.

発明の構成 本発明は、撮像面に結像している被写体の光学的情報を
電気信号に変換する撮像素子より前記電気信号を得、前
記電気信号より複数の異なる周波数帯域を有する周波数
成分を検出し、前記複数の周波数成分のうち少なくとも
１つが増加する方向にレンズ焦点整合装置を駆動し、前
記複数の周波数成分のうち少なくとも１つが極大に達し
ても、他の周波数成分のうち少なくとも１つが増加する
なら、増加する方向にレンズ焦点整合装置を駆動し、前
記複数の周波数成分の振幅が最大となる様に前記レンズ
の焦点整合装置を駆動するシステムを構成する自動焦点
整合装置であり、複数の異なる周波数帯域を有する周波
数成分を検出することにより、光学系レンズのレスポン
スがもつ零点により、合焦点以外に極大点があっても前
述した様な誤動作を防止できるものである。例えば第５
図に示すように高域周波数成分検出回路のレスポンスが
第４図の(2)の形で、円形アパーチャの半径がｒ１の位
置で極大となり誤動作の原因となっても、この時第４図
(1)のレスポンスによる第５図ａに示す高域周波数成分
の変化は単調であり誤動作を起こさない。すなわち、検
出する周波数帯域の異なる周波数成分は、同一の焦点整
合状態、円形アパーチャの半径で、極大点をもつことは
ない。従って、複数の異なる周波数帯域を有する周波数
成分を検出することによって、誤動作を防止できるもの
である。According to the present invention, the electric signal is obtained from an image pickup device that converts optical information of a subject imaged on an image pickup surface into an electric signal, and a frequency component having a plurality of different frequency bands is detected from the electric signal. Then, the lens focus matching device is driven in a direction in which at least one of the plurality of frequency components increases, and at least one of the other frequency components increases even if at least one of the plurality of frequency components reaches the maximum. If so, it is an automatic focus matching device that configures a system that drives the lens focus matching device in an increasing direction and drives the lens focus matching device such that the amplitudes of the plurality of frequency components are maximized. By detecting the frequency components having different frequency bands, the zero point that the response of the optical system lens has, even if there is a maximum point other than the in-focus point, Such a malfunction can be prevented. For example, the fifth
As shown in the figure, the response of the high frequency component detection circuit is in the form of (2) in Fig. 4, and even if the radius of the circular aperture becomes maximum at the position of r 1 and it causes a malfunction, at this time
The change in the high frequency component shown in FIG. 5a due to the response (1) is monotonous and does not cause a malfunction. That is, frequency components of different frequency bands to be detected do not have a maximum point with the same focus matching state and radius of the circular aperture. Therefore, malfunction can be prevented by detecting frequency components having a plurality of different frequency bands.

実施例の説明 第６図は本発明の第１の実施例における自動焦点整合装
置のブロック図を示すものである。第６図において１
３，１４は異なる周波数帯域を有する周波数成分検出回
路で、例えば第４図で示したバンドパスフィルタ(1),
(2)である。１５，１６は前記周波数成分検出回路１
３，１４の出力信号に含まれる基準周波数成分を検出す
る基準周波数検出回路である。１７は基準周波数成分検
出回路１５，１６の出力信号を切換え同期検波回路１０
に供給するものである。周波数成分検出回路１４は周波
数成分検出回路１３に比べ検出周波数が高く、第５図
(b)に示す様に合焦精度が高いため、通常切換回路１７
は基準周波数成分検出回路１６を選択している。１８，
１９は基準周波数成分のレベル（振幅）を検出するレベ
ル検出回路で、例えば前記レベルとある基準値を比較し
て大小関係を出力するものである。２０は前記レベル検
出回路１８，１９の出力をもとに切換回路の選択を制御
するものである。Description of Embodiments FIG. 6 is a block diagram of an automatic focusing device according to a first embodiment of the present invention. 1 in FIG.
Reference numerals 3 and 14 denote frequency component detection circuits having different frequency bands, for example, the bandpass filter (1) shown in FIG.
It is (2). Reference numerals 15 and 16 denote the frequency component detection circuit 1
3 is a reference frequency detection circuit for detecting a reference frequency component included in the output signals of 3 and 14. Reference numeral 17 is a synchronous detection circuit 10 for switching the output signals of the reference frequency component detection circuits 15 and 16.
Is to be supplied to. The frequency component detection circuit 14 has a higher detection frequency than the frequency component detection circuit 13,
Since the focusing accuracy is high as shown in (b), the normal switching circuit 17
Selects the reference frequency component detection circuit 16. 18,
Reference numeral 19 is a level detection circuit for detecting the level (amplitude) of the reference frequency component, which outputs a magnitude relation by comparing the level with a reference value, for example. Reference numeral 20 controls the selection of the switching circuit based on the outputs of the level detection circuits 18 and 19.

以上のように構成された本実施例の自動焦点整合装置に
ついて、以下その動作を説明する。The operation of the automatic focusing device of this embodiment constructed as described above will be described below.

いま、焦点が外れて円形アパーチャの半径がr1より大き
い時を考える。この時モータ１２の微変動による周波数
成分検出回路１４の変化は、第５図(b)のｂ３のように
なり、モータ１２はｃ３の方向に動く。ところが、円形
アパーチャの半径がr1になった時点で周波数成分検出回
路１４の出力は極大になり基準周波数成分の振幅が小さ
くなり、モータ１２は半径ｒ１の点で安定しようとす
る。レベル検出回路１９は前記基準周波数成分の振幅の
変化を検出し、制御回路２０に伝達する。一方周波数成
分検出回路１３は、円形アパーチャの半径ｒ１の点での
変化は第５図ａに示すように単調であり基準周波数成分
の振幅は小さくなく、そのことがレベル検出回路１８に
よって制御回路２０に伝達される。合焦点では、どちら
の周波数成分も極大に達し基準周波数成分の振幅は小さ
くなり、モータ１２が安定するから、前記の様な状態
は、円形アパーチャのレスポンスがもつ零点による誤動
作状態であることが容易に検出できる。制御回路２０は
切換回路１７の選択が基準周波数成分検出回路１５とな
る様にし、モータ１２は引き続きｃ３の方向に動き合焦
点に達する。基準周波数成分検出回路１５の振幅は小さ
くなり、前記変化はレベル検出回路１８によって制御回
路２０に伝達される。制御回路２０は、合焦精度の高い
基準周波数成分検出回路１６を再び選択する様に切換回
路１７を制御する。Now consider the case where the radius of the circular aperture is out of focus and larger than r 1 . At this time, the change of the frequency component detection circuit 14 due to the slight change of the motor 12 becomes as shown by b 3 in FIG. 5B, and the motor 12 moves in the direction of c 3 . However, when the radius of the circular aperture becomes r 1 , the output of the frequency component detection circuit 14 becomes maximum and the amplitude of the reference frequency component becomes small, so that the motor 12 tries to stabilize at the radius r 1 . The level detection circuit 19 detects a change in the amplitude of the reference frequency component and transmits it to the control circuit 20. On the other hand, in the frequency component detection circuit 13, the change in the radius r 1 of the circular aperture is monotonous as shown in FIG. 5A, and the amplitude of the reference frequency component is not small, which means that the level detection circuit 18 controls the control circuit. 20 is transmitted. At the in-focus point, both frequency components reach their maximums, the amplitude of the reference frequency component becomes small, and the motor 12 stabilizes. Therefore, it is easy for the above-mentioned state to be a malfunction due to the zero point of the response of the circular aperture. Can be detected. The control circuit 20 makes the selection of the switching circuit 17 the reference frequency component detection circuit 15, and the motor 12 continues to move in the direction of c 3 to reach the in-focus point. The amplitude of the reference frequency component detection circuit 15 becomes small, and the change is transmitted to the control circuit 20 by the level detection circuit 18. The control circuit 20 controls the switching circuit 17 so as to select the reference frequency component detection circuit 16 having a high focusing accuracy again.

以上のように本実施例によれば、２つの周波数帯域の異
なる周波数成分を検出し、前記各周波数成文の基準周波
数成分の振幅を検出することにより、円形アパーチャの
レスポンスがもつ零点による誤動作状態であることが容
易に検出でき、現在誤動を起こしている周波数成分とは
異なる周波数成分を選択することによって誤動作を防止
することができる。As described above, according to the present embodiment, by detecting frequency components of two frequency bands different from each other and detecting the amplitude of the reference frequency component of each frequency sentence, a malfunction due to the zero point of the response of the circular aperture is obtained. It is possible to easily detect that there is something, and it is possible to prevent malfunction by selecting a frequency component different from the frequency component that is currently malfunctioning.

以下に本発明の第２の実施例について、図面を参照しな
がら説明する。A second embodiment of the present invention will be described below with reference to the drawings.

第７図は本発明の第２の実施例を示す自動焦点整合装置
のブロック図である。FIG. 7 is a block diagram of an automatic focusing device showing a second embodiment of the present invention.

同図において、２１は周波数成分検出回路１４の出力信
号を直流成分に変換する検波回路、２２は前記検波回路
２２の出力信号のレベル（振幅）を検出するレベル検出
回路で、例えばある基準値と比較しその大小関係を出力
する。２３はレベル検出回路１８，２２の出力をもとに
切換回路１７を制御する制御回路である。In the figure, 21 is a detection circuit for converting the output signal of the frequency component detection circuit 14 into a DC component, and 22 is a level detection circuit for detecting the level (amplitude) of the output signal of the detection circuit 22, for example, a certain reference value. It compares and outputs the magnitude relation. A control circuit 23 controls the switching circuit 17 based on the outputs of the level detection circuits 18 and 22.

上記のように構成された第２の実施例の自動焦点整合装
置について、以下その動作を説明する。The operation of the automatic focusing device of the second embodiment constructed as described above will be described below.

円形アパーチャのレスポンスがもつ零点による極大は、
ある程度焦点外れの状態であり、例えば第５図ｂの場合
周波数成分の振幅は基準値Ｖｂより小さい。本実施例
は、検波回路２１、レベル検出回路２２によって、周波
数成分検出回路１４の出力信号の振幅が基準値Ｖｂより
小さいことを検出し、その時は制御回路２３によって切
換回路１７は基準周波数成分検出回路１５の出力信号を
選択する。前記選択によって、極大点による誤動作する
ことなくモータ１２は合焦する方向に動く。やがて周波
数成分検出回路１４の出力は、基準値Ｖｂを超え、その
事は検波回路２１、レベル検出回路２２によって検出、
制御回路２３に伝達され、合焦精度の高い基準周波数成
分検出回路１６の出力が選ばれる。また、例えば被写体
がコントラストのないもので、合焦時にも周波数成分検
出回路１４の出力信号の振幅が基準値Ｖｂに達しない場
合でも、レベル検出回路１８によって基準周波数成分検
出回路１５の出力信号の振幅変化を検出し、合焦によっ
て前記信号振幅が小さくなった時には合焦精度の高い基
準周波数成分検出回路１６を選択するようにしている。The maximum due to the zero point of the response of the circular aperture is
The state is out of focus to some extent, and for example, in the case of FIG. 5b, the amplitude of the frequency component is smaller than the reference value V b . In this embodiment, the detection circuit 21 and the level detection circuit 22 detect that the amplitude of the output signal of the frequency component detection circuit 14 is smaller than the reference value Vb , and at that time, the control circuit 23 causes the switching circuit 17 to change the reference frequency component. The output signal of the detection circuit 15 is selected. By the above selection, the motor 12 moves in the focusing direction without malfunction due to the maximum point. Eventually, the output of the frequency component detection circuit 14 exceeds the reference value V b , which is detected by the detection circuit 21 and the level detection circuit 22,
The output of the reference frequency component detection circuit 16 which is transmitted to the control circuit 23 and has high focusing accuracy is selected. In addition, for example, even when the subject has no contrast and the amplitude of the output signal of the frequency component detection circuit 14 does not reach the reference value Vb even during focusing, the level detection circuit 18 outputs the output signal of the reference frequency component detection circuit 15. Is detected, and the reference frequency component detection circuit 16 with high focusing accuracy is selected when the signal amplitude becomes small due to focusing.

以上のように、本実施例によれば、極大点をもつ低レベ
ルでは異なる周波数帯域をもつ周波数成分を選択するこ
とにより、第１の実施例と同じ効果をもつことができ
る。As described above, according to this embodiment, the same effect as that of the first embodiment can be obtained by selecting the frequency components having different frequency bands at the low level having the maximum point.

なお、本発明は撮像面に結像している被写体の光学的情
報を電気信号に変換する撮像素子より前記電気信号を
得、前記電気信号より高域周波数成分を検出し、前記高
域周波数成分が最大になるようにレンズの焦点整合装置
を駆動するものなら、どんなものにも適用できる。例え
ば単に高域周波数成分の増加する方向にレンズの焦点整
合装置を駆動し、最大となる所をさがす方式においても
同様な事が起こる。この場合も複数の異なる周波数帯域
を有する周波数成分を検出し、一つが極大に達しても、
他の周波数成分にまだ増加する方向があるなら、その方
向にレンズの焦点整合装置を駆動することによって誤動
作を防止できる。According to the present invention, the electric signal is obtained from an image pickup device that converts optical information of a subject imaged on an image pickup surface into an electric signal, a high frequency component is detected from the electric signal, and the high frequency component is detected. It can be applied to anything that drives the lens focusing device to maximize the. For example, the same thing occurs in a system in which the focus adjusting device of the lens is simply driven in the direction in which the high frequency component increases and the maximum position is searched. In this case also, the frequency components having a plurality of different frequency bands are detected, and even when one reaches the maximum,
If there is a direction in which the other frequency components are still increasing, the malfunction can be prevented by driving the focus adjusting device of the lens in that direction.

また、第１または第２の実施例において、極大点や合焦
点の検出を基準周波数成分のレベルによって行なった
が、極大点や合焦点の前後で基準周波数成分の位相が反
転することや、周波数成分の振幅が減少することを利用
したものでもよい。Further, in the first or second embodiment, the maximum point and the focal point are detected by the level of the reference frequency component. However, the phase of the reference frequency component is inverted before and after the maximum point and the focal point, and the frequency is changed. It is also possible to use the fact that the amplitude of the component is reduced.

また、第２の実施例においてレベル検出回路１８を設け
たが、必ずしも必要ではなく、被写体が低コントラスト
の場合それほど高い合焦精度が要求されないので基準周
波数成分検出回路１５を選択したままでもよい。Further, although the level detection circuit 18 is provided in the second embodiment, it is not always necessary, and if the subject has a low contrast, a high focusing accuracy is not required, so the reference frequency component detection circuit 15 may be left selected.

また、第１，２の実施例を一部または全部組み合わせた
形のものでもよいことはいうまでもない。Further, it goes without saying that the first and second embodiments may be partially or wholly combined.

また、第１，第２の実施例において基準周波数成分検出
回路を各周波数成分検出回路に設け、切換回路を基準周
波数成分検出回路の後に設けたが、複数の周波数成分検
出回路の後に切換回路を設け、その後に基準周波数成分
検出回路を設けてもよく、その時第１の実施例において
レベル検出回路は１個になり、各周波数成分を切換えて
基準周波数成分の振幅を検出することになるが、動作は
全く同じである。Further, in the first and second embodiments, the reference frequency component detection circuit is provided in each frequency component detection circuit and the switching circuit is provided after the reference frequency component detection circuit. However, the switching circuit is provided after the plurality of frequency component detection circuits. The reference frequency component detection circuit may be provided after that, and at that time, the number of the level detection circuits is one in the first embodiment, and each frequency component is switched to detect the amplitude of the reference frequency component. The operation is exactly the same.

また、第１，第２の実施例において２つの異なる周波数
帯域をもつ周波数成分を検出する場合について述べた
が、２つ限定されるものではなくいくつでもよいことは
言うまでもない。Further, in the first and second embodiments, the case where the frequency components having two different frequency bands are detected has been described, but it goes without saying that the number is not limited to two and any number may be used.

発明の効果 本発明の自動焦点整合装置は撮像面に結像している被写
体像を電気信号に変換する撮像素子より前記電気信号を
得、前記電気信号より複数の異なる周波数帯域を有する
周波数成分を検出し、前記複数の周波数成分のうち少な
くとも１つが増加する方向にレンズの焦点整合装置を駆
動し、前記複数の周波数成分のうち少なくとも１つが極
大に達しても、他の周波数成分のうち少なくとも１つが
増加するなら、前記増加する方向にレンズの焦点整合装
置を駆動することにより、光学系レンズの円形アパーチ
ャレスポンスがもつ零点による誤動作を防止することが
でき、その実用的効果は大きい。Advantageous Effects of Invention The automatic focusing device of the present invention obtains the electric signal from an image pickup device that converts an object image formed on an image pickup surface into an electric signal, and obtains frequency components having a plurality of different frequency bands from the electric signal. When detecting and driving the lens focus matching device in a direction in which at least one of the plurality of frequency components increases, even if at least one of the plurality of frequency components reaches a maximum, at least one of the other frequency components is detected. If the number increases, it is possible to prevent the malfunction due to the zero point of the circular aperture response of the optical system lens by driving the lens focus matching device in the increasing direction, and the practical effect is great.

【図面の簡単な説明】[Brief description of drawings]

第１図は従来の自動焦点整合装置のブロック図、第２図
は従来例の動作を説明するための原理図、第３図は光学
系レンズの円形アパーチャを説明するための図、第４図
は円形アパーチャのレスポンスを示す特性図、第５図ａ
−ｂは従来例の問題点を説明するための図、第６図は本
発明の第１の実施例における自動焦点整合装置のブロッ
ク図、第７図は本発明の第２の実施例における自動焦点
整合装置のブロック図である。 １……レンズ、２……撮像素子、９……基準周波数発生
回路、１０……同期検波回路、１２……モータ、１３…
…周波数成分検出回路、１４……周波数成分検出回路、
１５……基準周波数検出回路、１６……基準周波数検出
回路、１７……切換回路、１８……レベル検出回路、１
９……レベル検出回路、２０……制御回路。FIG. 1 is a block diagram of a conventional automatic focusing device, FIG. 2 is a principle diagram for explaining the operation of a conventional example, FIG. 3 is a diagram for explaining a circular aperture of an optical system lens, and FIG. Is a characteristic diagram showing the response of a circular aperture, FIG. 5a
6B is a diagram for explaining the problems of the conventional example, FIG. 6 is a block diagram of the automatic focus adjusting device in the first embodiment of the present invention, and FIG. 7 is an automatic diagram in the second embodiment of the present invention. It is a block diagram of a focus matching device. 1 ... Lens, 2 ... Image sensor, 9 ... Reference frequency generation circuit, 10 ... Synchronous detection circuit, 12 ... Motor, 13 ...
… Frequency component detection circuit, 14 …… Frequency component detection circuit,
15 ... reference frequency detection circuit, 16 ... reference frequency detection circuit, 17 ... switching circuit, 18 ... level detection circuit, 1
9 ... Level detection circuit, 20 ... Control circuit.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】撮像面に結像している被写体の光学的情報
を電気信号に変換する撮像素子より前記電気信号を得、
前記電気信号より複数の異なる周波数帯域を有する周波
数成分を検出し、前記複数の周波数成分のうち少なくと
も１つが増加する方向にレンズの焦点整合装置を駆動
し、前記複数の周波数成分のうち少なくとも１つが極大
に達しても、他の周波数成分のうち少なくとも１つが増
加するなら増加する方向にレンズの焦点整合装置を駆動
し、前記複数の周波数成分の振幅が最大となる様に前記
レンズの焦点整合装置を駆動するように構成した事を特
徴とする自動焦点整合装置。1. An electric signal is obtained from an image pickup device for converting optical information of a subject imaged on an image pickup surface into an electric signal,
A frequency component having a plurality of different frequency bands is detected from the electric signal, a focus matching device of a lens is driven in a direction in which at least one of the plurality of frequency components increases, and at least one of the plurality of frequency components is detected. Even if the maximum is reached, if at least one of the other frequency components is increased, the focus adjusting device of the lens is driven in an increasing direction so that the amplitudes of the plurality of frequency components are maximized. An automatic focusing device characterized by being configured to drive a. 【請求項２】複数の異なる周波数帯域を有する周波数成
分のうち第１の周波数成分が増加する方向にレンズの焦
点整合装置を駆動し、前記第１の周波数成分が極大に達
した後、第２の周波数成分が極大に達してなく増加する
なら増加する方向にレンズの焦点整合装置を駆動する事
を特徴とする特許請求の範囲第１項記載の自動焦点整合
装置。2. A focus adjusting device of a lens is driven in a direction in which a first frequency component increases among frequency components having a plurality of different frequency bands, and after the first frequency component reaches a maximum, 2. The automatic focusing device according to claim 1, wherein the focusing device of the lens is driven in an increasing direction if the frequency component of is increased to a maximum. 【請求項３】複数の異なる周波数帯域を有する周波数成
分のうち第１の周波数成分が増加する方向にレンズの焦
点整合装置を駆動し、前記第１の周波数成分が極大に達
した後、第２の周波数成分が極大に達してなく増加する
なら増加する方向にレンズの焦点整合装置を駆動し、前
記第２の周波数成分が極大に達した後、再び第１または
第３の周波数成分が増加する方向にレンズの焦点整合装
置を駆動する事を特徴とする特許請求の範囲第１項記載
の自動焦点整合装置。3. A focus adjusting device of a lens is driven in a direction in which a first frequency component increases among frequency components having a plurality of different frequency bands, and after the first frequency component reaches a maximum, If the frequency component of does not reach the maximum and increases, the focus adjustment device of the lens is driven in an increasing direction, and after the second frequency component reaches the maximum, the first or third frequency component increases again. The automatic focusing device according to claim 1, wherein the focusing device of the lens is driven in the direction.
JP58235348A 1983-12-13 1983-12-13 Automatic focusing device Expired - Lifetime JPH0619492B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58235348A JPH0619492B2 (en) 1983-12-13 1983-12-13 Automatic focusing device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58235348A JPH0619492B2 (en) 1983-12-13 1983-12-13 Automatic focusing device

Publications (2)

Publication Number Publication Date
JPS60126612A JPS60126612A (en) 1985-07-06
JPH0619492B2 true JPH0619492B2 (en) 1994-03-16

Family

ID=16984755

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58235348A Expired - Lifetime JPH0619492B2 (en) 1983-12-13 1983-12-13 Automatic focusing device

Country Status (1)

Country Link
JP (1) JPH0619492B2 (en)

Also Published As

Publication number Publication date
JPS60126612A (en) 1985-07-06

Similar Documents

Publication Publication Date Title
US7852398B2 (en) Image-taking apparatus
US7773873B2 (en) Image-pickup apparatus and focus control method
JP3500539B2 (en) Automatic focus adjustment method for infrared camera
US6734902B1 (en) Vibration correcting device
CN101247477B (en) Image-pickup apparatus and control method thereof
CN101620360B (en) Image capturing apparatus and control method for the same
CN101115146A (en) Image-pickup apparatus and focus control method
US5140357A (en) Automatic focusing device wherein loop gain is set responsively to variation of magnification
JPS6060616A (en) Automatic focus adjusting device
US7570298B2 (en) Image-taking apparatus with first focus control such that in-focus position is searched for based on first signal and second focus control such that one of in-focus position and drive amount is determined based on second signal
US5267044A (en) Automatic focusing system for use in cameras having zooming function
JPH039677B2 (en)
JPS60143068A (en) Automatic focus matching device
JPH0619492B2 (en) Automatic focusing device
JP2970902B2 (en) Automatic focusing device
JPH0443475B2 (en)
JP7427912B2 (en) Imaging device
JPH0614700B2 (en) Automatic focusing device
JPH0554305B2 (en)
JPH0628402B2 (en) Automatic focusing device
JPS63181571A (en) Automatic matching device for focal point
KR20000024811A (en) Method device for auto focusing of camera
JPH0628400B2 (en) Automatic focusing device
JPH04318772A (en) Automatic focus matching device
JPH0648857B2 (en) Automatic focusing device