JP4515511B2 - Focus device and focus control method - Google Patents

Focus device and focus control method Download PDF

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JP4515511B2
JP4515511B2 JP2008084085A JP2008084085A JP4515511B2 JP 4515511 B2 JP4515511 B2 JP 4515511B2 JP 2008084085 A JP2008084085 A JP 2008084085A JP 2008084085 A JP2008084085 A JP 2008084085A JP 4515511 B2 JP4515511 B2 JP 4515511B2
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健 岸田
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Acutelogic Corp
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Description

本発明は、ビデオカメラやデジタルスチルカメラ等のフォーカス技術に関するものであり、特に、映像信号に含まれる高域周波数成分を用いて合焦度の評価値を生成し、フォーカスレンズの移動速度を制御するフォーカス装置及びフォーカス制御方法に関する。   The present invention relates to a focus technology such as a video camera or a digital still camera, and in particular, generates an evaluation value of a degree of focus using a high frequency component included in a video signal and controls a moving speed of a focus lens. The present invention relates to a focus device and a focus control method.

従来、ビデオカメラやデジタルスチルカメラ等の撮像装置のオートフォーカス方式として、撮像素子から出力する映像信号に含まれる高域周波数成分の大きさから合焦度(被写体)の評価値(本書では焦点評価値という)を生成し、その焦点評価値が最大値になるフォーカスレンズの位置を合焦位置とするコントラスト検出方式が広く用いられている。   Conventionally, as an autofocus method for imaging devices such as video cameras and digital still cameras, the evaluation value of the focus degree (subject) from the magnitude of the high frequency component contained in the video signal output from the image sensor (focus evaluation in this document) A contrast detection method is widely used in which the focus lens position at which the focus evaluation value becomes the maximum value is generated.

前述のオートフォーカス方式では、被写体を撮影して得られる映像信号から所定のフィルタを介して高域周波数成分の信号が抽出され、その高域周波数成分の信号に基づいて被写体画像のコントラストの高低(合焦度)が評価される。そして、その焦点評価値が最大となるように、フォーカスレンズの位置が制御される。   In the above-described autofocus method, a high-frequency component signal is extracted from a video signal obtained by photographing a subject through a predetermined filter, and the contrast of the subject image is increased or decreased based on the high-frequency component signal ( The degree of focus is evaluated. Then, the position of the focus lens is controlled so that the focus evaluation value is maximized.

前述のフォーカス方式では、フォーカスレンズの位置と焦点評価値との関係を表したグラフが山型になって現れる。そこで、フォーカス合わせの際には、この山型の頂点を目指し、焦点評価値が増加を示す方向にフォーカスレンズを移動させ、焦点評価値が増加から減少に切り替わる位置でフォーカスレンズを停止させる、所謂山登り方式のフォーカス制御方法が一般的に知られている。   In the focus method described above, a graph representing the relationship between the position of the focus lens and the focus evaluation value appears in a mountain shape. Therefore, at the time of focusing, aiming at the peak of this mountain shape, the focus lens is moved in the direction in which the focus evaluation value increases, and the focus lens is stopped at a position where the focus evaluation value switches from increase to decrease. A hill-climbing focus control method is generally known.

そして、山登り方式によるフォーカス制御方法によれば、フォーカスレンズを合焦位置に移動させる際、焦点評価値が最大値であることを検出するために、フォーカスレンズがいったん合焦位置を通り過ぎる必要がある。   According to the hill-climbing focus control method, when the focus lens is moved to the in-focus position, the focus lens needs to once pass the in-focus position in order to detect that the focus evaluation value is the maximum value. .

また、ズーム機能を備えた撮像装置では、ズーム倍率が大きくなると、ズームの望遠側ではフォーカスレンズの移動範囲が広くなり、フォーカスレンズを合焦位置に移動させる際の所要時間が一般的に長くなる。そして、所要時間を短縮するためにフォーカスレンズの移動速度を速くすると、焦点評価値の算出及びフォーカスレンズ制御の周期を撮像素子から映像信号を出力する周期よりも短くできないので、フォーカスレンズが合焦位置を通り過ぎた際のピントボケが大きくなるという問題がある。
In addition, in an imaging apparatus having a zoom function, when the zoom magnification increases, the range of movement of the focus lens becomes wider on the telephoto side of the zoom, and the time required to move the focus lens to the in-focus position is generally longer. . If the moving speed of the focus lens is increased in order to shorten the required time, the focus evaluation value calculation and focus lens control cycle cannot be made shorter than the cycle in which the video signal is output from the image sensor. There is a problem that the out-of-focus when passing the position becomes large.

そこで、フォーカスレンズが合焦位置から遠い間では高速で移動させ、フォーカスレンズが合焦位置に近くなると低速で移動させることにより、合焦時間の短縮とピントボケの抑制を図る。   Therefore, the focus lens is moved at a high speed while it is far from the in-focus position, and is moved at a low speed when the focus lens is close to the in-focus position, thereby reducing the in-focus time and suppressing out-of-focus.

例えば、撮像素子から出力された映像信号の高域周波数成分(以下、高域成分という)を検出する際に、第一のバンドパスフィルタと第一のバンドパスフィルタより低域遮断周波数が高い第二のバンドパスフィルタを用い、第一のバンドパスフィルタの出力から第一の焦点評価値を生成すると共に、第二のバンドパスフィルタの出力から第二の焦点評価値を生成し、フォーカスレンズを合焦位置に向かって移動させた際に、第二の焦点評価値に対する第一の焦点評価値の比の微分値が正であればフォーカスレンズが合焦位置から遠いと判定してフォーカスレンズを高速で移動させ、一方、第二の焦点評価値に対する第一の焦点評価値の比の微分値が負であればフォーカスレンズが合焦位置から近いと判定し、フォーカスレンズを低速で移動させるように構成されたオートフォーカス装置が開示されている(例えば、特許文献1参照)。
特開平07−143387号公報
For example, when detecting a high-frequency component (hereinafter referred to as a high-frequency component) of a video signal output from an image sensor, a low-frequency cutoff frequency is higher than that of the first band-pass filter and the first band-pass filter. Using the second bandpass filter, the first focus evaluation value is generated from the output of the first bandpass filter, and the second focus evaluation value is generated from the output of the second bandpass filter. If the differential value of the ratio of the first focus evaluation value to the second focus evaluation value is positive when moved toward the focus position, it is determined that the focus lens is far from the focus position and the focus lens is moved. On the other hand, if the differential value of the ratio of the first focus evaluation value to the second focus evaluation value is negative, it is determined that the focus lens is close to the in-focus position, and the focus lens is moved at a low speed. Autofocus device configured so that it has been disclosed (e.g., see Patent Document 1).
Japanese Unexamined Patent Publication No. 07-143387

しかしながら、特許文献1によれば、映像信号の高域成分から生成される焦点評価値には光ショット雑音といわれるノイズの高域成分が混入する虞がある。ここで、光ショット雑音とは、撮像素子に光が入射した際に、光電変換素子(フォトダイオード)で光電変換されて発生する電子数が確率過程によって決まるために生ずる雑音であり、その大きさは光電変換素子に蓄積される電子数の平均値の平方根である。従って、映像信号の高域成分から生成される焦点評価値は、撮像素子に結像する被写体像のコントラストとは無関係に、撮像素子に入射する光量の変化に影響されることになる。   However, according to Patent Document 1, there is a possibility that a high frequency component of noise called optical shot noise is mixed in a focus evaluation value generated from a high frequency component of a video signal. Here, light shot noise is noise generated because the number of electrons generated by photoelectric conversion by a photoelectric conversion element (photodiode) is determined by a stochastic process when light enters the imaging element. Is the square root of the average value of the number of electrons accumulated in the photoelectric conversion element. Accordingly, the focus evaluation value generated from the high-frequency component of the video signal is affected by the change in the amount of light incident on the image sensor regardless of the contrast of the subject image formed on the image sensor.

詳しくは、特許文献1に記載のオートフォーカス装置において、フォーカスレンズが合焦位置から遠い位置にあって合焦位置に向かって移動している際、被写体又は撮像装置に動きが発生すると、撮像装置への入射光量と撮像素子に結像する被写体像のコントラストが変化して光ショット雑音の大きさが変化し、光ショット雑音の大きさの変化が第一の焦点評価値と第二の焦点評価値の両方に影響を与え、一方、被写体像のコントラストの変化が第一の焦点評価値のみに影響を与える。   Specifically, in the autofocus device described in Patent Document 1, when the focus lens is moved away from the in-focus position and is moving toward the in-focus position, if the subject or the image-capturing device moves, the image-capturing device The amount of incident light on the light and the contrast of the subject image formed on the image sensor change to change the magnitude of the light shot noise. The change in the magnitude of the light shot noise is the first focus evaluation value and the second focus evaluation. Both of the values are affected, while a change in the contrast of the subject image affects only the first focus evaluation value.

つまり、フォーカスレンズが合焦位置から遠い位置にあると、被写体像のコントラストには高い周波数成分が含まれず、低域遮断周波数が第一のバンドパスフィルタよりも高く設定された第二のバンドパスフィルタの出力から生成される第二の焦点評価値には被写体像のコントラストに起因する成分が含まれないためである。   In other words, when the focus lens is far from the in-focus position, the contrast of the subject image does not include a high frequency component, and the second bandpass in which the low-frequency cutoff frequency is set higher than that of the first bandpass filter. This is because the second focus evaluation value generated from the output of the filter does not include a component due to the contrast of the subject image.

この際、撮像素子への入射光量の変化と被写体像のコントラストの変化が互いに無関係であるため、第一の焦点評価値の変化量と第二の焦点評価値の変化量が無相関となって現れ、第二の焦点評価値に対する第一の焦点評価値の比が増加することも有れば減少することもある。   At this time, since the change in the amount of light incident on the image sensor and the change in the contrast of the subject image are unrelated to each other, the change amount of the first focus evaluation value and the change amount of the second focus evaluation value are uncorrelated. Appearing, the ratio of the first focus evaluation value to the second focus evaluation value may increase or decrease.

そして、特許文献1に記載のオートフォーカス装置によれば、第二の焦点評価値に対する第一の焦点評価値の比が減少することによってフォーカスレンズが合焦位置に近づいたことを検出するように構成されているので、被写体又はカメラに動きが生じることによって誤った検出結果を出す虞がある。   According to the autofocus device described in Patent Document 1, it is detected that the focus lens has approached the in-focus position by reducing the ratio of the first focus evaluation value to the second focus evaluation value. Since it is configured, there is a possibility that an erroneous detection result may be produced due to movement of the subject or the camera.

以上のように、特許文献1に記載のオートフォーカス装置によれば、フォーカスレンズが合焦位置に向かって移動している際に、被写体又は撮像装置に動きが発生すると、フォーカスレンズが合焦位置から遠い位置にあるにもかかわらず合焦位置に近いと判定してしまう虞があり、その結果、フォーカスレンズが合焦位置から遠い位置でフォーカスレンズの移動速度が低下し、合焦時間が長くなるという虞があった。   As described above, according to the autofocus device described in Patent Document 1, when the focus lens is moving toward the in-focus position and the subject or the imaging apparatus moves, the focus lens is in the in-focus position. The focus lens may be determined to be close to the in-focus position even though it is far from the focus position. There was a fear of becoming.

そこで、本発明は、コントラスト検出方式のオートフォーカスにおいて、フォーカスレンズを合焦位置に向かって移動させる際に、被写体又は撮像装置に動きが生じても、フォーカスレンズが合焦位置から近いか否かを正しく判定してフォーカスレンズの移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズが合焦位置を通り過ぎた際のピントボケを抑制できるフォーカス装置及びフォーカス制御方法を提供することを目的とする。
Therefore, according to the present invention, whether or not the focus lens is close to the in-focus position even when the subject or the imaging apparatus moves when the focus lens is moved toward the in-focus position in the contrast detection type auto-focus. A focus device and a focus control method capable of appropriately controlling the moving speed of the focus lens by correctly determining the focus lens, reducing the focusing time, and suppressing the out-of- focus blur when the focus lens passes the in-focus position. Objective.

かかる目的を達成するためになされた請求項1に記載の発明は、光軸方向に沿ってスライド自在に設置されたフォーカスレンズと、被写体像からの光を映像信号に変換する撮像素子と、前記撮像素子から出力される出力信号を増幅する可変利得増幅器と、前記撮像素子に結像した被写体像の合焦度の焦点評価値を生成する評価値生成手段と、前記焦点評価値に応じて、前記フォーカスレンズを光軸方向にスライドさせて前記撮像素子に結像する被写体像の焦点あわせを行うフォーカス制御手段と、を備えたフォーカス装置において、
前記可変利得増幅器を介して出力される前記映像信号を積算して第一の積算値を生成する第一積算手段と、前記可変利得増幅器を介して出力される前記映像信号の高域成分の絶対値を積算する第二積算手段と、を備え、前記第二積算手段において、前記可変利得増幅器を介して出力される前記映像信号の高域成分の絶対値を積算して第二の積算値を生成すると共に、予め前記撮像素子への入射光を遮光した状態において前記可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成し、前記評価値生成手段が、前記第一の積算値をL、前記第二の積算値をC、前記第三の積算値をD、前記可変利得増幅器の利得をG、前記焦点評価値をV、と表した際に、(式1)に記載の演算式を用いて前記焦点評価値を算出し、前記フォーカス制御手段が、該焦点評価値を所定の閾値と比較して前記フォーカスレンズの位置が合焦位置に近いか否かを判定し、該判定結果に基づいて、前記フォーカスレンズの位置が合焦位置に近い場合には、前記フォーカスレンズの移動速度を合焦位置が遠い場合よりも低速に制御し、前記フォーカスレンズの位置が合焦位置から遠い場合には、前記フォーカスレンズの移動速度を合焦位置に近い場合よりも高速に制御する、ことを特徴とする。

The invention according to claim 1, which has been made to achieve the above object, includes a focus lens that is slidably installed along an optical axis direction, an imaging device that converts light from a subject image into a video signal, and According to the focus evaluation value, a variable gain amplifier that amplifies an output signal output from the image sensor, an evaluation value generation unit that generates a focus evaluation value of the degree of focus of a subject image formed on the image sensor, A focus control unit that slides the focus lens in the optical axis direction and performs focusing on a subject image formed on the image sensor;
A first integration means for integrating the video signal output through the variable gain amplifier to generate a first integrated value; and an absolute value of a high frequency component of the video signal output through the variable gain amplifier. Second accumulating means for accumulating values, wherein the second accumulating means accumulates the absolute value of the high frequency component of the video signal output through the variable gain amplifier to obtain a second accumulated value. And generating a third integrated value by integrating the absolute value of the high frequency component output through the variable gain amplifier in a state where the incident light to the image sensor is shielded in advance. When the means represents the first integrated value as L, the second integrated value as C, the third integrated value as D, the gain of the variable gain amplifier as G, and the focus evaluation value as V. In addition, the focus evaluation value is calculated using the arithmetic expression described in (Expression 1), The focus control means compares the focus evaluation value with a predetermined threshold value to determine whether or not the position of the focus lens is close to the focus position, and based on the determination result, the position of the focus lens matches. When the focus lens is close to the focus position, the moving speed of the focus lens is controlled to be lower than when the focus position is far, and when the focus lens is far from the focus position, the movement speed of the focus lens is controlled. Control is performed at a higher speed than in the case of being close to the in-focus position .

請求項1に記載のフォーカス装置によれば、可変利得増幅器を介して出力される映像信号を積算して第一の積算値を生成する第一積算手段と、可変利得増幅器を介して出力される映像信号の高域成分の絶対値を積算する第二積算手段と、を備え、第二積算手段において、可変利得増幅器を介して出力される映像信号の高域成分の絶対値を積算して第二の積算値を生成すると共に、予め前記撮像素子への入射を遮光した状態において可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成し、評価値生成手段が、第一の積算値をL、第二の積算値をC、第三の積算値をD、可変利得増幅器の利得をG、焦点評価値をV、と表した際に、(式1)に記載の演算式を用いて焦点評価値を算出し、フォーカス制御手段が、この焦点評価値を所定の閾値と比較してフォーカスレンズの位置が合焦位置に近いか否かを判定し、この判定結果に基づいて、フォーカスレンズの位置が合焦位置に近い場合には、フォーカスレンズの移動速度を合焦位置が遠い場合よりも低速に制御し、フォーカスレンズの位置が合焦位置から遠い場合には、フォーカスレンズの移動速度を合焦位置に近い場合よりも高速に制御するように構成されているので、フォーカスレンズを合焦位置に向かって移動させる際に、被写体又は撮像装置に動きが生じても、フォーカスレンズが合焦位置から近いか否かを正しく判定してフォーカスレンズの移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズが合焦位置を通り過ぎた際のピントボケを抑制できる。

According to the focus device of the first aspect, the first integration means for integrating the video signals output through the variable gain amplifier to generate the first integrated value, and the output through the variable gain amplifier. Second integrating means for integrating the absolute value of the high frequency component of the video signal, and integrating the absolute value of the high frequency component of the video signal output through the variable gain amplifier in the second integrating means. The second integrated value is generated, and the third integrated value is generated by integrating the absolute value of the high frequency component output through the variable gain amplifier in a state where the incident on the image sensor is shielded in advance. When the value generation means represents the first integrated value as L, the second integrated value as C, the third integrated value as D, the gain of the variable gain amplifier as G, and the focus evaluation value as V, The focus evaluation value is calculated using the arithmetic expression described in Equation 1), and the focus control means Is compared with a predetermined threshold value to determine whether the position of the focus lens is close to the in-focus position, and based on the determination result, when the position of the focus lens is close to the in-focus position, Controls the moving speed of the focus lens at a lower speed than when the in-focus position is far, and controls the moving speed of the focus lens at a higher speed than when the focus lens is far from the in-focus position. It is configured so as to, when moving the focus lens toward the in-focus position, even if the motion to the object or the imaging apparatus, the focus lens is short or not is determined from the in-focus position correctly It is possible to appropriately control the moving speed of the focus lens, shorten the focusing time, and suppress out-of-focus when the focus lens passes the in-focus position.

つまり、高域成分の積算値には、被写体像のコントラストに起因する高域成分を含まない場合、光ショット雑音と読み出し雑音が加算されたノイズに起因する高域成分だけが含まれる。また、読み出し雑音には、撮像素子に光が入射しない状態で定常的に発生するすべてのノイズが含まれる。   That is, when the integrated value of the high frequency component does not include the high frequency component due to the contrast of the subject image, only the high frequency component due to the noise obtained by adding the light shot noise and the readout noise is included. Further, the readout noise includes all noises that are constantly generated in a state where light does not enter the image sensor.

この際、光ショット雑音と読み出し雑音が互いに無相関なノイズなので、光ショット雑音の分散の和と読み出し雑音の分散の和は、両者を加算したノイズの分散に等しい。一方、高域成分の積算値は、ハイパスフィルタ(又はバンドパスフィルタ)からの出力の絶対値を積算したものなので、ハイパスフィルタ(又はバンドパスフィルタ)への入力信号の標準偏差と同じ次元をもつ。   At this time, since the optical shot noise and the readout noise are uncorrelated noises, the sum of the variance of the optical shot noise and the variance of the readout noise is equal to the variance of the noise obtained by adding both. On the other hand, the integrated value of the high-frequency component is obtained by integrating the absolute value of the output from the high-pass filter (or band-pass filter), and therefore has the same dimension as the standard deviation of the input signal to the high-pass filter (or band-pass filter). .

従って、高域成分の積算値が被写体像のコントラストに起因する高域成分を含まない場合、高域成分の積算値(第二の積算値)をC、高域成分の積算値のうち光ショット雑音に起因する積算値をS、高域成分の積算値のうち読み出し雑音に起因する積算値(第三の積算値)をD、と表すと、(式2)が成り立つ。
Therefore, when the integrated value of the high frequency component does not include the high frequency component due to the contrast of the subject image, the integrated value of the high frequency component (second integrated value) is C, and the light shot of the integrated value of the high frequency component When the integrated value caused by noise is expressed as S, and the integrated value (third integrated value) caused by readout noise among the integrated values of high-frequency components is expressed as D, (Expression 2) is established.

一方、映像信号の輝度積算値(第一の積算値)をL、可変利得増幅器の利得をGと表すと、光ショット雑音の大きさが撮像素子で光電変換されて生じる電子数Nの平方根に比例し、さらに可変利得増幅器の利得Gの積に比例するので、(式3)が得られる。
On the other hand, when the luminance integrated value (first integrated value) of the video signal is represented by L and the gain of the variable gain amplifier is represented by G, the magnitude of the light shot noise is the square root of the number N of electrons generated by photoelectric conversion by the image sensor. Since it is proportional and further proportional to the product of the gain G of the variable gain amplifier, (Equation 3) is obtained.

また、輝度積算値Lが電子数Nと可変利得増幅器の利得Gとの積に比例するので、(式4)が得られる。
Further, since the luminance integrated value L is proportional to the product of the number of electrons N and the gain G of the variable gain amplifier, (Equation 4) is obtained.

さらに、(式3)に(式4)の関係式を代入すると、(式5)を導きだすことができる。すなわち、光ショット雑音の大きさSは、輝度積算値Lと可変利得増幅器の利得Gとの積の平方根に比例する。
Further, by substituting the relational expression of (Expression 4) into (Expression 3), (Expression 5) can be derived. That is, the magnitude S of the light shot noise is proportional to the square root of the product of the luminance integrated value L and the gain G of the variable gain amplifier.

さらに、(2式)と(5)式に基づいて、(式6)が得られ、さらには(式7)が得られる。
Furthermore, (Expression 6) is obtained based on (Expression 2) and (5), and further (Expression 7) is obtained.

従って、焦点評価値Vは、(式1)を用いて算出すれば、高域成分の積算値が被写体像のコントラストに起因する高域成分を含まない場合は、光ショット雑音の大きさが変化しても一定値に保たれ、フォーカスレンズを合焦位置に向かって移動させる際に、フォーカスレンズが合焦位置から近いか否かを正しく判定できる。   Therefore, if the focus evaluation value V is calculated using (Equation 1), the magnitude of the light shot noise changes when the integrated value of the high frequency component does not include the high frequency component due to the contrast of the subject image. Even when the focus lens is moved toward the in-focus position, it can be correctly determined whether or not the focus lens is close to the in-focus position.

また、フォーカスレンズの移動に伴う焦点評価値の差分を検出することにより、合焦位置に対するフォーカスレンズの移動方向を検出できる。   Further, by detecting the difference in the focus evaluation value accompanying the movement of the focus lens, it is possible to detect the movement direction of the focus lens with respect to the in-focus position.

次に、請求項1に記載のフォーカス装置は、請求項2に記載の発明のように、前記第二積算手段が、前記映像信号の高域成分を抽出する、低域遮断周波数の異なる2つのハイパスフィルタ又はバンドパスフィルタを備え、前記評価値生成手段が、前記2つのハイパスフィルタ又はバンドパスフィルタの内で、低域遮断周波数の低い方を第一のハイパスフィルタ又は第一のバンドパスフィルタとし、他方を第二のハイパスフィルタ又は第二のバンドパスフィルタとした際に、前記第一のハイパスフィルタ又は第一のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第一の焦点評価値を生成すると共に、前記第二のハイパスフィルタ又は第二のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第二の焦点評価値を生成し、前記第二の焦点評価値の変化量を所定の第一の閾値と比較する第一の比較手段と、前記第一の焦点評価値の変化量に対する第二の焦点評価値の変化量の比を所定の第二の閾値と比較する第二の比較手段と、を備え、前記フォーカス制御手段が、前記フォーカスレンズを合焦位置に向かって移動させる際に、前記第一の比較手段において第二の焦点評価値の変化量が第一の閾値よりも大きく、且つ第二の比較手段において前記変化量の比が第二の閾値よりも大きい場合には、前記フォーカスレンズの位置が合焦位置に近いと判定して前記フォーカスレンズを低速で移動させ、一方、前記第一の手段において前記第二の焦点評価値の変化量が前記第一の閾値よりも小さい場合、又は、第二の比較手段において前記変化量の比が第二の閾値よりも小さい場合には、前記フォーカスレンズの位置が合焦位置から遠いと判定して前記フォーカスレンズを高速で移動させる、ことを特徴とする。


Next, in the focusing device according to claim 1, as in the invention according to claim 2, the second integration unit extracts two high-frequency components of the video signal and has two different low-frequency cutoff frequencies. A high-pass filter or a band-pass filter, and the evaluation value generating means sets the lower one of the two high-pass filters or band-pass filters as the first high-pass filter or the first band-pass filter. When the other is the second high-pass filter or the second band-pass filter, the second high-pass filter or the second band-pass filter is associated with the size of the high-frequency component extracted through the first high-pass filter or the first band-pass filter. A first focus evaluation value is generated, and a second high-pass component corresponding to the size of the high-frequency component extracted through the second high-pass filter or the second band-pass filter is generated. A first comparison unit that generates a focus evaluation value and compares the amount of change in the second focus evaluation value with a predetermined first threshold; and a second focus evaluation for the amount of change in the first focus evaluation value Second comparison means for comparing the ratio of the amount of change in value with a predetermined second threshold, and when the focus control means moves the focus lens toward the in-focus position, When the change amount of the second focus evaluation value is larger than the first threshold value in the comparison means and the ratio of the change amount is larger than the second threshold value in the second comparison means, When it is determined that the position is close to the in-focus position and the focus lens is moved at a low speed, while the change amount of the second focus evaluation value is smaller than the first threshold in the first means, or , In the second comparison means, There the smaller than the second threshold value, the position of the focus lens moves farther and determination to said focus lens from the focus position at high speed, characterized in that.


請求項2に記載のフォーカス装置によれば、フォーカスレンズを合焦位置に向かって移動させる際に、第一の比較手段において第二の焦点評価値の変化量が第一の閾値よりも大きく、且つ第二の比較手段において変化量の比が第二の閾値よりも大きい場合には、フォーカスレンズの位置が合焦位置に近いと判定してフォーカスレンズを低速で移動させ、一方、第一の手段において第二の焦点評価値の変化量が第一の閾値よりも小さい場合、又は、第二の比較手段において変化量の比が第二の閾値よりも小さい場合には、フォーカスレンズの位置が合焦位置から遠いと判定して前記フォーカスレンズを高速で移動させることにより、フォーカスレンズの移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズが合焦位置を通り過ぎた際のピントボケを抑制できる。

According to the focus device of the second aspect, when the focus lens is moved toward the in-focus position, the amount of change in the second focus evaluation value is larger than the first threshold value in the first comparison unit, When the ratio of the amount of change is larger than the second threshold value in the second comparison means, it is determined that the position of the focus lens is close to the focus position, and the focus lens is moved at a low speed. When the change amount of the second focus evaluation value is smaller than the first threshold value in the means, or when the ratio of the change amounts is smaller than the second threshold value in the second comparison means, the position of the focus lens is By determining that the focus lens is far from the in-focus position and moving the focus lens at a high speed, it is possible to appropriately control the moving speed of the focus lens, shorten the in-focus time, and the focus lens passes through the in-focus position. The out-of-focus when the past can be suppressed.

次に、請求項3に記載の発明は、光軸方向に沿ってスライド自在に設置されたフォーカスレンズと、被写体像からの光を映像信号に変換する撮像素子と、前記撮像素子から出力される出力信号を増幅する可変利得増幅器とを備えた撮像装置のフォーカス制御方法であって、前記可変利得増幅器を介して出力される映像信号を積算して第一の積算値を生成する第一積算値生成ステップと、前記可変利得増幅器を介して出力される前記映像信号の高域成分の絶対値を積算して第二の積算値を生成する第二積算値生成ステップと、予め前記撮像素子への入射光を遮光した状態において前記可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成する第三積算値生成ステップと、前記第一の積算値をL、前記第二の積算値をC、前記第三の積算値をD、前記可変利得増幅器の利得をG、前記焦点評価値をV、と表した際に、(式8)に記載の演算式を用いて、前記撮像素子に結像した前記被写体像の焦点評価値を生成する評価値生成ステップと、前記焦点評価値を所定の閾値と比較して前記フォーカスレンズの位置が合焦位置に近いか否かを判定し、該判定結果に基づいて、前記フォーカスレンズの位置が合焦位置に近い場合には、前記フォーカスレンズの移動速度を合焦位置から遠い場合よりも低速に制御し、前記フォーカスレンズの位置が合焦位置から遠い場合には、前記フォーカスレンズの移動速度を合焦点位置に近い場合よりも高速に制御するフォーカス制御ステップと、を備えることを特徴とする。

According to a third aspect of the present invention, there is provided a focus lens that is slidable along the optical axis direction, an image sensor that converts light from a subject image into a video signal, and output from the image sensor. A focus control method for an imaging apparatus including a variable gain amplifier for amplifying an output signal, the first integrated value for generating a first integrated value by integrating video signals output through the variable gain amplifier A generating step, a second integrated value generating step for generating a second integrated value by integrating absolute values of high frequency components of the video signal output through the variable gain amplifier , A third integrated value generating step for generating a third integrated value by integrating the absolute value of the high frequency component output through the variable gain amplifier in a state where the incident light is shielded; and the first integrated value L, the second integrated value When C, the third integrated value is represented as D, the gain of the variable gain amplifier is represented as G, and the focus evaluation value is represented as V, the arithmetic expression described in (Equation 8) is used to An evaluation value generating step for generating a focus evaluation value of the image of the subject image formed; and comparing the focus evaluation value with a predetermined threshold value to determine whether or not the position of the focus lens is close to the in-focus position; Based on the determination result, when the position of the focus lens is close to the in-focus position, the moving speed of the focus lens is controlled to be lower than that in the case of being far from the in-focus position, and the position of the focus lens is And a focus control step for controlling the moving speed of the focus lens at a higher speed than when close to the in-focus position .

請求項3に記載のフォーカス制御方法によれば、可変利得増幅器を介して出力される映像信号を積算して第一の積算値を生成する第一積算値生成ステップと、可変利得増幅器を介して出力される映像信号の高域成分の絶対値を積算して第二の積算値を生成する第二積算値生成ステップと、予め撮像素子への入射光を遮光した状態において可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成する第三積算値生成ステップと、第一の積算値をL、第二の積算値をC、第三の積算値をD、可変利得増幅器の利得をG、焦点評価値をV、と表した際に、(式8)に記載の演算式を用いて、撮像素子に結像した被写体像の焦点評価値を生成する評価値生成ステップと、焦点評価値を所定の閾値と比較してフォーカスレンズの位置が合焦位置に近いか否かを判定し、この判定結果に基づいて、フォーカスレンズの位置が合焦位置に近い場合には、フォーカスレンズの移動速度を合焦位置から遠い場合よりも低速に制御し、フォーカスレンズの位置が合焦位置から遠い場合には、フォーカスレンズの移動速度を合焦点位置に近い場合よりも高速に制御するフォーカス制御ステップと、を備えているので、請求項1に記載の発明と同様に、フォーカスレンズを合焦位置に向かって移動させる際に、被写体又は撮像装置に動きが生じても、フォーカスレンズが合焦位置から近いか否かを正しく判定してフォーカスレンズの移動測度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズが合焦位置を通り過ぎた際のピントボケを抑制できる

According to the focus control method of the third aspect, the first integrated value generation step of generating the first integrated value by integrating the video signals output through the variable gain amplifier, and the variable gain amplifier A second integrated value generating step for generating the second integrated value by integrating the absolute values of the high frequency components of the output video signal, and through a variable gain amplifier in a state where the incident light to the image sensor is shielded in advance. A third integrated value generating step for generating a third integrated value by integrating the absolute values of the output high frequency components; a first integrated value of L; a second integrated value of C; and a third integrated value Is expressed as D, the gain of the variable gain amplifier is expressed as G, and the focus evaluation value is expressed as V, the focus evaluation value of the subject image formed on the image sensor is generated using the arithmetic expression described in (Equation 8). and evaluation value generation step of the focus lens by comparing the focus evaluation value with a predetermined threshold value If the position of the focus lens is close to the in-focus position based on the determination result, the moving speed of the focus lens is set to be higher than the distance from the in-focus position. And a focus control step for controlling the moving speed of the focus lens at a higher speed than when it is close to the in-focus position when the position of the focus lens is far from the in-focus position. As in the first aspect of the invention, when the focus lens is moved toward the in-focus position, it is correctly determined whether or not the focus lens is close to the in-focus position even if the subject or the imaging device moves. The focus lens movement measure can be controlled appropriately to reduce the focusing time and to reduce out-of-focus when the focus lens passes the in-focus position.

また、請求項3に記載のフォーカス制御方法は、請求項4に記載の発明のように、第一のハイパスフィルタ又は第一のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第一の焦点評価値を生成すると共に、第二のハイパスフィルタ又は第二のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第二の焦点評価値を生成し、前記第二の焦点評価値の変化量を所定の第一の閾値と比較する第一の比較ステップと、第一の焦点評価値の変化量に対する第二の焦点評価値の変化量の比を所定の第二の閾値と比較する第二の比較ステップとを備え、フォーカス制御ステップにおいて、フォーカスレンズを合焦位置に向かって移動させる際に、第一の比較手段において第二の焦点評価値の変化量が第一の閾値よりも大きく、且つ第二の比較手段において変化量の比が第二の閾値よりも大きい場合には、フォーカスレンズの位置が合焦位置に近いと判定してフォーカスレンズを低速で移動させ、一方、第一の比較手段において第二の焦点評価値の変化量が第一の閾値よりも小さい場合、又は、第二の比較手段において変化量の比が第二の閾値よりも小さい場合には、フォーカスレンズの位置が合焦位置から遠いと判定してフォーカスレンズを高速で移動させることにより、請求項2に記載の発明と同様に、フォーカスレンズの移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズが合焦位置を通り過ぎた際のピントボケを抑制できる。

According to a third aspect of the present invention, in the focus control method according to the fourth aspect, the size of the high frequency component extracted through the first high pass filter or the first band pass filter is set. The first focus evaluation value is generated in association with the second high-pass filter or the second band-pass filter, and the second focus evaluation value is determined in association with the size of the high-frequency component extracted through the second high-pass filter or the second band-pass filter. A first comparison step for generating and comparing the amount of change in the second focus evaluation value with a predetermined first threshold, and the amount of change in the second focus evaluation value relative to the amount of change in the first focus evaluation value A second comparison step that compares the ratio with a predetermined second threshold, and the focus control step moves the focus lens toward the in-focus position, and the second comparison evaluation is performed by the first comparison means. Value change amount is the first threshold And the ratio of the amount of change in the second comparison means is larger than the second threshold value, it is determined that the position of the focus lens is close to the in-focus position, and the focus lens is moved at a low speed. When the change amount of the second focus evaluation value is smaller than the first threshold value in the first comparison unit, or when the ratio of the change amount is smaller than the second threshold value in the second comparison unit, By determining that the position of the focus lens is far from the in-focus position and moving the focus lens at a high speed, the moving speed of the focus lens is appropriately controlled and the in-focus time is set as in the second aspect of the invention. In addition to shortening, it is possible to suppress defocusing when the focus lens passes the in-focus position.

本発明のフォーカス装置及びフォーカス制御方法は、可変利得増幅器を介して撮像素子から出力される映像信号を積算して第一の積算値を生成し、且つ、可変利得増幅器を介して出力される映像信号の、高域成分の絶対値を積算して第二の積算値を生成すると共に、予め撮像素子を遮光した状態において可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成し、第一の積算値をL、第二の積算値をC、第三の積算値をD、可変利得増幅器の利得をG、焦点評価値をV、と表した際に、(式1)に記載の演算式を用いて焦点評価値を算出し、次いで、焦点評価値を所定の閾値と比較してフォーカスレンズの位置が合焦位置に近いか否かを判定し、この判定結果に基づいて、フォーカスレンズの位置が合焦位置に近い際にはフォーカスレンズの移動速度を低速に制御し、フォーカスレンズの位置が合焦位置から遠い際にはフォーカスレンズの移動速度を高速に制御するように構成されているので、フォーカスレンズを合焦位置に向かって移動させる際に、被写体又は撮像装置に動きが生じても、フォーカスレンズが合焦位置から近いか否かを正しく判定してフォーカスレンズの移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズが合焦位置を通り過ぎた際のピントボケを抑制できる。 The focus apparatus and the focus control method of the present invention integrate a video signal output from an image sensor through a variable gain amplifier to generate a first integrated value, and output a video through the variable gain amplifier. The absolute value of the high frequency component of the signal is integrated to generate a second integrated value, and the absolute value of the high frequency component output via the variable gain amplifier in the state where the image sensor is shielded in advance is integrated. A third integrated value is generated, and the first integrated value is expressed as L, the second integrated value as C, the third integrated value as D, the gain of the variable gain amplifier as G, and the focus evaluation value as V. At this time, the focus evaluation value is calculated using the arithmetic expression described in (Expression 1), and then the focus evaluation value is compared with a predetermined threshold value to determine whether or not the position of the focus lens is close to the in-focus position. Based on the determination result, the focus lens position is close to the in-focus position. It controls the movement speed of the focus lens at low speed in the case, since the time position of the focus lens is far from the in-focus position is configured to control the moving speed of the focus lens at high speed, focusing the focus lens When moving toward the position, even if movement occurs in the subject or the imaging device, it is correctly determined whether or not the focus lens is close to the in-focus position, and the focus lens moving speed is appropriately controlled, and the in-focus time And the out-of-focus when the focus lens passes the in-focus position can be suppressed.

次に、本発明のフォーカス装置及びフォーカス制御方法の一実施例を図面にもとづいて説明する。図1が本実施例のフォーカス装置の構成を表すブロック図、図2がフォーカス制御方法の手順を表すフローチャート、図3が図2中の評価値演算の手順を表すフローチャートである。   Next, an embodiment of the focus apparatus and focus control method of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the focusing apparatus of the present embodiment, FIG. 2 is a flowchart showing the procedure of the focus control method, and FIG. 3 is a flowchart showing the procedure of evaluation value calculation in FIG.

図1に表したように、本実施例のフォーカス装置1は、被写体(撮像信号S)を撮影してデジタル画像信号を出力する撮像部100と、撮像部100から入力したデジタル画像信号を用いて被写体の合焦度(焦点合せのためのパラメータ)を検出し、フォーカスレンズ6を光軸Xに沿って移動させ、被写体像の焦点が合うように、フォーカスレンズ6の位置を調整するフォーカス制御部200とによって構成されている。   As shown in FIG. 1, the focus apparatus 1 of the present embodiment uses an imaging unit 100 that captures a subject (imaging signal S) and outputs a digital image signal, and a digital image signal input from the imaging unit 100. A focus control unit that detects the degree of focus (parameter for focusing) of the subject, moves the focus lens 6 along the optical axis X, and adjusts the position of the focus lens 6 so that the subject image is focused. 200.

撮像部100には、前部レンズ2、ズームレンズ3、Iris(絞り)4、手ぶれ補正のための補正レンズ5、フォーカスレンズ6、有害な赤外線及び有害な反射光などを除去するフィルタ(赤外線除去フィルタや光学フィルタである)7、撮像素子(CCD:Charge Coupled Devices)8、撮像素子8から出力されるアナログ画像信号をデジタル画像信号に変換して出力するAFE(Analog Front End)9、ズームレンズ3の光軸方向の駆動を行うズーム駆動部13、センサ14aを介してズームレンズ3のスライド量を検出する検出部14、Iris4の駆動を行うIris駆動部15、Iris4の駆動量を検出する検出部16、フォーカスレンズ6の光軸方向のスライド駆動を行うフォーカス駆動部17、センサ18aを介してフォーカスレンズ6のスライド量を検出する検出部18、撮像素子8及びAFE9を所定の周期で制御するTG(Timing Generator)19、シャッタ43等が備えられている。   The imaging unit 100 includes a front lens 2, a zoom lens 3, an iris (aperture) 4, a correction lens 5 for correcting camera shake, a focus lens 6, a filter for removing harmful infrared rays and harmful reflected light (infrared removal). 7 which is a filter or an optical filter, an image pickup device (CCD: Charge Coupled Devices) 8, an analog image signal output from the image pickup device 8 is converted into a digital image signal, and an AFE (Analog Front End) 9 is output. 3 for driving in the optical axis direction, a detecting unit 14 for detecting the slide amount of the zoom lens 3 via the sensor 14a, an Iris driving unit 15 for driving Iris4, and a detection for detecting the driving amount of Iris4. Focus that performs slide drive in the optical axis direction of the unit 16 and the focus lens 6 Pivot portion 17, TG (Timing Generator) 19 for controlling the detection unit 18, the imaging device 8 and AFE9 for detecting the slide amount of the focus lens 6 through the sensor 18a at a predetermined period, the shutter 43 and the like are provided.

撮像素子8は、複数の光電変換素子がマトリクス状に並設され、夫々の光電変換素子毎に撮像信号Sを光電変換してアナログ画像信号を出力するように構成されている。   The imaging element 8 is configured such that a plurality of photoelectric conversion elements are arranged in a matrix, and the imaging signal S is photoelectrically converted for each photoelectric conversion element to output an analog image signal.

また、撮像素子8は、光電変換素子に対応付けてR(赤)G(緑)B(青)3色のBayer配列からなるカラーフィルター(図示せず)を備え、各色のフィルタ部を通過した光量を電気信号に変換して出力する。   Further, the image sensor 8 includes a color filter (not shown) composed of a Bayer array of R (red), G (green), and B (blue) colors in association with the photoelectric conversion elements, and has passed through the filter portions of the respective colors. The light quantity is converted into an electrical signal and output.

AFE9は、撮像素子8を介して出力されたアナログ画像信号に対してノイズを除去する相関二重サンプリング回路(CDS:Corelated Double Sampling)10、相関二重サンプリング回路10で相関二重サンプリングされた画像信号を増幅する可変利得増幅器(AGC:Automatic Gain Control)11、可変利得増幅器11を介して入力された撮像素子8からのアナログ画像信号をデジタル画像信号に変換するA/D変換器12、等によって構成され、撮像素子8から出力された画像信号を、所定のサンプリング周波数でデジタル画像信号に変換し、フォーカス制御部200に出力する。   The AFE 9 is a correlated double sampling circuit (CDS: Correlated Double Sampling) 10 that removes noise from an analog image signal output via the image sensor 8, and an image that has been correlated double sampled by the correlated double sampling circuit 10. A variable gain amplifier (AGC) 11 that amplifies the signal, an A / D converter 12 that converts an analog image signal from the image sensor 8 input via the variable gain amplifier 11 into a digital image signal, and the like The image signal configured and output from the image sensor 8 is converted into a digital image signal at a predetermined sampling frequency and output to the focus control unit 200.

撮像部100は、撮像素子8、相関二重サンプリング回路10、可変利得増幅器11、A/D変換器12等に代えて、CMOS(Complementary Metal Oxide Semiconductor)センサを用いて構成してもよい。   The imaging unit 100 may be configured using a CMOS (Complementary Metal Oxide Semiconductor) sensor instead of the imaging device 8, the correlated double sampling circuit 10, the variable gain amplifier 11, the A / D converter 12, and the like.

次に、フォーカス制御部200は、撮像部100から入力されたデジタル画素信号に基づいて輝度信号(所謂、本発明における映像信号である)を生成する輝度信号生成部21、所定の画像領域における輝度信号(所謂、可変利得増幅器11を介して撮像素子8から出力される映像信号である)を積算する映像信号積算手段22、輝度信号の高域成分を抽出する高域成分抽出手段23、高域成分抽出手段23で抽出された輝度信号の絶対値を積算する高域成分積算手段26、映像信号積算手段22及び高域成分積算手段26で生成された積算値に基づいて被写体像の合焦度の焦点評価値を生成する評価値生成手段29、評価値生成手段29で生成された焦点評価値に基づいてフォーカスレンズ6の移動及び移動速度を制御するフォーカス制御手段32、CPU(Central Processing Unit)40、ROM(Read Only Memory)41等によって構成され、CPU40がROM41に格納された制御用プログラムに従って、当該フォーカス制御部200の各処理を制御する。
Next, the focus control unit 200 generates a luminance signal (a so-called video signal in the present invention) based on the digital pixel signal input from the imaging unit 100, and luminance in a predetermined image area. Video signal integration means 22 for integrating signals (so-called video signals output from the image sensor 8 via the variable gain amplifier 11 ), high-frequency component extraction means 23 for extracting high-frequency components of the luminance signal, high-frequency The focus degree of the subject image based on the integrated values generated by the high frequency component integrating means 26, the video signal integrating means 22 and the high frequency component integrating means 26 for integrating the absolute values of the luminance signals extracted by the component extracting means 23. Evaluation value generation means 29 for generating the focus evaluation value of the lens, and focus control for controlling the movement and moving speed of the focus lens 6 based on the focus evaluation value generated by the evaluation value generation means 29 Is constituted by a step 32, CPU (Central Processing Unit) 40, ROM (Read Only Memory) 41 or the like, CPU 40 is in accordance with the stored control program in ROM 41, controls each processing of the focus control unit 200.

なお、本発明における第一積算手段が映像信号積算手段22によってその機能が発現され、本発明における第二積算手段が高域成分抽出手段23及び高域成分積算手段26によってその機能が発現され、本発明における評価値生成手段が評価値生成手段29によってその機能が発現される。   The function of the first integrating means in the present invention is expressed by the video signal integrating means 22, and the function of the second integrating means in the present invention is expressed by the high frequency component extracting means 23 and the high frequency component integrating means 26, The function of the evaluation value generation means in the present invention is expressed by the evaluation value generation means 29.

輝度信号生成部21は、撮像素子8のBayer配列に対応つけて、所定のサンプリング毎に、隣接する縦2画素および横2画素の4画素を1単位とする輝度信号を順次生成する。   The luminance signal generation unit 21 sequentially generates a luminance signal in which four adjacent pixels of two vertical pixels and two horizontal pixels are taken as one unit every predetermined sampling in association with the Bayer array of the image sensor 8.

高域成分抽出手段23は、映像信号の高域成分を抽出する、低域遮断周波数の異なる2つの、第一のハイパスフィルタ24及び第二のハイパスフィルタ25によって構成されている。詳しくは、第一のハイパスフィルタ24の低域遮断周波数が、輝度信号のナイキスト周波数の1/16程度の周波数に設定され、第二のハイパスフィルタ25の低域遮断周波数が、輝度信号のナイキスト周波数の1/4程度の周波数に設定されている。   The high-frequency component extracting unit 23 includes two first high-pass filters 24 and 25 that extract high-frequency components of the video signal and have different low-frequency cutoff frequencies. Specifically, the low-frequency cutoff frequency of the first high-pass filter 24 is set to a frequency that is approximately 1/16 of the Nyquist frequency of the luminance signal, and the low-frequency cutoff frequency of the second high-pass filter 25 is the Nyquist frequency of the luminance signal. Is set to about 1/4 of the frequency.

高域成分積算手段26は、第一のハイパスフィルタ24から出力された高域成分を積算する第二積算手段27と、第二のハイパスフィルタ25から出力された高域成分を積算する第三積算手段28によって構成されている。   The high-frequency component integrating unit 26 integrates the high-frequency component output from the first high-pass filter 24 and the second integrating unit 27 that integrates the high-frequency component output from the second high-pass filter 25. It is constituted by means 28.

ここで、映像信号積算手段(第一積算手段)22、第二積算手段27、第三積算手段28における積算領域は、予め定められた共通の画像領域である。また、これらの積算周期は、撮像素子8から出力されるフレーム周期に対応付けられており、フレーム周期に依存して更新される。   Here, the integration areas in the video signal integration means (first integration means) 22, the second integration means 27, and the third integration means 28 are predetermined common image areas. Further, these integration cycles are associated with the frame cycle output from the image sensor 8 and are updated depending on the frame cycle.

評価値生成手段29は、第二積算手段27で積算された高域成分の積算値に対応つけて(所謂、第一のハイパスフィルタを通過して抽出された高域成分の大きさに対応つけられる)第一の焦点評価値を生成する第一評価値生成手段30と、第三積算手段28で積算された高域成分の積算値に対応つけて(所謂、第二のハイパスフィルタを通過して抽出された高域成分の大きさに対応つけられる)第二の焦点評価値を生成する第二評価値生成手段31と、によって構成されている。
The evaluation value generation means 29 associates with the integrated value of the high frequency component integrated by the second integration means 27 (corresponds to the size of the high frequency component extracted through the so-called first high pass filter. The first evaluation value generating means 30 for generating the first focus evaluation value and the integrated value of the high frequency component integrated by the third integrating means 28 (passing the so-called second high-pass filter) And second evaluation value generating means 31 for generating a second focus evaluation value ( corresponding to the size of the high frequency component extracted in this manner).

詳しくは、第一焦点評価値をV、撮像素子8へ被写体を結像させた際に第二の積算手段27で生成した映像信号の高域周波数成分の積算値をC、撮像素子8への入射光を遮光した際に第二の積算手段27で生成した高域周波数の積算値をD映像信号積算手段22で積算された映像信号の積算値をL、可変利得増幅器11の利得をG、と表した際に、第一の焦点評価値Vを(式9)記載の演算式を用いて算出する。
Specifically, the first focus evaluation value is V 1 , the integrated value of the high frequency component of the video signal generated by the second integrating means 27 when the subject is imaged on the image sensor 8 is C 1 , and the image sensor 8. D 1 is the integrated value of the high frequency generated by the second integrating means 27 when the incident light is blocked , L is the integrated value of the video signal integrated by the video signal integrating means 22, and the variable gain amplifier 11 When the gain is expressed as G, the first focus evaluation value V 1 is calculated using the arithmetic expression described in (Expression 9).

また、第二焦点評価値をV、撮像素子8へ被写体を結像させた際に第三の積算手段28で生成した映像信号の高域周波数成分の積算値をC、撮像素子8への入射光を遮光した際に第三積算手段28で生成した高域周波数の積算値をD映像信号積算手段22で積算された映像信号の積算値をL、可変利得増幅器11の利得をG、と表した際に、第二焦点評価値Vを(式10)記載の演算式を用いて算出する。
Further, the second focus evaluation value is V 2 , and the integrated value of the high frequency component of the video signal generated by the third integrating means 28 when the subject is imaged on the image sensor 8 is C 2 . The integrated value of the high frequency generated by the third integrating means 28 when the incident light is blocked is D 2 , the integrated value of the video signal integrated by the video signal integrating means 22 is L, and the gain of the variable gain amplifier 11 is G, when expressed as calculated by using the second focus evaluation value V 2 of the arithmetic expression (expression 10), wherein.

次に、フォーカス制御手段32は、所定の周期毎に、第二評価値生成手段31で生成された第二焦点評価値Vの変化量ΔVを所定の第一の閾値THと比較する第一の比較手段33と、第一焦点評価値Vの変化量ΔVに対する第二焦点評価値Vの変化量ΔVの比を所定の第二の閾値THと比較する第二の比較手段34と、第一の比較手段33及び第二の比較手段34の比較結果に基づいてフォーカスレンズ6の移動速度を設定するフォーカス速度設定手段35と、によって構成されている。 Next, the focus control unit 32 compares the change amount ΔV 2 of the second focus evaluation value V 2 generated by the second evaluation value generation unit 31 with a predetermined first threshold value TH 1 every predetermined period. a first comparison means 33, a second comparing a second ratio of the focus evaluation value V 2 of the amount of change [Delta] V 2 with respect to the change amount [Delta] V 1 of the first focus evaluation value V 1 and the predetermined second threshold value TH 2 The comparison means 34 and a focus speed setting means 35 for setting the moving speed of the focus lens 6 based on the comparison results of the first comparison means 33 and the second comparison means 34 are configured.

また、フォーカス制御手段32は、フォーカスレンズ6を所定の方向に移動させた際に、第一の焦点評価値Vの変化量ΔVを予め定められた第三閾値THと比較し、合焦位置の向きを判定する。この際、第三閾値THは、予め、雑音に影響されて誤判定しない値に設定されている。 The focus control unit 32 compares the time of moving the focus lens 6 in a predetermined direction, and the third threshold value TH 3 defined amount of change [Delta] V 1 of the first focus evaluation value V 1 in advance, if The direction of the focal position is determined. At this time, the third threshold TH 3 is set in advance to a value that is not erroneously determined due to noise.

詳しくは、フォーカス制御手段32は、第一の焦点評価値Vの変化量ΔVが第三閾値THよりも大きい(量ΔV>TH)場合には、フォーカスレンズ6を移動させた方向に合焦位置があると判定し、第一の焦点評価値Vの変化量ΔVが第三閾値THの負の値よりも小さい(ΔV<(−TH))場合には、フォーカスレンズ6を移動させた方向の逆方向側に合焦位置があると判定し、フォーカスレンズ6を合焦位置に向かって移動させる。 Specifically, the focus control unit 32 moves the focus lens 6 when the change amount ΔV 1 of the first focus evaluation value V 1 is larger than the third threshold value TH 3 (amount ΔV 1 > TH 3 ). When it is determined that the in-focus position is in the direction, and the change amount ΔV 1 of the first focus evaluation value V 1 is smaller than the negative value of the third threshold value TH 3 (ΔV 1 <(− TH 3 )) Then, it is determined that the focus position is on the opposite side of the direction in which the focus lens 6 is moved, and the focus lens 6 is moved toward the focus position.

フォーカス速度設定手段35は、フォーカスレンズ6を合焦位置に向かって移動させる際に、第一の比較手段33において第二の焦点評価値Vの変化量ΔVが第一の閾値THよりも大きく(ΔV>TH)、且つ第二の比較手段34において変化量(ΔV/ΔV)の比が第二の閾値THよりも大きい((ΔV/ΔV)>TH)場合には、フォーカスレンズ6の位置が合焦位置に近いと判定してフォーカスレンズ6の速度を低速に設定する。また、フォーカス速度設定手段35は、低速に設定した後、第二焦点評価値ΔVが増加から減少に変化する変化点を検出し、この変化点を合焦位置としてフォーカスレンズ6の駆動を停止させる停止信号を出力する。 When the focus speed setting unit 35 moves the focus lens 6 toward the in-focus position, the change amount ΔV 2 of the second focus evaluation value V 2 in the first comparison unit 33 is greater than the first threshold value TH 1 . (ΔV 2 > TH 1 ) and the ratio of the change amount (ΔV 2 / ΔV 1 ) in the second comparison means 34 is larger than the second threshold TH 2 ((ΔV 2 / ΔV 1 )> TH 2. ), It is determined that the position of the focus lens 6 is close to the focus position, and the speed of the focus lens 6 is set to a low speed. The focus speed setting means 35 detects a changing point where the second focus evaluation value ΔV 2 changes from increasing to decreasing after setting to a low speed, and stops driving the focus lens 6 with this changing point as a focusing position. A stop signal is output.

一方、フォーカス速度設定手段35は、第一の比較手段33において第二の焦点評価値の変化量ΔVが第一閾値THよりも小さい(ΔV<TH)場合、又は、第二の比較手段33において変化量の比(ΔV/ΔV)が第二閾値よTHよりも小さい((ΔV/ΔV)<TH)場合には、フォーカスレンズ6の位置が合焦位置から遠いと判定してフォーカスレンズ6の速度を高速に設定する。 On the other hand, the focus speed setting means 35 is the first comparison means 33 when the change amount ΔV 2 of the second focus evaluation value is smaller than the first threshold TH 1 (ΔV 2 <TH 1 ), or the second When the ratio (ΔV 2 / ΔV 1 ) of the change amount is smaller than the second threshold value TH 2 ((ΔV 2 / ΔV 1 ) <TH 2 ) in the comparison unit 33, the position of the focus lens 6 is the in-focus position. The speed of the focus lens 6 is set to a high speed.

この際、第一の比較手段33において、第一閾値THは、雑音の影響を考慮し、誤判定することのない適切な値に設定されている。 In this case, in a first comparison means 33, the first threshold value TH 1 is to consider the effects of noise, is set to an appropriate value not to misjudgment.

また、第二の比較手段34において、第二閾値THは、合焦時間を短縮しつつピントボケの生じないように、適切な値に設定されている。 Further, in the second comparison means 34, the second threshold value TH 2, as does not cause out-of-focus while shortening the focusing time is set to an appropriate value.

つまり、第二閾値THを大きく設定するに従い、合焦位置の近傍でフォーカスレンズ6の速度が高速から低速に切り替わることになり、フォーカスレンズ6が合焦位置に達する時間が短くなるが、第二閾値THを大きく設定しすぎると、フォーカスレンズ6が高速で移動している間に合焦位置を通過してしまって、画像のピントボケを生じさせてしまう虞がある。 That is, in accordance with setting a large second threshold value TH 2, the speed of the focus lens 6 in the vicinity of the focus position will be switched to a low speed from the high speed, the time of the focus lens 6 reaches the focal position becomes shorter, the If two threshold TH 2 is set too large, gone through the focus position while the focusing lens 6 is moving at a high speed, there is a fear that cause defocusing of the image.

一方、第二閾値THを小さく設定しすぎると、フォーカスレンズ6が低速で移動している区間が長くなり、合焦位置に達する時間が長くなる。
On the other hand, if set too small second threshold value TH 2, the section becomes long focus lens 6 is moving at a low speed, the time to reach the in-focus position is long.

次に、CPU40は、フォーカス制御手段32で得られた結果にもとづき、フォーカス駆動部17を介して、フォーカスレンズ6の光軸方向の移動及び移動速度を制御する。   Next, the CPU 40 controls the movement and movement speed of the focus lens 6 in the optical axis direction via the focus driving unit 17 based on the result obtained by the focus control means 32.

次に、図2、図3に基づいて、フォーカス装置1における、フォーカスレンズ6の駆動制御の手順を説明する。この手順は、CPU40がROM41に格納されたプログラムにもとづいて、各機能部に指令信号を与えて実行する。また、図2、図3におけるSはステップを表している。   Next, based on FIG. 2 and FIG. 3, a procedure for driving control of the focus lens 6 in the focus device 1 will be described. This procedure is executed by giving a command signal to each functional unit based on a program stored in the ROM 41 by the CPU 40. Moreover, S in FIG. 2, FIG. 3 represents the step.

まず、この手順は、オペレータによってフォーカス装置1に起動信号が入力された際にスタートする。   First, this procedure starts when an activation signal is input to the focus device 1 by the operator.

次いで、図1に表したように、S100において、以前に演算されたフォーカス制御のためのデータ(輝度データ、積算値、焦点評価値等)を消去して初期化し、その後、S110に移る。   Next, as shown in FIG. 1, in S100, the previously calculated data for focus control (luminance data, integrated value, focus evaluation value, etc.) are deleted and initialized, and then the process proceeds to S110.

次いで、S110において、CPU40が、オペレータが選択した撮影条件に基づき、ROM41を介して焦点合せのための画素領域及びその画素領域における読み出し開始位置を取得するとともに、フォーカス制御のための閾値TH〜THを取得し、その後S120に移る。 Then, in S110, CPU 40, based on the shooting condition selected by the operator, acquires the read start position in the pixel region and the pixel region for focusing through the ROM 41, the threshold value TH 1 ~ for focus control TH 3 is acquired, and then the process proceeds to S120.

次いで、S120において、撮像部100を用いて被写体像の撮影を開始し、Bayer配列に対応つけて画素信号を読み込み、その後、S130に移る。   Next, in S120, shooting of the subject image is started using the imaging unit 100, and pixel signals are read in association with the Bayer array, and then the process proceeds to S130.

次いで、S130において、フォーカスレンズ6を、予め定められた低速度で、所定の光軸方向に沿って駆動させ、その後、S140に移り、焦点評価値の演算を行う。   Next, in S130, the focus lens 6 is driven along a predetermined optical axis direction at a predetermined low speed, and thereafter, the process proceeds to S140 to calculate a focus evaluation value.

焦点評価値の演算は、図3に表したように、S141において、撮像部100から出力される1フレーム毎の出力周期に対応付けられた同期信号の有無(同期信号とのマッチング)を判定し、同期信号が無い(No)場合には、同期信号があるまで待機し、同期信号が有った(Yes)場合には、S142に移る。   As shown in FIG. 3, in the calculation of the focus evaluation value, in S141, the presence / absence of a synchronization signal (matching with the synchronization signal) associated with the output period for each frame output from the imaging unit 100 is determined. If there is no synchronization signal (No), the process waits until there is a synchronization signal. If there is a synchronization signal (Yes), the process proceeds to S142.

次いで、S142において、輝度信号生成部21を用い、撮像素子8のBayer配列に対応つけて、所定のサンプリング毎に、隣接する縦2画素および横2画素の4画素を1単位とする輝度信号を生成し、その後、S143に移る。   Next, in S142, the luminance signal generation unit 21 is used to correspond to the Bayer array of the image sensor 8, and for each predetermined sampling, a luminance signal having 4 pixels of 2 vertical pixels and 2 horizontal pixels as one unit is generated. After that, the process proceeds to S143.

次いで、S143において、映像信号積算手段22を用い、所定の画像領域における輝度信号を積算して第一の積算値Lを求め、その後、S144に移る。   Next, in S143, the video signal integrating means 22 is used to integrate the luminance signals in a predetermined image area to obtain the first integrated value L, and then the process proceeds to S144.

次いで、S144において、高域成分積算手段26を用い、第一ハイパスフィルタ24を介して生成された映像信号の高周波成分の絶対値の積算値Cを生成すると共に、第二ハイパスフィルタ25を介して生成された映像信号の高周波成分の絶対値の積算値Cを生成し、その後、S145に移る。 Then, in S144, and generates an integrated value C 1 of the absolute value of the high-frequency component of the high band using the components integrating means 26, a video signal generated through a first high pass filter 24, via a second high-pass filter 25 generating an integrated value C 2 of the absolute value of the high-frequency component of the generated video signal Te, then it proceeds to S145.

次いで、S145において、あらかじめ撮像素子8への入射光を遮光した状態で高域成分積算手段26を用いて算出しておいた、第一ハイパスフィルタ24を介して生成された読み出し雑音の高周波成分の絶対値の積算値Dおよび、第二ハイパスフィルタ25を介して生成された読み出し雑音の高周波成分の絶対値の積算値DをROM41より読み出し、その後、S146に移る。なお、積算値Dおよび積算値Dを算出したときの可変利得増幅器11の利得と、現在の可変利得増幅器11の利得とが異なる場合は、高域成分積算手段26で積算される読み出し雑音の高周波成分の絶対値は可変利得増幅器11の利得は比例するものとして、積算値Dおよび積算値Dの値を補正する。 Next, in S145, the high-frequency component of the readout noise generated through the first high-pass filter 24, which is calculated using the high-frequency component integrating unit 26 in a state where the incident light to the image sensor 8 is shielded in advance. integrated value D 1 and the absolute value, the absolute value of the integrated value D 2 read from the ROM41 of the high-frequency component of the second high-pass filter 25 reads the noise generated through, then proceeds to S146. In the case where the gain of the variable gain amplifier 11 when the calculated integrated value D 1 and the integrated value D 2, and the gain of the current of the variable gain amplifier 11 is different from the read noise to be integrated in the high-frequency component integrating means 26 the absolute value of the high frequency component gain of the variable gain amplifier 11 as proportional, to correct the value of the integrated value D 1 and the integrated value D 2.

次いで、S146において、第一評価値生成手段30を用い、(式9)の演算式によって第一の焦点評価値Vを算出すると共に、(式10)の演算式によって第二の焦点評価値Vを算出し、その後、図2のS150に移る。 Then, in S146, using the first evaluation value generating unit 30, and calculates the first focus evaluation value V 1 by the arithmetic equation of (Equation 9), a second focus evaluation value by the calculation formula (Equation 10) calculates V 2, then moves to S150 in FIG.

次いで、S150において、フォーカス制御手段32を用い、第一の焦点評価値Vの変化量ΔVが第三閾値THよりも大きい(量ΔV>TH)場合には、フォーカスレンズ6を移動させた方向に合焦位置があると判定し、第一の焦点評価値Vの変化量ΔVが第三閾値THの負の値よりも小さい(ΔV<(−TH))場合には、フォーカスレンズ6を移動させた方向の逆方向側に合焦位置があると判定し、フォーカスレンズ6を合焦位置に向かって移動させる。 Then, in S150, using the focus control unit 32, when the first change amount [Delta] V 1 of the focus evaluation value V 1 is greater than the third threshold value TH 3 (amount ΔV 1> TH 3) is a focusing lens 6 It is determined that the in-focus position is in the moved direction, and the change amount ΔV 1 of the first focus evaluation value V 1 is smaller than the negative value of the third threshold value TH 3 (ΔV 1 <(− TH 3 )). In this case, it is determined that the focus position is on the opposite side of the direction in which the focus lens 6 is moved, and the focus lens 6 is moved toward the focus position.

次いで、S160において、S141〜S146と同一の手順を繰り返し、その後、S170に移る。   Next, in S160, the same procedure as in S141 to S146 is repeated, and then the process proceeds to S170.

次いで、S170において、所定の周期毎に、S146で算出された第二焦点評価値Vの変化量ΔVを第一の閾値THと比較すると共に、第一焦点評価値Vの変化量ΔVに対する第二焦点評価値Vの変化量ΔVの比(ΔV/ΔV)を所定の第二の閾値THと比較して、ΔV>TH、(ΔV/ΔV)>THの両方の条件を満足するか否かを判定し、満足する(Yes)場合には、S180に移る。 Then, at S170, at every predetermined period, the second focus evaluation value V 2 of the amount of change [Delta] V 2 while comparing with the first threshold value TH 1, the amount of change in the first focus evaluation value V 1 calculated in S146 compared second focus ratio of the evaluation value V 2 of the amount of change [Delta] V 2 relative to [Delta] V 1 a (ΔV 2 / ΔV 1) and the predetermined second threshold value TH 2, ΔV 2> TH 1 , (ΔV 2 / ΔV 1 )> TH 2 It is determined whether or not both conditions are satisfied. If satisfied (Yes), the process proceeds to S180.

一方、S170において、ΔV>TH、(ΔV/ΔV)>THのうちの少なくとも何れかを満足しない(No)場合には、S171に移り、フォーカスレンズ6の移動速度を予め定められた高速に設定し、その後、S160〜S170を繰り返し、S170においてΔV>TH、(ΔV/ΔV)>THの両方の条件を満足した際にS180に移る。 On the other hand, if at least one of ΔV 2 > TH 1 and (ΔV 2 / ΔV 1 )> TH 2 is not satisfied (No) in S170, the process proceeds to S171, and the moving speed of the focus lens 6 is determined in advance. After that, S160 to S170 are repeated, and when both conditions of ΔV 2 > TH 1 and (ΔV 2 / ΔV 1 )> TH 2 are satisfied in S170, the process proceeds to S180.

次いで、S180において、フォーカスレンズ6の移動速度を予め定められた低速に設定し、その後、S190において前述のS141〜S146と同一の処理を行う。   Next, in S180, the moving speed of the focus lens 6 is set to a predetermined low speed, and then the same processing as S141 to S146 described above is performed in S190.

次いで、S200において、第二焦点評価値の変化量ΔVが正から負に切り替わる変化の有無を判定し、負に切り替わる変化が有る(Yes)の場合には、その後、S210に移る。一方、S200において負に切り替わる変化が無い(No)の場合には、S190からS200を繰り返し、S200において負に切り替わる変化が有る(Yes)と判定された場合に、S210に移る。 Then, in S200, if the change amount [Delta] V 2 of the second focus evaluating value determines the presence of the changes is switched from positive to negative, the change there to switch to negative (Yes), then it proceeds to S210. On the other hand, if there is no change to be negative in S200 (No), S190 to S200 are repeated, and if it is determined that there is a change to be negative in S200 (Yes), the process proceeds to S210.

次いで、S210において、フォーカスレンズ6が合焦位置に至ったとし、フォーカスレンズ6の駆動を停止し、本フォーカス制御処理の手順を終了する。   Next, in S210, assuming that the focus lens 6 has reached the in-focus position, the drive of the focus lens 6 is stopped, and the procedure of this focus control process is terminated.

なお、本発明における第一積算値生成ステップがS143によってその機能が発現され、本発明における第二積算値生成ステップがS144によってその機能が発現され、本発明における第三積算値生成ステップがS145によってその機能が発現される。   The function of the first integrated value generation step in the present invention is expressed by S143, the function of the second integrated value generation step in the present invention is expressed by S144, and the third integrated value generation step in the present invention is performed by S145. Its function is expressed.

また、本発明における評価値生成ステップがS146によってその機能が発現され、本発明におけるフォーカス制御ステップがS160〜S210によってその機能が発現される。   Further, the function of the evaluation value generation step in the present invention is expressed by S146, and the function of the focus control step in the present invention is expressed by S160 to S210.

以上、本実施例に記載のフォーカス装置1及びフォーカス制御方法によれば、映像信号積算手段22において、可変利得増幅器11を介して出力される映像信号を積算して第一の積算値Lを生成し、高域成分積算手段26において、可変利得増幅器11を介して出力される映像信号の高域成分の絶対値を積算して第二の積算値Cを生成すると共に、可変利得増幅器11を介して出力される読み出し雑音の高域成分の絶対値を積算して第三の積算値Dを生成し、評価値生成手段29が、第二の積算値Cと第三の積算値Dとの差分に対して、第一の積算値L及び可変利得増幅器11に設定された利得Gで除算し、焦点評価値Vを生成するように構成されているので、フォーカスレンズ6を合焦位置に向かって移動させる際に、被写体又は撮像部100に動きが生じても、フォーカスレンズ6が合焦位置から近いか否かを正しく判定してフォーカスレンズ6の移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズ6が合焦位置を通り過ぎた際のピントボケを抑制できる。
As described above, according to the focus apparatus 1 and the focus control method described in the present embodiment, the video signal integration means 22 integrates the video signal output through the variable gain amplifier 11 to generate the first integrated value L. Then, the high frequency component integrating means 26 integrates the absolute value of the high frequency component of the video signal output through the variable gain amplifier 11 to generate the second integrated value C, and also through the variable gain amplifier 11. The third integrated value D is generated by integrating the absolute value of the high frequency component of the readout noise that is output , and the evaluation value generating means 29 calculates the difference between the second integrated value C and the third integrated value D. On the other hand, since the focus evaluation value V is generated by dividing the first integrated value L by the gain G set in the variable gain amplifier 11 , the focus lens 6 is moved toward the in-focus position. When moving, subject or imaging unit 1 0 even if motion, with the focus lens 6 is short or not is determined from the in-focus position correctly appropriately controls the movement speed of the focus lens 6 can be shortened focusing time, the focus lens 6 Conjunction It is possible to suppress out-of-focus blur when passing through the focal position.

また、本実施例に記載のフォーカス装置1及びフォーカス制御方法によれば、フォーカスレンズ6を合焦位置に向かって移動させる際に、第一の比較手段33において第二の焦点評価値の変化量ΔVが第一の閾値THよりも大きく、且つ第二の比較手段34において変化量の比(ΔV/ΔV)が第二の閾値THよりも大きい場合には、フォーカスレンズ6の位置が合焦位置に近いと判定してフォーカスレンズ6を低速で移動させ、一方、第一の比較手段33において第二の焦点評価値の変化量ΔVが第一の閾値THよりも小さい場合、又は、第二の比較手段34において変化量の比(ΔV/ΔV)が第二の閾値THよりも小さい場合には、フォーカスレンズ6の位置が合焦位置から遠いと判定して前記フォーカスレンズ6を高速で移動させることにより、フォーカスレンズ6の移動速度を適切に制御し、合焦時間を短縮できると共に、フォーカスレンズ6が合焦位置を通り過ぎた際のピントボケを抑制できる。 Further, according to the focus device 1 and the focus control method described in the present embodiment, when the focus lens 6 is moved toward the in-focus position, the first comparison unit 33 changes the second focus evaluation value. When ΔV 2 is larger than the first threshold value TH 1 and the ratio of change (ΔV 2 / ΔV 1 ) is larger than the second threshold value TH 2 in the second comparison unit 34, It is determined that the position is close to the in-focus position, and the focus lens 6 is moved at a low speed. On the other hand, the change amount ΔV 2 of the second focus evaluation value is smaller than the first threshold value TH 1 in the first comparison unit 33. In the case where the ratio (ΔV 2 / ΔV 1 ) of the amount of change is smaller than the second threshold value TH 2 in the second comparison unit 34, it is determined that the position of the focus lens 6 is far from the in-focus position. The focus By moving the lens 6 at a high speed, by appropriately controlling the movement speed of the focus lens 6, it is possible to shorten the focusing time can be suppressed defocusing when the focus lens 6 has passed the focus position.

以上、本発明の一実施例について説明したが、本発明は、前記実施例に限定されるものでなく、各種の態様を取ることができる。   As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, Various aspects can be taken.

本実施例のフォーカス装置の構成を表すブロック図である。It is a block diagram showing the structure of the focus apparatus of a present Example. 同実施例のフォーカス制御方法の手順を表すフローチャートである。It is a flowchart showing the procedure of the focus control method of the embodiment. 図2中の評価値演算の手順を表すフローチャートである。It is a flowchart showing the procedure of the evaluation value calculation in FIG.

符号の説明Explanation of symbols

1…フォーカス装置、2…前部レンズ、3…ズームレンズ、4…Iris、5…補正レンズ、6…フォーカスレンズ、7…フィルタ、8…撮像素子、9…AFE(Analog Front End)、10…相関二重サンプリング回路、11…可変利得増幅器(AGC:Automatic Gain Control)、12…A/D変換器、13…ズーム駆動部、14…検出部、15…Iris駆動部、16…検出部、17…フォーカス駆動部、18…検出部、19…TG(Timing Generator)、21…輝度信号生成部、22…映像信号積算手段(第一積算手段)、23…高域成分抽出手段、24…第一ハイパスフィルタ(HPF)、25…第二ハイパスフィルタ(HPF)、26…高域成分積算手段、27…第二積算手段、28…第三積算手段、29…評価値生成手段、30…第一評価値生成手段、31…第二評価値生成手段、32…フォーカス制御手段、33…第一の比較手段、34…第二の比較手段、35…フォーカス速度設定手段、40…CPU(Central Processing Unit)41…ROM(Read Only Memory)、43…シャッタ。 DESCRIPTION OF SYMBOLS 1 ... Focus apparatus, 2 ... Front lens, 3 ... Zoom lens, 4 ... Iris, 5 ... Correction lens, 6 ... Focus lens, 7 ... Filter, 8 ... Image sensor, 9 ... AFE (Analog Front End), 10 ... Correlated double sampling circuit, 11... Variable gain amplifier (AGC), 12... A / D converter, 13... Zoom drive unit, 14... Detection unit, 15. ... Focus driving unit, 18... Detecting unit, 19... TG (Timing Generator), 21 .. luminance signal generating unit, 22... Video signal integrating unit (first integrating unit), 23. High-pass filter (HPF), 25 ... second high-pass filter (HPF), 26 ... high-frequency component integrating means, 27 ... second integrating means 28 ... third integrating means, 29 ... evaluation value generation means, 30 ... first evaluation value generation means, 31 ... second evaluation value generation means, 32 ... focus control unit, 33 ... first comparison means, 34 ... second comparison means, 35 ... focus speed setting means, 40 ... CPU (Central Processing unit ) 41 ... ROM (Read Only Memory), 43 ... shutter.

Claims (4)

光軸方向に沿ってスライド自在に設置されたフォーカスレンズと、被写体像からの光を映像信号に変換する撮像素子と、前記撮像素子から出力される出力信号を増幅する可変利得増幅器と、前記撮像素子に結像した被写体像の合焦度の焦点評価値を生成する評価値生成手段と、前記焦点評価値に応じて、前記フォーカスレンズを光軸方向にスライドさせて前記撮像素子に結像する被写体像の焦点あわせを行うフォーカス制御手段と、
を備えたフォーカス装置において、
前記可変利得増幅器を介して出力される前記映像信号を積算して第一の積算値を生成する第一積算手段と、
前記可変利得増幅器を介して出力される前記映像信号の高域成分の絶対値を積算する第二積算手段と、を備え、
前記第二積算手段において、前記可変利得増幅器を介して出力される前記映像信号の高域成分の絶対値を積算して第二の積算値を生成すると共に、予め前記撮像素子への入射光を遮光した状態において、前記可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成し、
前記評価値生成手段が、前記第一の積算値をL、前記第二の積算値をC、前記第三の積算値をD、前記可変利得増幅器の利得をG、前記焦点評価値をV、と表した際に、(式1)に記載の演算式を用いて前記焦点評価値を算出し、
前記フォーカス制御手段が、該焦点評価値を所定の閾値と比較して前記フォーカスレンズの位置が合焦位置に近いか否かを判定し、該判定結果に基づいて、前記フォーカスレンズの位置が合焦位置に近い場合には、前記フォーカスレンズの移動速度を合焦位置から遠い場合よりも低速に制御し、前記フォーカスレンズの位置が合焦位置から遠い場合には、前記フォーカスレンズの移動速度を合焦位置に近い場合よりも高速に制御する、
ことを特徴とするフォーカス装置。
A focus lens that is slidable along the optical axis direction, an imaging device that converts light from a subject image into a video signal, a variable gain amplifier that amplifies an output signal output from the imaging device, and the imaging An evaluation value generating means for generating a focus evaluation value of the degree of focus of the subject image formed on the element, and the focus lens is slid in the optical axis direction according to the focus evaluation value to form an image on the image sensor. A focus control means for focusing the subject image;
In a focusing device with
First integrating means for integrating the video signals output through the variable gain amplifier to generate a first integrated value;
Second integrating means for integrating the absolute value of the high frequency component of the video signal output through the variable gain amplifier,
In the second integrating means, the absolute value of the high frequency component of the video signal output through the variable gain amplifier is integrated to generate a second integrated value, and the incident light to the image sensor is preliminarily generated. In a light-shielded state, the absolute value of the high frequency component output through the variable gain amplifier is integrated to generate a third integrated value,
The evaluation value generating means is configured such that the first integrated value is L, the second integrated value is C, the third integrated value is D, the gain of the variable gain amplifier is G, the focus evaluation value is V, When calculating the focus evaluation value using the arithmetic expression described in (Expression 1),
The focus control means compares the focus evaluation value with a predetermined threshold value to determine whether or not the position of the focus lens is close to the focus position, and based on the determination result, the position of the focus lens is adjusted. When the focus lens is close to the focus position, the moving speed of the focus lens is controlled to be lower than when the focus lens is far from the focus position, and when the focus lens position is far from the focus position, the focus lens moving speed is controlled. Control faster than near the in-focus position,
Focus device characterized by that.
前記第二積算手段が、
前記映像信号の高域成分を抽出する、低域遮断周波数の異なる2つのハイパスフィルタ又はバンドパスフィルタを備え、
前記評価値生成手段が、
前記2つのハイパスフィルタ又はバンドパスフィルタの内で、低域遮断周波数の低い方を第一のハイパスフィルタ又は第一のバンドパスフィルタとし、他方を第二のハイパスフィルタ又は第二のバンドパスフィルタとした際に、
前記第一のハイパスフィルタ又は第一のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第一の焦点評価値を生成すると共に、前記第二のハイパスフィルタ又は第二のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第二の焦点評価値を生成し、
前記第二の焦点評価値の変化量を所定の第一の閾値と比較する第一の比較手段と、前記第一の焦点評価値の変化量に対する第二の焦点評価値の変化量の比を所定の第二の閾値と比較する第二の比較手段と、を備え、
前記フォーカス制御手段が、
前記フォーカスレンズを合焦位置に向かって移動させる際に、
前記第一の比較手段において第二の焦点評価値の変化量が第一の閾値よりも大きく、且つ第二の比較手段において前記変化量の比が第二の閾値よりも大きい場合には、前記フォーカスレンズの位置が合焦位置に近いと判定して前記フォーカスレンズを低速で移動させ、一方、前記第一の比較手段において前記第二の焦点評価値の変化量が前記第一の閾値よりも小さい場合、又は、第二の比較手段において前記変化量の比が第二の閾値よりも小さい場合には、前記フォーカスレンズの位置が合焦位置から遠いと判定して前記フォーカスレンズを高速で移動させる、ことを特徴とするとする請求項1に記載のフォーカス装置。
The second integrating means is
Two high-pass filters or band-pass filters with different low-frequency cut-off frequencies for extracting the high-frequency component of the video signal,
The evaluation value generating means
Of the two high-pass filters or band-pass filters, the one with the lower low-frequency cutoff is the first high-pass filter or first band-pass filter, and the other is the second high-pass filter or second band-pass filter. When
A first focus evaluation value is generated in correspondence with the magnitude of the high-frequency component extracted through the first high-pass filter or the first band-pass filter, and the second high-pass filter or second The second focus evaluation value is generated in correspondence with the size of the high-frequency component extracted through the band-pass filter of
A first comparing means for comparing the amount of change in the second focus evaluation value with a predetermined first threshold; and a ratio of the amount of change in the second focus evaluation value to the amount of change in the first focus evaluation value. A second comparison means for comparing with a predetermined second threshold,
The focus control means
When moving the focus lens toward the in-focus position,
When the change amount of the second focus evaluation value is larger than the first threshold value in the first comparison unit and the ratio of the change amount is larger than the second threshold value in the second comparison unit, It is determined that the position of the focus lens is close to the in-focus position, and the focus lens is moved at a low speed. On the other hand, the change amount of the second focus evaluation value in the first comparison unit is smaller than the first threshold value. If it is small, or if the ratio of the amount of change is smaller than the second threshold in the second comparison means, it is determined that the position of the focus lens is far from the in-focus position, and the focus lens is moved at high speed. The focusing apparatus according to claim 1, wherein
光軸方向に沿ってスライド自在に設置されたフォーカスレンズと、被写体像からの光を映像信号に変換する撮像素子と、前記撮像素子から出力される出力信号を増幅する可変利得増幅器とを備えた撮像装置のフォーカス制御方法であって、
前記可変利得増幅器を介して出力される映像信号を積算して第一の積算値を生成する第一積算値生成ステップと、
前記可変利得増幅器を介して出力される前記映像信号の高域成分の絶対値を積算して第二の積算値を生成する第二積算値生成ステップと、
予め前記撮像素子への入射光を遮光した状態において、前記可変利得増幅器を介して出力される高域成分の絶対値を積算して第三の積算値を生成する第三積算値生成ステップと、
前記第一の積算値をL、前記第二の積算値をC、前記第三の積算値をD、前記可変利得増幅器の利得をG、前記焦点評価値をV、と表した際に、(式2)に記載の演算式を用いて、前記撮像素子に結像した前記被写体像の焦点評価値を生成する評価値生成ステップと、
前記焦点評価値を所定の閾値と比較して前記フォーカスレンズの位置が合焦位置に近いか否かを判定し、該判定結果に基づいて、前記フォーカスレンズの位置が合焦位置に近い場合には、前記フォーカスレンズの移動速度を合焦位置から遠い場合よりも低速に制御し、前記フォーカスレンズの位置が合焦位置から遠い場合には、前記フォーカスレンズの移動速度を合焦点位置に近い場合よりも高速に制御するフォーカス制御ステップと、
を備えることを特徴とするフォーカス制御方法。
A focus lens installed slidably along the optical axis direction, an image sensor that converts light from a subject image into a video signal, and a variable gain amplifier that amplifies an output signal output from the image sensor A focus control method for an imaging apparatus,
A first integrated value generating step of generating a first integrated value by integrating the video signal output through the variable gain amplifier;
A second integrated value generating step of generating a second integrated value by integrating the absolute value of the high frequency component of the video signal output through the variable gain amplifier;
A third integrated value generating step for generating a third integrated value by integrating the absolute value of the high frequency component output through the variable gain amplifier in a state where the incident light to the image sensor is shielded in advance ;
When the first integrated value is expressed as L, the second integrated value as C, the third integrated value as D, the gain of the variable gain amplifier as G, and the focus evaluation value as V, An evaluation value generating step for generating a focus evaluation value of the subject image formed on the image sensor using the arithmetic expression described in Equation 2) ;
The focus evaluation value is compared with a predetermined threshold value to determine whether or not the position of the focus lens is close to the focus position. Based on the determination result, when the position of the focus lens is close to the focus position Controls the moving speed of the focus lens at a lower speed than when it is far from the in-focus position, and when the position of the focus lens is far from the in-focus position, the moving speed of the focus lens is close to the in-focus position. Focus control step to control faster than ,
A focus control method comprising:
前記第二積算ステップにおいて、前記映像信号の高域成分を抽出する、低域遮断周波数の異なる2つのハイパスフィルタ又はバンドパスフィルタを用い、
前記評価値生成ステップにおいて、
前記2つのハイパスフィルタ又はバンドパスフィルタの内で、低域遮断周波数の低い方を第一のハイパスフィルタ又は第一のバンドパスフィルタとし、他方を第二のハイパスフィルタ又は第二のバンドパスフィルタとした際に、
前記第一のハイパスフィルタ又は第一のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第一の焦点評価値を生成すると共に、前記第二のハイパスフィルタ又は第二のバンドパスフィルタを通過して抽出された高域成分の大きさに対応つけて第二の焦点評価値を生成し、
前記第二の焦点評価値の変化量を所定の第一の閾値と比較する第一の比較ステップと、前記第一の焦点評価値の変化量に対する第二の焦点評価値の変化量の比を所定の第二の閾値と比較する第二の比較ステップと、を備え、
前記フォーカス制御ステップにおいて、
前記フォーカスレンズを合焦位置に向かって移動させる際に、
前記第一の比較手段において第二の焦点評価値の変化量が第一の閾値よりも大きく、且つ第二の比較手段において前記変化量の比が第二の閾値よりも大きい場合には、前記フォーカスレンズの位置が合焦位置に近いと判定して前記フォーカスレンズを低速で移動させ、一方、前記第一の手段において前記第二の焦点評価値の変化量が前記第一の閾値よりも小さい場合、又は、第二の比較手段において前記変化量の比が第二の閾値よりも小さい場合には、前記フォーカスレンズの位置が合焦位置から遠いと判定して前記フォーカスレンズを高速で移動させる、
ことを特徴とする請求項3に記載のフォーカス制御方法。

In the second integration step, two high-pass filters or band-pass filters having different low-frequency cutoff frequencies that extract the high-frequency component of the video signal are used.
In the evaluation value generation step,
Of the two high-pass filters or band-pass filters, the one with the lower low-frequency cutoff is the first high-pass filter or first band-pass filter, and the other is the second high-pass filter or second band-pass filter. When
A first focus evaluation value is generated in correspondence with the magnitude of the high-frequency component extracted through the first high-pass filter or the first band-pass filter, and the second high-pass filter or second The second focus evaluation value is generated in correspondence with the size of the high-frequency component extracted through the band-pass filter of
A first comparison step of comparing the change amount of the second focus evaluation value with a predetermined first threshold; and a ratio of the change amount of the second focus evaluation value to the change amount of the first focus evaluation value. A second comparison step for comparing with a predetermined second threshold,
In the focus control step,
When moving the focus lens toward the in-focus position,
When the change amount of the second focus evaluation value is larger than the first threshold value in the first comparison unit and the ratio of the change amount is larger than the second threshold value in the second comparison unit, It is determined that the position of the focus lens is close to the in-focus position, and the focus lens is moved at a low speed. On the other hand, the change amount of the second focus evaluation value is smaller than the first threshold value in the first means. If the ratio of the amount of change is smaller than the second threshold value in the second comparison means, it is determined that the position of the focus lens is far from the in-focus position, and the focus lens is moved at high speed. ,
The focus control method according to claim 3 .

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