Automatic focus adjusting device
AssigneeCanon Kabushiki Kaisha
InventorsMasaki Higashihara, Yasuo Suda, Ichiro Ohnuki, Akira Akashi, Terutake Kadohara
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Abstract
An automatic focusing device for foreseeing or predicting the position of object after a predetermined time, based on plural past focusing operations on the object, utilizing a function of a higher order, and driving a lens for focusing to the predicted object position. According to the present invention there is provided a correcting circuit for correcting the coefficients of the higher-order function to reduce the influence of the measuring errors contained in the past focusing results, thus constantly enabling appropriate focusing.
Claims18
An automatic focusing device for driving a lens according to the output of a focus state detecting circuit, comprising:
- (a) an operation circuit for determining the amount of lens driving for focusing to an object position after a predetermined time, utilizing a plural-order function and based on past plural focusing data in past plural focusing operations conducted by the focusing device;
- (b) a driving circuit for driving the lens by the amount of lens driving determined by said operation circuit;
- and
- (c) a compensation circuit for correcting a high-order coefficient of said plural-order function.
An automatic focusing device for driving a lens according to the output of a focus state detecting circuit, comprising:
- (a) an operation circuit for determining the amount of lens driving for focusing to an object position after a predetermined time, utilizing a plural-order function and based on past plural focusing data in past plural focusing operations conducted by the focusing device;
- (b) a driving circuit for driving the lens by the amount of lens driving determined by said operation circuit;
- and
- (c) a compensation circuit for correcting a high-order coefficient of said plural-order function according to said focusing data.
Dependencies are inferred from the claim text.