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Automatic focusing apparatus and control method therefor

a technology of automatic focusing and control method, which is applied in the direction of camera focusing arrangement, printers, instruments, etc., can solve the problems of constant focus fluctuation, visual quality may decline, tracking ability to the object may deteriorate, etc., and achieve the effect of preventing the deterioration of tracking ability to an obj

Inactive Publication Date: 2010-03-18
CANON KK
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0007]The present invention is directed to an automatic focusing apparatus capable of preventing tracking ability to an object from deteriorating, even if a distance between the automatic focusing apparatus and the object does not change, when continuously performing an adjustment of position of a focus lens to make focus on an object, and to a control method therefor.

Problems solved by technology

For this reason, a focus fluctuation always occurs, and a tracking ability to the object may deteriorate.
In particular, in an electronic viewfinder (EVF) display using consecutive captured images, or the like, frames which are out-of focus may be generated, and accordingly visual quality may degrade.
Further, the focus lens is sequentially moved, thus leading to an increase in battery consumption.

Method used

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  • Automatic focusing apparatus and control method therefor
  • Automatic focusing apparatus and control method therefor

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Embodiment Construction

[0028]Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings.

[0029]FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus 1 according to an exemplary embodiment of the present invention. As illustrated in FIG. 1, the imaging apparatus 1 is an electronic still camera, which captures an image by an image sensor 108, the image being formed via a photographic optical system including a photographic lens 101, a diaphragm and shutter 102, and a focus lens 104. Further, the imaging apparatus 1 includes an AF processing unit 105, which moves the focus lens 104 under the control of a control unit 115, and is configured to perform focus adjustment by moving the focus lens 104 according to image data captured by the image sensor 108.

[0030]The photographic lens 101 is an optical lens including a zoom mechanism and so on. The diaphragm and shutter 102 controls a light amount from an object acc...

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Abstract

An automatic focusing apparatus detects presence or absence of change in a distance between an object and the automatic focusing apparatus while operating in an operation mode to continuously perform an adjustment of the position of a focus lens to focus on the object, and stops a movement of the focus lens if a change in the distance is not detected.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an automatic focusing apparatus, e.g., a camera, and a control method therefor.[0003]2. Description of the Related Art[0004]Conventionally, an automatic focusing apparatus of an auto-focusing (AF) system which focuses on an object by moving a focus lens position according to a luminance signal obtained from an image sensor, such as a charge-coupled device (CCD), has been used in an electronic still camera or the like. In the automatic focusing apparatus, a focus evaluation value indicating a contrast within an AF area is calculated by integrating high-frequency components of a signal in the AF area set within an image plane. Then, a focus detection operation for acquiring a focus evaluation value for each position of a focus lens is performed by shifting the focus lens, to detect a position of the focus lens enabling the highest focus evaluation value, which is regarded as an in-focus po...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G03B13/00
CPCG02B7/36G02B27/0093G03B13/20H04N5/23212G03B13/36H04N23/673H04N23/61H04N23/634H04N23/631G02B7/09G02B7/38
Inventor UENISHI, MASAAKI
Owner CANON KK
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