Television – Camera – system and detail – Optics
Reexamination Certificate
1996-03-26
2002-10-29
Ho, Tuan (Department: 2612)
Television
Camera, system and detail
Optics
C348S362000
Reexamination Certificate
active
06473127
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image pickup apparatus which designates a position and an area in the image pickup screen and performs a focus detection or photometry operation on the basis of the designated position and area.
2. Related Background Art
In the field of commercial image pickup apparatuses represented by video built-in type cameras, various efforts have been made to obtain a high-quality image more easily. Auto-focus (AF) and automatic exposure adjustment (AE) mechanisms equipped as standard functions at present are used for eliminating troublesome operations for adjusting the focusing and exposure states in every photographing operation, and are typical examples of the functions that can attain the object of easily obtaining a good image.
Since-the camera or the like uses these AF and AE mechanisms to “automatically” determine the photographing condition and to adjust the lens position and iris to an exposure state which may be suitable for the determined condition, the photographer's will may not often be reflected in the photographed image. For example, when both a far object and a near object are present in the photographing screen, if an AF operation is executed on the basis of information of the entire photographing screen, one of these objects is set in an in-focus state, but the camera cannot determine if the object set in the in-focus state is a principal object on which the photographer wants to focus. When an image of a principal object is photographed with the blue sky as a background, if an AE operation is executed based on information of the entire screen, the principal object image becomes undesirably dark since the AE function adjusts the iris in correspondence with the brightness of the sky.
In order to avoid such a situation, conventionally, it is a general practice to preponderantly perform the distance measurement and photometry operations for an object located at the center of the photographing screen, and to execute the AF and AE operations based on these results. This technique is based on the fact that the photographer often sets a principal object at the center of the screen in a photographing operation. However, this method suffers a drawback that when the principal object is set at a position other than the center of the screen, the focusing and exposure states cannot be adequately adjusted with respect to the principal object.
In view of this problem, the present applicant proposed a photographing apparatus which selects a principal object on the basis of the viewpoint of the photographer who is looking into the finder so as to obtain optimal focusing and exposure states independently of the position of the principal object in the photographing screen (Japanese Patent Application Laid-Open No. 4-154165). According to this photographing apparatus, the position of the principal object can be freely changed while limiting the AF and AE. In this case, a position designation means for selecting the principal object is not limited to a means for detecting the viewpoint. For example, a means such as a joystick, a mouse, or the like, which determines the moving direction and position by synthesizing moving amounts on two axes, may be used instead.
When one of the former center fixing method and the latter viewpoint position limiting method may be selected using, e.g., a switch in correspondence with the photographing methods (e.g., the photographer looks into or does not look into the finder), each of the photographing methods may be covered.
However, in the above-mentioned example, since a display frame displayed on the screen to designate a position in the screen, an AF area, and an AE area are set using a common area, if these areas are set to optimize the focus adjustment, such areas are not optimal to photometry; and vice versa. Therefore, it is difficult to set optimal areas.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image pickup apparatus which can solve the above-mentioned problems and can optimally perform both photometry and distance measurement operations.
In order to achieve the above object, according to a preferred embodiment of the present invention, there is disclosed an image pickup apparatus comprising position designation means for designating a position in a screen within which image pickup means performs an image pickup operation, photometry gate means for determining a photometric detection area in the screen in correspondence with the position information designated by the position designation means, and extracting a signal corresponding to the photometric detection area from a video signal obtained from the image pickup means, and focus gate means for determining a focus detection area in the screen in correspondence with the position information designated by the position designation means independently of the photometric detection area, and extracting a signal corresponding to the focus detection area from the video signal obtained from the image pickup means.
It is another object of the present invention to provide an image pickup apparatus wherein when the position designation means designates a desired principal object in the photographing screen, the photometry gate means and the focus gate means respectively determine a photometric detection area and a focus detection area in correspondence with the designated position, and respectively extract their evaluation values from a video signal in correspondence with the determined areas, and the apparatus performs AE and AF control operations on the basis of the outputs from these gate means so as to optimally control the AE and AF operations.
Other objects and features of the present invention will become apparent from the following description of the specification taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5040072 (1991-08-01), Tsuji et al.
patent: 5051833 (1991-09-01), Tsuji
patent: 5060074 (1991-10-01), Kinugasa et al.
patent: 5161025 (1992-11-01), Nakao
patent: 5349415 (1994-09-01), Nishida
patent: 5541655 (1996-07-01), Kaneda
patent: 5570156 (1996-10-01), Arai et al.
patent: 5694168 (1997-12-01), Toji
patent: 6088060 (2000-06-01), Suda et al.
patent: 4154165 (1992-05-01), None
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Ho Tuan
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