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US 5,689,740 AGranted
Focus detection device
AssigneeNikon Corporation
InventorShigeyuki Uchiyama
Life of this patent
Estimating the term…
Abstract
A focus detection device to improve the level of confidence of focus detection results of an object image by determining the defocus amount based on the filter processing data computed by a filter processing circuit for high frequencies of the subject image is disclosed. Computations may be repeated related to successively lower frequencies until a high level of confidence of the computed defocus amount is achieved.
Claims16
A focus detection device having a phototaking lens, comprising:
- a plurality of focus detection areas within an image field of an object;
- a plurality of photo-electric conversion devices, each of said photo-electric devices corresponding to each of said focus detection areas;
- a focus detection optical system guiding light rays from said object to said photo-electric conversion devices, wherein each of said photo-electric devices outputs electrical signals corresponding to the light intensity distribution of said focus detection areas;
- a filter processing device that utilizes a plurality of filter algorithm processes for extracting a plurality of frequency components, said filter processing device generating filter processing data corresponding to said frequency components for each of the electrical signals, the filter processing device outputting a plurality of filter processing data that corresponds to said focus detection areas;
- a focus detection algorithm device that calculates focus adjustment condition signals for each of said filter processing data, the focus adjustment condition signals representing focus adjustment conditions of said phototaking lens at each of said focus detection areas;
- and
- a final focus determination device that determines a final focus adjustment condition signal based on focus adjustment condition signals calculated by the focus detection algorithm device using filter processing data that corresponds to the highest frequency component among the plurality of filter processing data.
4 more elements
A focus detection device having a phototaking lens, comprising:
- a plurality of photo-electric conversion means for converting light into electrical signals, each of said photo-electric means corresponding to respective focus detection areas and said electrical signals corresponding to light intensity distributions on said focus detection areas;
- optical means for guiding light rays from an object to said plurality of photo-electric conversion means to determine said light intensity distributions;
- filter processing means that utilizes a plurality of filter algorithm processes for extracting a plurality of frequency components, said filter processing means generating filter processing data corresponding to said frequency components for each of the electrical signals, the filter processing means outputting a plurality of filter processing data that corresponds to said focus detection areas;
- focus detection algorithm means that calculates focus adjustment condition signals for each of said filter processing data, the focus adjustment condition signals representing focus adjustment conditions of said phototaking lens at each of said focus detection areas;
- and
- final focus determination means that determines a final focus adjustment condition signal based on focus adjustment condition signals calculated by the focus detection algorithm device using filter processing data that corresponds to the highest frequency component among the plurality of filter processing data.
3 more elements
A method of determining a final defocus amount in a focus detection device having a phototaking lens, comprising the steps of:
- providing a plurality of focus detection areas within an image field of an object;
- providing a plurality of photo-electric conversion devices, each of said photo-electric devices corresponding to each of said focus detection areas;
- guiding light rays from said object to said photo-electric conversion devices, wherein each of said photo-electric devices outputs electrical signals corresponding to the light intensity distribution of said focus detection areas;
- utilizing each of said electrical signals to generate filter processing data by conducting one of a plurality of filter algorithm processes that extracts various frequency components and outputting a plurality of filter processing data that correspond to said focus detection areas;
- calculating focus adjustment condition signals that represent focus adjustment conditions of said phototaking lens at each of said focus detection areas by each of said filter processing data;
- and
- determining a final focus adjustment condition signal that represents a final focus adjustment condition of said phototaking lens, based on said focus adjustment condition signals and said filter algorithm processes.
4 more elements
Dependencies are inferred from the claim text.