Focus detection device

A focus detection device for a camera having a photographing lens, comprising:

• a pupil dividing system that divides a pupil of the photographing lens into a pair of focus detection areas;
• an intensity distribution pattern forming system that receives light passed through said focus detection areas and forms a pair of intensity distribution patterns, a relative position thereof varying depending on a focusing condition of the photographing lens;
• a plurality of light receiving elements arranged in a direction where the pupil is divided;
• a focus detection area defining system that has a focus detection opening, said focus detection area defining system being arranged on or in a vicinity of a plane equivalent to a focal plane of the photographing lens, light passing through said pair of focus detection areas passing through said focus detection opening;
• a deflection prism arranged between said focus detection opening and said pupil dividing system, said deflection prism deflecting the light passed through said focus detection opening in a direction perpendicular to the pupil dividing direction and an optical axis of the photographing lens;
• and
• an optical element provided in a vicinity of said pupil dividing system, said optical element having an anamorphic refractive power, a refractive power in the pupil dividing direction being greater than a refractive power in a direction perpendicular to the pupil dividing direction, wherein said optical element is an element different from one of said deflection prism and said intensity distribution pattern forming system, said optical element having a light receiving surface and a light emerging surface, a surface having the anamorphic refractive power being formed on at least one of said light receiving surface and said light emerging surface, said optical element being disposed between said deflection prism and said pupil dividing system.

A focus detection device for a camera having a photographing lens, comprising:

• a plurality of pupil dividing systems, each of said plurality of pupil dividing systems dividing a pupil of the photographing lens into a pair of focus detection areas;
• a plurality of intensity distribution pattern forming systems, each of which receives light passed through corresponding focus detection areas and forms a pair of intensity distribution patterns, a relative position thereof varying depending on a focusing condition of the photographing lens;
• a plurality of light receiving elements elongated in a direction where the pupil is divided, said plurality of light receiving elements receiving the plurality of intensity distribution patterns formed by said plurality of intensity distribution pattern forming systems, respectively;
• a focus detection area defining member that has a plurality of focus detection openings, said focus detection area defining member being arranged on or in a vicinity of a plane equivalent to a focal plane of the photographing lens, light passed through said detection areas passing said focus detection openings;
• a plurality of deflection prisms respectively arranged between said focus detection openings and said pupil dividing systems, each of said deflection prisms deflecting the light passed through one of said focus detection openings in a direction perpendicular to the pupil dividing direction and an optical axis of the photographing lens;
• and
• an optical element provided on or in a vicinity of each of said pupil dividing systems, said optical element having an anamorphic refractive power, a refractive power of said optical element in the pupil dividing direction being greater than a refractive power in a direction perpendicular to the pupil dividing direction.

A focus detection device for a camera having a photographing lens, comprising:

• a plurality of pupil dividing systems, each of said plurality of pupil dividing systems dividing a pupil of the photographing lens into a pair of focus detection areas;
• a plurality of intensity distribution pattern forming systems, each of which receives light passed through corresponding focus detection areas and forms a pair of intensity distribution patterns, a relative position thereof varying depending on a focusing condition of the photographing lens;
• a plurality of light receiving elements elongated in a direction where the pupil is divided, said plurality of light receiving elements receiving the plurality of intensity distribution patterns formed by said plurality of intensity distribution pattern forming systems, respectively;
• a focus detection area defining member that has a plurality of focus detection openings, said focus detection area defining member being arranged on or in a vicinity of a plane equivalent to a focal plane of the photographing lens, light passed through said detection areas passing said focus detection openings;
• a plurality of deflection prisms respectively arranged between said focus detection openings and said pupil dividing systems, each of said deflection prisms deflecting the light passed through one of said focus detection openings in a direction perpendicular to the pupil dividing direction and an optical axis of the photographing lens;
• and
• an optical element provided on or in a vicinity of each of said pupil dividing systems, said optical element having an anamorphic refractive power, a refractive power of said optical element in the pupil dividing direction being greater than a refractive power in a direction perpendicular to the pupil dividing direction, wherein said optical element are elements different from said deflection prisms or said intensity distribution pattern forming systems, each of said optical elements having a light receiving surface and a light emerging surface, a surface having the anamorphic refractive power being formed on at least one of said light receiving surface and said light emerging surface, said optical elements being respectively disposed between said deflection prisms and said pupil dividing systems.