IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0728756
(2003-12-08)
|
우선권정보 |
JP-0366601 (2002-12-18) |
발명자
/ 주소 |
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
1 인용 특허 :
6 |
초록
▼
A focus detecting optical includes a condenser lens placed in the proximity of a preset imaging plane equivalent to the imaging plane of a photographic lens, a pair of aperture stops dividing the pupil of the photographic lens placed on the exit side of the condenser lens into two areas, and a pair
A focus detecting optical includes a condenser lens placed in the proximity of a preset imaging plane equivalent to the imaging plane of a photographic lens, a pair of aperture stops dividing the pupil of the photographic lens placed on the exit side of the condenser lens into two areas, and a pair of re-imaging lenses for forming two secondary object images corresponding to the aperture stops, and satisfies the following conditions:0.45<|mg|<0.750.75<|R1/R2|<1.25|R3/R4|?0.02where mg is an imaging magnification of the focus detecting optical system, R1 is the radius of curvature of the entrance surface of the condenser lens, R2 is the radius of curvature of the exit surface of the condenser lens, R3 is the radius of curvature of the entrance surface of each of the re-imaging lenses, and R4 is the radius of curvature of the exit surface of each of the re-imaging lenses.
대표청구항
▼
1. A focus detecting optical system detecting a focus position of a photographing optical system from a positional relationship between at least one pair of secondary object images, wherein the focus detecting optical system comprises:a condenser lens placed in the proximity of a preset imaging plan
1. A focus detecting optical system detecting a focus position of a photographing optical system from a positional relationship between at least one pair of secondary object images, wherein the focus detecting optical system comprises:a condenser lens placed in the proximity of a preset imaging plane equivalent to an imaging plane of a photographic lens; a pair of aperture stops that are placed on an exit side of the condenser lens and that divide a pupil of the photogrphic lens into two areas; and a pair of re-imaging lenses for forming two secondary object images corresponding to the aperture stops, and satisfies the following conditions: 0.45<|mg|<0.75 0.75<|R1/R2|<1.25 |R3/R4|?0.02 ?where mg is an imaging magnification of the focus detecting optical system, R1 is a radius of curvature of an entrance surface of the condenser lens, R2 is a radius of curvature of an exit surface of the condenser lens, R3 is a radius of curvature of an entrance surface of each of the re-imaging lenses, and R4 is a radius of curvature of an exit surface of each of the re-imaging lenses. 2. A focus detecting optical system according to claim 1, further comprising a light receiving element having a light-receiving surface, and satisfying the following condition:|Δ|<1.55λwhere Δ is a difference of a position of a center of gravity between spots of C and F lines on the surface of the light-receiving element and λ is a wavelength of the E line.3. A focus detecting optical system according to claim 1, further satisfying the following condition:3.50×10?4>|δd/D|where δd is an image height error (mm) on a most peripheral side of a range measuring area and D is a distance (mm) between two images made by the pair of re-imaging lenses.4. A focus detecting optical system according to claim 1, wherein a plurality of sets, each of which is a combination of the pair of aperture stops with the pair of re-imaging lenses corresponding thereto, so that, in each set, centers of the aperture stops and the re-imaging lenses corresponding thereto are decentered from an optical axis of the photographic lens and an amount of decentration varies with each set.5. A focus detecting optical system according to claim 1, further comprising a light-receiving element having a light-receiving surface, and satisfying the following condition:0.85<LTL/fl<1.75 where LTL is an optical path length (a length from the preset imaging plane to the light-receiving surface) of the focus detecting optical system and fl is a focal length of an entire focus detecting optical system.6. A focus detecting optical system according to claim 1, wherein the re-imaging lenses are placed so that an optical axis of each of the re-imaging lenses is decentered farther away from a center of each of the aperture stops with respect to the optical axis of the photographic lens.7. A camera comprising:a focus detecting optical system; a finder optical system; a photographic lens; path splitting means splitting an optical path from the photographic lens to direct the optical path toward an image sensor or a film and toward the finder optical system; and a reflecting means conducting the optical path of the photographic lens to the focus detecting optical system, the focus detecting optical system detecting a focus position of a photographing optical system from a positional relationship between at least one pair of secondary object images, wherein the focus detecting optical system comprises: a condenser lens placed in the proximity of a preset imaging plane equivalent to an imaging plane of a photographic lens; a pair of aperture stops that are placed on an exit side of the condenser lens and that divide a pupil of the photographic lens into two areas; and a pair of re-imaging lenses for forming two secondary object images corresponding to the aperture stops, and satisfies the following conditions:0.45<|mg|<0.75 0.75<|R1/R2|<1.25 |R3/R4|?0.02 where mg is an imaging magnification of the focus detecting optical system, R1 is a radius of curvature of an entrance surface of the condenser lens, R2 is a radius of curvature of an exit surface of the condenser lens, R3 is a radius of curvature of an entrance surface of each of the re-imaging lenses, and R4 is a radius of curvature of an exit surface of each of the re-imaging lenses.8. A camera according to claim 7, wherein a diameter of an image circle of the camera is substantially a half of the diameter of the image circle of a 135 format camera.9. A camera according to claim 7, further comprising the image sensor placed on the optical path of the photographic lens.10. A camera comprising:an image sensor provided with a light-receiving surface receiving light from a photographing optical system; and a focus detecting optical system detecting a focus position of the photographing optical system from a positional relationship between at least one pair of secondary image objects with light from the photographing optical system, wherein a diameter of an image circle of the camera is substantially a half of the diameter of the image circle of a 135 format camera. 11. A camera according to claim 10, wherein the focus detecting optical system satisfies the following condition:0.45<|mg|<0.75 where mg is an imaging magnification of the focus detecting optical system.12. A camera according to claim 10, further comprising a reflecting mirror reflecting the light from the photographing optical system to conduct the light to the focus detecting optical system.13. A camera according to claim 12, wherein the reflecting mirror is moved to conduct the light from the photographing optical system to the image sensor.
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