| 摘要 |
The purpose of the present invention is to reduce the size of an image pick-up lens unit. A part of a bundle of rays representing subject optical images is deflected vertically downward by a polarization prism, and is further deflected forwards by a total reflection mirror. A bundle of rays totally reflected by the total reflection mirror is split in three directions by a tri-directional splitting prism. The bundle of rays, which is split in three directions, is incident on a first optical-path-length-difference image pick-up element, a second optical-path-length-difference image pick-up element, and a phase-difference image pick-up element included in a phase-difference AF optical system. Auto focus (AF) is performed on the basis of the optical path length difference from signals obtained from the optical-path-length-difference image pick-up elements, and AF is performed on the basis of the phase difference from a signal obtained from the phase-difference image pick-up element. Since the phase-difference AF optical system is disposed so as to be parallel to the axis of the light forming the subject optical images, the size of the image pick-up lens unit can be reduced. |
| 主权项 |
1. A lens device comprising:
a subject image pick-up optical system that allows a bundle of rays, which represents subject optical images, to form images on a light-receiving surface of a subject image pick-up element; a phase-difference AF optical system that includes a phase-difference image pick-up element in which a plurality of subject optical images, which are obtained when an incident bundle of rays having an optical axis parallel to an optical axis of said subject image pick-up optical system is split into a plurality of light components by pupil splitting, are formed on a light-receiving surface of the phase-difference image pick-up element; an optical-path-length-difference AF optical system that includes a first image pick-up element and a second image pick-up element having different optical path lengths; and a light branching optical system that leads a part of a bundle of rays, which is led to the subject image pick-up element by said subject image pick-up optical system, to said phase-difference AF optical system and said optical-path-length-difference AF optical system; wherein said phase-difference AF optical system comprising a phase-difference image pick-up element unit holding the phase-difference image pick-up element; and a lens holding barrel, which is fixed to the phase-difference image pick-up element, including a separator lens that pupil-splits an incident bundle of rays and forms an image on the light-receiving surface of the phase-difference image pick-up element; said lens device further comprising: a holder at which a hole through an optical axis of said subject image pick-up optical system is formed; a support which extends forward from said holder; and a mounting member which is bent so as to be perpendicular to said support, at which a hole is formed, and which is fixed to the front of said support; wherein said lens holding barrel is inserted in the hole formed at said mounting member rotably. |
