The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 29, 1997
Filed:
Jun. 21, 1995
Keiji Moriyama, Kanagawa-ken, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A focus state detection device includes a field mask aperture having a shape created from the overlapping portions of two areas. The first area is formed by the outermost perimeter of the cross-section of light rays passing through the field mask plane toward each of the arrays of photoelectric conversion devices from each of point of the conjugal images of the arrays of photoelectric conversion devices at the primary imaging plane. The second area is formed by line segments that are the projection onto the field mask plane of the boundary lines at the surface of each re-imaging lens on the side toward the arrays of photoelectric conversion devices. The use of this shape causes light to be directed within the boundary lines of the outer perimeter of each of the re-imaging lenses. Through the use of this shape, the creation of stray light and internal reflection in the focus state detection optical system are suppressed, and stable focus state detection precision is enabled.