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:
May. 17, 2011
Filed:
Dec. 31, 2009
Norihisa Sakagami, Osaka, JP;
Norihisa Sakagami, Osaka, JP;
Nalux Co., Ltd., Osaka, JP;
Abstract
To provide a compact image forming optical system in which an incident angle to an imaging plane of a solid-state imaging device is small and whose chromatic aberration, astigmatism, field curvature, and distortion are reduced. An image forming optical system of a first embodiment of the present invention comprises four lenses arranged from the object side to the imaging plane side in order, that are a first lens that is a double-convex lens, a second lens that is a double-concave lens, a third lens that is a positive meniscus lens that is convex toward an image side, and a fourth lens that is a negative meniscus lens that is convex toward an object side. An aperture is placed closer to the object than the image side surface of the first lens. The image forming optical system of the first embodiment of the present invention satisfies the following equations, where fis an absolute value of a focal length of i-th lens, f is an absolute value of a focal length of a whole optical system, vis Abbe's number of i-th lens, and TTL is a distance from the object side surface of the first lens, in the object side surface and an aperture side surface, to the imaging plane.0.425<<0.7  (1)25<v<28  (2)50<v,v,v<57  (3)0.595<<1.05  (4)1.5<<2.2  (5)f<f  (6)1.05<<1.18  (7)