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:
Dec. 30, 2008
Filed:
Jan. 17, 2008
Tatsumaro Yamashita, Miyagi-ken, JP;
Eiki Matsuo, Nagano-ken, JP;
Tatsumaro Yamashita, Miyagi-ken, JP;
Eiki Matsuo, Nagano-ken, JP;
Alps Electric Co., Ltd., Tokyo, JP;
Abstract
To provide a high-brightness, small, low-cost optical apparatus which covers a wide-angle to super-wide-angle region and which reliably corrects various aberrations with a small number of lenses. At least one negative lens unit, a meniscus lensthat is convex on an object side, an aperture stop S, and a double-convex positive lensare arranged in order from the object side. At least one of the lenses positioned on the object side of the aperture stop S and the positive lensinclude respective aspherical surfaces. When va is an average Abbe number of all of the lenses excluding the meniscus lens, vb is an Abbe number of the meniscus lens, f is a focal length of the entire system, fis a combined focal length of the negative lens unit and the meniscus lens, ts is a distance between the aperture stop and the positive lens along an axis, L is a distance between a vertex of a lens surface nearest to the object side and a vertex of a lens surface nearest to the image side, tis a central thickness of the meniscus lens, θs is an incident angle of a chief ray that passes through the aperture stop at a maximum angle of view, 1.4<va/vb, 0<ts/L<0.1, 0.2<t/L<0.5, −10<f/f<−1.0, and 25°<θs<40° are satisfied.