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:
Nov. 25, 2003
Filed:
Oct. 16, 2001
Akihiro Hayashi, Toyokawa, JP;
Noritsugu Nozawa, Toyokawa, JP;
Yuichiro Kanazawa, Gamagori, JP;
Hidetaka Hoshino, Nukata-gun, JP;
Nidek Co., Ltd, Gamagori, JP;
Abstract
A visual function test apparatus for testing a visual function by presenting an optotype to an examinee's eye is disclosed. This apparatus includes a first half mirror disposed on a projection optical axis of light of the optotype; an illumination light source having a projection optical axis which is made substantially coaxial with the projection optical axis of the optotype light by the first half mirror; a concave mirror which reflects an illumination light from the illumination light source and the optotype light; a second half mirror disposed between the first half mirror and the concave mirror, the second half mirror reflecting the optotype light and the illumination light both reflected by the concave mirror toward the examinee's eye; and a control section which changes a ratio between a light quantity of the optotype light and a light quantity of the illumination light in accordance with a predetermined contrast ratio.