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:
Oct. 25, 1977
Filed:
Dec. 08, 1975
John Talley Winthrop, Wellesley, MA (US);
American Optical Corporation, Southbridge, MA (US);
Abstract
A multifocal ophthalmic lens is described on which one refractive surface is formed to provide a plurality of vertically juxtaposed viewing zones each of which has constant dioptric focal power. The constant dioptric focal power in the various zones increases successively from top to bottom of the multifocal ophthalmic lens. The refractive surface in the zones other than the viewing zone having the lowest focal power at the top of the lens is divided into a plurality of laterally disposed areas. In those areas near the periphery of the lens, the lens is provided with an aspheric surface formed from sections of a figure of revolution such that the principal axes of astigmatism lie in vertical and horizontal planes so that a wearer of the multifocal ophthalmic lens continues to perceive horizontal lines as being horizontal and vertical lines as being vertical and unbroken. However, the height of the ledge which exists between the various zones is restricted to a minimum height over the entire width of the lens which may then be blended during the manufacturing process into the adjacent viewing zones such that the dividing lines between the various viewing zones are rendered invisible.