Multifocal spectacle lens

US5784144A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventors

• Gerhard Kelch · Aalen, DE
• Hans Lahres · Aalen, DE
• Konrad Saur · Aalen, DE
• Helmut Wietschorke · Laberweinting, DE

Key dates

• Filing date: Mar 14, 1997
• Grant date: Jul 21, 1998
• Expiry date: Mar 14, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G02C7/061
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A multifocal spectacle lens has two optically effective surfaces with powers in the far reference point from -4.0 dpt to +4.0 dpt in the stronger principal section. The spectacle lens has cylinders from 0.0 dpt to 4.0 dpt and an addition of 1.00 dpt to 3.00 dpt. The multifocal area is at least aspherical and can be differentiated continuously at least twice and is not axial symmetrical. The multifocal surface includes a far vision zone, a near vision zone and a progression zone lying between the near and far vision zones. The lens body is configured to incorporate a plurality of features within an elliptical region on the surface of the lens body extending 50 mm measured horizontally and 40 mm measured vertically from the measurement point. These features are all satisfied together within the elliptical region. One of the features is that the near-reference point is at most 21 mm perpendicularly below the far-reference point and displaced by about 2.5 mm toward the edge. Also, a principal viewing line interconnects the far-vision zone and the near-vision zone and the principal viewing line defines a curve swung toward the edge more or less in dependence upon the dioptric power of t…