Projection objective having four groups for projecting light onto a projection surface and a projector including the projection objective

US8985776B2 · kind B2 · utility

Assignee

• SYPRO OPTICS GMBH · DE

Inventors

• Guenther Benedix · Jena, DE
• Gudrun Schroeter · Jena, DE
• Gertrud Blei · Jena, DE
• Rainer Fischer · Monschau, DE
• Eberhard Piehler · Jena, DE

Key dates

• Filing date: Oct 7, 2009
• Grant date: Mar 24, 2015
• Expiry date: Apr 6, 2031

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N9/3197
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A projector for projecting light onto a projection surface includes a first group (1) with a negative meniscus, a second group (2) with positive refractive power, a third group (3) with a single lens, a fourth group (4) with a lens with positive refractive power, and a field lens (5) with positive refractive power, such that the light passes through the projection objective from the fourth to the first group. In order to be provide a high image quality with a small number of optical components and the smallest dimensions, the projector is configured so the common focal width of the fourth group (4) and the field lens (5) is smaller than twice the image circle diameter (9) of the projection objective and the maximum free diameter (8) is smaller than the overall focal width, and in particular smaller than 0.8 times the overall focal width of the projection objective.