Visor for a helmet
US6715150B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 4, 2001 |
| Grant date | Apr 6, 2004 |
| Priority date | — |
| Expiry date | Oct 4, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/0025
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Visors for helmets are generally of spherical shape and of constant thickness, and articulated to the side walls of a helmet at the level of the forehead, about an axis of articulation passing through the center of their sphere. Thus shaped and mounted, they are seen off axis by a helmet wearer leading to optical distortions for him caused by diffraction effects on their internal and external faces. Visors with shapes modified to minimize the optical distortions perceived by a helmet wearer are proposed here. A first type of modification consists of a relative pivoting, in the vertical plane, of one of the faces of the visor with respect to the other and of a slight reduction in the ratio of the radius of curvature of the outer face of the visor to that of the inner face of the visor compared to the usual concentric bispherical visor. A second type of modification consists of adopting one or two aspherical surfaces of particular shape. A third type of modification consists of using a holographic diffraction mask fixed to one of the faces of the visor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.