Head-up display
US5710646A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 10, 1995 |
| Grant date | Jan 20, 1998 |
| Priority date | — |
| Expiry date | May 10, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B2027/0129
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A head-up display includes a projector which projects an image light and a hologram lens which diffracts and reflects the projected image and form a virtual image located ahead of a windshield. The hologram lens has a vertical diffraction characteristic which is equivalent to a hyperbolic or parabolic-curve mirror along a line formed by the intersection of the hologram lens and a vertical plane which includes an axis of the image light and a horizontal diffraction characteristic which is equivalent to a parabolic or elliptic curve mirror along a line which is formed by the intersection of the hologram lens and a horizontal plane which includes the axis of the image light. When the hologram is directly attached on a curved windshield which has a focal length fs (in case it is a mirror), the focal length fo of the hologram and the former focal length fs has the following relationship; 1/fo=1/fh+1/fs, where fh is a focal point when the hologram is flat.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.