Projection apparatus and projection lens thereof capable of reducing focal length and aberration
US9612515B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 26, 2011 |
| Grant date | Apr 4, 2017 |
| Priority date | — |
| Expiry date | Nov 17, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B17/0852
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projection lens including a reflective unit and a refractive unit is provided. The projection lens is disposed between an object side and an image side. The reflective unit is disposed between the object side and the image side and has a negative refractive power. The refractive unit is disposed between the object side and the reflective unit and has a positive refractive power. The refractive unit includes a first lens group and a second lens group. The first lens group is disposed between the object side and the reflective unit and includes at least one cemented lens and an aperture stop. The at least one cemented lens is disposed between the object side and the aperture stop. The second lens group is disposed between the first lens group and the reflective unit and includes at least one aspheric lens. A projection apparatus including the projection lens is also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.