Variable magnification projection optical system and image projection apparatus
US9285574B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 2015 |
| Grant date | Mar 15, 2016 |
| Priority date | — |
| Expiry date | Jan 30, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B21/142
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A variable magnification projection optical system includes, in order from a magnification conjugate side to a reduction conjugate side, a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and an optical stop which is arranged at any position from a front of a lens arranged closest to the magnification conjugate side in the fourth lens group to a front of a lens arranged closest to the magnification conjugate side in the fifth lens group, wherein the fourth lens group is configured to include, in order from the magnification conjugate side, two or more negative lenses and a positive lens, and wherein the following condition expressions (1), (2) and (3) are satisfied:|Et/ft|≧10 (1)|EW/fW|≧15 (2)0.87≦23φT/23WT≦1.15 (3).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.