Invention Grant
- Patent Title: Projection lenses having larger back focal length to focal length ratios
- Patent Title (中): 投影镜头具有较大的后焦距与焦距比
-
Application No.: US857358Application Date: 1997-05-16
-
Publication No.: US5870228APublication Date: 1999-02-09
- Inventor: Melvyn H. Kreitzer , Jacob Moskovich
- Applicant: Melvyn H. Kreitzer , Jacob Moskovich
- Applicant Address: OH Cincinnati
- Assignee: U.S. Precision Lens Inc.
- Current Assignee: U.S. Precision Lens Inc.
- Current Assignee Address: OH Cincinnati
- Main IPC: G02B9/12
- IPC: G02B9/12 ; G02B13/16 ; G02B13/18 ; G02B13/24 ; H04N5/74 ; H04N9/31 ; G02B3/00
Abstract:
A projection lens for use with LCD or DMD panels is provided. The lens has three lens units, the first unit having a negative power and at least one plastic lens element having two aspheric surfaces, a second lens unit having a negative power or a weak positive power and at least one color correcting doublet, and a third lens unit having a positive power and an aspheric surface either on a glass element or on a weak plastic element. The projection lens has a back focal length to focal length ratio of at least 3.0, the ratio being achieved by arranging the first, second, and third lens units so that:D.sub.12 /f.sub.0 >1.0,D.sub.23 /f.sub.0 >0.7, and1.5
Public/Granted literature
- US4765882A Hydroconversion process Public/Granted day:1988-08-23
Information query