Condensers for overhead projectors
US5475535A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 1, 1994 |
| Grant date | Dec 12, 1995 |
| Priority date | — |
| Expiry date | Dec 1, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S353/03
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A family of condenser lenses for an overhead projector (OHP) are designed to balance overall brightness in the projected image versus uniformity of illumination. The lenses are plano-convex and aspheric, and their conic constant is a function of the radius of curvature. The radius of curvature is further selected from a range which depends upon the size of the stage of the OHP. Preferred values of other parameters of the lens and OHP optical system are selected to complement the lens design. The lens is constructed of a heat-resistant material, such as borosilicate, to withstand the high temperatures generated by the incandescent lamp within the OHP base. Condenser lenses which are members of the described family provide performance, in terms of total luminous flux and uniformity of that flux, which is superior to the performance of previous designs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.