Encapsulated light emitting diode and method for encapsulation
US5122943A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 15, 1991 |
| Grant date | Jun 16, 1992 |
| Priority date | — |
| Expiry date | Apr 15, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S362/80
Abstract
A light emitting diode with reduced stray light includes a base with an active light emitting element mounted in the base. An epoxy envelope is mounted on the base. The envelope includes a conical side portion and a spherical dome portion. The envelope is encapsulated with optically absorbing material of low reflectivity. The optically absorbing material is in direct contact with the side portion of the envelope and part of the spherical dome portion leaving an exposed portion through which rays of light pass. The diameter d of the exposed portion is equal to: 2r[sin (x+arcsin (r/s/n))], wherein r is the radius of a spherical dome portion, x<arcsin (1/n) is the maximum angle between a surface normal and a ray emitted from the active light emitting element that strikes the envelope at the edge of the exposed portion of the spherical dome portion, s is the distance between the active light emitting element and the center of the spherical dome portion, and n is the index of refraction of the material of the epoxy envelope.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.