Browse Prior Art Database

Optical Dispersion Plate

IP.com Disclosure Number: IPCOM000061307D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Gfeller, F: AUTHOR

Abstract

A plate, for the collection of diffusely scattered overhead light for focusing on photodiodes in an array and for transforming the light pattern of an array of light-emitting diodes (LEDs) into a beam pattern, is injection molded of transparent plastic with the optical elements disposed in a circular configuration. The LEDs are positioned around the periphery, and the photodiodes are positioned centrally shielded by a stray light protection member. Fig. 1 shows the plan and elevation view of the optical dispersion plate for incremental angular positioning. Fig. 2 shows the plan and elevation view of the optical dispersion plate for continuous angular positioning. Fig. 3 shows details of the transmitter prism/lens assembly with dimensions in millimeters.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 60% of the total text.

Page 1 of 2

Optical Dispersion Plate

A plate, for the collection of diffusely scattered overhead light for focusing on photodiodes in an array and for transforming the light pattern of an array of light- emitting diodes (LEDs) into a beam pattern, is injection molded of transparent plastic with the optical elements disposed in a circular configuration. The LEDs are positioned around the periphery, and the photodiodes are positioned centrally shielded by a stray light protection member. Fig. 1 shows the plan and elevation view of the optical dispersion plate for incremental angular positioning. Fig. 2 shows the plan and elevation view of the optical dispersion plate for continuous angular positioning. Fig. 3 shows details of the transmitter prism/lens assembly with dimensions in millimeters. Surface I recollimates rays from the LED and transforms them into a bundle of parallel or slightly conical (less than 5 degrees) beams. Surface I consists of a sphere to collect paraxial rays and a tangential cone to collect off-axis rays. The curvature must be adapted to the particular type of LED used. Surface II acts as a totally reflecting flat mirror. No reflective coating is therefore required, and losses are minimal. For commonly used materials (Epoxy, LUCITE*, PLEXIGLASS**) the refractive index is approximately n=1.5. This corresponds to a critical angle of 42 degrees (off the surface normal axis). All rays coming from the LED must fall within the cone formed by the critical angle...