Browse Prior Art Database

Prism for Redirecting Infrared Light in a Data Communications System

IP.com Disclosure Number: IPCOM000114574D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Grady, PE: AUTHOR [+2]

Abstract

Disclosed is a method of redirecting modulated infrared light from transmitters located in one or more portable terminals to a common receiver centrally located in a docking station. A common prism design that utilizes three light redirecting properties is used in each of the transmitter locations.

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Prism for Redirecting Infrared Light in a Data Communications System

      Disclosed is a method of redirecting modulated infrared light
from transmitters located in one or more portable terminals to a
common receiver centrally located in a docking station.  A common
prism design that utilizes three light redirecting properties is used
in each of the transmitter locations.

The following Figure shows the three primary ways that the prism
redirects the light.

      The distribution of light from each prism is identical;
however, one of three properties dominates the reception of light
from a given transmitter.  Which property dominates depends solely on
the geometry of the transmitter (1), prism (2), and receiver (6)
locations.

      Two of the properties of the prism are reflection and
refraction.  Depending on the angle of the incident light coming from
the LED transmitter (1), light is either reflected from (3) or
refracted through (5) the internal sloped surface of the prism (2).
The LED transmitters in the portable terminals emit light with a
specified beam angle that allows both modes of redirection to be
active in the prism.  If the receiver (6) is located far to the left
of the prism, then most of the received light is reflected off the
internal sloped surface of the prism at nearly a 90 degree angle from
the transmitted light.  For prisms close to the receiver, most of the
received light is refracted through the sloped surface of the prism.

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