HIGH EFFICIENCY DIRECT COUPLING OF RADIANT ELECTROMAGNETIC ENERGY INTO DIELECTRIC WAVE GUIDE STRUCTURE

COUPLAGE DIRECT DE HAUTE EFFICACITE D'ENERGIE DIELECTRIQUE DANS UNE STRUCTURE DE GUIDE D'ONDE DIELECTRIQUE

English Abstract

A radiant electromagnetic energy transmitting apparatus (10) comprises an
elongated rod (11) consisting of electromagnetic energy transmitting material
and a source of energy (12) having an end portion received into a recess (13)
in an end portion (11a) of the rod to transmit the energy in different
directions therein for effecting energy travel lengthwise along the rod.

French Abstract

L'invention porte sur un appareil (10) de transmission d'énergie électromagnétique rayonnante comprenant une tige allongée (11) constituée d'un matériau transmetteur d'énergie électromagnétique, et une source d'énergie (12) dont la partie terminale est reçue dans un évidement (13) d'une partie terminale (11a) de la tige de sorte que l'énergie soit transmise dans différentes directions et qu'elle se déplace le long de la tige.

Claims

8
CLAIMS
1. Radiant electromagnetic energy transmitting apparatus,
comprising
a) an elongated rod consisting of electromagnetic energy
transmitting material,
b) and a source of said energy having an end portion received into
said rod to transmit said energy in different directions therein for effecting
energy
travel lengthwise of the rod,
c) said energy source comprising multiple LEDs embedded into
a portion of the rod and spaced at substantially equal angular intervals about
the
center of the rod, said LEDs offset from said center.
2. The combination of claim 1 wherein said rod material consists
of light transmitting synthetic resin.
3. The combination of claim 1 wherein said rod defines multiple
recesses, and said LEDs are received into said recesses.
4. The combination of claim 6 wherein said recesses are spaced
apart along the rod.
5. The combination of claim 4 wherein the rod has opposite side
wall extents which are relatively convergent at said recess locations.
6. The combination of claim 5 wherein the rod is narrowed at and
proximate said locations.
7. The combination of any one of claims 1 through 6 wherein said
rod has length "1", and said recesses are located at or proximate to 1/4 "1"
and 3/4

9
"1", along rod length.
8. The combination of claim 7 wherein the rod has opposite side
wall extents which are relatively convergent at said recess locations.
9. The combination of claim 1 wherein said LEDs have cube
shape.
10. The combination of claim 1 wherein said light source comprises
multiple LEDs embedded into the rod.
11. The combination of claim 1 including an electromagnetic energy
reflection means facing said rod, sidewise thereof.
12. The combination of claim 11 wherein said reflector means is a
light reflection means characterized as providing substantial uniformity of
collimated
light reflection.

Description

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WO 99/14521 PCTNS97/~6766
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HIGH EFFICIENCY DIRECT COUPLING OF RADIANT
ELECTROMAGNETIC ENERGY INTO DIELECTRIC
WAVE GUIDE STRUCTURE
This invention relates generally to coupling of radiant electromagnetic
energy into solid dielectric wave guide structure, and more particularly to
efficient
coupling of light from light sources into light transmitting media for travel
therein.
There is need for simple, efficient coupling of electromagnetic energy,
such as light from LEDs, into solid wave guide structures such as rods, slabs
and etc.
Apparatus of this type can be formed into many shapes for a large number of
uses,
one example being lighting conformed to or fitting external or internal
locations on
vehicles, and in or on buildings, or displays of many types.
It is a major object of the invention to provide simple, efficient and
rugged apparatus meeting the above need.
Basically, the radiant electrical energy transmitting apparatus of the
invention comprises:
a) an elongated element consisting of electromagnetic energy
transmitting material,
b) and a source of such energy having an end portion received into
the element to transmit energy in different directions therein for effecting
energy
travel lengthwise.
All will appear, the element such as a rod or wave guide may consist
of light transmissive material which is bendable to desired shape, and the
light source
end portion, such as an LED, is advantageously and protectively received in a
recess
in the wave guide, or embedded in the latter. In this regard the rod or wave
guide
may consist of synthetic polymeric material.

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Another object is to provide the light source receiving recess at an end
portion of the rod or wave guide, or sidewardly at a location along its
length.
Multiple such recesses may be provided, for reception of multiple light
sources, such
as LEDs.
Yet another object is to provide rod opposite side wall extents which
are relatively convergent at the recess location. Such a rod or wave guide
may, for
example, have reduce cross-sectional area at or proximate such locations. Such
locations may be provided at or proximate to '/ and/or 3/4 "1", along rod
length "1",
for efficient light coupling into the rod.
A further object is to efficiently couple LEDs to a synthetic resinous,
light transmitting rod or rods.
These and other d~jects and advantages of the invention, as well as the
details of an illustrative embodiment, will be more fully understood from the
following specification and drawings, in which:
Fig. 1 is an elevation showing one preferred form of apparatus
incorporating the invention;
Fig. 2 is an elevation taken in section on lines 2-2 of Fig. 1;
Fig. 3 is an enlarged section taken in elevation through one end of
light transmitting rod, showing LED embedding;
Fig. 4 is an elevation taken in section on lines 4-4 of Fig. 3;
Fig. 5 is an enlarged perspective view showing an LED of the type
used in Figs. 1-4;
Fig. 6 is a view like Fig. 1, but showing light sources embedded in
reduced cross sectional zones along a light transmitting rod; and
Fig. 7 is an enlarged section taken on lines 7-7 of Fig. 6.

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DETAILED DESCRIPTION
Referring first to Figs. 1-4, radiant energy transmitting apparatus is
indicated generally at 10, such energy for example consisting of light, as in
the
visible wave length zone of the spectrum. The apparatus includes an elongated
wave
guide such as a rod 11 consisting of electromagnetic energy transmitting
material, and
a source or sources of such energy, each having an end portion recessed into
the rod
to transmit energy in a preferred direction, for effecting energy travel
lengthwise of
(i.e. along) the rod. See for example the LEDs 12 received in recesses 13 in
the end
portion lla of the rod, so that the LEDs are effectively embedded in the rod
end
portion. Light from LEDs is shown being transmitted in different directions
14a--14f,
over a range of angles, these showings being illustrative only. A large
portion of
such light is typically (i.e. within cone of angle a) transmitted as rays
extending at
angles such as to enable successive total internal reflections off the
boundary or
periphery of the rod, along its length, for travel lengthwise along and
internally of
the rod. As shown the LEDs may be completely embedded, along their lengths in
the rod end portion, and may have tight wall-to-wall fits in the recesses 13.
LED
terminals appear at 16, and a low voltage source 17 is schematically shown or
connected with such terminals; in Fig. 1. The rod typically consists of
synthetic
polymeric material, and may be flexible so as to be bendable. The rod may be
considered as a "wave guide", i.e. to guide the light waves for transmission
lengthwise of the rod. Usable synthetic polymer include polymers of silicone,
urethane, epoxy, polyamid, acrylic, polyesters and others. Glasses are usable.
These
are transparent.
Figs. 1 and 2 also show a reflector 18 located at one side of the rod.
Light emanating from the rod is reflected, as for example as shown by rays 20
reflected from the interior curved surface 18a of the reflector. The reflector
may take
the form of discreet light scattering dots, with varying spacing to provide
uniformity
of collimated light reflection as viewed from the aperture A.

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Fig. 5 shows one form of LED 12 having a cube shape, with terminals
16 projecting from the end wall 12a. Light generated by the LED emanates from
different walls such as all five remaining walls 12b. Recesses 13 in the rod
may have
cube shape for embedding such LEDs, with tight fits. A typical cube dimension
t is
0.01 inch.
In the form of the invention shown in Figs 6 and 7, the light source
receiving recess is formed sidewardly into the rod at a location along the rod
length.
See recesses 23 which are spaced inwardly of the cylinder formed outer surface
24a
of rod 24. Light sources such as LEDs embedded in such recesses appear at 26.
Preferably, the rod is "necked down" at recess general locations 27 and 28
along the
rod length, and has narrowed or venturi shape at such locations. The recesses
are
formed in rod side wall extents 27a and 28a which are axially tapered or
relatively
convergent, as shown, whereby the LEDs in such recesses are well positioned to
transmit light lengthwise of the rod, as indicated by broken line rays 29, 30,
31 and
32 extending from the LEDs and traveling along and internally of the "wave
guide"
rod. Maximum light transmission throughout the rod is effected if locations 27
and
28 are at ~~4 1 and s/a 1, where 1 is the rod overall length, as shown.
Radiation may be caused to exit the wave guide by a variety of means,
including surface roughness to cause frustrated total internal reflection, the
addition
of bulk scattering agents to generate radiation outside the T.LR. envelope,
shape
modifications such as reducing cross-sectional area, and form changes such as
overall
curving of the wave guide.

Representative Drawing