Note: Descriptions are shown in the official language in which they were submitted.
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OPTICAL DISTRIBUTION SYSTEM
INCLUDING LIGHT GUIDE
Background of the Invention
This relates in general to light transmission
and distribution systems comprising light guides an more
particularly, to such a system in which the transmitting
light guide serves as a primary light source.
For some years optical fibers have been utilized
in the prior art for transmitting optical energy from a
source to a preselected destination with minimal energy
loss along the transmission path Accordingly, as de-
scribed in detail in an article entitled The Fiber Light Guide by Alan G. Chenoweth~ Volt 29, No 5, May 1976 of
Physics Today page 28 et seq., and in Patent No.
3,641,332, issued to Franklin I. Reck and Michael Exert,
February 8, i972, for Fiber Optics Illumination System,
the principal object of such systems is to practically
eliminate the lateral diffusion of the optical rays from
the core during course of light transmission. This is
accomplished my forming the optical transmission core of a
material which has a substantially higher index of refract
lion than the surrounding sleeve. This is enhanced, as disclosed in Patent No. 3,641,332, Syria, by inter
posing an Andre layer of air between toe core and the
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1 surrounding sleeve. The light from a source at one end of
the optical fiber, or bundle of fibers, is totally reflect
ted from the periphery back toward the center of the core,
so that almost no energy is lost through the sidewalls of
the transmitting fiber, and almost the entire light energy
from the source is delivered to the selected destination
at the other end. Thus, the sidewalls of the transmitting
fiber or bundle of fibers, appear dark, and unable to
function as a primary light source.
Line or strip sources of light are provided in the
prior art by elongated tubes filled with rare gases, such
as neon or argon. These are inexpensive to fabricate and
install and require high voltages to operate.
Further, prior art safety signs and the like art
fabricated using reflecting strips, which act as secondary
sources of light. But none of the foregoing is fully
satisfactory for safety or other utilitarian purposes, or
for decorative purposes.
Summary of the Invention
Accordingly, it is the principal object of the
invention to provide a primary light source comprising a
light guide in the form of a flexible rod or strip bright
along its length, which is simple and inexpensive to
manufacture and install.
In accordance with the present invention such a
light guide comprises a single optical transmission core
of clear resinous plastic or the like having a trays-
parent or translucent sleeve which is shrink-fitted or
otherwise tightly fitted around the periphery so as to
substantially remove the air interface, and wherein the
sleeve is designed to laterally disperse diffuse, or
refract through its sidewall a substantial component of
light transmitted along the core from a source at one end.
This causes the sleeve to have a bright appearance and to
serve as a primary source of light.
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1 In accordance with one modification the surface
of the core it scored with angular cuts or discontinuities
at intervals the length for the purpose of deflecting
the traversing light beams outwardly through the sleeve.
The inside surface of the tube may be etched or otherwise
treated chemically or mechanically to cause light striking
it to diffuse. Another device for providing discontinue-
ties for deflecting light through the sleeve wall is by
introducing air bubbles into the core material while
it is still molten. In accordance with another modifica-
lion, light is deflected outwardly from the core by
reflective particles on the form of powder embedded in the
material of the sleeve. In another form, the sleeve may
comprise a material having an index of refraction which
exceeds that of the core.
The source of light, which may either be steady-
state or pulsating, such as a strobe light, may preferably
comprise a tiny light bulb interposed into the end of the
sleeve, immediately adjacent the end of the core, although
the source or bulb may be located beyond the end of the
light guide. For variation, color filters, or a color
wheel may be interposed between the light source and the
input end of the light guide, imposing preselected colors
on the light diffused through the walls of the sleeve.
One method of forming a combination in accordance
with the present invention is by providing a tube of
radially expanded plastic, such as tetrafluoroethylene,
manufactured by ELI. Dupont de Numerous under the trade-
mark TEFLON (TOE), having a 2 to 10 percent fill, with
reflective or refractive powders such as for example,
titanium dioxide (Shea), or bismuth sub carbonate
(Buick
A thermosetting resin, which may for example,
comprise a liquid mixture of from 60-90% of ally dimly-
Cole carbonate (CRY), with a 1.5 to 3.0 per cent solution
of isopropylpercarbonate (IMP), and the balance methyl
melhacrylate, is poured through a funnel into one end of
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1 the coil of tubing which is open at the other end, so that
the liquid mixture flows down into the same by gravity.
the coil is then transferred to a liquid bath where the
core is polymerized and substantially hardened by heating
for a period of 12 to 24 hours at a temperature within the
range 125 to 185 degrees Fahrenheit. The core material
may be under catalyzed in order for it to remain flexible
The tetrafluoroethylene sleeve may be shrink-fitted onto
the polymerized core by heating the core and sleeve
combination up to a temperature within the range, say,
from 200 lo 400 degrees Fahrenheit. In accordance with
one embodiment the inner diameter of the enclosing
sleeve is slightly less than the outer diameter of the
core in order to impose a slight compression on the core
and squeeze out any air remaining at the interface between
the core and the sleeve.
Another alternative is to provide a sleeve con-
sitting essentially of AROCLOR resins (polychlorinated
polyphenyls) which have indices of refraction ranging from
1.617 to 1.665, which is generally less than that of the
herein disclosed core materials which range around 1.5~
If shapes other than round are desired, such as
elliptical, square, triangular, etc., the casing may be
drawn through a die of the proper shape, in accordance
with well-known extrusion practice
The light guide of the present invention is adapted
to be used for many applications Because of its flex-
ability it can be used to form signs, both for utilitarian
and decorative purposes, such as road safety signs,
similar to the neon signs presently in user and for line
sources, both in and out of doors, for providing a soft
inexpensive light of any desired color over an extended
area. The flexible rod fight source of the present
invention is also useful to light up strips on safety
clothing, such as vests for traffic policemen; and for
placement around the rims of vehicle wheels, or as the
core of a rigid plastic rod, to be fastened to the rear of
a bicycle, for safety purposes.
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Other applications of the present invention, which are within the
contemplation of this disclosure are to surround meters on incitory-
mint panels and the like, and to surround mirrors and pictures,
giving a uniform light around the edges.
The principal advantages of the light diffusing light
guide of the present invention over prior art line sources are
the simplicity and inexpensiveness of its manufacture, the ease
with which it may be applied, and the many applications to which
it is adapted.
Thus, in accordance with one broad aspect of the
invention, there is provided an optical distribution system
comprising in combination:
a source of light:
means to apply light derived from said source to an
area requiring illumination;
said means comprising a flexible light guide coupled
in light-transmitting relation to said source, said light guide
comprising a flexible core of light transmitting material; and
a sleeve of transparent or translucent material
tightly surrounding said core in a manner to substantially
eliminate air from the interface between said core and said
sleeve, said sleeve and said core being constructed and arranged
to laterally diffuse, disperse or refract through the sidewall
of said sleeve a substantial component of the light traversing
said core longitudinally.
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In accordance with another broad aspect of the
invention there is provided the method of forming a light guide
which is constructed to function as a primary light source which
comprises the steps of:
radially expanding a length of translucent or
transparent flexible plastic tubing to the desired dimensions;
filling said tubing with resinous plastic material
which is adapted to form a flexible substantially transparent core;
and
polymerizing and hardening said core by baking said
light guide in a hot liquid bath for 12 to 24 hours at a temper-
azure of 125 to 185 degrees Fahrenheit, whereby said flexible
plastic tubing is shrink-fitted onto said core substantially
squeezing the air out of the interface between said core and said
tube.
In accordance with another broad aspect of the in-
mention there is provided a light guide comprising in combination:
a flexible core of light transmitting meteorology
a sleeve of transparent or translucent material
tightly surrounding said core in a manner to substantially
eliminate air from the interface between said core and said
sleeve, said sleeve and said core being constructed and arranged
to laterally diffuse, disperse or refract through the sidewall
of said sleeve a substantial component of the light traversing
said core longitudinally.
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These and other objects, features, and advantages
will be better understood from a detailed study of the
invention with reference to the attached drawings.
Short Description of the Drawings
_ _
Figure 1 is a longitudinal section of a light guide
in accordance with the present invention showing the external
sleeve shrunk tightly onto the inner light transmitting core so
that air is substantially evacuated from the interface
Figure 2 is a schematic showing of a light beam from
a light source passing down the core of a light guide shown in
longitudinal section in accordance with the present invention,
part being inwardly reflected, and part being refracted and/or
reflected or diffused through the walls of the external sleeve.
Figure 3 shows, in cross-section, a series of
typical shapes into which the light guide of the present invent
lion can be extruded.
Figure PA and 4B are longitudinal and cross-sectional
showings in accordance with the present invention in which a
series of cuts or discontinuities have been interposed through
the sleeve into the surface of the inner core, to cause the light
rays to be deflected outwardly.
Figure 5 is a longitudinal section showing in
accordance with the present invention in which particles of powder
have been mixed into the matrix material of the sleeve to cause
light from the core to be reflected, refracted or diffused
outwardly.
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¦ 1 Fig. 6 is a side elevation of a modification in
accordance with the present invention in which a spiral
marking has been etched or otherwise engraved onto the
surface of the core to cause light to be deflected
outwardly
Fig. 7 is a longitudinal sectional showing of a
further modification of the light guide of the present.
invention in which the inside of the sleeve has been
either chemically or mechanically roughened to cause light
from the core to be diffused or deflected outwardly
Fig. 8 shows the process in accordance with the
present invention of pouring a liquid mixture of core
material into the sleeve.
Fig, PA and I show the process of heat treating a
coil of filled tubing in a heated bath for polymerizing
the core of the light guide of the present invention.
Fig. 10 is an application of the light guide tubes
of the present invention to a safety vest for traffic
directors, miners, and other applications.
Fig. 11 shows a sign formed from a light guide in
accordance with the present invention in combination with
a pulsing device
Fig 12 shows a cane for the disabled 9 employing
the light guide of the present invention
Fig. 13 shows a bicycle having light guides in
accordance with the present invention surrounding the
inner periphery of the wheel rims; and a light guide in
accordance with the present invention incorporated into a
safety light rod attached to the rear of the bicycle.
Fig. 14 shows application of the light guide of
the present invention to a meter dial in an instrument
panel.
Detailed Description of the Invention
Whereas, as explained herein before the principal
object of the prior art was to provide a light guide which
delivers optical energy substantially without loss, to a
selected destination the object of the present invention
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1 is to provide various embodiments of light guides, each of
which outwardly deflects or refracts a substantial come
potent of the light being transmitted along its core.
Referring to Fig. 1 of the drawings, there is
shown in enlarged section, a flexible light guide 1 of the
present invention in which a tube or sleeve 2 of a smooth,
flexible transparent or translucent plastic material, is
shrink-fitted onto a transparent, transmitting core 3, or
transparent plastic or resinous material, so as to sub
staunchly eliminate any air interface between the core 3
and the sleeve 2. In at least one embodiment of the
invention, the external sleeve has an index of refract
lion No which exceeds the index of refraction No of
the core, so that total reflection does not take place.
In other embodiments, the courier the sleeve are provided
with discontinuities which outwardly diffuse or deflect a
substantial component of the light traversing the core.
When any conventional light source 4 is disposed
adjacent to one end of light guide 1, as shown in Fits. 1
and 2 of the drawings, a substantial amount of light
energy impinges on the adjacent end, and is transmitted
along the core of the guide in a manner depending on the
angle of incidence of the beam. A beam, designated pa,
which enters the core parallel to its principal axis will
travel in a substantially straight path along the core
without being reflected or refracted. A beam 5b, which
enters the core at an angle i, is partially reflected at
an angle r1, equal to the angle i, forming a beam 5c
which passes in a zigzag path along the core 3. A come
potent of beam Ed is also partly refracted through annoyingly r2 at the inner periphery of the sleeve 2, forming
a beam So which passes out through the sleeve, and which
is again refracted through an angle r3 at the outer
periphery of the sleeve, to form an outwardly-directed
beam ye.
This tends to cause the sleeve 2 to appear bright,
as a substantial proportion of the light from the source
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1 would be refracted outwardly, depending on the ratio of
the indices of refraction and the angle of the incident
light, as determined by the position of the source I
As shown in Fig 3, it is contemplated that the
S cross-section of the light guide 1 need no be round as
shown in pa, but can assume numerous different shapes such
as square, triangular, elliptical, hexagonal pentagonal,
star-shaped, etc. as indicated in 6b-6g. This is achieved
in accordance with well-known technology by passing the
light guide casing through a die of the desired shape dun-
processing. Pulsation or twisting may be applied during
extrusion to achieve what is termed a nbel1Owsn effect.
An alternative embodiment of the invention is
shown in longitudinal and cross-section in Figs PA and 4B
of the invention in which a series of angular cuts 7 are
interposed into the sleeve 2 of the light guide 1 along
its length, and extended into the surface of the guide,
forming discontinuities therein. Thus, beams 5g and oh
traversing the core 3 from the source I impinge on
these discontinuities and are deflected outwardly through
the sleeve 2; causing it to appear bright along its
length. It is contemplated for example, that the cuts
taken at intervals along the core may be shaped, as shown
in Fig byway In order to provide substantially uniform
brightness along the length of the light guide, the shaped
cuts are made progressively larger as the longitudinal
distance along the axis from the source increases, to
reflect out a substantially larger percentage of the
remaining light traversing the core at each cut.
Another device for achieving the same result it
shown in Fig 5 of the drawings wherein the sleeve 2
comprises a matrix of plastic material which, during
preparation, has been mixed with powdered reflecting
material, such as certain types of metal oxides, to render
it translucent. Beams I and 5j, for example, traversing
the core 3 tend to strike the powder granules and are
thereby deflected to pass out through the sleeve, thus
causing the sleeve to appear bright.
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¦ 1 Other devices for achieving this result are by
etching or otherwise engraving a spiral strip on the
surface of tube core 3, prior to enclosing the same in the
outer sleeve.
Another device is Jo bleed in bubbles or foreign
materials through a needle into the inner core while the
same is still in a viscous state, or by vigorously shaving
up the core material before pouring it into the sleeve
during processing
Another technique in accordance with the present
invention, illustrated by the longitudinal sectional
showing of Fig. up comprises etching or taking other
mechanical or chemical steps, such as treating with sodium
napthalene, to roughen the inner surface of the sleeve 2
15 before the core material it added
The following is a typical numerical example for
preparing a light guide in accordance with the present
invent ion . 12~
A tubular coil I of sleeve material, say 10 feet
B 20 long, 16 inch outer diameter and 4 inch inner diameter,
has a matrix consisting essentially of tetrafluorethylene
TOE, is filled with from 2 to 10 percent of reflecting
metal oxide powder, having an average grain size of talcum
powder, or the like.
The radially-expanded tubular coil I is filled
with a viscous liquid core material, wish in the present
example comprises the following formulation:
Range Preferred
ally diglycol carbonate (CRY) 60-90% 88%
isopropylpercarbonate (IMP) 1-3 Swahili% sol.
methyl methacrylate Balance 10~
The liquid mixture 10 is then poured through a
funnel into one end of the coiled tetrafluorethylene
sleeve , which is open at the other end. (See Fig 8)
The coil 12 containing the liquid core material 3
is then mounted on a screen support aye for a period of
from 12-24 hours in conventional container 14 of a liquid
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bath 15, which is maintained at a temperature of 120 to
170 degrees Fahrenheit by a conventional heater 16, and
which it constantly stirred by an impeller 17 driven by
motor 18~ This enables the core material to polymerize,
forming a flexible thermoses transparent inner core.
In accordance with an alternative embodiment
B the tubular coil can be formed of a material having an
index of refraction exceeding that of the core material.
A suitable material for this purpose is a polychlorinated
polyphenyl resin known by the trademark AURICLE which has
an index of refraction of about 1.6. Referring again to
Fig I when a sleeve of such a material us used, it is
unnecessary to use filler materials or discontinuities in
the sleeve 2 or the core 3 as a beam from the source 4
or _.
'I impinging on the inner wall of the sleeve 2 will be
outwardly refracted through the sleeve -
Applications of the Present Invention
Numerous applications are contemplated for use of
the light guide of the present invention.
Referring to Fig 10~ there is shown a vest 19
which is particularly applicable to night-time operations
for use by traffic policemen and other directors of
traffic, miners, and various types of sports persons, such
as, for example jogger and skiers This may be formed of
any of the materials used for such garments cut to a
conventional pattern adapted to slip over the head of the
user, providing a highly visible front and back panel. A
pair of vertical strips aye and 21b, each about three
inches wide are sewn or otherwise secured along their long
edge, parallel to the lateral edges of the vest, in such
a manner that in each case an inside vertically extending
channel is provided between the strips and the backing
material of the vest. Elongated light guides aye and 23b,
wormed in accordance with any one of Figs. 1-7 of the
present invention, are respectively accommodated in the
channels provided by each of strips aye and 21b. The
input ends of aye and 23b are each connected to light
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j 1 source 22 This may comprise a pair of small 2 watt bulbs
aye and 22b secured in the respective ends of light guides
aye and 23b which are energized by means of a conventional
battery It is contemplated that for most applications
1 5 light guides aye and 23b are extended over the shoulders
! and down the rear of the vests It is also within the
contemplation of the present invention thaw a conventional
pulsing device may be incorporated into the source 22
which causes the light bulbs aye and 22b to flash on and
off. The source 22 may be fitted into a small pocket pro-
voided for that purpose at the lower end of the vest 19~
- Another application of the fight guides owe the
present invention is for incorporation into various types
of signs and indoor and outdoor line sources for both
utilitarian and decorative illumination in the manner of
neon, argon, and other gas-filled tubes used in the prior
art for such purposes.
One illustration of such use is shown in Fig. 11
of the drawings, in which the light guide of the present
invention is sufficiently flexible to form such letters as
may be desired. In accordance with the alternative prove
piously indicated, a conventional power source may incur-
I prorate pulsing means 25 connected to turn on an off the
¦ light source I In this embodiment, the light source
! 25 may, for example comprise a 1 to 1000 watt bulb, ever-
gibed either by a battery or conventional source of power,
which may either ye fitted into the input end of the light
guide forming the letters SIGN, or may be slightly spaced-
apart therefrom. In the latter case, it may he desired to
interpose a motor-driven color wheel 27 which would lung-
lion to periodically change the color of the sign. For
this application it is contemplated that any of the light
guides of the types disclosed in Figs. 1-7 can be used.
Other applications of the light guides disclosed
in any one of Fits. 1-7 are shown in Figs. 12~ 13 and 14.
Fig. 12 shows a cane 28 for the disabled in which, for
example, battery operated light source is built into the
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1 upper end. Although a subsequential partaken of the light
traversing the 1 length of the cane is dissipated laterally,
it is contemplated that a portion of the light will travel
to the lower end 30; providirlg a lighted lower tip, for
5 guidance purposes; and a portion of light would also be
available at the upper end.
i One of the most important applications of the
invention it for safety lights for vehicles, which is
illustrated by the bicycle of Fig. 13 A flexible light
guide in accordance with the present invention is disposed
around the inner periphery of the wheels. An additional
light guide is interposed into a rigid tube of LEAN
(polycarbonate~, or similar material, vertically fastened
to the rear of the vehicle It is contemplated that all
of these light guides will be lighted by small 2-10 watt
bulbs, incorporated into the light guide sleeves, in each
case.
They will be energized from a battery source 33
fastened to the frame or by an on-board venerator. As an
additional feature, the LEAN tube including light guide 4
may terminate at its upper end in a lighted ball aye
which may comprise a ball of transparent or translucent
material similar to the core material.
It will be understood that similar safety lights
in accordance with the present invention can be utilized
for many different types of vehicles, such as automobiles,
trains, ships, boats, aircraft, etc.
Another application of the invention illustrated
in Fig. to, which shows the dial of a meter 35 with a
I light guide 36 in accordance with the present invention
disposed around its inner periphery. It is contemplated
that this can be energized by batteries, or another con-
ventional source at the rear of the dial or elsewhere
which energized one or more small light bulbs of 9 say 10
to 1 watt, incorporated unto the sleeve of the light guide.
So 1
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though a number of examples have been given of
applications of the light guide of the present invention,
it will be understood that the invention is not limited to
the specific applications or forms set forth herein by way
5 of example, but only by the scope of the appended claims.
