Note: Descriptions are shown in the official language in which they were submitted.
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PHOTORAD IATOR
BACKGROVND OF TE~E INVENTION
The present invention relates to a photoradiator
for effectively radiating light prGpagating therethrough
in a desired direction and in a desired quantity to the
ambience, while furnishing it with an optical property
suitable for a desired application.
Effective use of solar energy is tne key to energy saving
today and has been studied in various fields actively.
For the most effective use of solar energy, solar energy
has to be availed as it is without being transformed
into another kind of energy such as thermal energy or
electrical energy. In light of this, I have made
various proposals for an illumination system which
utilizes solar energy. The illumination system employs
a light conducting element such as a fiber optic cable
through which the sunlight converged by a lens or the
like is conducted to a desired location to stream out
thereat to illuminate the ambience.
In the illumination system of tne type described,
the light advancing through the light conductor has
directivity. Therefore, if the light is;output at a
simple cut end of the light conductor, it becomes
radiated over an angle ~ which is usually as small as
about 46~. The light streaming through the simple cut
end of the light conductor would fail to evenlv
illuminate a desired space such as a room. I have
proposed in various forms a photoradiator which is
designed to effectively diffuse light conducted by a
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fiber optic cable to provide even illumination over a wide
range.
Another problem encountered with a light
conducting element of the kind described is that when it is
laid over a length sufficient for practical use, fringes
develop in the light emanating from the light conductor
which are undesirable for ordinary lighting applications,
although some particular applications may rather prefer
them. Where the light propagating through the light guide
is a laser or the like, fringes appear therein even if the
light conductor is of a very small diameter such as an
optical fiber, rendering the light unfeasible for use with a
laser microscope or the like.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention
to provide a photoradiator which is capable of effectively
diffusing light transmitted therethrough to the outside by
means of a simple construction.
It is another object of the present invention to
provide a photoradiator which allows light propagating
therethrough to be radiated to the outside in a desired
direction and in a desired quantity.
It is another object of the present invention to
provide a photoradiator which radiates light having a
desired optical property.
It is another object of the present invention to
provide a generally improved photoradiator.
According to the present 1nvention, there is
provided a photoradiator for diffusing light transmitted
therethrough comprising a first and second cylindrical light
co~ducting rods each having a longitudinal axis and each
having an outer cylindrical wall, the first cylindrical light
conducting rod having a first longitudinal end section, the
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first longitudinal end section having an inner frusto-
conical wall and an inner flat end wall, the inner frusto-
conical wall having a large diameter end and a small
diameter end, the large diameter end being coincident with a
circumferential line on the outer cylindrical wall of the
first cylindrical light conducting rod, the inner flat end
wall having a circular configuration, the smaller diameter
end of the inner frusto-conical wall being coincident with
the inner flat circular end wall, the second cylindrical
light conducting rod having a second longitudinal end
sections,the second longitudinal end section having an outer
frusto-conical wall and an outer flat end wall, the outer
frusto-conical wall having a large diameter end and a small
diameter end, the last large diarneter end being coincident
with a circumferential line on the outer cylindrical wall of
the second cylindrical light conducting rod, the outer flat
end wall having a circular configuration, the small diameter
end of the outer frusto-conical wall being coincident with
the outer flat circular end wall, the inner frusto-conical
wall, along with the inner flat circular end wall, being
complementarily arranged and axially aligned respectively
with the outer frusto-conical wall along with the outer flat
circular end wall; and a semitransparent layer deposited on
either one of the inner frusto-conical wall of the first
cylindrical light conducting rod and the outer frusto-
conical wall of the second cylindrical light conducting rod,
whereby light propagating through the first cylindrical
light conducting rod is transmitted to the second
cylindrical light conducting rod via the inner and outer
flat circular end walls while the rest of the light being
propagated is partly reflected laterally outwardly by the
inner and outer frusto-conical wall via the semitransparent
layer and partly transmitted through the inner and outer
frusto-conical walls and the semitransparent layer into the
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second cylindrical light conducting rod.
According to the present invention, there i5 also
provided a photoradiator for difusing light transmitted
therethrough comprising first and second cylindrical light
conducting rods each having a longitudinal axis and each
having an outer cylindrical wall, the first cylindrical
light conducting rod having a first longitudinal end
section, the first longitudinal end section having an inner
frusto-conical wall and an inner flat end wall, the inner
frusto-conical wall having a large diameter end and a small
diameter end, the large diameter end being coincident with
a circumferential line on the outer cylindrical wall of the
first cylindrical light conducting rod, the inner flat end
wall having a circular configuration, the small diameter end
of the inner frusto-conical wall being coindident with the
inner flat circular end wall, the second cylindrical light
conducting rod having a second lingitudinal end section, the
second longitudinal end section having an outer frusto-
conical wall and an outer flat end wall, the outer frusto-
conical wall having a large diameter end and a small
diameter end, the last large diameter end being coincident
with a circumferential line on the outer cylindrical wall of
the second cylindrical light conducting rod, the outer flat
end wall having a circular configuration, the small diameter
end of the outer frusto-conical wall being coincident with
the outer flat circular end wall, the inner frusto-conical
wall being fully complementary with the outer frusto-conical
wall, and a semitransparent layer deposited on either one of
the inner frusto-conical walls of the first cylindrical
light conducting rod and the outer frusto-conical wall of
the second cylindrical light conducting rod, the first and
second cylindrical light conducting rods being disposed in
an axially aligned position with the inner frusto-conical
wall being separated from the outer frusto-conical wall by
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the semitransparent layer and with both the inner and outer
frusto-conical walls in contact with the semitransparent
layer, whereby light propagating through the first
cylindrical light conducting rod is transmitted to the
second cylindrical light conducting rod via the inner and
outer flat c~ircular end walls while the rest of the light
being propagated is partly reflected laterally outwardly by
the inner and outer frusto-conical wall via the semitrans-
parent layer and partly transmitted through the inner and
outer frusto-conical walls and the semitransparent layer
into the second cylindrical light conducting rod.
According to the present invention, there is also
provided a photoradiator for diffusing light transmitted
therethrough comprising first and second cylindrical light
15 ` conducting rods each having a longitudinal axis and each
having an outer cylindrical wall, the first cylindrical
light conducting rod having a first longitudinal end
section, the first longitudinal end section having an inner
frusto-conical wall and an inner flat end wall, the inner
frusto-conical wall having a large diameter end and a small
diameter end, the large diameter end being coincident with a
circumferential line on the outer cylindrical wall of the
first cylindrical light conducting rod, the inner flat end
wall having a circular configuration, the small diameter end
of the inner frusto-conical wall being coincident with the
inner flat circular end wall, the second cylindrical light
conducting rod having a second longitudinal end section, the
second lingitudinal end section having an outer frusto-
conical wall and an outer flat end wall, the outer frusto-
conical wall having a large diameter end and a smalldiameter end, the last large diameter end being coincident
with a circumferential line on the outer cylindrical wall of
the second cylindrical light conducting rod, the outer flat
end wall having a circular configuration, the small diameter
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end of the outer frusto-conical wall being coincident with
the outer flat circular end wall, the first and second
cylindrical light conducting rods being dispased in an
axially aligned position with an air space between the inner
frusto-conical wall and the outer frusto-conical wall,
whereby light propagating through the first cylindrical
light conducting rod is transmitted to the second
cylindrical light conducting rod via the inner and outer
flat circular end walls while the rest of the light being
propagated is partly reflected laterally outwardly by the
inner and outer frusto-conical wall via the air space and
partly transmitted through the inner and outer frusto-
conical walls and the air space into the second cylindrical
light conducting rod.
The above and other objects, features and
advantages of the present invention will become apparent
from the following detailed description taken with the
accompanying drawings.
BRIEF DESCRIPTION OF THE D~AWINGS
Figures lA and lB to 4A and 4B are views of
various embodiments of a photoradiator in accordance with
the present invention, suffix "A" indicating a sectional
side elevation and suffix "B", a cross-section; ,
Figures 5-9 are views of other embodiments of the
present invention;
Figures 10-15 are perspective views of other
embodiments of the present invention;
Figure 16 is a perspective view of a modification
to a transparent control member included in the
photoradiator of Figure 15;
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1;Z587~38
Figure 17 is a side elevation o~ -the control
member of Figure 16 which is positioned to reflect
incoming light;
Figures 18 and 19 are views of a prior art simple
cylindrical light conducting element; and
Figures 20A and 20B to 22A and 22B are views of
other embodiments of the present invention.
DESCRIPTIOl`l OF T~E PREFERRED EMBODIMENTS
While the photoradiator of the present invention
is susceptible of numerous physical embodiments,
depending upon the environment and requirements of use,
substantial numbers of the herein shown and described
embodiments have been made, tested and used, and all
nave performed in an eminently satisfactory manner.
Referring to Figures lA and lB, a photoradiator
embodying the present invention is shown and comprises
a light conducting element in the form of a rod 10. The
light conductor 10 optically connects at one end thereof
(not shown) to a source of converged light supply (not
shown). The other end of the light conductor 10 is
formed with a single conical notch lOa in order to
effectively diffuse light as will be described.
Light such as sunlight L is converged by a lens
or the like into the light conductor 10 at the source.
The light L propagates through the light conductor 10
while being repeatedly reflected by the rod wall. At
the notch lOa in the end of the rod 10, the light L
is partly transmitted through the conical surface to
the outside and partly reflected thereby to change its
course before being radiated. Stated another way, the
light L propagating through the rod 10 is diffused to
the outside at the conical end lOa over a substantial
radiation angle.
A modification to the structure of Figures lA and
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and lB is shown in Figures 2A and 2B. As shown, the
light conducting element lO' is ormed with a number of
conical notches lO'a at the light outlet end tnereof.
The effect attainable with such a multi-notch structure
is essentially common to that achieved with the single
notch structure.
In both the structures shcwn in Figures lA and lB
and 2A and 2B, the conical notch configuration is only
illustrative and may be replaced by a polygonal pyramid
such as triangular pyramid or quadrangular pyramid.
If desired, the notched surface or surfaces rnay be
finished for diffusion in order to effectively scatter
the light to make the illumination tender to the eyesO
The principle described above is similarly
applicable to a light conducting element in the form
of a pipe. In Figures 3A and 3B, a light conducting
pipe 20 comprises an annular wall 22 the light outlet
end of which is cut aslant to define a radially outwardly
flared opening 20a. In Figures 4A and 4B, a light
conducting pipe 20' comprises an annular wall 22' the
light outlet end of which is formed with a number of
recesses or notches 20'a at spaced locations along the
circumference of the pipe.
In the photoradiator shown in Figures 3A and 3B
or 4A and 4B, the converged light L such as sunlight
propagates through the pipe wall 22 or 22' while being
repeatedly reflected by the other peripheral surface
thereof. The notch 20a or notches 20'a serve to
effectively diffuse the light L to thereby radiate it
to the ambience.
If desired, the embodiment shown in Figures 3A and
3B and that shown in Figures 4A and 4B may be combined,
that is, the light outlet end of a light conducting
pipe ~ay be cut to have a flared opening and formed
with a number of recesses along the circumference
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thereof. Again, the light outlet end may be finished
to serve as a light scattering surface and the
illustrated notch configuration is only illustrative.
Referring to Figure 5, another embodiment of the
present invention is shown which is applied to a light
conducting rod. The light conductor 30 in Figure 5
is formed with a plurality of spaced notches 30a along
the circumference thereof and in a selected position
between axially opposite ends. Part of light L
propagating through the rod 30 is partly di~fused
radially outwardly by the walls of the notches 30a.
This type of circumferential notch arrangement is also
applicable to a light conducting pipe, as shown in
Figure 6. The pipe 32 in Figure 6 is formed with
notches 32a at spaced locations along the circu-.nference
thereof and in a selected position between axially
oppoiste ends. The pnotoradiator in Figure 6 functions
in the same manner as the photoradiator shown in
Figure 5, except that it reflects the light at both the
inner and outer walls thereof.
In the photoradiator shown in Figure 5 or 6, a
lower end wall 30al or 32al of each notch may be
inclined radially outwardly with its associated upper
end wall 3a2 or 32a2 formed perpendicular to the
direction of light propagation as illustrated (to the
axis of the light conductor 30 or 32). Alternatively,
the upper end wall 3a2 or 32a2 may be oriented
substantially parallel to the inclined lower end wall,
as indicated by a phantom line in the drawing. Such
a set of notches may be located at a number of spaced
locations along the direction of light propagation, or
the axis of the light conductor. In this case, the
radial depth _ of the notches may be sequentially
increased in the direction of light propagation in
order to set up substantially uniform radiation of
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lignt along the axis of the light conductor.
Referring to Figure 7, another embodiment of the
present invention is shown which has a plurality of
light conducting rods (34-38 in the drawing) interconnect-
ed end-to-end in the illustrated order along the direction
of light propagation. As shown, the rod 36 is formed
with notches 36a so that the inclined walls 36al thereof
may effectively diffuse light coming out from the
bottom of the rod 34. Likewise, the rod 38 below the
rod 36 is formed with notches 38a to diffuse light at
the inclined walls 38al thereof. Such a serial inter-
connection scheme is applicable to light conducting
pipes as well. As shown in Figure 8, pipes 40-44 are
interconnected sequentially along the direction of
light propagation. The pipe 42 has notches 42a with
inclined walls 42al and the pipe 44, notches 44a with
inclined walls 44al.
It will be seen that the diffusion of li~ht
attainable with the photoradiator shown in Figure 7
or 8 is as effective as that attainable with the photo-
radiator of Figure 5 or 6. Nevertheless, the photo-
radiator of Figure 7 or 8 is distinguishable over the
photoradiator of Figure 5 or 6 by the easier and more
accurate production due to the serial connection
of a plurality of light conducting elements which
have been individually machined to have the notches.
A modification to the photoradiator of Figure 8
is illustrated in Figure 9. As shown, the pipe 40 is
connected to the pipe 42 by a light conducting rod 46
whose refractive index is larger than that of the
pipe 40. Likewise, the pipe 42 is connected to the
pipe 44 by another light conducting rod 46. The
photoradiator having such a construction attains
efficient transmission of light, since the light
transmitted through the bore of any pipe is introduced
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~2587~8
into the annular wall of the adjacent pipe by the rod
46; the pipe walls have a higher li~ht transrnission
efficiency than air.
Referring to Figures 10-13, other embodiments of
the present invention are shown which are commonly
designed to diffuse light raidally outwardly to the
ambience. In Figure 10, the photoradiator comprises
light conducting elements 50 and 52 which are connected
end-to-end to each other. The end of the element 50
adjacent to the other element 52 comprises a flat surface
50a, while the end of the element 52 comprises a
frustoconical inclined surface 52a which terminates at
a flat top 52b. T~hen the light conductors 50 and 52 are
assembled together, light propagating through the light
conductor 50 will be partly introduced into the follow-
ing light conductor 52 and the rest is diffused
effectively to the outside by refelection at the
inclined surface 52a while being partly routed into the
element 52.
In the photoradiator shown in Figure 10, the
inclination angle ~ of the inclined surface 52a is
variable to steer the light in a desired direction out
of the photoradiator. Where the angle 0 is 45 degrees,
for example, the light will be radiated perpendicular
to the axis of the photoradiator if it is parallellight, and over a substantial radiation angle if it is
converged light. Also, the ratio in area between the
inclined surface 52a and the flat top 52b may be
varied to set up any desired ratio between the quantity
of light steered to the outside and the quantity of
light transmitted to the subsequent light conductor.
In Figure 11, a light conductin~ element 50'
is formed with a frustoconical recess 50'a and a flat
surface 50'b which are generally complementary to the
contigu~us frustoconical surface 52a and flat surEace
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52b of the light conducting element 52, which is the
same as the element 52 of Figure 10. In this construc-
tion, light propagating through the element S0' is
partly transmitted to the element 52 via the aligned
flat surfaces 50'b and 52b, while tne rest is partly
refelected outwardly by ~he inclined surfaces 50'a and
52b and partly transmitted into the element 22. The
photoradiator construction shown in Figure 11 is
advantageous in that it allows the two elements 50' and
52 to be aligned with ease to each other.
In Figure 11, should the interconnecting surfaces
of the rods 50' and 52 be configured fully complementary
to each other, no light would be refelected by the
inclined surfaces. It is preferable, therefore, to
desposite a semitransparent layer on the inclined
surface of either one of the rods 50' and 52. Generally,
however, it will suffice to form them approximately
complementary so that an air space may be defined
therebetween to reflect part of the propagating light
at the inclined surfaces.
In Figure 13, the photoradiator comprises a
cylindrical light conducting element 54 having a flat
end 54a, and a light conducting element 56 having two
inclined surfaces 56a and 56b which converge to a
flat top 56c. In this case, light transmitted through
the light conductor 54 will be diffused outwardly in
two directions by the inclined surfaces 56a and 56b.
Again, the light conductor 54 may have its end formed
colmplementary to that of the light conductor 56 as shown
in Figure 13. In Figure 13, the element 54' has a recess
defined by opposite inclined surfaces 54'a and 54'b
and a flat surface 54'c. The construction shown in
Figure 13, like that shown in Figure ll, will promote
` easy alignment between the two coactive light conductors
54' and 56.
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While in the embodiment shown in Figure 12 or 13
the opposite inclined surfaces 56a and 56b are assumed
to be equal in area to each other, they may be provided
with diferent areas such that a laryer quantity of
light is reflected by one of them than by the other.
In the extreme case, the configuration may be such that
the light is reflected by one inclined surface 60a of
a light conducting element 60 as indicated by an arrow
A. In this case, light may be supplied from the light
conductor 60 into an upper light conductor 58 as
indicated by an arrow B.
Referring to Figure 15, another embodiment of the
present invention is shown which is furnished with means
for controlling a quantity of light radiation. The
photoradiator in Figure 15 comprises a first lignt
conducting element 62, a second light conducting element
64 and a transparent control member 68. Either one
of the elements 62 and 64 (64 in this particular
embodiment) is formed with a recess 64a at an end
thereof which connects to the other element. The
transparent control member 68 is removably disposed in
the recess 64a. As shown, the control member 64
includes a flat surface 68a and an inclined surface 68b.
In this photoradiator construction, light propagating
through the light conductor 62 is partly transmitted
to the light conductor 64 via the flat surface 68a of
the control member 68 and the rest is partly reflected
outwardly by the inclined surface 68b while being
partly routed into the light conductor 64.
A characteristic feature of the photoradiator
shown in Figure 15 is that the quantity of light steered
by the inclined surface 68b of the control member 68
is adjustable by controlling the position of the
control member 68 in the recess 64a. Light from the
li~ht conductor 62 will be partly reflected by the
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inclined surface 6gb of the control member 68 as
indicated by an arrow A, while light from the light
conductor 64 will be reflected by the inclined surface
86b as indicated by an arrow B. Therefore, light may
be supplied in either one of the opposite directions
as desired.
Another example of the transparent control member is
shown in Figure 16. As shown, the alternative
transparent control member 70 comprises two inclined
surfaces 70al and 7a2 which reflect light from the
light conductor 62 (Figure 15) in two different
directions, as indicated by arrows A. The position of
such a control member is adjustable in the recess 64a
(Figure 15) to vary the proportions of the light
reflected by the opposite inclined surfaces 70al and
70a2 to each other. Again, only one inclined surface
may be formed on the member 70 in the extreme case.
The control member 70, different from the control
member 68 of Figure 15, is incapable of reflecting
light coming in from the light conductor 64 (Figure 15),
since it would reflect it back thereinto at the inclined
surfaces 70al and 7a2 as indicated by arrows B.
It will be apparent that a number of interconnec-
tion surfaces each including an inclined surface or
surfaces as described may be defined sequentially along
the axis of the photoradiator. In such a case, the
control member 70 shown in Figure 16 may be installed
in the photoradiator in the position shown in Figure 17
to return light reached the last light conductor n,
thereby causing more effective radiation of light.
It is necessary then to treat a flat surface 70b
between the inclined surfaces 70al and 7a2 to reflect
incident light.
Now, assume a simple cylindrical light conducting
element 80 as shown i~ Figures 18 and 19. When parallel
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light Ll is introduced into one end A of the light
conductor 80 as shown in Figure 18, it will be radiated
from the other end B without any divergence. ~hen the
incident light is converged light as indicated by L2
in Figure 19, it will be radiated over a divergence
angle ~ of about 46 degrees. However, such a simple
cylindrical light conductor suffers from the drawbacks
previously discussed. Farther embodiments of the
present invention will be describe which are elaborated
to radiate light after varying its optical property
to suit a desired application.
Referring to Figures 20A and 20B, the photoradiator
comprises a light conducting element 90 which is made
up of a cylindrical portion 9Oa and a frustoconical
portion 90b which extends tapered from the cylindrical
portion 90a. When converged light L2 is incident on an
end A of the cylindrical portion 90a, it will propagate
through the light conductor 90 while being reflected
by the wall of the continuous portions 9Oa and 9Ob.
The light output from an end B of the frustoconical
portion 9Ob has a substantial divergence angle due to
the N.A which has increased during the travel of the
light through the frustoconical portion 90b. Fringes
which develop in the light output from the photo-
radiator 90 will be feasible to special decorativeapplications. For more general lighting applications,
parallel light Ll may be introduced into the light
conductor 90 as shown in Figure 20B. The light outgoing
the light conductor shown in Figure 20s is substantially
identical in optical property with the incoming light.
Referring to Figure 21A, the photoradiator
comprises a light conducting element 92 having a
cylindrical portion 92a and a frustoconical portion
92b, and a second light conducting element 94 having a
cylindrical portion 94a and a frustoconical portion 94b.
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1258788
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The light conductors 92 and 94 are interconnected at
the ends of their frustoconical portions 92b and 94b
as illustrated. This type of construction eliminates
fringes in the light radiated from the photoradiator,
since the fringes developed in the light conductor 92 is
cancelled in the second light conductor 94. If desired,
use may be made of a single piece light conductor 96
as shown in Figure 21B, which is identical in configura-
tion with the interconnected light conductors 92 and
94.
Another embodiment of the present invention is
shown in Figure 22A which comprises a light conducting
element 98 having a cylindrical portion 98a and a
frustoconical portion 93b contiguous with the cylindrical
portion 93a, and a second light conducting element 100
having a frustoconical portion lOOa, a cylindrical
portion lOOb and a frustoconical portion lOOc. This is
similar to the construction shown in Figure 21A except
for the additional conical portion lOOc which, as in the
construction of Figure 20A, serves to increase the
radiation angle of output light by reflection. Again,
the two light conductors 93 and 100 may be replaced
with a single light conductor 102 configured generally
identical thereto.
Various modifications will become possible for
those skilled in the art after receiving the teachings
of the present disclosure without departing from the
scope theFeof-
