CA1264584A - Photoradiator - Google Patents

Abstract

ABSTRACT
A photoradiator includes a notch at an axial end or in the periphery thereof in order to radiate light which propagates therethrough. Light is radiated in a desired direction and in a desired quantity at the notch. Even the optical property of the light radiated from the photoradiator may be varied for a desired application.

Description

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The present invention is a division of the canadian patent application 442,-243 filed on November 30, 1983.
The present invention relates to a photoradiator for effectively radiating light propagating therethrough in a desired direction and in a desired quantity to the ambience, while urnishing 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 macle 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 aesired 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 evenly illuminate a desired space such as a room. I have proposed in various forms a photoradiator which is designed to ~ffectively diffuse light conducted by a ~26~

fiber optic cable to provide even illumination over a wide range.
Another problem encountered with a light conducting element of the kind aescribed is that when it is laid over a le~ sufficient for practical use, fringes de~elop in the light emanating from the light conductor which are undesirable for ordinary lighting applications, although some particular applications may rather preer them~ Where the light propagating through the light ~uide 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 effective-ly diffusing light transmitted tnerethrough to the outside by means of a simple construction.
It is another object of the present invention to provide a photoradiator which allows light propagat-ing 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 invention there is provided a serially connected cylindrical light conducting rods for propagating light along the axial length of the cylindrical light conducting rods and for reflecting the light laterally outwardly in two directions, comprising a first and a second cylindrical ~Z64S84 h!- 3 -light conducting rod each having a longitudinal axis and each having an outer cylindrical wall, the first cylindrical light conducting rod having a first longitudinal end section with a first flat end wall, the second cylindrical light conducting rod having a second longitudinal end section, the second longitudinal end section having two outer converging flat walls and a second outer flat end wall, the second outer flat end wall having two sides and two ends, the two outer converging flat walls each having an outer terminating end which is coincident with the sides of the second outer flat end wall, the two outer converging flat walls extending to the longitudinal end of the second longitudinal end section, the two converging flat walls converging as the longitudinal end of the second longitudinal end section is approached the first and second light conducting rods being connected end-to-end to each other at the first flat end wall and the second outer flat end wall in serial and axial alignment, whereby light propagating through the first cylindrical light conducting rod is transmitted to the second cylindrical light conducting rod via the first flat end wall and the second outer flat end wall, while the rest of the light being propayated is partly reflected laterally outwardly in two directions by the two converging outer flat walls and partly transmitted through the two converging outer flat walls into the second cylindrical light conducting rod, the serially connected conducting rods thereby propagating the light axially and reflecting the light laterally outwardly thereof in two directions.
Preferably, the first flat end wall is perpendi-cular to the longitudinal axis of the first cylindricallight conducting member and the second outer flat end wall is perpendicular to the longitudinal axis of the second cylindrical light conducting member.
Preferably, the first flat end wall has a circular il Z6~S8~
- 3a -configuration having a diameter equal to the diameter of the first cylindrical light conduc-ting member.
Preferabl~, the two ends of the second outer flat end wall are defined by the outer cylindrical surface of the second cylindrical light conducting member.
The area of each of the two converging flat walls may be e~ual, or it may be different such that one of the two converging flat walls reflects more light laterally outwardly than the other converging flat wall.
The above and other objects, features and advantages of the present invention will become apparent from the following dettailed description taken with the accompanying drawings.

~RIEF DESCRIP~ION OF THE DRAWINGS

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 c ross-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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Figure 17 is a side elevation of the controlmember of Figure 16 which is positioned to reflect incominy light;
Figures 18 and 19 are views of a prior art simple cylindrical light conducting elernent; and Figures 20A and 20B to 22A and 22B are views of other embodiments of the present invention.

DESCRIPTIOL~ OF THE 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 10a 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 10a in the end of the rod 10, the light L
is partly transmitted through the conical surface to the ou~side and partly reflected tnereby 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 10a over a substantial radiation angle.
A modification to the structure of Figures lA and ~2641~S~

and lB is shown in Figures 2A and 2s. As shown, the light conducting element 10' is formed with a number of conical notches lO'a at the light ou~let end tnereof.
l'he 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 quadrangùlàr pyramid.
If desired, the notched surface or surfaces may be finished for diffusion in order to effectively scatter the light to make the illumination tender to the eyes.
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 periphe~al 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 L5~

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 E'igure 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 diffused 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 circ~nference thereof and in a selected position between axially oppoiste ends. ~he photoradiator 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 tne 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 ~Z~i4S8~

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-S ed end-to end in the illustrated order along the direction of li~ht 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 3Ç îs formed with notches 38a to diffuse li~ht at the inclined walls 38a1 thereof. Such a serial inter-connection scheme is applicable to light conducting pipes as well. As shown in Fig~re 8, pipes 40-44 are interconnected sequentially along the direction of lS li~ht 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 light attainable with the photoradiator shown in Figure 7 or 8 is as effective as that attainable with the photo-radiator o~ Figure 5 or 6. NeVerthelesS, the photo~
radiator of Figure 7 or 3 is distinguishable over the photoradiator of Figure S 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 1~4584~

into the annular wall of the adjacent pipe by the rod ~6; the pipe walls have a higher li~ht transmission efficiency than air.
Referring to Fi~ures 10-13, other embodiments of S the present invention are shown which are commonly designed to diffuse light raidally outwardly to the ambience. In Figure 10, the photoradiator comprises light ~~onducting 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 terminat~s at a flat top 52b. When 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 pilotoradiator 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 conducting element 50' is formed with a frustoconical recess 50'a and a flat surface 50'b which are generally complementary to the contiguous frustoconical surface 52a and flat surface 51~

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 50' is partly transmitted to the element 52 via the aligned flat surfaces 50'b and 52b, while tne rest is partly refelected outwardly by the inclined surfaces SO'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 complementary 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 11, 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 different areas such that a larger 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. ln this case, light may be supplied from the light conductor 60 into an upper light conductor 58 as indicated by an arrow B.
~ eferring 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 light 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 e~bodiment) is foxmed 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 tne control member 68 i~ 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 ~;~64~i89~

inclined surface 6~b 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 s. Therefore, light may S 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 Bo It will be apparent that a number of interconnec-tion surfaces each including an inclined surface or surfaces as described may be deEined 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, 3Q 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 in Figures 18 and 19. When parallel ~Z~5~

light l,l 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 ~rom 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 o the continuous portions 9Oa and 9Ob.
The light output ~rom an end B of the frustoconical portion 90b has a substantial divergence angle due to the N.A which has increased during the travel of the light through the frustoconical portion 9Ob. Fringes which develop in the light output from the photo-radiator 90 will be feasi~le 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 20B 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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The light conductors 92 and 94 a~e interconnected at the ends of their frustoconical portions 92b and 9~b as illustrated. This type of construction eliminates fringes in the light radiated from the photoradiator, S 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 thè interconnected light conductors 92 and 94.
Another embodiment of the present invention is shown in Figure 22A which comprises a light conducting element 93 having a cylindrical portion 98a and a frustoconical portion 9~b contiguous with the cylindrical lS portion 98a, 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 98 and 100 may be replaced with a sin~le 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 thereof.

Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Serially connected cylindrical light conducting rods for propagating light along the axial length of the cylindrical light conducting rods and for reflecting the light laterally outwardly in two directions, comprising a first and a second cylindrical light conducting rod each having a longitudinal axis and each having an outer cylindrical wall, said first cylindrical light conducting rod having a first longitudinal end section with a first flat end wall, said second cylindrical light conducting rod having a second longitudinal end section, said second longitudinal end section having two outer converging flat walls and a second outer flat end wall, said second outer flat end wall having two sides and two ends, said two outer converging flat walls each having an outer terminating end which is coincident with said sides of said second outer flat end wall, said two outer converging flat walls extending to the longitudinal end of said second longitudinal end section, said two converging flat walls converging as said longitudinal end of said second longitudinal end section is approached, said first and second light conducting rods being connected end-to-end to each other at said first flat end wall and said second outer flat end wall in serial and axial alignment, whereby light propagating through said first cylindrical light conducting rod is transmitted to said second cylindrical light conducting rod via said first flat end wall and said second outer flat end wall, while the rest of the light being propagated is partly reflected laterally outwardly in two directions by said two converging outer flat walls and partly transmitted through said two converging outer flat walls into said second cylindrical light conducting rod, the serially connected conducting rods thereby propagating the light axially and reflecting the light laterally outwardly thereof in two directions.

2. Serially connected cylindrical light conducting rods according to claim 1, wherein said first flat end wall is perpendicular to the longitudinal axis of said first cylindrical light conducting member and said second outer flat end wall is perpendicular to the longitudinal axis of said second cylindrical light conducting member.

3. Serially connected cylindrical light conducting rods according to claim 1, wherein said first flat end wall has a circular configuration having a diameter equal to the diameter of said first cylindrical light conducting member.

4. Serially connected cylindrical light conducting rods according to claim 1, wherein said two ends of said second outer flat end wall are defiend by the outer cylindrical surface of said second cylindrical light conducting-member.

5. Serially connected cylindrical light conducting rods according to claim 1, wherein the area of each of said two converging flat walls is equal.

6. Serially connected cylindrical light con-ducting rods according to claim 1, wherein the area of each of said two converging flat walls is different such that one of said two converging flat walls reflects more light laterally outwardly than the other converging flat wall.