KR100463934B1 - Back-coupled lighting system to regenerate light - Google Patents

Abstract

The light output of the back-coupled lighting system is improved by reproducing reflected and misdirected light rays. The array of microprisms with reflectors and reflecting elements in the light source effectively redirects false rays, increasing the overall available light output and improving efficiency. Both reflectors and diffuse reflecting materials can be used in combination to enhance light output.

Description

Back-coupled lighting system using optical recycling

Currently available lighting systems for direct lighting and other applications suffer from losses due to absorption and emission of light in unwanted directions. If light rays lost through absorption or radiation in unwanted directions can be captured and used, the usable power of the light source may be increased. Lighting systems that can achieve this are highly desirable. The present invention achieves this and other objects by inducing and recycling the light that is otherwise lost.

With reference to the following detailed description of the invention and the accompanying drawings, the invention will be more fully understood and the advantages will be apparent:

1 is a conceptual schematic block diagram of an illumination system;

2 is a schematic cross-sectional view of one embodiment of an illumination system;

3 to 5 are schematic cross-sectional views of an optional reflector for the light source;

6 is a cross-sectional view of the microprism of the light-inducing assembly of FIG. 2;

7-12 are perspective views of optional microprism structures;

13 is a perspective view of an array of straight microprisms;

14 is a cross-sectional view of an embodiment of a back coupled illumination system without a lens;

15 is a cross sectional view of an array of lenses and microprisms offset relative to the geometric center of the microprism;

16-23 are cross-sectional views of a light guide assembly with various other reflecting members;

24 is a top view of a mask used in the illumination system of FIG. 18;

25-28 are perspective views of another lighting system;

29-32 are cross-sectional views of yet another lighting system;

33 is a sectional view of a lighting system;

34 and 35 show examples of downlight and commercial troffers in combination with the lighting systems described herein.

The present invention is arranged in (a) a light source and (b) close to the light source, (i) an input surface for receiving light emitted from the light source and an output surface parallel to the input surface and positioned at the distal end of the input surface. And at least one sidewall disposed adjacent between the input surface and the output surface and positioned to form an obtuse oblique angle with respect to the input surface and positioned to allow total reflection of the light rays received by the input surface. And a light guide assembly having a microprism and (ii) at least one blocking means for blocking the passage of light through said sidewalls.

A conceptual representation of the invention is the lighting system 10 of the block diagram of FIG. 1. The lighting system 10 is divided into two subassemblies, namely the lighting assembly 120 and the light guide assembly 14. The arrow 20 passes through the light guide assembly 14 and is directed towards the intended subject (not shown). It shows the direction of the intended light path of the light waves from the illumination source 12. Note that this figure is intended merely to illustrate the structure and not to indicate the actual or relative dimensions or physical arrangement of the members of the system. shall.

A particular embodiment 100 of the lighting system is shown in FIG. 2. The system 100 includes a light guide assembly 12 having at least one microprism 122 optionally supported on one side of the lighting assembly 110 and the base wall 124. The light guide assembly 12 optionally has a lens array or lens array of individual lenses 142 on the other side of the base wall 124 to control the angular dispersion of the light output of the illumination system 100.

Lighting assembly

The lighting assembly 110 has a light source, which may be selected from incandescent lamps, light emitting diodes (LEDs), metal or halogen high brightness discharge (HID) lamps, fluorescent lamps or other light sources suitable for use.

In a preferred embodiment, the lighting assembly 110 has a reflector 150 located behind and / or around the light source 112, ie in a direction away from the light guide assembly 12.

The reflector 150 directs the light propagating out of the light-directing assembly 120 back to the microprism 122. The reflector 150 may be made from a diffusion material or a highly specular material such as polished aluminum or white paint, although in some applications a reflective material may be desirable. The material selected as the reflector should have a reflectance in the range of about 75% -90%, preferably at least 90%. Reflectance is Macbeth # 7100 Spectrophotometer, New Windsor, N.Y ,. Or several commercially available instruments, such as the Perkin Elmer # 330 spectrophotometer, Danbury, CT.

The position of the reflector relative to the light source and the light-directing assembly, and the distance between them, should be selected to maximize the light directed to the light-directing assembly. As will be readily appreciated by those skilled in the art, the position and distance can be determined from the relative size of the light source and reflector, and the design of the reflector. Depending on the physical dimensions of the light source, the distance between the light source and the reflector is usually one to two times the diameter of the light source. The distance between the light source and the light-directed assembly is also usually one to two times the diameter of the light source. For example, if a T-5 fluorescent lamp is employed as the 5/8 diameter as the light source, the distance between the lamp and the reflector will usually range from 0.625 "to 1.375" along with the distance between the lamp and the light-directing assembly.

The reflector 150 of FIG. 2 has a parabolic shape, but other shapes and contours may also be used, as would be readily apparent to those skilled in the art. For example, as illustrated in FIG. 3, the reflector 230 is straight and has two side walls 232 and a base 234.

To adjust the geometry and dispersion pattern of the light source 112, the angle of the sidewalls 232 relative to the base 234 may be adjusted to define a right angle, acute angle, or an obtuse angle. Other reflector types may be used, such as cusp-shaped reflector 240, or shaved or split reflector 250, as shown in FIGS. 4 and 5, respectively. Additionally, the reflector 150 may have two or more cross sections instead of being a continuous piece of material.

Instead of an artificial light source as described above, natural (eg, direct sunlight) or ambient light may be used. In such a case, the lighting assembly 110 would not have a reflector.

Light-directing assembly

The microprism 122 shown in FIG. 2 is a polyhedron with four angled faces. The structures of these particular microprisms are described in detail in US Pat. No. 5,396,350, issued by March 7, 1995, "Backlighting Apparatus Employing an Array of Micropoisms." 6 and 7, each microprism 122 has an input face 132, an output face 134, and opposite sidewalls 136 adjacent to the input face and output face 132, 134, respectively; The junction of the side wall 136 and the input surface 132 defines an obtuse angle of inclination α. 13 shows an array 200 of straight microprisms 210 supported on the base wall 220.

Instead of the geometry of the microprism 122 of FIG. 6, other shapes may be used. 8-12 show selectable microprisms: conical (FIG. 8), polyhedral (FIG. 9), polyhedral curved (FIGS. 10 and 11) and curved (FIG. 12) microprisms. The following list is for illustration only; Other geometric shapes could be used that would be readily conceived by one skilled in the art. In addition, the cross section of the microprism 122 may be asymmetric (eg, rectangular).

The dimensions of the microprism 122 affect the light output distribution of the light-directing assembly 120. Specifically, the area of the input surface 132, the height of the sidewall surface 136, and the inclination angle α of the sidewall 136 can be adjusted relative to each other to redirect the light through the microprism 122. . Narrower output angle distribution can be achieved by reducing the surface area of the input surface 132, while increasing the height of the sidewall 136 and minimizing the oblique angle α of the obtuse angle. Alternatively, the output angle distribution can be increased while decreasing the height of the sidewall 136 and increasing the size of the obtuse angle α of the obtuse angle by increasing the surface area of the input surface 132.

In the case where the base wall 124 is used, additional control of the output angular dispersion of the irradiator 100 can be achieved by varying the thickness of the wall 124. For a given amount of radius of curvature of the lens 142, an increase in the thickness of the base wall 124 increases the separation of the output angular distribution of the irradiator 100 while increasing the separation between the microprism 122 and the lens array 140. Will cause an increase.

Although the lenses 142 depicted in FIG. 2 are convex, they are also spherical concave, aspherical, cylindrical concave, cylindrical convex, or any suitable other shape as dictated by a particular case and as readily understood by those skilled in the art. Can be. In addition, the lens 142 may be located directly above the output surface 134 in the absence of the base wall 124. Moreover, the lens can be either diffraction or refraction, or a combination of both diffraction and refraction elements.

It should be understood that the lighting assembly 110 and the light-directing assembly 120 of the back-coupling illumination system 100 can be used without a lens, as shown in the structure of FIG. 14. Moreover, the axis of the lens 142 in FIG. 2 is aligned with the geometric center 126 of each microprism 122. If desired, the lens 142 may be offset or hidden with respect to the geometric center 126 of the microprism 122 as shown in FIG. 15. Finally, the cross-sectional size of the lens 142 may vary with respect to the cross-section of the microprism 122.

The distance between the geometric center 126 of each microprism 122 and the geometric center of the lens 142 varies from zero to half the width of the outer surface 134 of the microprism 122. The lens 142 may be positioned adjacent to the outer surface 134 of the microprism 122 or at a point that bisects the length between the inner surface of the microprism 122 and the outer surfaces 132 and 134.

The microprism 122 and associated structures (including arbitrary lens arrays) are described in US Patent No. 5,396,350, an illumination system employing an array of microprisms, all of which are incorporated herein by reference. Zimmerman et al., US Patent No. 5,248,468, issued June 27, 1995, and Zimmerman et al., 1996, for a Direct View Display with Array of Tapered Waveguide. The material disclosed in US Pat. No. 5,481,385, issued January 2, 1, and may be manufactured according to the method.

As disclosed in these cited patents, microprisms and lenses include polycarbonate, acrylic, polystyrene, glass, transparent ceramics, and a process for making a tapered photopolymerized waveguide array incorporated herein by reference. It can be made from a wide variety of materials, including monomer mixtures as described in US Pat. No. 5,462,700 (Bayson, Oct. 31, 1995) to Photopolymerized Waveguidse. When selecting the materials that make up these structures, the heat generated by the light source must be taken into account. If desired, the lens assembly may be provided as a separate sheet laminated to the base wall of the light-directing assembly, or may be combined with the light-directing assembly using injection molding or other techniques readily available to those skilled in the art. It can be manufactured as a single structure.

Area adjacent to the side wall

The sidewall 136 of the microprism 122 of the light-directing assembly 120 defines an area 128 adjacent to the sidewall 136, and the light-directing assembly 120 having multiple microprisms 122. Within these, these areas may be referred to as "interstitial" areas. These regions 128 have reflective elements, which in the structure of FIG. 2 are highly reflective solid fillers 160. The solid filler 160 may either reflect the light passage or simply block it. Solid filler 160 may be reflective or diffusive and may include materials such as BaSO ₄ , TiO _2, or MgO, which are highly reflective to visible light due to their microstructure. These materials can be used as carriers such as dry powder, paint or putty. Alternatively, materials that are stable to environmental conditions brought about by optical installations such as Spectralon ^™ (Labosphere, Inc.) or Teflon ^R (du Pont) may also be suitable for this area to provide high reflectance for visible light.

Although the solid filler 160 preferably has a high reflectivity, ie a reflectance higher than 90%, a less reflective material or an absorbent material may be desired. Reflectance can be measured as described above.

Other reflective materials can be used as the reflective component. In FIG. 16, sidewall 136 of microprism 122 has a coating 260 of reflective material. Coating 260 may be silver, aluminum, gold, white emamel, or any other material that would be readily apparent to one skilled in the art. These materials can be coated by techniques such as chemical vapor deposition, electron beam deposition, and sputtering. In FIG. 17, the reflective component is a reflective lining 270 molded as a component with the sidewall 136 or applied to the sidewall 136 by adhesive or other known means. In FIG. 18, mask 280 is used as a reflective component and covers the area between the microprisms 122. As illustrated in FIG. 24, a plan view of the mask 280 represents a grating having an opening 282 that receives the input surface 132 of the microprism 122. The mask reflects or diffuses as described above.

Reflective components (coatings, linings and masks) of FIGS. 16-18 reflect or diffuse, with reflectivity in the range of about 75% -90% and preferably greater than 90%. One example of a suitable reflective material is Silverlux ^™ from 3M, but others may be used that would be readily apparent to those skilled in the art. Reflectance can be measured as described above.

Different forms of reflective component can be used in combination. As shown in FIG. 19, sidewall 136 has two reflective components: a coating 260 and a mask 280. Reflective lining 270 and solid filler 160 are provided in region 128 of the assembly shown in FIG. 20.

In this arrangement, other combinations may be employed, but a reflective material for lining 270 and a diffusion material for filler 160 may be selected.

In FIG. 21, sidewall 136 has a coating 260 and a solid filler 160. Reflective lining 270 and mask 280 are provided in portion 128 of the assembly shown in FIG. 22. Finally, the combination of solid filler 160 and mask 280 is provided in portion 128 in FIG.

The arrangements discussed up to this point were either straight or planar. The lighting system could also be formed in a curved or spherical arrangement as shown in FIGS. 25 and 26, respectively, and other arrangements will readily appear to those skilled in the art. In FIG. 25, the light source 300 is directed towards the curved arrangement 310 of the microprism. In FIG. 26, the light source 320 is included in the partial spherical arrangement 330 of the microprism. In order to arrange the light-controlled assembly in this form, the inclination angle of the microprism sidewalls with respect to the input surface needs to be adjusted to provide an angle distribution suitable for the spherical illuminant. In addition, the space between the microprisms may need to be changed to obtain proper control of the light. The input and output surfaces of the microprism can be flat, curved or spherical. 25 and 26 may also be provided in the manner taught in FIG. 2 with any base wall near the output face of the microprism and any lens on the base wall. In addition, a plurality of planar and / or curved light-controlling assemblies 340 and one or more light sources 350 are combined to form a polyhedral illumination system as shown in FIGS. 27 and 28 to provide multidirectional bladder. Could be

Each microprism of one flat assembly is shown in FIG. 27A.

The intensity of light entering the light guide assembly 120 can be controlled by introducing a light element 400 between the light source 112 and the light guide assembly 12 as shown in FIG. 29. By reducing the direct transmission of light from the light source 112 to the microprism 122, the output of the light guide assembly 120 becomes more uniform and the light is minimized. Light element 400 may be assembled from a rectangular piece of material (eg, plastic, glass, or some other material) having substantially the same planar dimensions as the cross section of light traversing from light source 112 to microprism 122. It may be. The material may be scattering or partially reflective.

The lighting assembly 110 protects the light source 112 with a light transmitting material 410 having a larger refractive index n ₁ than the light source instead of simply deviating from the light source 112 suspended in air as shown in FIG. 30. May be further modified. The light transmissive material 410 may fill an area surrounding the light source 112 and is adjacent to the input surface 132 of the microprism 112. This will avoid Fresnel reflections at the input surface 132 of the microprism 122 and will make the light source 112 more easily fill the array of the input surface 132 that is significantly larger than the light source 112. The light transmitting material 410 is connected to the input surface by the adhesive layer 412. For optimal transport of light the refractive indices are chosen such that they increase as one proceeds outward from the light source 112.

Thus, when the refractive index values of the optically transmissive material 410: n ₁ , the adhesion layer 412: n ₂ , and the light directing assembly 120: n ₃ are selected as follows:

n ₁ ≤ n ₂ ≤ n ₃

An optical element 414 similar in function to the element 400 of FIG. 29 may be located on the attachment 412. The refractive index of element 414 should be approximately equal to n ₂ .

Light transmission from the light source 112 to the input surface 132 may also be enhanced by introducing curvature in the microprism that complements the radiation pattern of the light source 112. As shown in FIG. 31, the input surface 422 of the microprism 420 forms an arc to ensure that the angle of incidence is less than the attenuation angle at the microprism 420 furthest from the light source. The attenuation angle is defined by the formula:

Rs = ² Φ _i Φ′ ² Φ _i Φ′

Rp = ² Φ _i Φ′ ² Φ _i Φ′

Where:

n ₁ sin Φ i = n ₃ sin Φ'And

R _s is the reflectance of light polarized perpendicular to the plane of incidence;

R _p is the reflectance of light polarized parallel to the plane of incidence;

Φ _i is the angle of the ray incident on the input surface 422:

&Quot; " is the angle of light incident through the microprism 420; And

Φ _i and Φ'are defined from the normal to the face of the input surface 422.

In FIG. 32 the intermediate optical element 430 is introduced to regulate the angular distribution of the light guiding assembly 120. Although this figure shows a state positioned between the lighting assembly 110 and the light guiding assembly 120, this element 430 may be located within the lighting assembly closer to the light source 112. Moreover, a second optical element 440, similar to the optical element 400 of FIG. 29, may be positioned between the intermediate optical element 430 and the light source 112 to reduce the light output of the lighting assembly 110. These optical elements 430, 440 may be made of plastic, glass, or some other material.

The refractive index N ₃ of the intermediate optical element 430 may be selected to selectively reduce the high angle of incidence of the light beam from the light source 112 to reduce the angular distribution into the light guiding assembly 120. For example, using the equation on the previous page to calculate R _S and R _P , the reflectivity at the incident angle ø _i increases as the refractive index n ₃ increases. If n1 is 1 for the values n ₃ of the refractive indices of 1.52, 1.7, and 4.0, the reflectivity at the incident angle of 45 ° will be 17.5%, 24%, and 65%, respectively.

Lighting system operation

The operation of this system will be described with reference to FIG. Without a particular structure, the light source 112 emits light towards the covalentness assembly 120 and also in other directions.

It is to be understood that the present invention is applicable to a variety of devices such as commercial, office, home, outdoor, automotive, and direct lighting devices including lighting for facility applications. The present invention can be applied to computers, automobiles, military, aviation, consumer, commercial, and industrial applications, and any other device that requires a light source. Two examples are illustrated in recesses 500 and downlights 600 of commercial ceilings, respectively, in FIGS. 34 and 35. The recess 500 of the ceiling has two light sources 510, such as T-5 or T-8, a reflector 520, and a light guide assembly 530 of microprism. The downlight 600 similarly includes a light source 610 (ie, a CFL lamp), a reflector 620, and a light guide assembly 630.

Although described through preferred embodiments of the present invention, those skilled in the art will recognize that other and further changes may be made without departing from the spirit of the present invention, and all such embodiments are within the scope of the present invention. For example, other variations and combinations can use the structures disclosed in the prior patents.

Such rays that are transmitted straight to the input surface 132 of the microprism 122 and reflected as described by the equations for calculating R _S and R _P are: the remainder of the light as described by ray A is the microprism. Moved through 122 and ultimately exits through coupled lens 142.

If light leaves the light source 112 and away from the light guide assembly 120 for the first time it will encounter the reflector 150. As described by ray B there it will be reflected back towards the light guide assembly 120 and pass through the microprism 122 and the lens 142.

Some rays are directed from the light source 112 toward the light guide assembly 120 but will enter the region 128 adjacent the sidewall 136. It would be easy to enter the microprism 122 through the sidewall 136 if such light rays were allowed to continue to travel on that path. However, they do not properly move out of the light guide assembly and actually twist the light output distribution. Thus, reflective elements are supplied in the area 128 to block and redirect the wrong rays. As shown, light rays leaving light source 128 reach solid filler 160 and are reflected back to reflector 150 there. There, as described by ray C, the ray reflects back towards and passes through the ray guide assembly. If an antireflective filler was used in the region 128 instead of the reflective material, the light beam would simply be absorbed by the filler. Alternatively, light rays may be reflected back toward the light source 112 but this is undesirable because most of the light will be absorbed by the light source 112. Thus the reflection of this mode should be minimized, for example by the use of smaller light sources.

Claims (7)

(a) a light source; And (b) a light guidance assembly proximate to the light source, the light guidance assembly comprising an input surface capable of emitting light from the light source, an output surface spaced parallel to the input surface, and between the input surface and the output surface At least one micro-prism disposed adjacently, the at least one microprism forming an obtuse oblique angle with respect to the input surface, the at least one sidewall being positioned to allow total reflection of the light received by the input surface; And (c) at least one blocking means for blocking the passage of light through the sidewalls. (a) a light source; (b) a reflector positioned proximate the light source; (c) a light guide assembly in proximity to the light source, the light guide assembly comprising an input surface on which each micro prism is capable of emitting light from the light source, an output surface spaced in parallel from the input surface, and the input surface; At least one sidewall disposed adjacent between the output surfaces, the oblique oblique angle being formed with respect to the input surface, and positioned to allow total reflection of the light received by the input surface to form a gap region between the micro prisms A plurality of micro prisms including; And (d) at least one blocking means positioned to block the passage of light through the side wall. 5. A lighting system according to claim 4, comprising a stove assembly comprising at least one lens and proximate the output surface of the micro-prism. 7. The light guide assembly of claim 6, wherein the light guide assembly further comprises a base wall having two surfaces, wherein the output surface of the micro-prism is adjacent to one surface of the base wall, and the lens assembly is formed of the base wall. An illumination system characterized by adjoining another surface. 7. An illumination system according to claim 6, wherein the micro prisms are coplanar or offset with respect to the axis of at least one lens. 5. An illumination system according to claim 4, wherein the reflector is directed to direct reflected light towards the input surface of the microprism. 5. A lighting system according to claim 4, wherein said blocking means comprises a solid filled reflective material in the gap region.