MXPA98007993A - Lighting system that comprises microprisms with block medium - Google Patents

Abstract

The present invention relates to a light output of a lighting system coupled by the rear, it is improved by recycling reflected and misdirected light rays. A reflector (150) in the light source (112) and a micro-prism arrangement (122) have reflective elements (160) therebetween of errant light rays effectively directed to increase the total available light aperture and the improved efficiency. Both diffuse reflection and specular materials can be used in combination to improve the output of the

Description

LIGHTING SYSTEM THAT COMPRISES MICROPRISMS WITH BLOCKING ENVIRONMENT BACKGROUND OF THE INVENTION Lighting systems currently available for direct lighting and other applications suffer from losses due to absorption and radiation from use in undesired directions. If the light rays lost by absorption or radiation in unwanted directions could be captured and used, the useful output of the light source would be increased. A lighting system that achieves this would be highly desirable. This invention achieves this and other objectives by re-directing and recycling light that would otherwise be lost.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be understood more fully and other advantages will be apparent when reference is made to the following detailed description of the invention and the accompanying drawings, in which: Figure 1 is a block diagram, schematic, conceptual of the lighting system; Figure 2 is a diagram of a schematic section of an embodiment of the lighting system; Figures 3-5 are schematic diagrams of alternative reflectors for a light source; Figure 6 is a diagram of a section of a microprism of the unit for directing the light of Figure 2; Figures 7-12 are perspective views of alternative structures of the microprism; Figure 13 is a perspective view of an array of rectilinear icropris; Figure 14 is a diagram of a schematic section of a retro-coupled lighting system embodiment without lenses; Figure 15 is a diagram of a schematic section of an array of micro-prisms and lenses displaced with respect to the geometric centers of the micro-prisms. Figures 16-23 are diagrams of schematic sections of the units for directing the light without the different alternative reflector elements; Figure 24 is a top view of a mask used in the lighting system of Figure 18; Figures 25-28 are perspective views of alternative lighting systems, Figures 29-32 are schematic diagrams of alternative, additional lighting systems; Figure 33 is a diagram of a schematic section of a lighting system; and Figures 34 and 35 are examples of a commercial pipe rack and a down lamp incorporating the lighting systems described herein.

DESCRIPTION OF THE INVENTION The present invention relates to a lighting system comprising: (a) a light source, and (b) a unit for directing light in close proximity to the light source, and comprising (i) at least a microprism, wherein the microprism consists of an entrance surface that admits radiant light from the light source, an exit surface distal to and parallel to the entrance surface, and at least one side wall positioned between and contiguous with the surfaces of entrance and exit, and forming an inclined angle obtuse with respect to the entrance surface and further placed to effect the total reflection of the light rays that are received on the entrance surface, and (ii) at least one locking means to block the passage of light through the side wall. A conceptual representation of the invention is a lighting system 10 in the schematic block diagram of Figure 1. The lighting system 10 is divided into two sub-units: a lighting unit 12 and a unit for directing the light 14. The arrow 20 indicates the proposed direction of the path of the light waves from the light source 12, through the unit for directing the light 14, and toward the proposed objective (not shown). It should be appreciated that this drawing is simply a schematic representation of the structure and is not intended to communicate real or relative dimensions of the system components or their physical arrangement. A specific embodiment 100 of the lighting system is illustrated in Figure 2. System 100 has a lighting unit 110 and a unit for directing light 120, at least one micro-prism 122 that is optionally carried within a span of a base wall 124. The light directing unit 120 may optionally have a lens or array of lenses 140 of individual lenses 142 on the other side of the base wall 124 for controlling the angular distribution of the light output of the lighting system 100.

Lighting unit La. lighting unit 110 has a light source 112, for which it is possible to select an incandescent lamp, a light emitting diode (LED), a high intensity discharge lamp (HID) of metal or halogen, a fluorescent lamp and some other Suitable sources for the application. In a preferred embodiment, the lighting unit 110 has a receiver 150 positioned behind and / or around the light source 112, that is, in the opposite direction of the unit for directing the light 120. The reflector 150 redirects the light rays which they propagate away from the unit to direct the light 120 back to the micro-prisms 122. The reflector 150 can be made of a diffuse material or a highly specular or reflective material, such as polished aluminum or white paint, although in some applications it can be preferable specular material. The material selected for the reflector should have a reflectivity or reflectance in a range of approximately 75% -90%, preferably greater than 90%. Reflectance can be measured with various commercially available instruments such as Macbeth # 7100 Spetrophotometer. New Windsor, N.Y. or a Perkin Elmer # 330 Spetrophotometer, Danbury. CT. The location of the reflector with respect to the light source and the unit to direct the light, and the distances between them must be selected to maximize the light directed towards the unit to direct the light. As will be readily apparent to those skilled in the art, the locations and distances can be determined from the relative sizes 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 unit for directing the light is also usually one to two times the diameter of the light source. For example, if the fluorescent lamp T-5 is used as the light source, with a diameter of 5/8", the distance between the lamp and the reflector, as well as the distance between the lamp and the unit to direct the light, it will usually be in the range of 0.625"to 1375. Although the reflector 150 of Figure 2 has a parabolic shape, it is possible to use other shapes and configurations, as will be appreciated by those skilled in the art, for example, as illustrated in FIG. Figure 3, the reflector 230 has a rectilinear shape and has two side walls 232 and a base 234. To accommodate the geometry and dispersion pattern of the light source 112, the angle of the side walls 232 with respect to the base 234 can be adjusted to define a right, acute or obtuse angle Other reflector shapes may also be employed, such as a horn-shaped reflector 240 or a faceted or segmented reflector 250 as shown in Figures 4 and 5, respectively. , instead of a piece of continuous material, the reflector 150 can be instrumented in two or more sections. Instead of an artificial light source of the kind mentioned above, it is also possible to use natural light (for example, direct sunlight) or ambient light. In this case, the lighting unit 110 may not have a reflector.

Unit for directing light The microprisms 122 shown in Figure 2 are polyhedra having four angled sides. The structure of these particular microprisms is described in detail in U.S. Patent 5,396,350, published March 7, 1995, by Beeson et al, for a Background Projector Apparatus employing a micro-prism array, which is incorporated herein by reference . As shown in Figures 6 and 7, each microprism 122 has an entry surface 132, an exit surface 134 and opposite side walls 136 each adjacent to the entry and exit surfaces 132 and 134; the joining of the side walls 136 and the entrance surface 132 define an obtuse inclined angle a. Figure 13 shows an array 200 of rectilinear microprisms 210 supported on a base wall 220. Instead of the geometric figure of microprobe 122 of Figure 6, it is possible to employ other figures. Figures 8-12 illustrate alternative microprisms; conical (Figure 8), polyhedron (Figure 9), curvilinear polyhedral (Figures 10 and 11), and curvilinear microprisms (Figure 12). The aforementioned list is illustrative only; it is possible to use other geometric figures, as will be apparent to those skilled in the art. In addition, the cutting of the microprisms 122 can be asymmetric (eg, rectangular). The dimensions of the micro-prisms 122 affect the distribution of the light output 120. Specifically, the area of the entrance surface 132, the height of the surfaces of the side wall 136 and the angle of inclination a of the side walls 136 can be adjusted one with respect to the others to modify the passage of light through the micro-prisms 122. A narrower angular distribution of output can be achieved by reducing the surface area of the entrance surface 132, while increasing the height of the side walls. and the obtuse tilt angles a. Otherwise, the angular distribution of the outlet can be increased by increasing the surface area of the entrance surface 132, together with the reduction of the height of the side wall 136 and the increase in the size of the obtuse inclination angles a. Where a base wall 124 is employed, additional control the angular dispersion of the exit of the lighting system 100 can be achieved by varying the thickness of the wall 124. For a given positive radius of curvature of the lenses 142, an increase in the thickness of the base wall 124, increased separation between micro-prisms 122 and array of lenses 140, will result in an increase in the angular distribution of the output of the lighting system 100. Although the lenses 142 shown in Figure 2 are convex, they are they could also be spherically concave, aspherical, cylindrically concave, cylindrically convex or some other suitable shape as dictated by the specific application and as will be readily apparent to those skilled in the art. Also, the lenses 142 can be located directly on the output surfaces 134 in the event that there is no base wall 124. In addition, the lenses can be diffractive or refractive, a combination of diffractive and refractive elements. It should be understood that the lighting unit 110 and the light directing unit 120 of the retro-coupled lighting system 100 can be used without lenses, as shown in the structure of Figure 14. In addition, the axes of the lenses 142 in the Figure 2, are aligned with the geometric centers 126 of the individual microprisms 122. If desired, the lenses 142 can be displaced or eclipsed with respect to the geometric centers 126 of the microprisms 122, as shown in Figure 15. Finally , the size of the cross section of the lenses 142 could vary with respect to the cutting of the microprisms 122. The distance between the geometric centers 126 of the individual microprisms and the geometric centers of the lenses 142 varies from 0 to V-- of the width of the output surfaces 134 of the micro-prisms 12. The lenses 142 can be placed adjacent to the output surfaces 134 of the micro-prisms 122 or at a distance of up to one half of the distance between the entry and exit surfaces 132 and 134 of the micro-prisms 122. The micro-prisms 122 and the associated structure (including the optional lens array) can be manufactured according to the methods and using the materials described in FIG. U.S. Patent No. 5,396,350 already mentioned, U.S. Patent No. 5, 248,468 published June 27, 1995, by Zimmerman et al, for an Illumination System employing a microprism array, and U.S. Patent No. 5,481,385, published January 2, 1996, by Zimmerman et al, for a Direct display screen with arrangement of conical waveguides, which are incorporated herein by reference. As described in the aforementioned patents, microprisms and lens arrays can be made from a wide range of materials, including polycarbonate, acrylic, polystyrene, glass, transparent ceramics and a mixture of monomers, as described in U.S. Patent No. 5,462,700, of October 31, 1995, by Beeson et al, for a Process to prepare a waveguide photoconductor guide arrangement, which is incorporated herein by reference. The heat generated by the light source must be considered when choosing a construction material for these structures. If desired, the lens unit can be provided as a separate sheet laminated to the base wall of the unit for directing the light or it can be manufactured with the unit to direct the light as a unitary structure using injection molding techniques or others that they will be readily apparent to those skilled in the art.

The regions adjacent to the side walls The side walls 136 of the micro-prisms 122 of the light-directing unit 120 define regions 128 adjacent the side walls 136; in a light directing unit 120 with multiple micro prisms 122, these regions may be known as "interstitial regions". These regions 128 are provided with a reflective element which, in the configuration of Figure 2, is a highly reflective solid filler material 160. The solid filler material 160 may be reflecting or simply blocking the passage of light. The solid charge material 160 may be specular or diffuse and may include materials such as BaS04, Ti0, or MgO, which are highly reflective to visible light due to their micro structures. These materials can be used in carriers such as dry powder, paint or putty.

Otherwise, materials stable to the environmental conditions to which the lighting installations are exposed, such as Spectralon ™ (Labsphere, Inc.), or Teflon® (du Pont) may be suitable in this region to provide high reflection to visible light Although the solid charge material 160 is preferably highly reflective, ie, greater than ninety percent (90%) of reflectivity, there may be applications where the less highly reflective material or an absorbent material would be desirable. The reflectivity can be measured as previously indicated. Other reflective materials can be used as the reflective element. In Figure 16, the side walls 136 of the micro prisms 122 have coating 260 of reflective material. The coating 260 can be silver, aluminum, gold, white enamel or other material that will be readily apparent to those skilled in the art. These materials can be deposited by techniques such as chemical vapor deposition, vapor deposition of electron gases, cationic sublimation and the like. Figure 17, the reflective element is a reflective liner 270 molded integrally with the side walls 136, or applied by adhesive or some other known means to the side walls 136. In Figure 18, a mask 280 is employed as the element reflective and covers the regions 128 between the microprisms 122. As illustrated in Figure 24, a top view of the mask 280 would appear as a grid with holes 282 receiving the input surfaces 132 of the micro prisms 122. The mask can be processed of solid materials that are specular or diffuse as already mentioned. The reflective elements of Figures 16-18 (coating, coating and mask) can be specular or diffuse, with a reflectivity in the range of about 75% -90%, and preferably greater than 90%. An example of a suitable specular material is Silverlux®, a 3M product but it is possible to employ others, as will be apparent to those skilled in the art. The reflectivity can be measured as indicated. Different types of reflective elements can be used in combination. As shown in Figure 19 the side walls 136 have two reflective elements: a covering 160 and a mask 280. A reflective coating 270 and a solid loading material 160 are provided in the regions 128 of the unit shown in the Figure 20. In this configuration, it is possible to select a mirror material for the liner 270 and a diffuse material for the filler material 160, although other combinations may be employed. In Figure 21, the side walls 136 have a coating 260 and a solid loading material 160. A reflective coating 270 and a mask 280 are provided in the regions 128 of the unit shown in Figure 22. Finally the combination of a solid charge material 160 and a mask 280 are provided in the regions 128 of Figure 23. The arrangements described to this point have been linear or flat. The lighting system can also be configured as curvilinear or spherical arrangements, as shown in Figures 25 and 26, respectively, and other configurations will be readily apparent to those skilled in the art. In Figure 25, a light source 300 is facing a curvilinear arrangement 310 of microprisms. In Figure 26, a light source 320 is contained within a partial spherical array 330 of microprisms. To configure the units to direct light in this manner, the angles of inclination of the side walls of the microprism with respect to the entry surfaces need to be adjusted to provide an adequate angular distribution to a spherical radiator. In addition, it may be necessary to vary the space between the microprisms to achieve adequate control of the light. The entrance and exit surfaces of the microprisms can be curvilinear or spherical flat. Also, the units for directing the light of Figures 25 and 26 can be provided with optional base walls adjacent to the output surfaces of the micro-prisms and optional lenses on the base walls, in the manner shown in Figure 2. , flat and / or curvilinear, direct light directing units 340 and one or more light sources 350 may be combined to form polyhedral illumination systems, as illustrated in Figures 27 and 28 to provide multidirectional radiation. In Figure 27a the individual microprisms of a planar unit are illustrated. The intensity of the light entering the unit to direct the light 120 can be controlled by introducing an optical element 400 between the light source 112 and the unit for directing the light 120, as shown in Figure 29. By reducing the direct transmission of the light from the light source 112 in the micro-prisms 122, the output of the unit for directing the light 120 is more uniform and the brightness is reduced. The optical element 400 can be manufactured from a rectangular piece of material (for example, plastic, glass or some other material) having planar dimensions, approximately the same as the cross section, in this location, of the light traveling from the light source 112 to the micro prisms 122. The material may be diffuse or partially specular. The lighting unit 110 can be further modified as illustrated in Figure 30 by encapsulating the light source 112 with an optically transmissive material 410 having a Refractive Index (n2) greater than 1, instead of simply leaving the light source 112 suspended. in the air. The optically transmissive material 410 can fill the area surrounding the light source 112 and be contiguous with the input surfaces 132 of the micro-prisms 122. This will prevent Fresnel reflections on the input surfaces 132 of the micro-prisms 122 and allow the light source 112 more easily fill an input surface array 132 considerably larger than the source 112. The optically transmitting material 410 is attached to the input surfaces by an adhesive layer 412. For optimum light transfer, the refractive indexes are chosen from so that these increase as one proceeds outward from the light source 112. In this manner, where the values of the refractive indices of the optically transmitting material 410 (nj) the adhesive layer 412 (n?) and the unit for directing the light 120 (n3) is chosen so that An optical element 414 similar in function to the element 400 of Figure 29 could be placed on adhesive layer 412. The refractive index of element 414 should be approximately equal to n-. The transmission of light from the source 112 to the input surfaces 132 can also be improved by introducing a curvature in the microprisms that complement the radiation pattern of the light source 112. As shown in Figure 31, the input surfaces 422 of the microprisms 420 define an arc to ensure that the angle of incidence is less than the attenuation angle in the microprisms 420 furthest from the light source 112. The attenuation angle is defined by the following equations: _ sinYf, -F 'Rs = sinVf.-F'J _ tanVF, -F 'R? ta ?? Yf, + F 'where: n, without f ± = n without f 'and R3 is the reflectance of the polarized light perpendicular to the plane of incidence; Rp is the reflectance of polarized light parallel to the plane of incidence; f is the angle of the incident light beam on the entrance surface 422; f 'is the angle of the incident light beam transmitted through the microprism 420; and fL and f 'are defined from the normal to the plane of the entrance surface 422. In Figure 32, an intermediate optical element 430 is introduced to limit the angular distribution of the light entering the unit to direct light 120. Although the drawing is shown located between the lighting unit 110 and the unit for directing the light 120, the element 430 can be placed inside the lighting unit in close proximity to the light source 112. Moreover, a second optical element 440, similar to the optical element 400 of Figure 29, could be provided between the light source 112 and the intermediate optical element 430 to reduce the light output of the lighting unit 110. The optical elements 430 and 440 can be Made of plastic material, glass or some other. The refractive index of the intermediate optical element 430 (n3) can be chosen to selectively attenuate the upper incidence angle light rays from the light source 112 and decrease the angular distribution in the light directing unit 120. For example , using the equations of the previous page to calculate Rs and Rol the increase in reflectance at an angle of incidence f as the Refractive Index n3 increases. Assuming that it is not equal to 1, then for values of the Refractive Index n of 1.52, 1.7, and 4.0, the reflectance at an angle of incidence of 45 ° will be 17.5%, 24% and 65%, respectively.

Operation of the lighting system The operation of the system will be explained with reference to Figure 33. In the absence of a special structure, the light source 112 radiates light towards the unit to direct the light 120 and in other directions as well. Those light rays that travel directly to an input surface 132 of a micro-prism 122 and are reflected as dictated by the equations for calculating Rs and RD, the rest of the light is transmitted through the micro-prism 122 and finally passes through an associated lens 142 and out, as represented by the light beam A. If the light coming out of the light source 112 initially travels away from the unit to direct the light 120, it will meet the reflector 150. There, it will be reflected back towards the unit for directing the light 120 passing through a micro-prism 122 and a lens 142, as represented by the light beam B. Part of the light rays can travel from the light source 112 towards the unit for directing the light 120, but it will enter the regions 128 adjacent to the side walls 136. If these light rays were allowed to continue in this path, they would most likely enter the microprisms 122 through the walls. s 136. However, these would not pass properly from the unit to direct light 120 and, in fact, they would distort the distribution of the light output. In this way, the reflective elements are provided in the regions 128 to block and redirect these wandering light rays. As shown, a beam of light coming out of the source 112 arrives at the solid charge material 160 where it is reflected back to the reflector 150. There, the light beam is again reflected back to and through the unit to direct the light 120, as represented by the beam of light C. If a non-reflective filler material were used in the regions 128 instead of a reflective material, the beam of light would simply be absorbed by the filler material. Otherwise, the light could be reflected back to the light source 112, although this is not desirable as most of the light would be absorbed by the light source 112. Therefore, this mode of reflection would be reduced to a minimum, for example , using a smaller light source. It should be understood that this invention is applicable to a wide variety of devices, such as direct lighting devices that include lighting for commercial, office, residential, outdoor, automotive and home appliance applications. The invention can also be applied to computer screens, automotive, military, aerospace, consumer, commercial, and industrial applications, and any other device that requires a source of illumination. Two examples are the commercial tube holder 500 and the down lamp 600 that are illustrated in Figures 34 and 35, respectively. The tube duct 500 has two light sources 510, such as T-5 or T-8 fluorescent lamps, a reflector 520 and a unit for directing the light 530 of micro-prisms. The down lamp 600 in the same manner has a light source 610 (for example, a CFL lamp), a reflector 620 and a light directing unit 630. Although what has been described as the preferred embodiment of the invention has been described, the Those skilled in the art will recognize that other and more modifications can be made to it without departing from the spirit of the invention, and it is intended to claim all these modalities that fall within the true spirit of the invention. For example, it should be understood that other variations and combinations are possible using the structures described in the referred patents.

Claims (8)

1. A lighting system comprising: a) a light source, and (b) a unit for directing light in close proximity to the light source, and comprising: at least one microprism, the microprism containing an entry surface that admits light radiating from the light source, an outlet surface distal to and parallel to the entrance surface, and at least one side wall positioned between and contiguous with the entrance and exit walls, and forming an obtuse inclined angle with respect to the entrance surface and further positioned to effect total reflection of the light rays received by the entrance surface, and (c) at least one blocking means to block the passage of light through the side wall.

2. A lighting system consisting of: a) a light source; a reflector located in close proximity to the light source; (c) a unit for directing light in close proximity to the light source, and comprising a plurality of microprisms, the microprism containing an input surface receiving light radiating from the light source, a distal and parallel output surface to the entrance surface, and at least one side wall placed between and contiguous with the entrance and exit surfaces, and forming an obtuse angle of inclination with respect to the entrance surface and furthermore placed to effect total reflection of the rays of light received by the entrance surface, the side walls of the microprisms defining interstitial regions between the microprisms; and (d) at least one blocking means for blocking the passage of light through the side walls.

3. The lighting system as set forth in claim 4 further comprises a lens unit consisting of at least one lens, the lens unit being in close proximity to the output surfaces of the microprism. The lighting system, as set forth in claim 6, wherein the unit for directing light further comprises a base wall having two surfaces, the outlet surfaces of the microprisms contiguous with a surface of the base wall and the lens unit adjacent to the other surface of the base wall. The lighting system as set forth in claim 6, wherein the microprism has a collinear geometric center or offset with respect to the axis of at least one lens. 6. The lighting system, as set forth in claim 4, wherein the reflector is oriented to direct the reflected light toward the entry surfaces of the microprisms. The lighting system, as set forth in claim 4, wherein the blocking means comprises reflective material material with solid charge in the interstitial regions. The lighting system, as set forth in claim 4, wherein the blocking means is selected from the group consisting of a reflective coating on the side walls that receives light radiating from the light source, an output surface distal of and parallel to the entrance surface, and at least one side wall placed between and contiguous with the entrance and exit surfaces and forming an obtuse inclined angle with respect to the entrance surface and furthermore placed to effect the total reflection of the light rays received by the entrance surface, the side walls of the microprisms defining interstitial regions between the microprisms; a base wall having two surfaces, wherein the exit surfaces of the microprisms abut a surface of the base wall; (d) at least one blocking means for blocking the passage of light through the side walls, wherein the blocking means is selected from the group consisting of a reflective coating on the side walls, a reflective coating on the side walls , a solid charge material in the interstitial regions, a reflecting mask adjacent to the entry surfaces of the microprisms and combinations thereof; and (e) a lens unit comprising a plurality of lenses, wherein the lens unit abuts the other surface of the base wall