Patent Publication Number: US-6217197-B1

Title: Reflector system for a lighting fixture

Description:
RELATED U.S. PATENT APPLICATIONS 
     This invention relates in subject matter to U.S. Pat. No. 5,404,076, issued on Apr. 4, 1995, the disclosure of which is incorporated herein by reference. 
    
    
     STATEMENT OF GOVERNMENT INTEREST 
     This invention was made pursuant to contract No. DE-AC03-76SF00098 between the U.S. Department of Energy and the University of California. The U.S. Government retains certain rights in this invention. 
    
    
     STATEMENT OF DISCLAIMER 
     The term of this patent shall not extend beyond the term of U.S. Pat. No. 5,404,076 issued on Apr. 4, 1995. 
     FIELD OF THE INVENTION 
     This invention relates generally to lighting systems and more particularly to reflectors which disperse light from a light source. 
     BACKGROUND OF THE INVENTION 
     Lighting is a critical element in any human endeavor, whether the activity takes place in an indoor or outdoor environment. In indoor environments, people work more efficiently and are happier when there is proper lighting. In exterior lighting environments, sufficient light is necessary just to have the activity and plays a critical factor in many situations such as parking lots or residential, or commercial streets where proper lighting dramatically increases the safety of the people involved. As can be appreciated such lighting usually comes from very high power lighting systems and therefore efficiency is extremely desirable. 
     Proper lighting means that there is sufficient illumination and natural color for interior and exterior conditions. Of course, in some lighting instances it may be desirable to have a tint on the color. It therefore would be desirable to have an illumination source in which the color is changeable to match the desired environment. 
     High power lighting fixtures have been known for many years. Such fixtures are characterized by high powered lamps, also known as a high lumen packages, typically having several thousand lumens. Typically, such lighting fixture systems include a lamp fill having an envelope. The fill contains a material which is energized by means within the fixture, e.g. a microwave power source to radiate light energy. In one such instance, the fill material comprises mercury to provide relatively inexpensive and high efficiency lighting. As discussed in Dolan et al., U.S. Pat. No. 5,404,076, which is specifically incorporated herein by reference, such a fill while efficient and desirable as a lighting source also provides a potential environmental hazard. Dolan et al. discusses and discloses an electrodeless sulfur lamp in which the light source is disclosed as sulfur or selenium. A microwave source excites the sulfur fill element causing illumination. The microwave source radiates microwave energy into an envelope surrounding the sulfur fill. The envelope retains the microwave energy and does not allow the microwave energy to pass through the envelope. By its nature, the exterior of the envelope attenuates light rays crossing it. Thus, any light ray which crosses the envelope will be attenuated, either absorbed or scattered, to a fairly high degree. 
     Thus, while the Dolan et al. disclosure advances the art of lighting because it discloses a light source which is environmentally acceptable and highly efficient, it does not address the problem of reflected light being attenuated by the envelope before leaving the luminaire, or, as set forth in Dolan et al., the microwave screen. Additionally, Dolan et al. does not discuss, disclose, or teach its light source being used in a system for reflected lighting. 
     Other reflectors have been developed for high intensity discharge (HID) lamps. Naum, U.S. Pat. No. 4,992,695, is an example of an HID lamp which discloses a reflector-based light system employing a single reflector plate to distribute light energy from a high intensity discharge lamp. Naum discloses a single reflector which is generally concave in shape. As will be evident from Applicants&#39; FIG. 1, such a reflector would tend to have reflected light rays intersect with the envelope or microwave screen. As described above, such reflected light rays are attenuated, either absorbed or scattered, and significantly decrease the efficiency of the lighting system. 
     The benefits of indirect light for reading and working are becoming more evident. Such indirect light enables one to work without the usual shadows and other drawbacks of a conventional incandescent or HID lamp system. However, such a system also requires increased lumens to provide the same quantity of task lighting. In order to provide such lighting in an economic manner, a highly efficient lighting system is necessary. No currently known system yields such results in a manner as efficient as the instant invention. It is also desirable to provide a reflected lamp system which is environmentally acceptable and which allows wide spread, efficient, and even illumination of interior and exterior space. 
     It is unnecessary for the purposes of this invention whether the light source has electrodes, or whether it is electrodeless. It is preferable to provide a reflector system for whatever chosen light source that results in efficient and even distribution of light. While the invention will be disclosed with respect to indirect lighting systems, direct lighting systems also benefit from the results of Applicants&#39; reflector system and its inherent efficiency. Accordingly, the Applicants herein have developed a reflector system which is believed to fulfill the long felt industry need as set forth above. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a reflector system for an efficient lighting fixture. 
     It is another object of this invention to provide a reflector system which includes a first reflector being non-contiguous with the second reflector for efficiently providing generally even and uniform lighting. 
     It is another object of this invention to provide an electrodeless reflector-based lighting fixture having a first and a second reflector which are non-contiguous and which improve the absorption and scattering characteristics of presently known such lighting fixtures. 
     It is a further object of this invention to provide a reflector system for a lighting fixture which provides wide area illumination for minimizing the number of fixtures which are used to illuminate an interior environment and allow for the use of high lumen package lamps. 
     In accordance with the objects mentioned above and those that will be more fully appreciated and mentioned below, the reflector system for a lighting fixture of the present invention, comprises: 
     a light source element having an envelope surrounding the light source; 
     a first reflector member surrounding the light source element; 
     a second reflector member, non-contiguous with the first reflector member and surrounding the light source; and 
     the light source element generating light rays creating an angle of incidence and an angle of reflection with each of the first and second reflectors and each of the reflectors being designed so that the angle of reflection substantially causes the reflected rays not to cross the envelope surrounding the light source, 
     whereby, the reflected light rays emitted from the light source provide illumination without crossing the envelope and thereby provide illumination without being attenuated to a substantial degree. 
     In a preferred embodiment the reflector system for a lighting fixture in accordance with this invention includes an electrodeless light source fill. The electrodeless light source fill may be chosen from the group of elemental material, namely sulfur, selenium, or phosphorus. 
     In a preferred embodiment the first reflector is concave and the reflected rays are directed toward the center axis of the fixture and hit the target without the reflected rays crossing the envelope. The second reflector is sized and shaped to diverge the reflected rays from the center line of the fixture. Thus, the second reflector also directs reflected light rays for illumination without the rays intersecting the envelope. Additionally, the lenses provide additional light control. 
     In yet another preferred embodiment the light source, the first reflector, and the second reflector are held together by a frame. The frame includes a base for each of the reflectors and a series of rods and bolts which bind together all of the components. 
     In yet another preferred embodiment, the first and second reflectors each include a glass lens, such that when light is reflected for illumination, it passes through the glass lens for each of first and second reflectors. This glass lens assists in retaining microwaves within the lighting fixture should any escape the envelope. Additionally, the lenses can provide additional light control via refraction. 
     It is an advantage of this invention to provide an environmentally safe reflector-based luminaire which illuminates evenly and gives a natural lighting effect. 
     It is a further advantage of this invention to provide an illumination device such that the number of fixtures are minimized for any given situation and that the superior efficiency of high lumen package lamps are utilized. 
     These and other advantages will be appreciated with reference to the detailed description of the invention as follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a further understanding of the objects and advantages of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawing, in which like parts are given like reference numerals and wherein: 
     FIG. 1 is an example of a prior art sulfur lighting fixture. 
     FIG. 2 is a perspective view of an exemplary embodiment of the non-contiguous bi-phase reflector system for a lighting fixture in accordance with this invention. 
     FIG. 3 is a perspective view of another exemplary embodiment of the non-contiguous bi-phase reflector system for a lighting fixture in accordance with this invention. 
     FIG. 4 is a cross sectional view of the non-contiguous bi-phase reflector system for a lighting fixture of FIG. 3 in accordance with this invention. 
     FIG. 5 is a schematic representation of the light output distribution of the non-contiguous bi-phase reflector system for a lighting fixture of FIGS.  3  and  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention will now be described with regard to its particularized elements and functional characteristics as exemplified by certain preferred and exemplary embodiments. It will be understood that these embodiments may be combined or modified slightly to define a preferred embodiment depending on the particular application to which the invention is applied. It will be further understood that what is preferred for one application may not be preferred for another application and the invention is to be all inclusive of the described detail regardless of whether one application would prefer certain features as opposed to another. The best method of carrying out this invention will depend upon the particular circumstances to which the invention is applied. 
     With particular respect to FIG. 1, there is shown a prior art example of a sulfur reflector lamp having a single parabolic-like reflector. The lamp is generally indicated by the numeral  10  and is a general example of those lamps in the prior art which use an elemental fill such as sulfur or selenium, as described in Dolan et al., U.S. Pat. No. 5,404,076, the disclosure which is specifically incorporated herein by reference. 
     As noted in Dolan et al. a mercury lamp could be used as fill. However, because of environmental concerns the fill is usually sulfur or selenium, or other environmentally safe material. Such material, while environmentally safe, also serves as an acceptable fill in a reasonably efficient manner necessary for illumination. 
     The prior art device includes a single parabolic-like reflector  12 , a microwave screen  14 , a microwave source  16 , a fill of elemental material  18 , such as sulfur or selenium. The fill  18  is held in place by an appropriate structure and then provides illumination through excitation by activation of the microwave source  16 . The microwave source excites the fill  18  by bombarding the fill with microwave radiation. The microwave radiation is reflected and retained within the microwave screen  14 . The microwave screen  14  is typically composed of a mesh material which allows most of the light to be transmitted, but which contains microwave energy, and causes it to be reflected and, in some cases, directed back toward the fill source. 
     As shown in FIG. 1, the path of incidence  20  causes the light rays generated by the fill  18  to be reflected from the parabolic reflector  12 . The angle of incidence causes the angle of reflection and the reflected path  22  to intersect the microwave screen exterior  24 . The light rays being so reflected and intersecting the microwave screen exterior  24  are attenuated, both absorbed and scattered. The absorbed rays, primarily, will decrease the system efficiency so that approximately 40 to 50 percent or more of those light rays are not available for illumination. This dramatic decrease in efficiency is typical of such a known lamp structure. 
     In a effort to improve the fixture, the applicants herein have designed the present invention which accordingly works generally on the principle of reflected lighting, as set forth in the description of the fixture described with respect to FIG.  1 . However, the fixture efficiency of the instant invention is between 80 and 95R percent. This increased efficiency allows fewer fixtures over a greater distance to be used while providing the required even and effective lighting. Thus, fewer fixtures will be used and there will be considerable savings both financially and spatially. 
     As particularly described with respect to FIG. 2, there in shown the first exemplary embodiment of the invention denoted generally by the numeral  50 . The first exemplary embodiment  50  of the reflector system in accordance with this invention includes a light source element  52  within the interior of an envelope  54 . The light source  52  is surrounded by the envelope  54 . The reflector-based fixture  50  additionally includes a first reflector member  56  being designed and shaped so that the reflected rays intersect with the envelope only minimally or not at all. In particular, the first reflector  56  is sized and shaped so that reflected light rays are directed toward the center line of the fixture  50 . Despite the fact that the reflected light rays are so directed, they are more particularly so directed that such reflected rays do not intersect the envelope  54 . The first reflector member  56  has an open center bottom  58  and generally surrounds the light source  52  and the envelope  54 . 
     The reflector-based fixture  50  includes a second reflector  60  which is non-contiguous with the first reflector member  56 , as clearly shown in FIGS. 2 through 5. The second reflector  60  is curved at a different angle than the first reflector  56  and has a different phase of reflection. As will be more fully appreciated with respect to the description of FIG. 5, the angles of incidence and reflection for the second reflector  60  are very different from those of the first reflector  56 . However, it will be appreciated that with respect again to the description of FIG. 5 that the second reflector  60  also has angles of incidence and reflection so that the reflected rays do not cross the microwave screen, but rather diverge from the centerline of the fixture  50  and envelope  54 . In particular, the second reflector  60  is sized and shaped to diverge reflected rays away from the center line axis of the fixture. 
     The second reflector has a bottom portion  62 , which has an opening  64  through which the light source  52  and an envelope  54  are inserted. As will also be appreciated from the illustration in FIG. 2, the bottom end of the light source  52  and the bottom  62  of the second reflector  60  generally lie in the same plane. The bottom  58  of the first reflector  56  lies in a plane spaced above the bottom plane of the second reflector  60 . 
     With particular reference to FIG. 3, there in shown another embodiment of the reflector lamp in accordance with this invention. In FIG. 3, there is shown an electrodeless reflecting lamp  100 , having an electrodeless light source  102 , an envelope  104  defining a microwave screen  106 . Additionally, the first reflector  56  includes a glass lens  108  and the second reflector includes a glass lens  110 . Additionally, the electrodeless reflector lamp  100  includes a frame defined by a series of rod members  112  and bolts  114 . The reflector  56  and second reflector  60  are held together with the rods  112  and bolts  114  in the manner substantially shown in FIG.  3 . 
     With particular respect to FIG. 4., there is shown a cross section of the embodiment of the reflector lamp of FIG. 3, generally indicated by the numeral  100 . Each of the reflectors,  56  and  60 , respectively, has a concave shape. However, the reflected light rays from the first reflector  56  converge toward the centerline of the envelope  54  and generally fixture  50  to provide illumination to the center of the lighted surface without striking the envelope  54 , while the second reflector  60  has a different curvature than the first reflector  56  and directs reflected rays so that they diverge from the centerline of the envelope  54  to provide illumination to the edge regions of the lighted surface. In other words, the first concave reflector  56  has a different phase than the second concave reflector  60 . It will also be appreciated that the first reflector  56  is non-contiguous with the second reflector  60 . Thus, the reflector lamp according to the invention described herein is a non-contiguous bi-phase reflector lamp. 
     As described earlier, a microwave source  16  excites the fill or light source  102  within the envelope  104 . Upon sufficient excitation of the fill material, in this case fill material is chosen from the group of sulfur, selenium, or phosphorus. It will be appreciated that the primary fill should be selected from a group consisting of an elemental material. As noted earlier mercury is environmentally unsound and is not recommended for use although in terms of illumination, it would work almost as well. Upon sufficient excitation of the fill material, light is generated and emitted through the semi-transmissive microwave screen  106 . Incident rays follow lines  120  and  122 , for example. As the incident rays  120  strike the first reflector  56 , an angle of reflection is created whereby light is reflected through the glass lens  108  without crossing the exterior of the microwave screen  106 . 
     Additionally, reflected rays  126  are created which likewise are reflected by second reflector  60 . As illustrated the angle of reflection is created, such that reflected rays  126  are sent through the glass lens  108  without crossing the exterior of the microwave screen  106 . 
     Also shown with particular reference to FIG. 4 is the frame generally denoted by the numeral  150 . The frame  150  includes, as mentioned above, a senes of rods  112  and bolts  114 . Additionally, the frame includes a first base member  152  along the same plane as the bottom plane of the envelope  104  and the second reflector  60 . The frame also includes a second level base member  154 . The rods  112  are threaded through the second level base  154  and are secured at either end by bolts  114  both at the outer extreme of the first reflector  56  and on the first base  152 . Between the top and bottom of the rod  114 , the second level base  154  is secured by bolts  114 . 
     With particular respect to FIG. 5, there is shown an exemplary embodiment of the electrodeless reflector lamp in accordance with this invention generally designated by numeral  100 . Illustrated in FIG. 5 is a computer generated model of the rays  120 ,  122 ,  124 , and  126  which represent incident and reflected rays for each of the first reflector  56  and second reflector  60 . As is clearly illustrated, virtually none of the reflected rays  124 ,  126 , which provide the illumination, are absorbed or scattered by the envelope  104  since they do not cross the exterior of the envelope. 
     Although not directly a part of the inventive concept, it will be appreciated that the lamp described herein as the invention, can be of various sizes and intensities with regard to its lumen output. Various lumen packages in the range of from about 2,000 to 500,000 lumens are to be expected. 
     It will also be appreciated that as a result of the high output and efficiency possible from the non-contiguous reflector fixture in accordance with the instant invention, various fixture designs are possible which have heretofore have not been readily useful. Such fixtures utilizing the instant reflector system may be mounted on the floor, suspended from the ceiling, or fixed to a ceiling. Such fixtures would by their design be less in number since the reflector system of the instant invention yields such light efficiently and with a widespread and relatively uniform distribution, allowing for the use of generally higher efficiency of high lumen packages. Thus, considerable economic and spatial savings would be apparent from virtually any fixture employing a reflector system in accordance with the above described invention. 
     It will also be appreciated that various embodiments of the invention are possible that have not been discussed particularly with respect to the illumination element. The light source exist independently of the reflector or fixture design. The applicants are not limited to the invention of a particular style of illumination device, but rather only limited to the claims as set forth below.