Abstract:
Hybrid lighting systems use light distributor tubes to distribute artificial light and natural sunlight through the same distributor tubes. Devices for gathering uncollimated light from conventional sources (such as electrically energized arcs or filaments housed in evacuated or gas filled glass envelopes) and directing the light into the ends of tubes designed to distribute such light. Devices for gathering and concentrating inherently collimated sunlight to be fed into the same light distributing tubes used by the artificial light. One preferred embodiment comprises a light gathering and concentrating system in the form of a pair of opposed parabolic reflectors, one which is preferably large, e.g. having a diameter of five feet, and the other much smaller, e.g. the size of the much smaller distribution tubes. This light gathering system is connected to the light distribution tubes through a pair 90° elbows which are rotatable in the X and Y axis in order to track the location of the sun in the sky. The two parabolic reflectors are positioned to share a common focal point so that the larger reflector will direct the sunlight through the focal point of the smaller reflector, which will, reflect the light as concentrated, collimated light. A central aperture in the larger reflector passes the concentrated beam on its way to the distribution tubes.

Description:
RELATED APPLICATION DATA  
       [0001]    This application claims the benefits of U.S. Provisional Patent Application No. 60\221,604 filed on Jul. 28, 2000. 
     
    
     
         [0002]    The present invention is related to lighting systems using sunlight, artificial light or both simultaneously in any proportion in a common light distribution system.  
         BACKGROUND OF THE INVENTION  
         [0003]    Fossil fuel is a finite resource, the burning of which has incipient environmental consequences. An increase in the use of alternative energy sources is desirable, as is better efficiency in the use of all energy. Photovoltaic generation of electricity is a broad, high tech energy source but still has limitations with respect to scale and storage.  
           [0004]    Solar interior illumination is a relatively low tech alternative source, and offers huge saving in terms of fossil fuel. Except for window panes and sky lights, however, interior solar lighting has been clumsy, costly and difficult because both the intensity and the angles of sunlight vary so widely with time of day, with the seasons, and with the weather. Meanwhile, lighting systems which use a lot of electricity while the sun shines are almost universal.  
           [0005]    One improvement in the use and distribution of light has come with the inventions disclosed in U.S. Pat. No. 6,014,849 owned by the Ply-Light Corporation of Saint Paul Minn. and sold under the trademark Ply-Light. The tubes receive substantially collimated light and distribute it efficiently over large areas in the form of diffused i.e. uncollimated, light. The Ply-Light® tubes distribute artificial light which starts life inherently uncollimated. Since these tubes work best if their inputs are in the form of substantially collimated light, one aspect of the present invention addresses the technology for converting uncollimated artificial light sources to substantially collimated light for more efficient use in the new tubes.  
           [0006]    The technology for making artificial light is improving with new, powerful, energy-efficient light sources such as metal halide-based electric lamps as well as small glass envelopes filled with gaseous sulphur compounds that virtually burst into luminescence in the presence of a microwave electromagnetic field. The basic appeal is savings in fuel required to make the electricity to power the new lights. Since the new light sources are centralized and can use light-distributing tubes, they can also eliminate some labor-intensive and costly procedures such as installing many discrete, heat-generating electric light fixtures, to say nothing of the life time chore of changing many dead bulbs and fluorescent tubes, often in inaccessible places, and disposing of them safely.  
           [0007]    So single lighting systems which can efficiently distribute either solar light when the sun shines or controllable artificial light through the same tubes when sufficient sunlight is not available, will have appeal to the environmentalist and economist alike. The various aspects of the present invention are directed to this new technology. The new high-intensity light sources, however, crave better and more efficient means of distribution.  
         SUMMARY OF THE INVENTION  
         [0008]    Various embodiment of the present invention provide devices for gathering uncollimated light from conventional sources (such as electrically energized arcs or filaments housed in evacuated or gas filled glass envelopes) and directing the light in the form of a beam of substantially collimated light into the ends of tubes designed to distribute such light, such as those disclosed in U.S. Pat. No. 6,014,489.  
           [0009]    Aspects of the present invention also provide devices for gathering and concentrating inherently collimated sunlight to be fed into the same light distributing tubes used by the artificial light. One preferred embodiment of the present invention comprises a light gathering and concentrating system in the form of a pair of opposed parabolic reflectors, one which is preferably large, e.g. having a diameter of five feet, and the other much smaller, e.g. the size of the much smaller distribution tubes. This light gathering system is connected to the light distribution tubes through a pair 90° elbows which are rotatable in the X and Y axis in order to track the location of the sun in the sky. The two parabolic reflectors are positioned to share a common focal point so that the larger reflector will direct the sunlight through the focal point of the smaller reflector, which will, by optical definition, reflect the light as concentrated, collimated light. A central aperture in the larger reflector passes the concentrated beam on its way to the distribution tubes.  
           [0010]    The collimation can be accomplished, for example, by precision, parabolic reflectors, with or without attachments or by directing the internally reflected light from an elliptical reflector into the back end of a parabolic reflector, with the light source positioned at the first focal point within the elliptical reflector and the parabolic reflector located with its own focal point in precise coincidence with the second focal point of the elliptical reflector. The collimated light output is then directed to the distributing tubes, changing direction where required, using reflectors, e.g., planar reflectors.  
           [0011]    Another preferred embodiment described in further detail below comprises two sets of larger-smaller parabolic reflectors arranged to minimize the losses inherently caused by the position of the smaller parabolic reflector in the path of the sun striking the larger parabolic reflector.  
           [0012]    This unique use of dual light sources with a single distribution system is made possible by a light blending device which preferably comprises two oppositely directed, planar, partially reflecting surfaces both of which pass light bi-directionally through both surfaces at the same time. The two types of light, in this case sunlight and artificial light, are arranged into two substantially collimated light beams which intersect within a certain range of angles. The light blending device is placed at the intersection of the two beams at an angle which is precisely half of the angle of intersection of the beams. According to one preferred embodiment, two output light beams are produced, fulfilling the equation ½ (S+A) where S is the beam of sunlight and A the beam of artificial light. The outputs can also be all sunlight, all artificial light or any combination of the two. The outputs are conducted into light distributing tubes designed to use substantially collimated light. In a system based on solar light supplemented or supplanted by artificial light, the intensity of the artificial light is controlled as a function of the intensity of the light in the area being illuminated. The intensity of the artificial light is automatically adjusted up or down as required to maintain uniform lighting. Passing clouds in the daytime, will result in a small increase in the artificial light level while the darkness of night can result in a shift to artificial light.  
           [0013]    According to another aspect of the present invention, one or more of the several reflectors in the system can be made to separate the visible spectrum of the light from the invisible (including infra red). The visible light can be directed into the light distribution system while the invisible light can be filtered to eliminate it. The visible light will be “cool”, significantly lowering the demand for air conditioning. Another advantage of the present systems is that they allow the artificial light sources to be centralized where their excess heat can be vented to the outdoors in warm weather and into the building in cold weather.  
           [0014]    Preferred embodiments of the present invention comprise light sensors which can monitor and adjust the amount of artificial light added to the system necessitated by fluctuations in available sunlight.  
           [0015]    Other aspects of the present invention comprise improved sunlight collimators and concentrators, improved reflectors for both natural and artificial light, and improved connectors for connecting artificial light with distributor tubes.  
           [0016]    These and other advantages of the various embodiments of the present invention are described in greater detail below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a schematic view of one embodiment of the present invention.  
         [0018]    [0018]FIG. 2 is a schematic view of an embodiment of the present invention from above.  
         [0019]    [0019]FIG. 3 is a top view of a parabolic reflector of an embodiment of the present invention.  
         [0020]    [0020]FIG. 4 is another sunlight collector and concentrator of the present invention.  
         [0021]    FIGS.  5 - 9  illustrate the attachment of the sunlight concentrator of FIG. 4 with light distributor to according to one preferred embodiment of the present invention.  
         [0022]    FIGS.  10 - 13  illustrate components of one preferred device for blending artificial and natural light of the present invention.  
         [0023]    FIGS.  20 - 23  illustrate various light beam splitters of the present invention.  
         [0024]    [0024]FIG. 24 illustrates a device of the present invention for changing the diameter of a collimated beam of light.  
         [0025]    [0025]FIG. 25 illustrates the device of FIG. 24 connected to a light distributor tube.  
         [0026]    [0026]FIG. 26 is a cross-sectional diagramatic view of a device for collimating artificial light of the present invention.  
         [0027]    [0027]FIG. 27 illustrates the device of FIG. 26 connected to a light distributor tube.  
         [0028]    [0028]FIG. 14 illustrates one source of artificial light useful with the present invention.  
         [0029]    [0029]FIG. 15 is a graphic display of the intensity of light distributed from the artificial light source shown in FIG. 31.  
         [0030]    [0030]FIGS. 16 and 17 illustrate a device designed to maximize the amount of useful collimated light obtained form the artificial light source shown in FIG. 31.  
         [0031]    [0031]FIG. 18 illustrates an alternative device for collimating light from an artificial light source.  
         [0032]    [0032]FIG. 19 illustrates the device shown in FIG. 17 attached to a light distributor tube.  
         [0033]    [0033]FIGS. 28 and 29 illustrate an embodiment of the present invention designed to eliminate areas of high intensity immediately proximate an artificial light source and to increase the amount of collimated light directed into a light distributor tube.  
         [0034]    [0034]FIG. 30 illustrates another embodiment of the present invention.  
         [0035]    [0035]FIG. 31 illustrates another arrangement of the present invention.  
         [0036]    [0036]FIG. 32 illustrates still a further embodiment of the present invention.  
         [0037]    [0037]FIGS. 33 and 34 illustrate an other embodiment of the present invention.  
         [0038]    FIGS.  34 A-D illustrate a preferred light distributor tube useful with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0039]    Various embodiments of the present invention relate to systems for collecting and concentrating sunlight and directing concentrated sunlight and/or collimated artificial light into at least one light distributor tube. FIG. 1 is a schematic of one embodiment of the present invention comprising a parabolic reflector  10  having a central through hole  15  which allows for the passage for concentrated sunlight reflected off parabolic reflector  20 . Parabolic reflector  10  and concave parabolic reflector  20  are positioned to share a common focal point F such that sunlight entering in the direction of arrow S will strike parabolic reflector  10  and be reflected to concave parabolic reflector  20  which will then reflect the light through the central hole  15  in parabolic reflector  10 . The combination of the parabolic reflector  10  and concave parabolic reflector  20  concentrate and recollimate the sunlight for introduction into a single distributor system. This illustrated system also comprises four light tubes  30 , three artificial light sources  40 , light blender devices  50  and light sensors  60 . The sunlight passing down through entrance tube  25  is reflected into distributor tubes  30  and, where desired, supplemented or supplanted by the artificial light from artificial light sources  40 . FIG. 2 is a plan view of a similar embodiment as viewed from above when the parabolic reflector is facing upwardly. In order to facilitate installation a large parabolic reflector can be formed in segments as shown in FIG. 3.  
         [0040]    [0040]FIG. 4 illustrates a preferred arrangement for collecting, concentrating and recollimating sunlight comprising in large concave parabolic reflector  110 , a large convex parabolic reflector  120 , the back end of which forms a small parabolic reflector  111  and a smaller concave reflector  121 . The large concave parabolic reflector  110  and large convex parabolic reflector  120  are positioned to share a common focal point. Similarly, smaller concave parabolic reflective surface  111  and small convex parabolic reflector  121  also share a common focal point. This preferred sunlight concentrator advantageously minimizes the amount of lost sunlight which is blocked by the non-reflective side of reflector  20  shown in FIG. 1. In the embodiment shown in FIG. 4, the sunlight striking parabolic reflector  110  is directed to concave reflector  120  and then reflected as a concentrated, collimated beam of sunlight through center hole  115  in parabolic reflector  110  and to the distributor system. Similarly, sunlight striking parabolic reflective surface  111  on the back of reflector  120  is directed to reflector  121  which then directs that sunlight as a collimated concentrated beam through the center hole of parabolic reflector  120  and to the light distributing system. This preferred light concentrator also comprises sunlight detectors  1   16  which are used to maintain the proper orientation of the sunlight concentrator in order to maximize the amount of sunlight striking the parabolic reflectors  110  and  120 . It is preferable to have at least three and possibly more sunlight detectors  116  at spaced positions around the periphery of the support for parabolic reflector  110 . Sunlight detectors  116  are preferably linked to suitable controls for affecting the movement of the entire sunlight concentrator. The precise controls, linkages, computer hardware software.  
         [0041]    [0041]FIG. 5 illustrates one preferred embodiment of the present invention in the form of a hybrid lighting system which utilizes natural sunlight and/or artificial light at any given time. This illustrated embodiment includes the sunlight concentrator of the type shown in FIG. 4. The sunlight concentrator is connected to two elbows each comprising a reflector. Upper elbow  70  receives light directly from the sunlight concentrator and comprises a planar reflector, e.g. a mirror  71  which reflects incoming sunlight at an angle of 90 degrees. Reflector  71  can be rectangular or oval, or any other desired shape which adequately reflects sunlight received from the sunlight concentrator. Upper elbow  70  is advantageously rotatable about axis A-A and is controlled by motor  75  and suitable linkages. The linkages can be belts, gears or other linkages as desired. Light exiting upper elbow  70  enters lower elbow  80  which is rotatable about axis B-B. Lower elbow  80  comprises a reflective surface such as a mirror which redirects the incoming sunlight downwardly through tube section  89  and through the roof. While the illustrated embodiments show natural sunlight being directed through a roof, this is solely for purposes of illustration. The advantages of the present invention can be enjoyed with systems that direct sunlight outside of a building or into other areas where illumination is desired. Lower elbow  80  is also advantageously rotatable around axis B-B and is controlled by motor  85  which is linked to lower elbow  80  by suitable linkage. The combined effect of the rotation of upper elbow  70  and lower elbow  80  permits the sunlight concentrator to track the sun through any position in the sky while always directing the sunlight down tube  89 . In this illustrated embodiment tube  89  directs the concentrated sunlight through roof  88  into a light blender. Tube  98  can, for example, be formed of a structural material such as aluminum and preferably has an internal surface which is highly reflective.  
         [0042]    In the embodiment illustrated in FIG. 5, sunlight exiting tube  89  strikes a beam splitter  90  which reflects a first portion of the sunlight into light distributor tube  91  while allowing another portion of the sunlight to pass through beam splitter  90  to reflector  92  which reflects the sunlight into light distributor tube  93 . While the preferred light distributor tubes are of the type disclosed in U.S. Pat. No. 6,014,849, other forms of distributor tubes can be utilized without departing from the scope of the present invention. Those skilled in the art will appreciate that if other types of distributor tubes are utilized, then it may be necessary to take steps to uncollimate the light in order to provide for proper light distribution out of such other light distributor tubes.  
         [0043]    In one embodiment, the first side of beam splitter  90  reflects substantially half of the incoming sunlight to light tube  91  while allowing the other half to proceed to reflector  92  and into light tube  93 . Artificial light source  95  is used to supplement and/or supplant the incoming sunlight. Substantially collimated artificial light from artificial light source  95  strikes the second side of beam splitter  90  opposite the side first encountered by incoming sunlight. Beam splitter  90 , according to this illustrated embodiment, allows half of the collimated artificial light to proceed relatively unimpeded to light distributor tube  91  while reflecting the other half to reflector  92  and ultimately to light distributor tube  93 .  
         [0044]    [0044]FIG. 6 provides an illustration of how incoming rays of sunlight are concentrated and transmitted through a sunlight concentrator, upper and lower elbows and into a building.  
         [0045]    [0045]FIG. 7 is a side view of the portion of the embodiment shown in FIG. 6 above the roof line with the sunlight concentrator shown in a tilted position.  
         [0046]    [0046]FIG. 8 is a segmented view of the upper and lower elbows.  
         [0047]    [0047]FIG. 9 is an enlarged view of the light blender section and distributor tubes shown in FIG. 6. In this embodiment, tube  89  is connected to a three-piece blender box formed by upper segment  101 , middle segment  102  and lower segment  103 . Light distributor tube  89  is connected to upper segment  101  with a silicone ring  105  artificial light source  95  is connected to middle segment  102  of the blender box by a silicone ring  105  and both light tubes  91  and  93  are connected to their respective blender box segments by silicone rings  105 . Middle segment  102  of the blender box is connected to the lower segment  103  by a silicone ring  106 . Each of the light distributor tubes is provided with an end cap  107  which secures a reflector  108  on the end of the distributor tube. Reflectors  108  direct any light which has not already been directed out of the distributor tubes back into the distributor tubes.  
         [0048]    [0048]FIGS. 10, 11, and  12  are elevation views, top views and side views, respectively, of upper segment  101  of the blender box shown in FIG. 10.  
         [0049]    [0049]FIG. 13 is a portion of a blender box. The circle on the right is the connector port for an artificial light source. This input  98  comprises a light baffle  99  which reflects light back into the bulb in order to prevent the bulb from overheating the light distributor element in the light distributor tube. This light baffle  99  is particularly useful when using distributor tubes of the type shown in U.S. Pat. No. 6,014,489 which comprise a gradually tapering light distributor for reflecting light out of the distributor tube. FIGS. 34 a  through  34   d  provide a representation of a light distributor tube  800  connected to an artificial light source  810  by a silicone ring  805 . FIGS. 34 b,    34   c  and  34   c  are cross-sectional views taken along lines BB, CC and DD, respectively. These cross-sectional views show the relatively increasing cross-section of light distributor  820  of this illustrated embodiment as the light distributor gradually intersects more of the light beam along the length of the distributor tube  800  as the light beam travels away from the artificial light source  800 . The baffle  99  is designed to prevent the heat from the artificial light source from overheating or burning the distributor  820  if this type of light distributor tube is utilized. Other shapes and sizes of baffles can be utilized without departing from the scope of the present invention in order to accommodate different sizes and shapes of light distributors and/or light distributor tubes.  
         [0050]    [0050]FIG. 14 is a schematic representation of an artificial light source, e.g. a Philips CDM-SA/T 150-watt metal halide bulb which may be utilized with the present invention. This type of artificial light source is particularly suitable since it has a relatively short arc which is readily positionable at the focal point.  
         [0051]    [0051]FIG. 15 is a schematic representation of the intensity of artificial light emanating from the artificial light source shown in FIG. 14. The dark lines on the draft indicate the intensity of the beam at various angles relative to the orientation of the light source. The angles on the graph in FIG. 15 correspond to the indications of 0°, 90°, 180° and 270° shown on FIG. 14. As indicated on the graph in FIG. 15, most of the artificial light leaving this artificial light source is directed between 25° and  1550 , and between 205° and 335°. If the arc of the light source, which is represented by the small circle A in the center of the bulb is placed at the focal point of a parabolic reflector having a focal length of 0.5 inches and the parabola is designed to be connected with a tube having a diameter of 5-{fraction ( 1 / 2 )} inches, then the portion of the light between 135° and 155° and between 205° and 225° would not hit the reflective surface of the parabolic reflector and therefore would not be collimated prior to entry into the light distributor tube. Since some distributor tubes, particularly the distributor tubes discussed in the above-referenced patent, operate most efficiently when receiving collimated light, it is desirable to collimate the maximum amount of light possible.  
         [0052]    [0052]FIG. 16 illustrates a modified parabolic reflector designed for an artificial light source such as that represented in FIG. 15. In this embodiment of the present invention, a serrated extension ring  97  having a highly reflective interior surface is connected to the end of the parabolic reflector and a central reflector  98  is mounted within the center of the parabolic reflector. As generally illustrated in FIG. 16, light exiting the artificial light source between angles 135° and 155° and between 205° and  225 ° strikes the interior, highly reflective serrated edges of extension ring  97  and are directed toward the centrally located reflector  98  which reflects those light beams as collimated light.  
         [0053]    [0053]FIG. 17 is another representation of a parabolic reflector comprising a serrated extension ring of the type shown in FIG. 16.  
         [0054]    [0054]FIG. 18 illustrates another embodiment of a reflector system for an artificial light source designed to capture additional light which would otherwise be lost as explained above. According to the embodiment illustrated in FIG. 18, the end of the parabolic portion of a reflector is provided with a downwardly sloping, inwardly facing parabolic reflective surface  297  which reflects incident light to a centrally located parabolic reflector  298  which then redirects the artificial light beams as a collimated, concentrated light into the distribution system or light blender device, as desired. Parabolic reflective surface  297  and parabolic reflector  298  share a common focal point F′ as indicated in FIG. 18.  
         [0055]    [0055]FIG. 19 is a view of an alternative embodiment, similar to the embodiment shown in FIG. 10, however, with an improved artificial light reflector having a serrated extension ring.  
         [0056]    As noted above, in the illustrated embodiments, the natural sunlight and artificial light are blended using beam splitters arranged at 45° to the incident light. One type of beam splitter useful with the present invention comprises a piece of glass having alternating sections which are uncoated, i.e. clear, and sections which are coated with a reflective material so that at least some incident light is reflected.  
         [0057]    [0057]FIG. 20 is a schematic diagram illustrating how a beam splitter of this type operates wherein the arrows designated S represent sunlight and arrows designated A represent artificial light. After encountering the beam splitter, the exiting beams comprise half sunlight and half artificial light. FIGS. 21A, B and C are top, side and cross-sectional views of one arrangement for a beam splitter of this configuration.  
         [0058]    [0058]FIGS. 22 and 23 illustrate another form of beam splitter which comprises a dichroic coating designed to allow certain portions of certain types of light to pass through the coating while reflecting the resulting portion of the incident light. Dichroic coatings can also be designed to substantially reflect light of certain wave lengths while allowing light of other wave lengths to pass through the coating. Dichroic beam splitters comprise at least one dichroic coating which reflects a certain portion of either artificial or natural light while allowing the balance of the incident light to pass through.  
         [0059]    [0059]FIG. 22 is a schematic illustration of a dichroic lens wherein the dichroic (beam splitting) coating is balanced so that half of both the incident sunlight and incident artificial light pass through the beam splitter while half of each is reflected. In this illustrated embodiment, the beam splitter is advantageously positioned at an angle of 45° to each of the incident beams of sunlight S and artificial light A. It may be possible to orient a beam splitter at different angles by adjusting the coating and/or the manner in which dichroic coating is applied to the substrate. As indicated in this illustrated embodiment, the result is a substantially equal amount of artificial light and an equal amount of sunlight leaving the dichroic lens. FIGS. 23 a,    23   b  and  23   c  are the top view, side view and a cross-sectional view of the dichroic lens shown in FIG. 22. With reference to FIG. 23 c,  surface  232  is anti-reflective while surface  233  is the beam splitting surface. The elliptical shape is design to fit in the opening shown in FIG. 10. As one example of a beam splitter useful with the present invention, a 7.75 inch by 5.5 inch by 3.2 millimeter borofloat substrate, having a clear aperture of 7.1 inches by 5 inches and having a surface quality of 80/50 scratch and dig, was coated on one side with a broad band anti-reflective coating having an average reflectance of less than 1 percent for light having wave length of 425-675 nm at a 45° angle of incidence. The opposite side was coated with a dielectric beam splitter with a transmission equal to 50 percent ±10 percent for light having a wave length of 425-675 nm at a 45° angle of incidence.  
         [0060]    For various applications, it can be desirable to use light distributor tubes of different diameters and also to couple light sources or tubes transmitting natural sunlight to a blender box or to a light distributor tube of a different diameter. Since the efficiency of many light distributor tubes is directly related to the ability to provide collimated light, it is desirable to always provide collimated light. The device shown in FIG. 24 is utilized to change the diameter and concentration of a beam of collimated light. This device can advantageously either concentrate either a collimated light beam into a narrower beam or can expand a narrow beam into a wider beam of collimated light. The illustrated device comprises two parabolic reflectors which are arranged to have an identical focal point. In the manner illustrated, collimated light entering either side of the device which strikes a reflective surface on one side will pass through the common focal point, strike the reflective surface on the opposite side of the device and exit in a collimated beam.  
         [0061]    [0061]FIG. 25 illustrates the use of this device wherein a wide beam of collimated light is first concentrated and then directed into a light distributor tube.  
         [0062]    [0062]FIG. 26 illustrates another device for collimating light from an artificial light source comprising an elliptical reflector  271  and a parabolical reflector  272 . According to this embodiment of the present invention, the illuminated arc of the light source is positioned at the first focal point  273  of the elliptical reflector and the parabolical reflector is positioned such that its focal point is common with the second focal point  274  of the elliptical reflector. In the manner illustrated in FIG. 26, light emanating from the arc at the first focal point  273  which strikes the interior reflective surface of the elliptical reflector  272  passes through the second focal point  274  of the elliptical reflector/parabolical reflector, then strikes the interior surface of the parabolical reflector and exits as a collimated beam of light. FIG. 27 illustrates this improved artificial light source connected to a light distributor tube.  
         [0063]    [0063]FIGS. 28 and 29 illustrate another aspect of the present invention which is designed to improve the even distribution of light from an artificial light source. When light is directed from a simple parabolic reflector such as the one shown in FIG. 29 connected to a light distributor tube, in the area immediately next to the light source, it is common to have intensity peaks. It has been found that a more even distribution of light emanating from the light distributor tube can be obtained by adding a mirror film  282  to the end of the light distributor tube proximate the artificial light source in the manner illustrated in crosssection in FIG. 28. This cross-sectional view of a light distributor tube section comprises a rigid polycarbonate clear tube  283 . The mirror film  282  extends only from the point proximate D artificial light source or about 30 inches. Below the mirror film is a light enhancement film, for example, a lexan film  284 . The mirror film may comprise a silverlux film available from 3M. The light distributor  285  can comprise a film available from 3M designated 3635-100 light enhancement film on suedelexan. Distributor  285  is not covered with the HP-92W lexan film. Light is emitted from this distributor tube in the area designated by the arc E at the bottom of the tube.  
         [0064]    [0064]FIG. 30 illustrates an alternative embodiment of the present invention wherein a flat reflector surface  410  is pivotally supported on a rotatable sunlight concentrator  420  comprising a parabolic reflector  430  which directs sunlight reflected off of flat reflector  410  onto a smaller parabolic reflector  440 . Parabolic reflector  440  then reflects a concentrated, collimated beam of sunlight onto a reflector  450  which directs the concentrated, collimated beam of sunlight down through the roof  401  into a light blending device. In this illustrated embodiment, tilting reflector  410  preferably has a diameter equal to the diameter of large parabola  430  in horizontal dimension and 1.75 times the diameter of the large parabola  430  in vertical dimension in order to maximize the light collected from the sun.  
         [0065]    [0065]FIG. 31 illustrates a simpler device wherein sunlight is reflected but is not concentrated. According to this simplified device, a planar reflector  510  which is supported for rotation in both the X and Y axis by support  515  reflects sunlight to a second planar reflector  510  which then simply directs the reflected beam of sunlight down through a skylight  530 . The sunlight passes through beam splitters  540  and  541  and into beam concentrators  550 ,  551 , respectively. Light concentrators  550  and  551  are of the general type shown above in FIGS. 24 and 25. The resulting concentrated light can then be blended with artificial light from an artificial light source  555  or can go directly to a light distributor tube  556 .  
         [0066]    [0066]FIG. 32 illustrates an alternative embodiment wherein the sunlight gathering device is similar to that shown in FIG. 31. However, according to this illustrated embodiment, the sunlight is concentrated using a device of the type shown in FIGS. 24 and 25. In this illustrated embodiment, the light concentrated device  600  is positioned in the roof  601  of the building. The concentrated beam of collimated sunlight is then directed into a blender box comprising a beam splitter  605  where the sunlight can be mixed with a collimated beam of artificial light emanating from artificial light source  610  and two resulting beams of combined natural and artificial light are distributed through distributor tubes  611  and  612 . In this illustrated embodiment, the light distributor tubes are on different floors of the illustrated building. As noted above, light from the sun or the artificial light source(s) can be used singly, i.e. without the alternate source.  
         [0067]    While the illustrated embodiments of the present invention show beams of sunlight passing generally vertically through the roof of a building, it is also within the scope of the present invention to pass sunlight through a roof on an angle. The embodiment of the present invention shown in FIG. 33 is similar to the embodiment shown in FIG. 30 wherein a pivotal and rotatable reflector  710  reflects light to a large parabolic reflector  730  and into a smaller parabolic reflector  740  which then sends the resulting collimated, concentrated beam of sunlight through the roof  701  on an angle into the building where it encounters reflector  750  and is then director into either light distributor tubes or blender boxes for possible mixing with artificial light.