Patent Publication Number: US-6220726-B1

Title: High efficiency highly controllable lighting apparaus and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of copending application(s) Ser. No. 08/375,650 filed on Jan. 20, 1995, now U.S. Pat No. 5,647,661. 
     This is a continuation-in-part from commonly owned, U.S. Ser. No. 07/820,486 filed Jan. 14, 1992, now U.S. Pat. No. 5,402,327; Ser. No. 08/242,746 filed May 13, 1994, now U.S. Pat. No. 5,595,440; and U.S. Ser. No. 08/242,745 filed May 13, 1994 now U.S. Pat. No. 5,519,590. 
    
    
     INCORPORATION BY REFERENCE 
     The entire contents, including specifications and drawings, of commonly owned issued U.S. Pat. Nos. 5,337,221 and 5,343,374; and of co-pending U.S. Ser. No. 08/242,745 filed May 13, 1994 now U.S. Pat. No. 5,519.590; U.S. Ser. No. 08/242,746, filed May 13, now U.S. Pat. No. 5,595,440 and U.S. Ser. No. 07/820,486, filed Jan. 14, 1992, now U.S. Pat. No. 5,402,327 are incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     A. Field of the Invention 
     The present invention relates to the lighting of relatively large areas or targets, and in particular, to the use of high intensity light sources to light such areas or targets in a highly efficient yet highly controllable manner. 
     B. Problems in the Art 
     There are many instances where highly efficient and highly controllable high intensity lighting could be advantageous. There are many known methods of high intensity lighting. Most utilize some sort of an arc lamp of relatively high wattage and a reflector system that attempts to direct part of the light from the arc lamp to a target area. An example is the widely used axially mounted arc lamp in a bowl-shaped hemispherical reflector. This type of known lighting is described in detail in U.S. Pat. Nos. 5,343,374 and 5,337,221. 
     Although this type of fixture can produce a relatively high intensity, controlled and concentrated beam, the nature of the fixture presents some difficulties with respect to efficiency and control. Such fixtures normally are elevated at least several tens of feet and then aimed towards the target location. Because the reflector is symmetrical, some light falls directly on the target area but other light falls outside the target area. Such light is known as spill light. It reduces the beneficial use of light because light which otherwise could be useful at the target area, and which is produced by the fixture, does not end up in the target area. 
     Additionally, even though such fixtures produce a relatively controlled, concentrated beam, the nature of light is such that even such a beam cannot be precisely collimated to long distances and therefore there is some beam spread and dispersion of light. It is therefore difficult to achieve sharp cutoff of the beam pattern from each of the fixtures at long distances and difficult to control the precise shape and other characteristics of the light. It is difficult to match the shape of the light from the fixture with the shape of the target area. 
     U.S. Pat. Nos. 5,343,374 and 5,337,221 show and describe apparatus and methods which address light control problems. Their preferred embodiments utilize a light fixture which can be, but is not required to be, a bowl-shaped reflector, a primary reflector, and an on-axis arc lamp. The light fixture is directed away from the target area into a mirror or secondary reflector. The mirror redirects at least a portion of the light from the primary light source. The nature of the combination is such that it produces a controlled beam with sharp precise cutoffs. Therefore, at a race car track as an example, these fixtures can be placed on the ground. Each fixture directs a light beam so that it covers the width of the track and yet cuts off at the top or very close to the top edge of the restraining wall of the outer edge of the track. The light is therefore placed on the track instead of off the track. It also is kept out of spectators&#39; eyes. A plurality of such fixtures can be placed around the interior of the track and coordinated to produce even, uniform but controlled lighting for the track. 
     Although such systems do have efficiencies, there is still room for improvement regarding such devices and methods. 
     For example, the size of such apparatus is substantial. In the preferred embodiment described in U.S. Pat. Nos. 5,337,221 and 5,343,374, the light producing fixtures are essentially the same size as conventional bowl-shaped fixtures with on-axis arc lamps. For example, the reflector can be several feet in diameter at its face. The mirrors or secondary reflectors can be on the order of several feet tall by several feet wide and are spaced several feet from the light producing fixtures. 
     Additionally, those types of arrangements introduce difficulties regarding efficient utilization of light. All of the light from the light producing fixture may not be redirected by the secondary reflector or mirror. For example, some light from the light producing fixtures may fall outside the mirror and therefore be lost. 
     Also, the flexibility of these arrangements in terms of ease of positioning and adjustability is limited. 
     It is therefore the principle object of the present invention to provide a high efficiency, highly controllable light fixture and method which improves upon the state of the art. 
     A further object of the present invention is to provide an apparatus and method which efficiently utilizes light. 
     Another object of the present invention is to provide a highly controllable light for large areas from a relatively compact fixture. 
     Another object of the present invention is to provide flexibility with regard to operational characteristics such as adjustability of the characteristics of the light produced. 
     Another object of the present invention is to provide flexibility with regard to directing light to a target area. 
     These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims. 
     SUMMARY OF THE INVENTION 
     The apparatus according to the present invention includes a high intensity light source. A first or primary reflector is positioned at or near the light source and is substantially the same order of size as the light source. A second or secondary reflector of substantially larger size than the light source redirects direct light from the light source in a highly controlled manner to a target. The primary reflector redirects light from the light source back through the light source and/or to the secondary reflector for redirection in a highly controlled manner to the target area. 
     The light source, primary reflector and secondary reflector can be contained within the same housing. The housing can be attachable to a base which can allow adjustable orientation of the housing with respect to the target. The base can be either placed on the ground or connected to some structure, including a structure that would elevate the housing. 
     The method according to the present invention includes redirecting at least a portion of the light output of the light source back through the light source, the redirection occurring very close to the light source. Light directly from the light source, and any light that has been redirected back through the light source, is in turn redirected in a highly controlled manner to the target area. 
     The invention can be utilized in a single fixture or with multiple fixtures to produce light which is highly controlled and efficiently utilized for an area or target. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the front and right side of an apparatus according to the preferred embodiment of the present invention. 
     FIG. 1A is an elevational diagrammatical view of multiple apparatus elevated on a pole. 
     FIG. 2 is an enlarged isolated perspective view of the apparatus of FIG. 1 with the front lens shown in an open position. The large secondary reflector, and the mount for the light source and primary reflector are partially shown in the interior of the housing of the fixture. 
     FIG. 3 is a side elevational view taken along line  3 — 3  of FIG.  4 . 
     FIG. 4 is an enlarged top plan view of the light source mount of FIG.  2 . 
     FIG. 5 is a rear elevational view taken along line  5 — 5  of FIG.  4 . 
     FIG. 6 is a simplified reduced front elevational view of FIG.  2 . 
     FIG. 7A is a side elevational diagrammatic view of a light source and a curved, separate primary reflector. 
     FIG. 7B is side elevational diagrammatic view of a light source and a flat, separate primary reflector. 
     FIG. 7C is a side elevational diagrammatic view of a light source and a primary reflector in the form of a coating. 
     FIG. 8 is an isolated perspective of an embodiment of a light source and primary reflector. 
     FIG. 9 is a perspective view of the rear and left side of the apparatus of FIG.  1 . 
     FIG. 9A is an enlarged perspective view of the housing of the fixture of FIG. 9, showing the rear wall pivoted open and the-back of the frame that supports the secondary reflector. 
     FIG. 10 is an enlarged isolated perspective view of the reflector frame with attached segments of the secondary reflector. 
     FIG. 11 is an enlarged side elevation of one mirror segment and connection components of one end of the segment to the frame of FIG. 10 taken generally from the viewpoint of line  11 — 11  of FIG.  10 . 
     FIG. 11A is a sectional view taken along line  11 A— 11 A of FIG.  11 . 
     FIG. 12 is an enlarged partial back elevation of FIG. 12 taken along line  12 — 12  of FIG.  10 . 
     FIG. 13 is an enlarged sectional view of part of the interior of the housing of FIG. 9 showing the positioning of the large reflector frame in the housing, taken generally along line  13 — 13  of FIG.  9 . 
     FIG. 14A is an enlarged isolated view of the elevational side of the large secondary reflector and frame, showing diagrammatically the line along which individual reflector segments are situated. 
     FIG. 14B is similar to FIG. 14A but shows alternative reflector segments to those of FIG.  14 A. 
     FIG. 15 is a rear elevational view of the interior of the fixture housing with the rear wall removed, showing the mounting of the secondary reflector on brackets allowing the adjustability of the frame of FIG. 10 in the fixture. 
     FIG. 16 is a similar view to FIG. 15 but showing the frame of FIG. 10 adjustably tilted in the fixture. 
     FIG. 17 is a vertical sectional view through the fixture of FIG. 1 showing how the support pole is mounted to the lower trunnion box. 
     FIG. 18 is a sectional view taken along line  18 — 18  of FIG.  9 . 
     FIG. 19 is a top plan view of a race track showing diagrammatically one example of positioning of apparatus according to FIG. 1 around the interior of the track. 
     FIG. 20 is a diagrammatic side elevational view illustrating the creation of a defined cutoff for the beam from a fixture according to the preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A. Overview 
     To better understand the invention, a preferred embodiment will now be described in detail. The preferred embodiment discussed is but one form the invention can take and does not and is not intended to limit the forms the invention can take. 
     Frequent reference will be taken to the appended drawings. Reference numbers will be used to indicate certain parts and locations in the drawings. The same reference numerals will be used to indicate the same parts and locations throughout the drawings unless otherwise indicated. 
     Examples of specific uses of the present invention can be found in U.S. Pat. Nos. 5,337,221 and 5,343,374. As an example, the present invention can be advantageously used for a target area such as a race car track. Other examples include sports field or court lighting, lighting of highways or intersections, and other uses where highly efficient and highly controllable hi-intensity lighting is needed or desired. The invention can be beneficially used in most lighting applications. 
     B. General Structure of Preferred Embodiment 
     FIG. 1 illustrates fixture  10  according to a preferred embodiment of the invention. A housing  12  has top  14 , bottom  16 , left side  18 , right side  20 , rear  22  (all of stainless steel), and front  24 . It is to be understood in this embodiment that front  24  consists of a substantially transparent window or lens within a stainless steel frame  26  that is attached to and forms a part of housing  12 . A base, designated generally at  28  is essentially a double trunnion in a sense that fork  30  is pivotably mounted to sides  18  (see pivot connection  32 ) and  20  of housing  12  to allow pivoting of housing  12  around a horizontal axis (see arrow  40 ) defined by pivot connections  32  (see FIG.  6 ); and fork  30  (having vertical spaced-apart arms extending from a trunnion box below housing  12 ) in turn is rotatable on post  42 , defining a vertical axis (see arrow  44 ). Post  42  is in turn rigidly mounted in the ground  46  so that the entire fixture  10  can be placed near the ground. Alternatively, post  42 , or some similar arrangement could be mounted upon almost any type of support, even those which are elevated. An example would be the mounting of several fixtures  10  on a cross-arm  48  elevated on pole  50  (see FIG.  1 A). Each fixture  10  in FIG. 1A could be rotatable and/or tiltable. It is to be understood, however, that the use of a trunnion mount is not required and housing  12  could be mounted by a number of ways, within the skill of those skilled in the art, to some supporting structure or to any of a variety of types of bases. 
     As can be seen in FIG. 1, fixture  10  therefore is a self contained unit which produces a light output from components contained within housing  12 . 
     In the preferred embodiment, housing  12  is 29¾″ wide by 34″ tall by 19¼″ in depth. Other configurations and dimensions are of course possible. The materials used for housing  12  are not critical. They may be sheet metal. The materials for the parts of base  28  likewise are not critical. In the preferred embodiment they are made of metal bars and tubing. 
     FIG. 2 illustrates front lens  24  pivoted open on hinge,  52  (with latches  56  released). Latches  56  are riveted or otherwise connected to housing  12  and have a middle resilient finger with a lip at the end which holds door  24  shut. The fingers on each side of the middle finger deter frame  26  from being pulled sideways and putting bending pressure on the glass. The front door (lens  24 ) and front perimeter of housing  12  have extended mating lips and a silicone gasket to create a seal when closed. Latches  56  securely close door  24  but are easy to operate to open door  24 . The interior of housing  12  includes what will be referred to generally as light source mount  58  (of metal or ceramic) suspended on oppositely extending steel rods  60  and  62  which are connected at outer ends to steel arms  64  and  66 . A secondary reflector (designated generally at  70 ) is spaced apart from but positioned around one side of light source mount  58  opposite lens  24 . The precise shape and size of reflector  70  can vary. For example, secondary reflector  70  could be made much bigger than shown in FIG.  2 . Its ends could extend much farther forward and ahead of light source mount  58 . However, sometimes increases in size of reflector  70  result in marginal benefits. Therefore, reflector size is minimized as much as possible without losing significant control of light. Optional side reflectors  72  and  74  (on each interior left and right side of housing  12 ) can also be utilized. Reflectors  72  and  74  are mounted in frames (not shown) which are attached to a vertical rod  73 . Electrical power is supplied to light source mount  58  by wires  76 . It is to be understood that other electrical components, such as ballasts, fuses, switches, etc., could be placed externally of housing  12 , such as in the interior of trunnion fork  30 , or in other enclosures. For example, the horizontal section of trunnion fork  30  (called the trunnion-box) could house the ballasts and other components. Heat producing components, particularly ballasts, could be placed outside of housing  12  to reduce thermal problems for fixture  10 . 
     FIGS. 3-5 show in more detail the light source mount  58  and associated components. A light source  80 , here an arc tube  82  (approximately 1⅛″ diameter, 4½″ long) surrounding electrodes  84  and  86 , is positioned generally horizontally between arms  88  and  90  which extend rearwardly from mount body  92 . 
     The rearward facing side of arc tube  82  is exposed and faces reflector  70 . As shown in FIG. 3, the forward facing side of arc tube  82  is surrounded by a reflector  94  which is closely positioned or in abutment to and only slightly bigger than arc tube  82 . Reflector  94  can be curved (see FIGS.  7 A and  8 ), flat (see FIG.  7 B), or form a coating or layer on arc tube  82  (see FIG.  7 C). In the preferred embodiment it is on the order of 1⅛″ tall by ⅛″ thick by 11.0″ tall. 
     By referring also to FIG. 2 along with FIGS. 3-5, it can be seen that mount body  92  effectively blocks arc tube  82  from view from the front of fixture  10 . The rearward exposure of arc tube  82  and reflector  94  ensures that most or all of the direct light of arc tube  82  to reflector  70  is reflectively controlled by reflector  70 . It is to be also understood that the shape and proximity of reflector  94  to arc tube  82  directs a substantial amount of light from arc tube  82  that does not go directly to reflector  70 , back through the arc stream of arc tube  82  and/or to reflector  70 . 
     In the preferred embodiment, arc tube  82  consists of a high intensity arc tube which is elongated and produces a somewhat elongated arc stream, as opposed to one that is closer to a point source of light. It is to be understood, however, that a shorter arc stream or shorter arc light source in the horizontal direction would produce a narrower beam from the fixture in a horizontal directions. There are certain high intensity light sources that have quite narrow arc streams for light sources. Some HMI lamps are of that nature. Wires  76  connect to electrodes  84  and  86  as shown. Insulators  77  and brackets  79  can be used to suspend and support wires  76 . 
     It is to be understood, however, that different types, shapes, and characteristics of light sources can be used with the present invention. The above preferred embodiment is useful in applications such as lighting race tracks where the elongated light source used with elongated rectangular mirror segments as described in more detail later can create very sharp defined cutoffs, particularly at the top of the beam. 
     Vertical beam spread. for the preferred embodiment is a function of the diameter of the arc tube  82  and the distance between the arc tube and the vertex of reflector  70 . The widest part of the beam is determined by light rays which are traced from the top and bottom of the arc tube to the vertex of the reflector and their respective reflective directions. Light rays from any position of the arc tube to any other position on reflector  70  will fall within the vertical beam spread defined by the rays from the top and bottom of the arc tube reflecting from the vertex of the reflector. In the preferred embodiment, reflector  70  has 4″ by 24″ segments  100  positioned along a parabola defined by the equation y 2 =4fx, where maximum x=8¾″, f=6½″, and maximum y=15″. There is about a 30″ distance between the top front edge and the bottom front edge of reflector  70  (the chord between the opposite ends of reflector  70 ). When installed there is about approximately {fraction (5/32)}″ separation between adjacent edges of segments  100 . For a 10° vertical beam spread, arc tube  82 , having a 1⅛″ diameter, and a distance of 4″ between electrodes, is placed about 6½″ from the vertex along the focal length of reflector  70 . 
     It is therefore to be understood that by increasing the diameter of the light source, a wider beam can be created. Alternatively, moving the light source near reflector  70  could create a wider beam. The converse is also true. A smaller diameter arc tube or placing the arc tube farther from reflector  70  can narrow the beam. If the position of the light source is changed it would defocus the beam. The segments would have to be re-aimed and/or the size of the parabola changed. A feature of fixture  10  is that beam width vertically can be adjusted to some degree without changing the position of the light source relative to reflector  70  by adjusting segments  100 . 
     It is also to be understood that because of the above described relationship, the entire fixture can be made smaller or must be made larger depending on the distance between the light source and the reflector. If the diameter of the light source can be made very small, it can be placed nearer reflector  70  than one of a larger diameter. This would shorten the distance. This shorter distance would then allow a reduced size fixture. 
     As will be described in more detail below, utilization of segments to make up mirror  70  allows an alternative way to widen or narrow a vertical beam spread. Each segment is individually adjustable in its orientation to the light source by being pivotable around a horizontal axis. By creating a greater angle of incidence of light from the light source to a segment, a wider beam can be created. This assists in the adjustability and flexibility of fixture  10 . 
     For a racetrack of a size suitable for NASCAR stock cars, a 10° vertical beam spread was selected. There is not as much concern about cutoff on the sides of the beam because the track is long in both directions. The relationship between the light source, the primary reflector, and the secondary reflector, as far as size, shape, and spacing, all can be adjusted or selected to create certain lighting effects. In many instances, it is advantageous to match the beam shape with the target. Correlating the shape of the secondary reflector mirrors with the shape of the beam allows this to take place. In the example of the preferred embodiment, this is done by having parallel surfaces between the bottom of arc tube  82  and the top of each mirror segment-of secondary reflector  70 , and then using somewhat linear light source  80  and rectangular mirror segments. Other shapes and relationships can be used to create other desired lighting effects. 
     In the preferred embodiment a 2,000 watt metal halide arc tube is utilized. Other types or wattages of lamps can be used. Wattages as low as 250 watts or even less are possible. There is no limitation on the wattage type or size of light source. 
     Reflector  94  is placed next to the outside of, arc tube  82  and is specifically coated to pass infrared radiation but reflect 85% of visible light. Thus, the infrared radiation is not reflected back through the arc tube  82  thus reducing heat to the seals or the hot points near the electrodes, but 85% of visible light is reflected back through the arc stream and/or to reflector  70 . 
     As shown in FIG. 3, reflector  94  is made to match the perimeter of arc tube  82 . Alternatively, it could be flat (FIG. 7B) or some other shape. It could be spaced slightly therefrom or alternatively it could be a direct coating on arc tube  82  (FIG.  7 C). For example, it could be a dielectric, dichroic (passes certain wavelengths of light and reflects others) or ceramic material such as aluminum oxide. 
     The curved reflector shapes of FIGS. 7A and 7C generally allow more control of light and will produce a narrower beam than a flatter or larger reflector  94  such as shown in FIG.  7 B. However, there may be instances where a wider beam is required or desired and thus a flat or less curved reflector  94  could be used. Furthermore, curved reflectors  94  such as FIGS. 7A and 7C can create thermal problems which can affect arc tube  82 , such as heating of the seals or other heating problems, or can affect reflector  94  such as degrading any bonding or fusing that is needed to place reflector  94 , either as a separate piece or as a coating, upon. the perimeter of arc tube  82 . Therefore, a material which passes infrared radiation but reflects a substantial amount of visible light, may be advantageous. 
     Reflector  94  is relatively close to and relatively similar in size to arc tube  82 . As compared to the primary reflector described in U.S. Pat. Nos. 5,337,221 and 5,343,374, by placing reflector  94  at this position relative to arc tube  82  and making it that size, the whole size of the fixture can be reduced significantly. 
     It is therefore generally advantageous to minimize reflector  94  in size relative to the light source. Reflector  94  is also generally very small relative to the secondary reflector  70 . Again, this helps to minimize the size of the entire fixture. 
     It is to be understood, however, that reflector  94 , the primary reflector, can be very specular. However, it can also be diffuse, such as made of ceramic or a ceramic coating, such as aluminum oxide. 
     FIG. 6 shows a front elevational view of fixture  10 . By referring also to FIG. 2, it can be seen that individual segments  100  are placed side by side along a curve in the vertical plane. Each segment  100  extends generally horizontally across the width of the interior of housing  12 . The segments basically surround over 180° of the suspended light source  80 . As will be explained later, the position of segments  100  relative to light source  80  is such that they redirect and project light out of lens  24  in a highly efficient and controlled manner. 
     FIG. 9 illustrates a rear perspective view of fixture  10 , and shows rear panel  22 , which is like front panel  24  in that it can be pivotable attached in a closed, sealed position by latches  56 . By referring to FIG. 9A, rear panel  22  can be pivoted open to have access to the back of reflector  70 . As is shown in FIG. 9A, a frame  110  is used in the preferred embodiment to create the parabolic shape of reflector  70  and to hold the individual segments  100  in place. Frame  110  is thus in turn mounted to housing  12 . 
     FIG. 10 shows frame  110  in more detail. A generally rectangular sub-frame  112  has two curved frames  114  and  116  attached to it. Frames  114  and  116  follow a parabolic line  106  (see FIGS.  14 A and  14 B). Ears  118  project outwardly along each curve  114  and  116  and are matched so that a segments  100  can be connected between corresponding ears  118  along curves  114  and  116 . 
     FIG. 10 also shows that mounting brackets  122  are attached to each ear  118  and served to support one end of a mirror segment  100 . Also side mirror mounts  123  and  125  extend forwardly from each side of frame  110  and includes slots  124 . Each pair of mounts  123  and  125  receive opposite ends of vertical rod  73  (see FIG. 2) and allow side mirrors  72  and  74  to be mounted inside housing  12 . Side mirrors are pivotable around rods  73  to alter their position to in turn affect the horizontal width of the light beam leaving fixture  10 . 
     FIG. 11 shows in more detail the structure of bracket  122 . A flange  128  of bracket  122  fits between halves of ear  118 . A screw  180  and bushing  188  (see FIG. 11A) extend through aligned apertures in ear  118  and flange  128 , and present a pivot axis upon which bracket  122  can pivot. A carriage bolt  126  is placeable through aligned apertures in the two matching halves of ear  118  and a curved slot  130  in flange  128 . Bolt  126  is securable by a nut to lock bracket  122  in position. The range of tilt of bracket  122  is defined by slot  130 . Thus, until bolts  126  of the brackets  122  holding opposite ends of a mirror segment  100  are tightened, the mirror segment  100  can be tilted over a range commensurate with the allowed range of movement of bolts  126  in slots  130 . 
     FIG. 11 also shows an arrangement by which mirror segments  100  can be mounted to bracket  122  with precision and with reduced risk that there will be any forces applied to relatively fragile mirror segment  100  that would break it because of such mounting. It also allows relatively easy and quick insertion or removal of a segment  100 . Bracket  122  has a main portion  134  which is C-shaped in cross-section. Flange  128  extends from one side of main portion  134 . Mirror segment  100  mateably fits within and can slide into main portion  134 . A flat spring  136  can be anchored by bolt, rivet, or other fastening member  138  to bracket  122  and be shaped so that its outer opposite ends extend to top and bottom edges on the back side mirror segment  120 . Screws  140  can then be threaded down through nuts  141  projection welded onto the back side of main portion  134  of bracket  122  and push the opposite ends of spring  136  against the back of mirror  120 . Pads  142  can be placed between the front side and top and bottom edges of mirror  100  and the jaws of main portion  134  and Teflon blocks  144  can be placed on the ends of spring  136  to provide some cushioning and protection of mirror  100  from the forces exerted upon it by this arrangement. The Teflon stands the heat generated inside fixture  10  by light source  80 . 
     It is to be understood that by applying pressure to the top and bottom edges on the back of mirror segment  100  against the front jaws of main portion  134  of bracket  122 , that a secure mount of segment  100  to frame  110  is accomplished plus the segment can be easily taken in and out. It also reduces the risk of applying forces or torque on mirror segment  100  which might lead to cracks or breakage or bowing of segment  100 . 
     It is noted in, FIG. 10 that main body  134  of each bracket  122  extends on one side of flange  128  of bracket  122 . In the arrangement shown in FIG. 10, brackets  122  are positioned on one segment  100  to both face one direction regarding main portion  134 , and on the following segment  100  face another direction. This allows the segments  100  be placed closely adjacent to one another and when fine adjustment of the pivoting of each segment is done, brackets  122  will not interfere with one another. 
     FIG. 11A sets forth in detail the attachment of bracket  122  to an ear  118  of frame  110 . Split halves  146  and  148  of ear  118  allow the insertion of flange  128  of bracket  122  between them. When slot  130  (see FIG. 11) of flange  128  aligns with apertures through each of halves  146  and  148  of ear  118 , carriage bolt  126  is inserted through all of those pieces. By referring to FIG. 11A, it can be seen that a bushing  188  (50% compression) is inserted through aligned apertures  178  through halves  146  and  148  of ear  118  and an aperture  181  in flange  128 . Outside washers  186  and  184  one at 1 opposite ends of bushing  188 . Both washers  186  and  184  are number 10 washers. A {fraction (5/16)}″ washer l 90  in between washer  186  and one end of bushing  188 . A Bellville washer  192 A, and a Bellville washer  192 B are positioned as shown between washer  190  and the outer side of portion  146  of ear  118 . 
     Bushing  188  is a precise pivot. Screw  180  and nut  182  are tightened just enough to compress washers  192 A and  192 B. Washers  192 A and  192 B then exert enough pressure to provide enough clamping force of the halves of ear  118  onto flange  128  of bracket  122  to allow easy and precise pivoting of flange  128  in ear  118 , but once any pivoting is done, the bracket  122  stays in that exact location. Therefore, the arrangement of FIG. 11A gives enough tension so that segments can be quickly, smoothly, precisely, and easily adjusted, but stay in place until carriage bolts  126  are tightened. 
     The locking of each bracket  122  to ear  118  by tightening of nut  127  on carriage bolt  126  can be done without affecting the precise alignment of segment  100 . 
     FIG. 12 illustrates in more detail frame  110 , and in particular curved frames  114  and  116 . Each curved frame  114  and  116  actually consists of an outer half  146  and inner half  148  that are held in slightly spaced apart positions by spacers  150  (spot welds on the rear edges of halves  148  and  146  so that halves  148  and  146  at the location of ears  118  can resiliently move towards one another). Flanges  138  of mounting brackets  122  can then be fit between the space of halves  146  and  148  at the location of each ear  118 . 
     FIG. 13 shows in more detail several items associated with fixture  10 . The right side of FIG. 13 shows connection of brackets  122  to ears  118  in more detail. The left side of FIG. 13 shows mounts  123  and mirrors  74 . 
     FIG. 13 also shows how frame  110  is secured by bolts  152  to brackets  154  which are fixed to the inside of housing  12 . Brackets  156  (see also FIG. 10) are fixed to and extend outwardly from the sides of frame  110 . As can be seen in more detail in FIGS. 15 and 16, vertical slots  158  exist in brackets  154 . Thus, as shown in FIG. 16, the entire frame  110  can be tilted by loosening bolts  152  and tilting frame  110  either to the right as shown in FIG. 16 or the left. FIG. 15 shows frame  110  and basically is in centered position. Bolts  152  can be used to tighten frame  110  into a desired position. 
     FIG. 14A provides a preferred cross-sectional shape of reflector  70  and how segments  100  are coordinated with that shape. It is preferred that the shape be parabolic. As shown in FIG. 14A, lines  102  and  104  represent the X and Y axes. Line  102  is the plane that passes through the center of the parabolic curve  106  (taken from a side elevational cross-section) of reflector  70 . Although different parabolic shapes can be used, a preferred shape is defined by the equation X 2 =4fy, where x equals horizontal distance, y equals vertical distance, and f is the focal point. FIG. 14A shows that once curve  106  is selected, individual segments  100  are placed side by side in an orientation to closely conform with curve  106 . In the embodiment shown in FIG. 14A, segments  100  are flat four inch tall mirrored segments. Each one is placed so that it is as close as possible to a fit of the line  106 . 
     In the preferred embodiment segments  100  are made of glass which has a mirrored back surface. These segments are highly specular (such as a mirror) with a minimum of diffusion. Less specular reflecting surfaces can be used. The amount of secularity depends on how much control is needed. In the race track example, high control is needed to get a very defined cutoff over a small distance between the light put on the track and the spectators. A mirrored back surface of a piece of glass is called a second surface mirror because the mirror is at the back side (the second surface) of the glass. Some reflection of light from the front or first surface of the glass takes place (around 4% of incident light). Some reflection also takes place from the second surface of the glass (also around 4% of incident light). Second surface mirrors are used because even though the glass reflects some light, and a small amount of light is lost by absorption, the glass will absorb ultraviolet radiation which could burn human eyes if reflected into them. A minimum amount of light will be lost because the reflections from the first and second surfaces of the glass will go in the same direction as light reflected from the mirrored surfaces. Also, the mirrored surface is fragile. Therefore, by placing it on the back of the glass, segments  100  can be cleaned without scratching or affecting the mirrored surface. It is to be understood, however, that first surface mirrors could be utilized. Reflection or absorption problems caused by the glass are avoided. 
     FIG. 14B is identical to FIG. 14A except it shows an alternative to segments  100  of FIG.  14 A. It may be preferable to more closely follow the curvature of parabola line  106  with the mirrored segments  100 . Therefore, because flat mirrored segments  100  only approximate that curvature, especially where curvature is more significant at the middle of the parabola, segments  100 A could be used which are curved in vertical cross-section to match the curvature at each individual location along line  106 . Therefore, segments  100 A at the outermost ends of parabola  106  would be less curved than those near the center. 
     The specifics of how each segment  100  or  100 A is attached to a brackets  122  are shown in more detail in FIGS. 10-14A and  14 B. 
     FIG. 17 illustrates the mounting of fork  30  to post  42 . A segment of tubing  160  is welded or otherwise secured around an aperture  162  in the bottom of the horizontal cross-member of fork  30 . The top of tubing  160  is closed except for an aperture  164 . The diameter of post  28  is slightly smaller than aperture  162  and the inside diameter of tubing  160 . The fork  130  can then be seated down upon post  42 . Apertures  163  and  164  allows wiring  166  to pass out of fork  30  into post  42  and down into the ground. 
     FIG. 18 shows in detail a pivotal connection  32  between fork  30  and housing  12  of fixture  10 . In this embodiment, bracket  154  which is used to tiltably adjust frame  110  inside housing  12 , is used as a part of pivot connection  32 . Plate  200  of bracket  154  abuts and is parallel to the inside side wall  18  of housing  12 . An inner tube  202  is welded (at  204 ) to plate  200  and extends through an aperture in housing  12  outwardly. A plate  206  and an outer tube  208  and a still further plate  212  surround the outside of inner tube  202 . Plates  206  and  212  are rigidly connected to outer tube  208  by welds  210  and  214  as shown. 
     Bolt and nut combination  216 / 218  securely and rigidly mount plate  206  to housing  12  by passing through apertures in plate  206 , housing  12  and plate  200 . This arrangement provides a strong and rigid connection for pivot  32 . Silicon flat gaskets  219  are placed between plate  206  and housing  12 . 
     Bolts  220  extend through apertures in the vertical arm of fork  30 . A small spacer  224  spaces a washer  226  away from the outer surface of fork  30 . Nut  228  tightens washer  226  against spacer  224 . As can be seen in FIG. 18, plate  212  fits between washers  226  and fork arm  30 . When nuts  228  are loosened, it would allow rotation of plate  212  relative to fork  30 . Inner tube  202  would rotate with housing  12  and plate  212  in an aperture  230  in the side of fork arm  30 . Nuts  228  could be tightened down so that washers  226  clamp plate  212  to fix pivoted orientation of housing  12  to a desired orientation. 
     C. Operation 
     FIG. 20 shows diagrammatically and not to scale, a race track  200 . As with U.S. Pat. Nos. 5,337,221 and 5,343,374, this could be a track of over a mile in length and of substantial width. To assist in understanding how fixtures  10  can be utilized in operation, they are shown spaced apart on the ground around the infield of track  200 . As is discussed in U.S. Pat. Nos. 5,337,221 and 5,343,374, the advantages of such an arrangement include the ability to eliminate tall poles in the infield which blocks the views of spectators in the infield of the track, blocks the views of the spectators outside the track of portions of the track on the far side of the track from them, and which creates “picket fence” problems with cars traveling at high speed not only for spectators but also for television coverage. Additionally, by placing fixtures  10  on the ground the light sources are near where the light needs to be, namely on the track, and the high control of controllability of fixtures  10  of light, allows placement of light on the track and abrupt cutoff so that light does not spill into spectators eyes, even in locations near the outer edge of the track. 
     It is to be understood, however, that fixtures  10  could also be placed on poles, including very tall poles. They could also be placed on elevated structures such as press boxes, beams, super-structure, etc. In many cases, use of fixtures  10  would allow a reduction of the number of fixtures of conventional types heeded. Thus, less energy, less cost, and less maintenance generally follows. 
     FIG. 20 depicts the type of beam pattern that can be generated from fixtures  10 . A very controlled pattern with sharp cutoffs is highly advantageous for the previously described reasons with regard to the race track. 
     Additionally, the preferred embodiment, with light source mount  58 , blocks from direct view the light source  80  to eliminate glare into spectators eyes and to eliminate glare for drivers. 
     Fixtures  10  are placed at spaced apart positions and are adjusted on the trunnion mounts to project the beams for optimum utilization on track  200 . It is to be understood that components such as lock nuts and set screws, or other methods can be used to allow adjustment of fixtures  10  and then lock them in place. 
     In practice, each segment  100  or  100 A is individually adjusted to insure the sharp cutoff line as to the spectators outside the track. It is to be understood that in the arrangement shown for fixture  10 , the bottom of arc tube  82  always defines the top of the beam projected by fixture  10 . Thus, by trial and error by individual adjustment of each segment for each fixture  10 , the cutoff line for each segment can be made to be the top of any retaining wall around the track, for example, to insure the sharp cutoff. Usually, there is not more than 5° or so adjustment for each segment, but this could vary and include larger adjustment angles. 
     The adjustability of each segment also allows for factory aiming of the segments. In other words, for a given lighting application, segments could be pre-aimed off site to produce a beam of certain characteristics so that they could be simply shipped to site and aligned according to the predetermined design. This would eliminate on site manipulation of the mirror segments. 
     Another aspect of the invention is the ability to adjust the secondary reflector inside the fixture. In other words, it can be rotated relative to the housing of the fixture and actually tilted. This would be in addition to rotation and tilting of the fixture housing. An example of when this would be needed would be in the race track setting. If the fixture as a whole is rotated to project most of the beam up the track to avoid it shining into the drivers eyes as they pass, the top precise cutoff of the fixture may not match precisely with the restraining wall on the other side of the track. By enabling the secondary mirror inside the fixture to be tilted relative to the fixture and relative to the ground, the cutoff along the restraining wall could be brought back into a match with the top of the restraining wall. 
     An increase in efficiency over the embodiments of U.S. Pat. Nos. 5,337,221 and 5,343,374 is a result of a number of factors. Efficiency as used above, relates primarily to how well the available light was utilized. For example, by fitting segments  100  or  100 A along the parabola, and designing their size and shape with reference to the size and shape of the light source, light from the light source can be better fit to the target. In other words, if the light from the fixture fits in the target, it is not wasting light outside the target and therefore is more efficient. 
     It is noted that utilization of curved mirror segments  100 A further helps this efficiency because of the ability to provide a very narrow vertical beam from each segment. In the example of a race track, the need for a very precise cutoff at the top of the outer wall, to prevent light from going to the spectators and to fit all light on the long and narrow track running laterally in front of the lights, allows use of the precise narrow 10° beams. Lighting according to the preferred embodiment can realize on the order of a three times more efficiency than the embodiment shown in U.S. Pat. Nos. 5,337,221 and 5,343,374. 
     A Second example of why efficiency is increased is the utilization of primary reflector  94 . Reflector  94  essentially gathers more light. Without it secondary reflector  70  would gather approximately 180° of light from the arc. With reflector  94  on the order of 120° more light from the light source is gathered. Some of that light would otherwise bounce to the sides of the fixture or outside the target area or would be too wide to use for the target area. 
     Another example of an increase in efficiency is utilization of side mirrors  72  and  74  (see FIGS.  2  and  13 ). These can actually be termed as third reflectors because they are gathering light not taken directly from the light source, but light that is reflecting off of the secondary reflector and which otherwise would be unusable or absorbed by the sides of the interior of the fixture, instead directing it back o the target. 
     A still further example of the ability to increase efficiency is to utilize a non-reflective coating on both surfaces of lens  24  on the front of the fixture. This reduces the reflective loss that occurs when light hits the first and second surfaces of glass. 
     Therefore, the total design of the present invention results in substantial increases of efficiency over fixtures disclosed in U.S. Pat. Nos. 5,337,221 and 5,343,374, and even further efficiency over standard lighting fixtures. 
     FIGS. 2 and 13 illustrate additional efficiency can be made possible by utilizing side mirrors  72  and  74  (normally they are both on interior sides of fixture  10 ). FIG. 13 shows that mirrors  72  and  74  can be hingeably adjusted (see rod  73 ) that extends between upper and lower brackets  125  and  123  on each side of frame  110 ) to take light and put it back to the target. It is to be understood that segments  72  and  74  can be used to narrow the width of the beam from fixture  10  if desired. It is to be understood that the efficiency of these fixtures is accomplished by fitting the beam to the shape of the target. There is not additional light created to any great degree. For example, in comparison with the fixtures in U.S. Pat. Nos. 5,337,221 and 5,343,375, in certain situations light from the light source of primary reflector falls outside the secondary reflector and therefore would be lost because it would not be transmitted back to the target. 
     The “efficiency” discussed with regard to these fixtures in certain situations would allow the substantial spacing between the fixtures. For example, compared to the lighting system in U.S. Pat. Nos. 5,337,221 and 5,343,374, fixtures  10  could be spaced at farther apart distances along a race track. One reason you would want to space the fixture further apart is to avoid having too much light built up on the track. The spacing between fixtures is driven primarily by how much light is produced for a certain wattage of lamps. To help understand this concept, fixtures  10  could be spaced closer together and smaller wattage light sources could be utilized. 
     It is to be understood that it is sometimes desirable to block off some of the light to eliminate glare. For example, light source mount  58  can have its exterior painted flat black. Mount  58  not only blocks light directly from arc tube  82  out of the fixture, but by painting it flat black it can absorb light that might otherwise cause glare or other problems. 
     D. Options, Features, and Alternatives 
     The included preferred embodiment is given by way of example only and not by way of limitations to the invention, which is solely described by the claims. Variations obvious to one skilled in the art will be included within the invention defined by the claims. It will be appreciated that the present invention can take many forms and embodiments. Some alternatives have been mentioned previously. Additional examples are as follows. 
     It is possible to use first surface or second surface reflectors or mirrors with regard to reflector  94 . A first surface mirror would be used in many instances because it would help better cutoff of the light. Small distances at or near the arc of the arc tube can translate into big differences out at the track. 
     The lens  24  at the front of fixture  10  can be glass. One option is to use an anti-reflection coating on both surfaces of front glass panel  24  to reduce the reflection of each surface of the glass lens and to reduce glare caused by such reflection. The utilization of segments  100  or  100 A can in some situations, if used alone, cause striation problems. For example, in the U.S. Pat. Nos. 5,337,221 and 5,343,374, the segmented type mirrors, each individually aimable, may have areas of decreased intensity followed by increased intensity, etc. The fixture of fixture  10  of the present invention deals with this problem by utilizing reflector  94  close to arc tube  82 . It redirects light back through the arc stream and cooperates with the light directly leaving the arc tube and traveling to reflector  70  to smoothly fill in between beams from segments  100  and  100 A. 
     It is also to be understood that since individual segments  100  and  100 A are used, they be switched or they could be adjusted to customize the beam. An example is as follows. By tilting the mirror segments around their horizontal axis the beam can be stretched vertically. But there is a limit, however, as to how far this could be stretched. If mirror segments (either flat segments  100  as shown in FIG. 14A or curved segments  100 A as shown in FIG. 14B) are tilted to widen the beam too far, it might create a non-smooth beam pattern at the target area with striations (areas of more light intensity and areas of less light intensity in an alternating fashion). In the case of the curved mirror segments  100 A of FIG. 14B, it is to be understood that the parabola of line  106  curves more substantially near the vertex of the parabola. Therefore, segments  100 A near the vertex have a larger curvature than those at the outer ends of mirror  70  to enable the inner segments  100 A to closely follow the curvature of line  106 . It has been discovered that beam width could be widened simply by switching the higher curvature inner segments  100 A with lower curvature outer segments  100 A. Thus, the structure described above regarding the mounting of segments  100 A allows relatively easy removal and switching of segments to accomplish this function. 
     It is also to be understood that each of the mirror segments can be pre-aimed. This means that it is possible to overlay the reflection from one segment onto the reflection of another to double the intensity out at the track for that area of the beam. It is also to be understood that the use of a trunnion or similar mounting system allows for precise aiming of the beam for different part of the track and of the adjustment of the beam. The individual adjustability of the mirror segments allows the matching of cutoff points for each reflected image, as previously explained. 
     The precise way in which segments  100  or  100 A are mounted to the reflector frame can also vary. In the present embodiment, a special mounting system is used to assist in aiming of the individual segments. 
     It is also to be understood that ballasts for the arc tubes can be placed inside of housing  12  or outside of the box to eliminate thermal problems. 
     It is to be understood that the preferred embodiment utilizes rectangular shaped mirror segments on the secondary reflector, and a somewhat elongated or linear light source that is elongated in the direction of the elongation of the mirror segments. This arrangement fits the light to the target area in the context of a race track because the race track and retaining wall which need to be lighted are elongated horizontally but require a very narrow vertical beam spread to place light on the relatively narrow horizontal strip and retaining wall defined by the track without placing light above the retaining wall into the spectators, or placing a lot of light on the infield side of the track. The preferred embodiment would therefore be applicable to such things as square rectangular target areas like basketball courts, hockey playing areas, football fields, rectangular stages, and the like. 
     To assist in understanding how precise cutoff at the top of the beam can be achieved, reference be taken to FIG.  20 . This view is diagrammatic, not to scale, and for illustration purposes only. It depicts a light source  82  and primary reflector  94  and several representative mirror segments  100  for a secondary reflector  70 . A race track  200  with retaining wall  223  and race cars  221  are depicted. 
     Numeral  226  represents generally the bottom of arc tube  94  and numeral  228  represents the top. Letters A, C, E, G, I, K, M, and  0  represent the top edge of each segment  100  whereas B, D, F, H, J, L, N, and P represent the bottom edges. 
     The basic law of angle of incidence equals angle of reflection means that the lowest point on arc tube  82  which projects light to the top edge of any segment  100  will define the top vertical portion of the reflected beam from that particular mirror segment  100 . Therefore, the present invention allows placement of segments  100  relative to light source  82  in such a fashion that they can be precisely adjusted so that the angles of reflection can be matched relative the top edges of segments  100  so they all basically converge at the top of retaining wall  223 . Therefore, none of the light from any of the segments  100  goes above the top of the wall, producing a very sharp cutoff. The remainder of the light goes across the track (see generally reference numeral  225  which corresponds generally with the beam in this elevational view). It is to be understood that because the segments closest to light source create wider vertical beams than those segments farther away. The closest segments are designed to have vertical beam spreads that cover most of or all the track. As illustrated in FIG. 20, the segments farther from the light source towards the ends of reflector  70  have narrower beam spreads. 
     Therefore, because each segment  100  is adjusted to have the top of its beam converge to the top of the wall. There is a cumulative overlaying of portions of beams from segments towards the farthest side of track  200 . This helps to have a uniform smooth lighting throughout track  200  because more intensity is sent a farther distance away from the fixture whereas less intensity is sent a shorter distance away. Basic laws of lighting thus are used to create uniformity, and this is possible by the individual segments. 
     FIG. 20 also illustrates that the use of primary reflector  94  gathers more light from light source to be then controlled by segments  100  to put more light in track  200 .