Patent Publication Number: US-2004047154-A1

Title: Tracklight system

Description:
BACKGROUND  
       [0001] 1. Field Of The Invention  
       [0002] This invention is a continuation-in-part of application Ser. No. 09/639,401. The present invention relates to the field of tracklight systems having elongated tracks provided with light sources that are positionable along the length of the track. Where long lengths of track are needed, several sections of track may be joined together. The primary advantage of tracklight systems over fixed-location lighting fixtures is the flexibility that permits light sources to be moved along the track to where illumination is needed, particularly when displays are changed. In many retail and museum display lighting systems, tracks are parallel to and spaced a distance from the walls, serving as wallwasher luminaires to illuminate both graphics and objects on the walls, on wallmounted shelves, or on counters along the walls.  
       [0003] 2. Description Of Prior Art  
       [0004] Most tracklight systems available today are ceiling mounted, generally U-shaped tracks, supporting and energizing incandescent or compact fluorescent downlights with reflectors that aim the light towards areas or objects to be illuminated. The result is usually an irregular light patterns on artifacts, forming irregular scalloping on a nearby wall. In order to avoid the scalloping, it is typical to install a number of closely-spaced light fixtures, as shown in the applicant&#39;s U.S. Pat. No. 4,822,292 Multiple line Circuit Track Lighting Systerm The result is a cluttered appearance from the depending track luminaires, along with a substantial amount of heat from the illumination. This type of tracklight system is also virtually incapable of producing smooth, uniform light distribution, but instead produces spaced pools of light on a floor, or scallops of light in a wall.  
       [0005] The visual clutter of depending luminaires has been eliminated with low-profile tracklight systems illustrated by the applicant&#39;s U.S. Pat. No. 6,439,749 Internal Fixture Track Lighting System and U.S. Pat. No. 6,409,524 Side-Mounted Tracklight System in which the luminaires may be operated within the track. It was also found that the heat from the illumination can be eliminated by employing fiber optic luminaires, as shown in the applicant&#39;s U.S. Pat. No. 5,325,272 Fiber Optic Track Lighting System and D.405,898 Intemally-Illuminated Lighting Track, in which discrete, aimable fiber-optic luminaires are spaced apart and hidden inside the track to emit light wherever it is needed. These fiber optic tracklight systems can provide  32  individual luminaires with the light projector feeding the  32  fibers being remotely located in an accessible service area that facilitates relamping and maintenance of the projectors.  
       [0006] Although the above-described tracklight systems all represent dramatic improvements in the state of the art, there is still a continuing need for an even lower profile, low-cost tracklight system, without a clutter of depending luminaires, with easily-accessed remote relamping, and in which a uniform light pattern can be produced without the need for any track luminaires.  
       PURPOSES OF THE INVENTION  
       [0007] The primary purpose of the present invention is to provide a low-proffle tracklight system, without the clutter of depending luminaires, that provides a smooth light distribution without scallops or discontinuities. It is a further purpose of the invention to provide a low cost tracklight system with the ability to position and relocate the light sources as needed.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0008] The foregoing purposes of the present invention are achieved by a tracklight system including an elongated, tubular track of constant cross-sectional shape. The track has a proximal end and a distal end, a light reflector and a light diffuser extend along the length of the track and form a tube. An elongated lens extends through the length of the tube and divides the reflector from the diffuser.  
       [0009] An elongated source of illumination is disposed between the reflector and the lens, emitting light generally perpendicular to the length of the tube. The light source may be an array of incandescent or fluorescent lamps or light-emitting diodes. The light source may also be one or more side-emitting optical fibers or an array of end-emitting optical fibers receiving light from an external source of illumination and emitting light through spaced ends at selected locations along the track. The selected light source may be inserted through the proximal end of the tube, the distal end, from both ends and extending towards the middle, or from the middle and extending towards both ends.  
       [0010] Embodiments of the tubular cross section may be nearly any geometric shape with a relatively low profile that visually blends in with architectural elements such as cornices, reveals, decorative moldings or inverted T-Bar ceiling runners. A first preferred embodiment described in detail herein is a 1-inch square cross section that has proven in practice to be well suited for low-proffle tracklight applications. A second preferred embodiment is a rectangular cross-sectional shape that may be mounted in either vertical or horizontal orientations. A third preferred embodiment is a generally circular cross section. The preferred embodiments may be mounted under shelves, inside display cases, or to suspended-ceiling T-bars without interfering with depending tegular ceiling panels. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a perspective view of a preferred embodiment of the tracklight according to the invention, having a square cross sectional shape;  
     [0012]FIG. 2 is an enlarged transverse cross-sectional view of the preferred embodiment of FIG. 1, showing light ray paths for asymmetric light distribution with a prismatic lens biasing light away from the center of an optical plane including a symmetric Cl (centerline).  
     [0013]FIG. 3 is a longitudinal cross-sectional view of the preferred embodiment of FIG. 1, showing 90° end-emitting optical fibers as light sources.  
     [0014]FIG. 4 is a longitudinal cross-sectional view of the preferred embodiment of FIG. 1, showing conical-end or side-emitting optical fibers or elongated lamps or arrays of lamps such as incandescent or fluorescent sources.  
     [0015]FIG. 5 is a transverse cross-sectional view of the preferred embodiment of FIG. 1, having a symmetric light distribution about the plane of a symmetric Cl (centerline).  
     [0016]FIG. 6 is a longitudinal cross-sectional view of the tracklight system of FIG. 1, having an downward-biased asymmetric light distribution from the plane of the symmetric Cl.  
     [0017]FIG. 7 is a longitudinal cross-sectional view of the tracklight system of FIG. 1, having an upward-biased asymmetric light distribution from the plane of the symmetric Cl.  
     [0018]FIG. 8 is a transverse cross-sectional view of a second, generally circular embodiment of the invention, having a circular cross-section and a symmetrical light distribution about the plane of the symmetric Cl.  
     [0019]FIG. 9 is a transverse cross-sectional view of the second preferred embodiment of the invention, having an asymmetric light distribution from the center of the plane of the symmetric Cl.  
     [0020]FIG. 10 is a transverse cross-sectional view of a third, preferred, rectangular embodiment of the invention having an asymmetric light distribution.  
     [0021]FIG. 11 is a view of the circular tracklight of FIG. 9, shown attached to a suspended ceiling inverted T-bar.  
     [0022]FIG. 12 is a view of the rectangular tracklight of FIG. 10, shown attached to a suspended ceiling T-bar.  
     [0023]FIG. 13 is optional longitudinal photometric distributions of a tracklight according to the invention.  
    
    
     REFERENCE NUMERALS IN THE DRAWINGS  
     [0024] 1  first preferred embodiment (square cross section)  
     [0025] 2  elongated tube  
     [0026] 3   p  proximal end  
     [0027] 3   d  distal end  
     [0028] 4  reflector  
     [0029] 4   a  first reflector angular portion  
     [0030] 4   b  second reflector angular portion  
     [0031] 4   c  edge of reflector  
     [0032] 5  diffuser  
     [0033] 5   a  first diffuser portion  
     [0034] 5   b  second diffuser portion  
     [0035] 5   c  corner of diffuser  
     [0036] 6  apex of symmetric plane  
     [0037] 7  lens  
     [0038] 7   a  lens prisms  
     [0039] 8  source of illumination  
     [0040] 8   a  side-emitting light source  
     [0041] 8   b  diagonal end-emitting fiber optic  
     [0042] 8   c  conical end fiber optic  
     [0043] 10  light-diffusing pattern  
     [0044] 11  second preferred embodiment (circular cross section)  
     [0045] 12  direct light rays  
     [0046] 12   b  biased light rays  
     [0047] 12   d  diffuse light rays  
     [0048] 12   r  reflected light rays  
     [0049] 14  arcuate reflector  
     [0050] 15  arcuate diffuser  
     [0051] 16  apex of arcuate reflector  
     [0052] 17  lens (circular embodiment)  
     [0053] 17   a  linear prisms (circular embodiment)  
     [0054] 19  T-bar attachment bracket (circular embodiment)  
     [0055] 19   a  inward flanges of bracket  19   
     [0056] 20  inverted T-bar ceiling runner  
     [0057] 21  third preferred embodiment (rectangular cross section)  
     [0058] 22  elongated tube (rectangular cross section)  
     [0059] 24  reflector (rectangular cross section)  
     [0060] 25  diffuser (rectangular cross section)  
     [0061] 27  lens (rectangular cross section)  
     [0062] 27   a  linear prisms (rectangular cross section)  
     [0063] 29  T-bar attachment means (rectangular embodiment)  
     [0064] 29   a  inward flanges of bracket  29   
     [0065] 32  elongated tube (rectangular cross section)  
     [0066] 41  photometry (uniform illumination)  
     [0067] 42  photometry (higher intensity in the center)  
     [0068] 43  photometry (higher intensity at the ends)  
     [0069] 44  photometry (higher intensity at one end)  
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0070] In FIG. 1 a first preferred embodiment of a tracklight system  1  according to the invention is shown having an elongated tube  2  with a proximal end  3  and a distal end  4 , mounted on a ceiling plane A-A. The overall dimensions can vary widely, but experience has shown the length “L” of 4 to 8 feet is convenient as a module that can be installed in end-to-end arrangements. The height “H” and width “W” can be of nearly any size, but they work well as 1-inch dimensions that are easy to hide in a reveal or behind a small molding. A 1-inch width also matches the width of the horizontal flange of an inverted T-bar ceiling runner. These convenient small dimensions will readily accommodate a variety of light sources  8 . Tube  2  is comprised of a light-reflector  4  comprised first angular portion  4   a  and second angular portion  4   b  that are joined at an apex  6  and extend to edges  4   c ; and a diffuser  5 , comprised of first portions  5   a  and second portion  5   b , extending along its length. Diffuser  5  has edges  5   c  engaged with edges  4   c  of reflector  4 . A lens  7  extends between diffuser edges  4   c , separating reflector  4  from diffuser  5  and providing a space for an elongated source of illumination  8 .  
     [0071] Illumination source  8  extends from proximal end  3  substantially along the length of the tube, between reflector  4  and lens  7 . Illumination source  8  can be one or more optical fibers. Alternatively small diameter T- 2  or T- 4  fluorescent lamps or a row of small incandescent lamps or Light-Emitting Diodes may be used (such conventional sources are not shown in detail) and energized from a remote power source (also not shown).  
     [0072] In FIG. 2 the first preferred embodiment of tracklightl of FIG. 1 is shown in cross section, with tube  2  having reflector  4 , diffuser  5 , with lens  7  dividing reflector  4  from diffuser  5 . Lens  7  is shown as a linear Fresnel lens with wedge-shaped prisms  7   a  biasing transverse light with respect to the 45° plane of a symmetric Cl. Diffuser  5  and lens  7  are shown as a single clear plastic extrusion, but could as well be separate parts in a glued or snap-together assembly. The source of illumination  8  emits direct light rays  12  through lens  7 , exiting as biased light  12   b , which then passes through diffuser  5 , including light diffusing pattern  10 , as biased, diffused light rays  12   d . Lens  7  may also be textured to further diffuse the emitted light.  
     [0073] In FIG. 3 the preferred embodiment of FIG. 1 is shown in a longitudinal cross section in which light source  8   b  is one or more end-emitting optical fibers having ends cut at an angle to emit light perpendicular to the fiber. In practice, it does not matter which way the angle faces, as by definition the light must either reflect from reflector  4  as reflected rays  12   r  or refract through lens  7  as biased rays  12   b  and then pass through diffuser  5  as diffused rays  12   d.    
     [0074] In FIG. 4 the preferred embodiment of FIG. 1 is shown in a longitudinal cross section in which light source  8  may be one or more conical end-emitting optical fibers  8   c . Light source  8   a  may be any side-emitting source, such as side-emitting optical fiber or side-emitting fluorescent, incandescent or LED lamps arrays.  
     [0075] In FIG. 5 a preferred embodiment of FIG. 1 is shown having a Fresnel lens biasing light rays parallel to and towards the 45° plane of symmetric Cl to produce a narrow unbiased and at least partially collimated beam distribution.  
     [0076] In FIG. 6 a preferred embodiment of FIG. 1 is shown with the lens and diffuser engaged into reflector edges  4   c , whereby the linear prisms  7   a  of lens  7  bias light downward from the 45° plane of the symmetric Cl.  
     [0077] In FIG. 7 a preferred embodiment of FIG. 1 is shown with the lens and diffuser reversed from the position shown in FIG. 6, whereby the linear prisms  7   a  of lens  7  lens bias light upward from the 45° plane of the symmetric Cl.  
     [0078] In FIG. 8 a second preferred embodiment  11  of the invention is shown having a generally circular cross section tube  22 , with an arcuate reflector  14  having portions  14   a  and  14   b  disposed about an apex  16  proximate to light source  8 . Lens  17  is provided with linear prisms  17   a  biasing light generally parallel to and collimated towards the plane of the symmetric Cl.  
     [0079] In FIG. 9 the second preferred embodiment  11  of the invention having a generally circular cross section including reflector  14  and diffuser  15  separated by lens  17 . Linear prisms  17   a  of lens  17  bias light downward, away from the plane of the symmetric Cl.  
     [0080] In FIG. 10 a third preferred embodiment  21  of the invention is shown having a rectangular cross section tube  32  including reflector  24  and diffuser  25  separated by lens  27 . Linear prisms  27   a  of lens  27  bias light downward, away from the plane of the symmetric Cl.  
     [0081] In FIG. 11 the second preferred embodiment  11  of the invention having a circular cross section is shown having T-bar attachment means  19  supporting the track from an inverted T-bar ceiling runner  20 . The attachment means is a generally U-shaped bracket conforming to the shape of the track and having inward-facing flanges  19   a  that may be snapped onto an inverted T-bar.  
     [0082] In FIG. 12 the third preferred embodiment  21  of the invention having a rectangular cross section is shown having an attachment means  29  supporting the track from an inverted T-bar ceiling runner  20 . The attachment means is a also generally U-shaped bracket conforming to the shape of the track and having inward-facing flanges  29   a  that may be snapped onto an inverted T-bar.  
     [0083] In FIG. 13 the photometry for a tracklight according to the present invention shows relative longitudinal intensity for placement of light sources along the length of the track. By installing the light sources uniformly spaced along the track, uniform illumination  41  along the track can be achieved. By concentrating more light sources near the center of the track length, the track will be longitudinally biased to produce higher intensity in the center, with dimmer ends  42 . By concentrating more light sources near the ends of the track, more illumination will be longitudinally biased towards the ends, with the center being dimmer  43 . And by concentrating more light sources at one end of the track, the illumination will be biased to be brightest at that end, diminishing to the opposite end  44  in proportion to the light source density.  
     SUMMARY, RAMIFICATIONS AND SCOPE  
     [0084] The primary purpose of the present invention is achieved and in practice provides an elongated tracklight system having smooth, uniform horizontal light distribution, and a smoothly graduated vertical light distribution without scallops or discontinuities in the light pattern. The preferred embodiment of the tracklight system of the invention has a very small cross-section of no more than 1-inch that is easily hidden in a narrow recess or surface-mounted behind a small decorative molding. It also can be attached to the 1-inch-wide flange of a standard suspended ceiling T-bar runner. Although the small size of an inch or less in cross section is an important advantage in many applications, the principles herein can easily be enlarged to use large diameter optical fibers or one or more standard (T-2, T-5 or T-8) fluorescent lamps, having diameters of {fraction (1/4 )}-inch, {fraction (1/2 )}-inch or 1 inch, respectively, within a 2-inch or even larger track cross section dimensions.