Patent Publication Number: US-7588345-B1

Title: Lighting system

Description:
RELATED APPLICATIONS 
   The present application claims priority to U.S. Provisional Application Ser. No. 60/641,703 filed on Jan. 6, 2005. 

   TECHNICAL FIELD 
   The present invention relates in general to an improved lighting system, particularly one that is characterized by high-efficiency lumenaire performance with minimized glare and brightness. The present invention also pertains to an improved lighting fixture that employs a novel lamp diffuser and reflector arrangement. 
   BACKGROUND OF THE INVENTION 
   There is a need in the field to provide lighting fixtures or systems that have enhanced efficiency and that yet are characterized by a minimized glare and brightness. In the past various techniques have been devised to improve the efficiency and glare characteristics of lumenaires. For example, a recent lighting fixture is disclosed in U.S. Pat. No. 5,967,648 in which, in the background discussion, various past techniques are described to enhance the efficiency and uniformity of the output light. The lumenaire disclosed in this patent describes the use of a sheet of polymeric light control film which is comprised of a thin sheet of clear polymeric material with an embedded layer of metallic foil that is perforated to allow a measured amount of light to pass therethrough. Even with this improvement existing lighting apparatus still has certain drawbacks associated therewith including, inter alia, excessive glare, excessive brightness, direct viewing of the lamp from certain angles, non-uniformity of the light pattern and degraded efficiency. 
   Accordingly, it an object of the present invention to provide an improved lumenaire that overcomes the limitations of known arrangements. 
   Another object of the present invention is to provide a lumenaire that is characterized by minimizing glare and brightness from the fixture, all while enhancing the efficiency of the lumenaire. 
   SUMMARY OF THE INVENTION 
   The foregoing and other objects of the invention are achieved by providing a lumenaire that is comprised of a lighting fixture; a lamp supported in the lighting fixture; and a diffuser disposed spaced from and at least partially about the lamp. The diffuser includes a middle portion under the lamp comprised of a material with a predetermined pattern for both reflecting and transmitting incident light from the lamp and end portions contiguous with the middle portion disposed toward the sides of the lamp and comprised of a material for refracting incident light from the lamp. 
   In accordance with other aspects of the present invention the middle portion may be arc-shaped and includes a translucent plastic base, for supporting inside thereof, a partially reflective liner that carries the predetermined pattern; the liner may include in the pattern, areas that are translucent to permit light to be transmitted and areas that are metallic to permit light to be reflected to a reflector disposed over the lamp; the end portions may be formed by respective extensions of the translucent plastic base, said extensions terminating at a position above a horizontal centerline of the lamp so as to obscure the image of the lamp from all viewing angles therebelow; a reflector is supported in the lighting fixture over the lamp with the lamp disposed asymmetrically relative to the reflector closer to one side of the fixture than another side of the fixture and with the end portions positioned to enable incident light from the lamp to be reflected from the reflector; the reflector may comprise a straight walled section adjacent the one side of the fixture and an arcuate shaped section adjacent the another side of the fixture; the end portions may have a ribbed construction and the liner terminates short of the extensions and liner retention tab may be included between the middle portion and each end portion for holding the liner in place. 
   In accordance with another version of the invention the lumenaire comprises a lighting fixture; a lamp supported in the lighting fixture; a diffuser disposed spaced from and at least partially below and about the lamp; and a reflector supported in the lighting fixture over the lamp with the lamp disposed asymmetrically relative to the reflector closer to one side of the fixture than another side of the fixture and the reflector includes a straight walled section adjacent the one side of the fixture and an arcuate shaped section adjacent the another side of the fixture. 
   In accordance with still other aspects of the invention the diffuser may include a middle portion under the lamp comprised of a material with a predetermined pattern for both reflecting and transmitting incident light from the lamp and end portions contiguous with the middle portion disposed toward the sides of the lamp and comprised of a material for refracting incident light from the lamp; the end portions may be positioned to enable incident light from the lamp to be reflected from the reflector; the reflector arcuate shaped section may include contiguous first and second arcuate shaped sections intercoupled by a step section; the first arcuate shaped section may step up from the second arcuate shaped section and the first arcuate shaped section may be more remote from the one side of the fixture than the second arcuate shaped section; the middle portion may be arc-shaped and includes a translucent plastic base, for supporting inside thereof, a partially reflective liner that carries the predetermined pattern and wherein the liner includes in the pattern, areas that are translucent to permit light to be transmitted and areas that are metallic to permit light to be reflected to the reflector disposed over the lamp. 
   In accordance with a further embodiment of the present invention there is provided a lumenaire system that is comprised of a plurality of separate lighting fixtures, each lighting fixture for support from a ceiling or the like and collectively directed to illuminate a predetermined area therebelow, each lighting fixture including at least a lamp, a reflector disposed over the lamp and a diffuser disposed under the lamp, said plurality of fixtures including at least one symmetric fixture in which the lamp is arranged symmetrically centered relative to the reflector and at least one asymmetric fixture in which the lamp is arranged asymmetrically relative to the reflector closer to one side of the fixture than another side of the fixture. 
   In accordance with other aspects of the present invention at least a pair of symmetric fixtures and at least a pair of asymmetric fixtures may be arranged in an array with the asymmetric fixtures disposed outside of the symmetric fixtures in the array; the asymmetric fixtures may be arranged so that the one side of the asymmetric fixture is disposed on the outside of the array; switch means is provided for controlling the operation of the fixtures and the switch means has at least two modes including a first mode in which only the pair of asymmetric fixtures are energized and a second mode in which both pairs of fixtures are energized. 
   In accordance with still another embodiment of the invention the lighting apparatus is adapted for support from a ceiling or the like and comprises: a lighting housing; a lamp supported in the lighting housing; a diffuser disposed spaced from and at least partially about the lamp and including an arc-shaped portion disposed under the lamp for both reflecting and transmitting incident light from the lamp and end ribbed portions contiguous with the arc-shaped portion disposed over the horizontal centerline of the lamp for refracting incident light from the lamp and a reflector supported in the lighting housing over the lamp. The lamp may be disposed asymmetrically relative to the reflector closer to one side of the lighting housing than another side of the lighting housing. The reflector may include a straight walled section adjacent the one side of the lighting housing and an arcuate shaped section adjacent the another side of the lighting housing. 

   
     DESCRIPTION OF THE DRAWINGS 
     Numerous other objects, features and advantages of the present invention should now become apparent upon a reading of the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a perspective view at the end of a lighting fixture constructed in accordance with the present invention with the diffuser clipped in place; 
       FIG. 2  is a perspective view at the end of the fixture similar to that illustrated in  FIG. 1  but with the diffuser exploded away from the lamp; 
       FIG. 3  is a partial perspective view of the diffuser alone and partially exploded to show further details; 
       FIG. 4  is a cross-sectional view through the diffuser such as along line  4 - 4  in  FIG. 3  and showing the placement of the diffuser relative to the lamp; 
       FIG. 5  is a cross-sectional view illustrating one embodiment of the present invention, an asymmetric distribution fixture; 
       FIG. 6  is a cross-sectional view illustrating a second embodiment of the present invention, a symmetric distribution figure with multiple lamps; 
       FIG. 7  is a schematic diagram of the first embodiment with an asymmetric distribution fixture and illustrating the light rays; 
       FIG. 8  is a schematic diagram of the second embodiment with a symmetric distribution fixture and illustrating the light rays; 
       FIG. 9  is a schematic diagram illustrating multiple asymmetric fixtures and the lighting pattern to a subject; 
       FIG. 10  is a schematic diagram illustrating a plurality of symmetric distribution fixtures relative to a subject; 
       FIG. 11  is a schematic diagram illustrating a switching arrangement that may be used with a particular lighting array in accordance with the present invention; and 
       FIG. 12  is a view similar to that shown in  FIG. 4  but for an arrangement in which a pair of lamps are associated with a single diffuser. 
   

   DETAILED DESCRIPTION 
   Reference is now made to both symmetric and asymmetric embodiments of the present invention as illustrated in  FIGS. 1-8 .  FIGS. 9-11  illustrate particular arrays of lumenaires that may be arranged in accordance with the present invention.  FIG. 12  describes an alternate embodiment using a pair of lamps with a single diffuser. This lamp apparatus in the main embodiment employs an extruded polymeric lamp diffuser with a polymeric light control film liner for use in lighting fixtures. The unique characteristics of the lumenaire of the present invention allow for high-efficiency lumenaire performance with minimized glare and brightness from all viewing angles. This makes the apparatus particularly appropriate for use as, for example, a patient exam light. This would thus find use in hospitals, dental offices, physician offices, etc. However, the lumenaire of the present invention also is suitable to applications such as video-teleconferencing and other general lighting applications where a direct view of the lighting fixture from abnormal viewing angles (typically looking straight up at, or otherwise into the fixture) is likely. 
   Reference is now made to the asymmetric distribution fixture illustrated in  FIGS. 1-5 . The lumenaire is embodied as a fixture that is comprised of a housing  10 . The housing may be considered as of conventional design and is typically constructed of fabricated steel, extruded aluminum or other suitable materials or a combination of materials. The housing  10  may be either surface mounted or recessed into a ceiling, wall or other surface support surface. Refer to  FIG. 5  for a typical arrangement in which the fixture is recessed into the ceiling structure  12 . 
   A reflector  15  is shown supported in the housing  10  and is adapted to direct illumination to specific controlled angles while cutting off illumination to other angles. Although various configurations of reflectors can be used with one aspect of the present invention, the asymmetric reflector  15 , such as shown in  FIG. 5 , has been particularly advantageous in accomplishing the desired lighting patterns. The specific construction of reflector  15  is discussed below. A fluorescent lamp  16  is positioned below the reflector  15 . The lamp  16  may be considered as of conventional type and can be provided in different diameters. A conventional ballast  17  may be supported in the housing  10  as schematically illustrated in  FIG. 5 . 
     FIGS. 1-5  also illustrate the polymeric lamp diffuser  20  that supports the polymeric light control film liner  24 . The diffuser is positioned so as to essentially envelop the lamp  16  and obscure it from all practical viewing angles.  FIG. 5  shows the viewing or sight angles at  23 . It is noted that these angle lines indicate that the diffuser preferably blocks any viewing from below. Neither of the lines  23  intersect any part of the lamp  16 . It is primarily the top ends of the diffuser that block the lamp. 
   In accordance with the invention there is provided a lumenaire including a lamp  16  supported in a lighting fixture and a diffuser  20  disposed spaced from and at least partially about the lamp  16 . The diffuser  20  may be considered as including a middle or lower portion  20 A under the lamp comprised of a material with a predetermined pattern for both reflecting and transmitting incident light from the lamp and end or upper portions  20 B contiguous with the middle portion disposed toward the sides of the lamp and comprised of a material for refracting incident light from the lamp  16 . 
   The diffuser  20  may be considered as provided in three sections, the lower portion  20 A, upper portion  20 B and an intermediate retaining portion  20 C. The entire diffuser can be constructed of the same material or each section can be constructed of a different material to provide particular characteristics. The diffuser is preferably constructed by an extrusion process. In the preferred embodiment the entire diffuser is constructed of a clear polymeric plastic material. The lower portion  20 A of the diffuser is preferably smooth and semi-cylindrical in shape as shown in  FIG. 4 . The upper portion  20 B of the diffuser on both sides has a series of fine v-shaped ribs  22  constructed and arranged to obscure the image of the lamp  16  from all viewing angles  23  while allowing a significant portion of the lamp&#39;s output to pass through the diffuser upper portion  20 B. As is noted from  FIG. 4 , the horizontal centerline  25  of the lamp  16  passes about through the area where the portions  20 A and  20 B interconnect. Also at that area is the intermediate portion  20 C in the form of elongated retention tabs or ridges  27  that are adapted to hold the liner  24  in place. These tabs  27  extend the length of the diffuser. 
   The interior surface of the lower portion  20 A of the diffuser  20  contains an inserted sheet of polymeric light control film  24  which is comprised of a thin sheet of clear polymeric material with an embedded layer of metallic foil that is perforated to allow a measured amount of light to pass through. The perforations are preferably in a predetermined pattern such as a series of holes disposed in a symmetric array. The holes are shown at  29  in  FIG. 4 . The foil as used in this application may be white, colored or otherwise decorated on the outer surface (away from the lamp) as a decorative feature. In order to maximize fixture efficiency, the inner surface of the foil has a highly reflective metallic surface to direct the portion of light from the lamp that does not pass through the perforated holes back towards the reflector  15 . The liner material  24  may be slid or snapped into position, thus allowing field replacement and/or the substitution of liners with varying perforation patterns. The tabs  27  hold the liner  24  in place. Refer to U.S. Pat. No. 5,967,648 for a description of various forms of polymeric materials used in lumenaires. U.S. Pat. No. 5,967,648 is hereby incorporated by reference in its entirety. 
   Thus, the diffuser in accordance with a preferred embodiment described herein includes a lower portion  20 A that is a clear smooth arc-shaped portion of the diffuser. This portion  20 A receives and is instrumental in shaping the liner  24 . The portion  20 A controls the output generated from the lower portion of the lamp  16 . The upper portion  20 B of the diffuser  20  is a clear ribbed structure that extends the length of the diffuser and is positioned symmetrically about the center line  25  of the tube  16 . These ribbed portions, as shown in  FIG. 4  are angled toward each other to obscure the view of the bare lamp  16  from normal viewing angles while directing and refracting the output from the upper half of the lamp toward the reflector  15 . The liner retention tabs  27  hold the liner  24  snugly in position while allowing interchangeability or replacement. Liner  24  is slid or snapped into position and is removable and replaceable. 
   In  FIGS. 1-3  there are illustrated further details of the support for the diffuser in the fixture. For this purpose there are provided a pair of end caps  21 , one at each end of the diffuser  20 . These end caps  19  also help to retain the liner  24  in place. A pair of clips  19  is supported adjacent to the conventional end supports for the lamp  16  as shown in  FIG. 2 . The end caps  21  are adapted to releasably engage with the clips  19  in order to support the entire diffuser  20  in the fixture, as shown in  FIG. 1 . 
   Reference is now made to  FIG. 5  for an illustration of an asymmetric distribution fixture in which the lamp  16  is disposed off-center of the housing (to the right of center) and the reflector is likewise non-symmetric. The reflector preferably is constructed in three sections including a first arcuate portion  15 A, a second arcuate portion  15 B and a straight end portion  15 C. The step  15 D interconnects the portions  15 A and  15 B. The arcuate portion  15 A preferably has a smaller radius of curvature than the arcuate portion  15 B. The reflector portion  15 C is preferably adjacent to the side of the housing that the lamp is closer to. Refer to  FIG. 7  for further descriptions of the reflector surfaces as relates to the light patterns from the lamp. 
   Reference is now made to  FIG. 6  for an illustration of a symmetric distribution fixture in which the lamp  16  is disposed centered in the housing in a symmetric distribution fixture. In this embodiment the lamp and diffuser may be identical to that previously described. The reflector  30  may be one continuous arcuate or parabolic surface or can be made from a pair of surfaces. The lamp  16  is disposed symmetric relative to the reflector  30 .  FIG. 6  also shows how multiple lumenaires can be formed in an array. Refer also to  FIG. 10  for an illustration of a symmetric array of four lamps. 
   Reference is now made to  FIGS. 7 and 8  for further descriptions of the light patterns emanating from the respective asymmetric and symmetric fixtures. In both  FIGS. 7 and 8  the fixtures are of the recessed type, however, the principles of the present invention apply equally to non-recessed fixtures and regardless of how or where they are mounted.  FIG. 7  illustrates a symmetric light distribution fixture design that may utilize a single lamp  16  per fixture. The lamp and diffuser are oriented so that the reflector portions on either side of the lamp and diffuser can be positioned to direct virtually all reflected light towards a single target point which is above nadir. 
     FIG. 7  also shows, by arrows, the different light beams and the direct and indirect lighting components thereof. This includes direct reflected light D, refracted/reflected light E and diffused light F. Light from the lower part of the lamp directed at the lower diffuser portion  20 A is shown diffused through the diffuser portion where the perforation are and also shows some light reflected toward the reflector portion  15 B. Light from an upper part of the lamp is shown as direct reflected light that is reflected from the reflector at least portions  15 A and  15 C.  FIG. 7  also shows refracted light through the upper portion  20 B of the diffuser  20 . To provide the preferred light direction toward a single target point the reflector has a substantially flat portion  15 C close to the lamp  16 . In addition, the reflector is preferably stepped so that the reflector portion  15 A directs the light toward the single target point. The single target point is where the reflected rays converge, usually several feet from the fixture. 
     FIG. 8  shows a symmetric light distribution fixture that may utilize multiple lamps within a single fixture. In  FIG. 8  only one of the lamp/reflector combinations is illustrated. The number of lamps  16  utilized determines the total lumen output of the fixture. Regardless of the number of lamps used, each lamp and diffuser is positioned within a reflector  30  that is specially designed to symmetrically direct illumination towards nadir with each lamp cell having a beam spread of approximately 20°. The beams on either side of the lamp are preferably formed to cross one another before hitting the target surface so as to minimize shadowing and to contain the illumination to the limits of the bed or other surface below. This design could also be used for wall washing, sign illumination or other similar purposes. 
     FIG. 8  also shows, by arrows, the different light beams and the direct and indirect lighting components thereof. This includes direct reflected light D, refracted/reflected light E and diffused light F. Light from the lower part of the lamp directed at the lower diffuser portion  20 A is shown diffused through the diffuser portion where the perforation are and also shows some light reflected toward the reflector  30 . Light from an upper part of the lamp is shown as direct reflected light that is reflected from the reflector  30 .  FIG. 8  also shows refracted light through the upper portion  20 B of the diffuser  20 . 
   Reference is now made to  FIGS. 9 and 10  for an illustration of different lighting schemes that can be employed in accordance with the present invention.  FIG. 9  shows the use of a pair of asymmetric fixtures  40 ,  42  arranged so that the respective lamps are directed outward and, in turn, direct the respective beams  41 ,  43  toward the target illumination area  44 . The fixtures  40 ,  42  are preferably equally disposed about the center line  45  that extends to the target area  44 . The asymmetric fixture array would typically be used in pairs mounted in opposing positions running lengthwise with the patient bed, dentist chair or similar application. The fixtures in  FIG. 9  may, for example, be spaced 2′ to 6′ apart. The fixture pairs are preferably mounted centered over a bed so that the light patterns from each fixture cross several feet above the surface of the bed, thus minimizing shadows which might be caused by an individual standing on one side of the bed. Several sizes and lengths are possible to suit differing needs. For example, a dentist typically only needs illumination on the patient&#39;s head while a physician might need whole-body illumination. 
     FIG. 10  shows an array of symmetric fixtures  50  arranged in a side-by-side position, as well as the beams  52  from each fixture. These beams symmetrically illuminate a target illumination area  54 . The symmetric distribution fixture may be mounted directly over a patient bed, dentist chair or similar application. Other reflector designs make it suitable for general illumination purposes. Multiple cells of reflectors/diffusers may be utilized to provide varying light levels. Each cell is designed to provide a narrow beam of illumination, as illustrated in  FIG. 10 . The beams are designed to cross above the bed or other surface in order to minimize shadows. Several sizes and lengths are possible to suit differing needs. For example, a dentist only needs illumination on the patients head while a chiropractor desires whole-body illumination. 
   Another lighting scheme is shown in  FIG. 11  including a switch for controlling the light array. This array has two outboard asymmetric fixtures  60  and two inboard symmetric fixtures  62 . These fixtures are controlled from the switch  64  which is adapted to provide electrical power to the lighting array. More particularly, control line  65  couples to only the asymmetric fixtures while line  66  couples to all fixtures. The switch  64  has two modes of operation. In a first mode only the line  65  is excited. This provides a light pattern like that shown in  FIG. 9 . In the second mode of the switch  64  all fixtures are excited via line  66  and the symmetric fixtures thus fill in additional light at the target area. 
   A further alternate embodiment of the invention is illustrated in  FIG. 12 . This differs from the single lamp version in that it includes two lamps  16 A and  16 B. In this case the diffuser  70  is of a like construction to that illustrated in  FIG. 4 , but has a more oval shape for the lower portion  70 A. This diffuser also includes the upper refracting portion  70 B and the intermediate portion  70 C. 
   One of the features of the present invention is the ability of the diffuser to essentially hide the lamp from normal viewing angles. This is clear from, for example,  FIGS. 4 and 5  wherein the very tip of the portions  20 C hides the lamp from viewing. This provides diminished glare upon a patient. The diffuser portion  20 A provides some level of diffused light while also, in combination with the reflector, provides reflected light to the target area. The portion  20 C, while blocking direct view by the patient, provides added refracted light therethrough. 
   Having now described a limited number of embodiments of the present invention it should be apparent to those skilled in the art that numerous other embodiments and modifications thereof are contemplated as falling within the scope of the present invention, as defined by the appended claims.