Abstract:
A windshield glare-reducing assembly includes a tubular sleeve configured to receive an elongated light source such as a fluorescent lamp. Louvers are supported along the sleeve so as to fit closely around such a lamp without touching or being mounted directly on the lamp. The louvers are shaped, spaced and positioned to reduce the amount of light emitted from the lamp towards a vehicle windshield and then reflecting from the windshield into the driver&#39;s eyes. The sleeve is shaped to allow the sleeve and louvers to be easily installed on and removed from a lamp and to ease replacement of burned-out and damaged lamps.

Description:
This application claims priority of U.S. provisional patent application Ser. No. 60/171,994 filed Dec. 23, 1999. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to a window glare-reducing assembly for reducing the amount of interior light reflected into a driver&#39;s eyes from the windshield of a mass transit vehicle as well as the amount of passenger-perceived glare reflected from side windows of a mass transit vehicle. 
     INVENTION BACKGROUND 
     Some mass transit vehicle interior lighting fixtures are known to include louvers or fins spaced axially along the length of an elongated cylindrical light source such as a fluorescent lamp. The louvers extend laterally from the lamps to direct light laterally into passenger seating areas and away from the windshield. 
     For example, U.S. Pat. No. 2,099,451, issued Nov. 16, 1937 to Schepmoes (the Schepmoes patent), discloses a lighting fixture intended for use in “railroad cars and the like” that includes a plurality of parallel louvers or fins spaced axially along the length of a fluorescent lamp. In addition, U.S. Pat. No. 4,717,992, issued Jan. 5, 1988 to Bartenbach et al. (the Bartenbach et al. patent), discloses a lighting fixture that includes a plurality of parallel louvers or fins spaced axially along the length of a fluorescent lamp. Each louver includes a circular hole sized to fit closely around the lamp. 
     U.S. Pat. No. 2,299,276 to Kirlin (the Kirlin patent) discloses racks of parallel louvers, each louver having a half-circular cutout sized to receive a fluorescent lamp. Each rack disclosed in the Kirlin patent includes a pair of C-shaped wire clips for clipping the louver racks onto the fluorescent lamp. In the louvers disclosed in the Shepmoes, Bartenbach et al. and Kirlin patents are configured to be supported directly on a fluorescent lamp. 
     What is needed is a window glare-reducing assembly that allows louvers to be mounted on and removed from an elongated cylindrical light source more quickly and easily. 
     INVENTION SUMMARY 
     According to the invention, a window glare-reducing assembly is provided for reducing the amount of glare reflected from a window of a mass transit vehicle by interior vehicle lighting. The assembly includes a first plurality of louvers configured to be supported in an axially spaced-apart disposition along the length of an elongated cylindrical light source. The window glare-reducing assembly also includes a tubular sleeve configured to receive an elongated cylindrical light source such as a fluorescent lamp. The first plurality of louvers is supported on the sleeve in an axially spaced-apart disposition. This allows each louver of the first plurality of louvers to fit closely around the cylindrical light source while simplifying installation and removal of the louvers and installation and replacement of cylindrical light sources that the louvers are supported on. Therefore, a window glare-reducing assembly constructed according to the invention is both easier to install and remove, and allows lamps to be replaced more easily. 
     According to another aspect of the invention, the sleeve comprises a plastic material, a transparent material and/or a colored material. The color and transparency of the sleeve material may be selected by a customer to complement existing interior color schemes, to control light dispersion, to affect passenger moods and/or to cause passengers to associate a certain color with the particular transport company that uses it. 
     According to another aspect of the invention, a support shaft is connected to each louver of the first plurality of louvers. The support shaft holds the louvers together making them easier to install on and remove from the tube. The support shaft also serves to stabilize the relative positions and attitudes of the louvers connected to it. 
     According to another aspect of the invention, the first plurality of louvers and the first support shaft are integrally formed as a single unitary piece. Forming the louvers and shaft as a single unitary piece eliminates the need to manufacture and assembly multiple parts. 
     According to another aspect of the invention, the assembly includes at least one additional plurality of louvers configured to be supported in an axially spaced-apart disposition along the length of an elongated cylindrical light source and a second support shaft connected to each louver of the additional plurality of louvers. The first support shaft is configured to interconnect with the second support shaft in an end-to-end disposition. Shorter lengths of louvered shafts are easy to manufacture and can easily be assembled end-to-end to cover whatever length of fluorescent tube is being used in a particular lighting fixture. 
     According to another aspect of the invention, one of the first and second support shafts includes an axial counter bore at one end. The other of first and second support shafts includes a complementary axially extending post at one end configured to be received into the axial counter bore. This pin-and-socket arrangement maintains alignment between adjacent lengths of louvered shafts providing aesthetically pleasing visual continuity. 
     According to another aspect of the invention, each louver includes a circular through-hole. The circular through holes are configured and coaxially aligned to receive the tubular sleeve. The holes allow the louvers to extend completely around the circumference of the lamp they are supported on thereby directing a maximum amount of light emitted from the host lamp. 
     According to another aspect of the invention, the louvers comprise non-reflective surfaces to further reduce non-lateral light emissions by absorbing rather than reflecting light. 
     According to another aspect of the invention, the louvers comprise translucent material to reduce the magnitude and harshness of non-lateral light emissions. 
     According to another aspect of the invention, the louvers comprise colored material to complement existing interior color schemes, to control light dispersion, to affect passenger moods and/or to cause passengers to associate a certain color with the particular transport company that uses it. 
     According to another aspect of the invention, the louvers are disposed parallel to each other to direct light evenly along the length of the vehicle. 
     According to another aspect of the invention, the louvers are disposed perpendicular to the support shaft to direct light exclusively in a lateral direction relative to the lamp. 
     According to another aspect of the invention, the louvers are angled relative to the support shaft and lamp to direct light toward a predetermined portion of the passenger compartment or away from a predetermined portion of the passenger compartment. 
     According to another aspect of the invention, the louvers are spaced apart by a distance that provides an interior illumination level of 15 foot-candles at each reading plane at each seat location within a vehicle to be illuminated, where the entire length of each elongated cylindrical light source mounted within the vehicle is disposed within the assembly and a plurality of like assemblies having identically spaced louvers. (Each reading plane is defined as a one square foot plane inclined at a 45 degree angle 33″ above a floor of the vehicle and 22″ in front of a seat back of one of the seats.) This insures that the lighting system meets minimum industry standards for mass transit vehicle interior lighting. 
     According to another aspect of the invention, each louver includes an inside edge configured to conform generally to the interior contours of a lamp housing in an interior light fixture. The conforming inside edge prevents light from escaping between the inside edge and the lamp housing and provides maximum louver surface area for light deflection. 
     According to another aspect of the invention, each louver includes an outside edge configured to conform generally to the interior contours of an interior light fixture lens. The conforming outside edge provides a maximum louver surface area for light deflection within the confines of the lens. 
     According to another aspect of the invention, the louvers are black in color to increase light absorption and to minimize light reflection. 
     The invention also includes a method for making a window glare-reducing assembly. The method includes molding the louvers and support shaft are together as a single unitary piece. The sleeve is then inserted through the circular through-holes of the louvers and an elongated cylindrical light source is provided within the sleeve. The light source, sleeve, louvers, and shaft are provided in the light fixture such that the light source is electrically connected to a light source power supply of the light fixture and is physically supported by light source receptacles of the light fixture. The method further includes providing a lens on the light fixture. This method greatly simplifies the process of assembling louvers to a lamp. 
     According to another aspect of the inventive method, the step of molding the louvers and support shaft together as a single unitary piece includes providing a mold including a mold cavity having an interior shape complementing the exterior shape of the louvers and support shaft. The mold also includes a pair of frusto-conical tapered rods configured to be inserted into the mold cavity from axially opposite ends of the mold and to form the circular through-holes of the louvers. The tapered rods are then inserted into the mold cavity from axially opposite ends of the mold and molten material is provided in the mold cavity. The molten material is allowed to harden, the tapered rods are withdrawn, the mold is opened and the finished product is removed. The use of tapered rods allows the rods to be removed easily and without binding within the circular apertures that the rods form in the louvers. 
     According to another aspect of the invention, a support shaft interconnects the first plurality of louvers to form a louver assembly. The louver assembly is split longitudinally to form interconnectable first and second louver assembly portions. This allows the louver assembly to be closed or assembled around the tubular sleeve rather than forcing the tubular sleeve through the louvers one louver at a time. 
     According to another aspect of the invention, the louver assembly includes a second support shaft. The incorporation of the second support shaft insures that the individual louvers will remain parallel to each other. 
     According to another aspect of the invention a method is provided for making a windshield glare-reducing assembly that includes molding interconnectable first and second louver assembly portions as separate pieces then interconnecting the louver assembly portions around the tubular sleeve such that the individual louvers of the louver assembly are supported in an axially spaced-apart disposition along the sleeve. 
    
    
     DRAWING DESCRIPTIONS 
     These and other invention features and advantages will become apparent to those skilled in the art when considered along with the following detailed description and drawings, in which: 
     FIG. 1 is a front view of a window glare-reducing assembly constructed according to the invention with a fluorescent lamp disposed within a transparent sleeve of the invention and with the sleeve partially cut away to expose a fluorescent lamp beneath; 
     FIG. 2 is a cross-sectional side view of the glare-reducing assembly and fluorescent lamp of FIG. 1 taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a front view of the glare-reducing assembly of FIG. 1 with the fluorescent lamp and transparent sleeve removed to show only a louver assembly of the glare-reducing assembly of FIG. 1; 
     FIG. 4 is a cross-sectional side view of the louver assembly of FIG. 3 taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a cross sectional front view of a window glare-reducing assembly constructed according to the invention and installed in a lighting fixture; 
     FIG. 6 is a partial perspective view of the sleeve of FIG. 1 disposed around a fluorescent lamp and within a louver assembly constructed according to a second embodiment of the invention; 
     FIG. 7 is a partial perspective view of the sleeve of FIG. 1 disposed within a louver assembly constructed according to a third embodiment of the invention; 
     FIG. 8 is a top view of the louver assembly and sleeve of FIG. 7 with first and second portions of the louver assembly shown split apart; and 
     FIG. 9 is a cross-sectional side view of the louver assembly and sleeve of FIG. 7 taken along line  9 — 9  of FIG.  8 . 
    
    
     DETAILED DESCRIPTION 
     A first embodiment of a window glare-reducing assembly for reducing the amount of driver-perceived glare reflected from the windshield of a mass transit vehicle and the amount of passenger-perceived glare reflected from side windows by interior vehicle lighting is generally indicated at  10  in FIGS. 1,  2  and  5 . Second and third embodiments are generally indicated at  10 ′ in FIG.  6  and  10 ″ in FIGS. 7-9. Reference numerals with the prime (′) designation in FIG.  6  and the double prime (″) designation in FIGS. 7-9 indicate alternative configurations of elements that also appear in the first embodiment. Unless indicated otherwise, where a portion of the following description uses a reference numeral to refer to the FIGS., we intend that portion of the description to apply equally to elements designated by primed numerals in FIG.  6  and double-primed numerals in FIGS. 7-9. 
     The glare-reducing assembly  10  includes a plurality of louvers generally indicated at  12  in FIGS. 1-5. The louvers  12  are configured to be supported in an axially spaced-apart disposition along the length of an elongated cylindrical light source such as a fluorescent lamp  14 . The glare-reducing assembly  10  also includes a tubular sleeve  16  configured to receive or slide over an elongated cylindrical light source  14 . Each louver  12  includes a circular through-hole  18 . The circular through-holes  18  are configured and coaxially aligned to receive the tubular sleeve  16 . The louvers  12  are supported on the sleeve  16  in an axially spaced-apart disposition along the length of the sleeve  16 . 
     The sleeve  16  comprises a transparent plastic material that may be either clear or colored, depending primarily on considerations as aesthetics and transport company identification for advertising and promotional purposes. However, in other embodiments, color choice may also be influenced by functional considerations. For example, it would be desirable to use red colored material in applications (such as law enforcement or military operations) where it is important for passengers to retain or acquire increased night vision capability. 
     The louvers  12  are connected to and integrally formed with an elongated cylindrical support shaft  20  as a single unitary louver assembly  22 . The louvers  12  and support shaft  20  are formed from a polycarbonate material by a molding process described below. However, in other embodiments louvers  12  may be post-applied to a pre-formed sleeve  16  either by gluing, fasteners, clips or by interference fit. In other embodiments, the louvers  12  and support shaft  20  may also be made of a material other than a polycarbonate material. Each louver assembly  22  in the present embodiment is molded to a length of approximately two feet as measured from one end of the support shaft  20  to the other. Several of the louver assemblies  22  are installed end-to-end in longer light fixtures. The number of louver assemblies  22  installed in each light fixture depends on the length of fluorescent lamps used in a light fixture. 
     The support shaft  20  of each louver assembly  22  is configured to interconnect with the support shafts  20  of adjacent louver assemblies in an end-to-end disposition. As shown in FIGS. 1 and 3, one end of each support shaft  20  includes an axial counter bore  24 . As is also shown in FIGS. 1 and 3, the other end of each support shaft  20  includes a complementary axially-extending post  26  configured to be received and glued into the axial counter bore  24  of an adjacent louver assembly  22 . In other embodiments, the louver assembly  22  may be formed or assembled to extend the full length of each fluorescent lamp  14 . 
     The louvers  12  and support shaft  20  are opaque, black in color, and comprise non-reflective front and back surfaces  28 ,  30 . However, in other embodiments the louvers  12  may comprise colored material coordinated with the sleeve color and/or interior colors of the vehicle they will be installed in. The louvers  12  may also alternatively comprise translucent material 
     As is best shown in FIG. 3, the louvers  12  are disposed parallel to each other and perpendicular to the support shaft  20  and the fluorescent lamp  14  they are supported on, primarily to prevent light from shining directly from the fluorescent lamp  14  onto a vehicle windshield then reflecting into a driver&#39;s eyes. However, in other embodiments the louvers  12  may be cast or attached at an angle other than perpendicular or at varying angles, depending on their position in the vehicle, to direct light into various desired locations. 
     The louvers  12  of each louver assembly  22  are preferably spaced apart by a distance that provides an interior illumination level of 15 foot-candles at each reading plane at each seat location within a vehicle to be illuminated. This assumes that the entire length of each elongated cylindrical light source  14  mounted within the vehicle is disposed within the assembly and a plurality of like louver assemblies having identically spaced louvers  12 . Each reading plane is defined as a one square foot plane inclined at a 45 degree angle 33″ above a floor of the vehicle and 22″ in front of a seat back of one of the seats. The 15 foot-candle illumination standard described above is a minimum requirement established by the American Public Transit Association (APTA). See  Passenger Interior Lighting , STANDARD BUS PROCUREMENT GUIDELINES, Section 5.4.4.6; April, 1999. The object is to provide minimum interior lighting levels while complying with the APTA standard. The approximate 2-inch spacing of the louvers  12  shown in the drawings and photographs met the above standard almost exactly in one bus. However, the optimum louver spacing is likely to differ from vehicle to vehicle. 
     To minimize axial light leakage and to maximize the area of the louver surfaces  28 ,  30  within the confines of a lamp housing, an inside edge  32  of each louver  12  is shaped to conform generally to the interior contours of a lamp housing in an interior light fixture as shown in FIG.  5 . Similarly, an outside edge  34  of each louver  12  is shaped to conform generally to the interior contours of an interior light fixture lens that fits over and closes the lamp housing. By conforming the inside and outside edges  32 ,  34  of each louver  12  to the respective interior contours of the lamp housing and the lens, each louver  12  is formed to include a maximum surface area for directing light emitted from the lamp  14  they are mounted on. 
     Each windshield glare-reducing assembly  10  is made by first molding louvers  12  and a support shaft  20  together as a single unitary piece. This includes providing a mold  36  including a mold cavity  38  having a shape complementary to that of the louvers  12  and support shaft  20 . The mold  36  also includes a pair of frusto-conically tapered rods  40  configured to be inserted into the mold cavity  38  from axially opposite ends of the mold  36  and to form the circular through-holes  18  of the louvers  12 . The tapered rods  40  are then inserted into the mold cavity  38  from axially opposite ends of the mold  36 . Molten material  42  is then provided in the mold cavity  38  and is allowed to harden. The tapered rods  40  are then withdrawn, the mold  36  is opened and the louver assembly  22  is removed. The sleeve  16  is then inserted through the axially aligned circular through-holes  18  of the louvers  12 . A fluorescent lamp  14  is then slid into the sleeve  16  and the lamp  14 , sleeve  16  and louver assembly  22  are installed in a light fixture by installing the lamp  14  in lamp receptacles formed in the light fixture such that the light source  14  is electrically connected to a light source power supply of the light fixture. Finally, the lens is fastened over the lamp housing. 
     The rods  40  are tapered to provide an approximate 2-degree draft to prevent the rods  40  from sticking within the circular through-holes  18  after the molten polycarbonate has hardened. To minimize the resulting difference circular through-hole diameters along the length of each louver assembly  22 , the length of each louver assembly  22  is limited to approximately 2 feet and two, rather than one, taper rods  40  are used. 
     The window glare-reducing assembly  10  may be configured for installation in new light fixtures and shipped with the fixtures from the factory. The glare-reducing assembly  10  may alternatively be configured for retrofitting into the lamp housings of existing light fixtures. 
     Supporting the louvers  12  on a tube as described above allows the louvers  12  to be formed to fit closely around the cylindrical light source  14  while simplifying louver installation and removal. Closer fitting louvers  12  more efficiently direct light emitted from the lamp  14  in the desired lateral direction and minimize axial dispersion. Louver installation and removal are simplified because the sleeve  16  is disposed in the circular through-holes  18  to act as an interface between the louvers  12  and the fluorescent lamp  14  the louvers  12  are supported on. The sleeve  16  allows lamps  14  to be quickly and easily installed and replaced within the through-holes  18  because it maintains the holes  18  in axial alignment and guides lamps through the holes  18 . 
     In other embodiments, such as the embodiment shown in FIG. 6, the louvers  12 ′ may be connected together by a small diameter metal rod  44  and spaced apart by plastic spacers  46 . In such an embodiment spacers  46  of varying lengths may be used to produce a glare-reducing assembly  10 ′ especially suited to a particular application. This type of embodiment also lends itself well to experimentation required to determine optimum louver spacing in a particular application. The spacers  46  may all be of the same length as shown in FIG. 6, or may be graduated in size along the length of a light fixture. Once the optimum uniform or graduated spacing has been determined, the lower cost injection molding method described above may then be used to mass-produce assemblies having the optimum spacing. 
     According to the third embodiment shown in FIGS. 7-9, the louvers  12 ″ are interconnected by upper and lower elongated support shafts  50 ,  52  to form a louver assembly  22 ″. The louver assembly  22 ″ is split longitudinally to form interconnectable first and second louver assembly portions  54 ,  56 . The upper and lower support shafts  50 ,  52  are connected to each louver  12 ″ at respective diametrically opposite locations relative to the circular through-hole  18 ″ in each louver  12 ″ and adjacent respective upper and lower edges  32 ″,  34 ″ of each louver  12 ″. 
     The upper support shaft  50  is rectangular in cross section and is split vertically and longitudinally to form interconnectable first and second elongated upper support shaft portions  58 ,  60 . Likewise, the lower support shaft  52  is rectangular in cross-section and is split vertically and longitudinally to form interconnectable first and second elongated lower support shaft portions  62 ,  64 . The upper and lower support shaft portions  58 ,  60 ;  62 ,  64  are interconnectable along their respective lengths to form the respective upper and lower support shafts  50 ,  52  and to interconnect the first and second louver assembly portions  54 ,  56  forming the first louver assembly  22 ″. 
     The first and second upper support shaft portions  58 ,  60  include fastener holes  66 ,  68  at corresponding spaced-apart locations along their respective lengths. As best shown in FIGS. 8 and 9, the fastener holes  66  of the first upper support shaft portion  58  are coaxially aligned with the fastener holes  68  of the second upper support shaft portion  60 . Likewise, as is best shown in FIG. 9, the first and second lower support shaft portions  62 ,  64  include fastener holes  70 ,  72  at corresponding spaced-apart locations along their respective lengths. The fastener holes  70  of the first lower support shaft portion  62  are coaxially aligned with the fastener holes  72  of the second lower support shaft portion  64 . As shown in FIG. 7, rivets  74  or other suitable fasteners are disposed in the aligned holes  66 ,  68 ;  70 ,  72  of the upper and lower support shaft portions  58 ,  60 ;  62 ,  64  and hold the first and second portions of the upper and lower support shafts  50 ,  52  together around the tubular sleeve  16 ″. 
     The louver assembly  22 ″ is configured to connect end-to-end with adjacent identical louver assemblies as shown in FIG.  8 . The window glare reducing assembly includes as many of these interconnectable louver assemblies  22 ″ as are required to cover whatever length tubular light source is required for a particular application. 
     As best shown in FIGS. 7 and 8, the first and second portions  58 ,  60  of the upper support shaft  50  of each louver assembly  22 ″ are longitudinally offset from each other. As is also best shown in FIGS. 7 and 8, the first and second portions  62 ,  64  of the lower support shaft  52  of each louver assembly  22 ″ are longitudinally offset from each other. Consequently, at each end of each louver assembly  22 ″, upper and lower support shaft end sections  76 ,  78  that extend from endmost louvers  12 ″ of each louver assembly  22 ″, each include first and second end section portions  80 ,  82 ;  84 ,  86  that differ in length. In other words, one end section  80 ,  84  of the each support shaft portion of each louver assembly  22 ″ extends farther than does the corresponding end section  82 ,  86  of the mating support shaft portion. 
     As shown in FIG. 8, the longer end sections  80 ,  84  of the upper and lower support shafts  50 ,  52  of one louver assembly  22 ″ are configured to overlap and connect via rivets or other suitable fasteners to the longer end sections  80 ,  84  of the upper and lower support shafts  50 ,  52  of an adjacent louver assembly  22 ″ while abutting the shorter end sections  82 ,  86  of the upper and lower support shafts  50 ,  52  of the adjacent louver assembly  22 ″. 
     In practice, a windshield glare-reducing assembly constructed according to the third embodiment shown in FIGS. 7-9 can be assembled by first molding the interconnectable first and second louver assembly portions  54 ,  56  as separate pieces. The first and second louver assembly portions  54 ,  56  are then interconnected around the tubular sleeve  16 ″ such that the individual louvers  12 ″ of the louver assembly  22 ″ are supported in an axially spaced-apart disposition along the sleeve  16 ″. A fluorescent bulb or other suitable elongated cylindrical light source is then slid into the sleeve  16 ″. The fluorescent bulb and surrounding tubular sleeve  16 ″ and louver assembly  22 ″ are then installed in the light fixture by plugging axially opposite ends of the fluorescent bulb  16 ″ into respective bulb sockets in a light fixture. 
     This description is intended to illustrate certain embodiments of the invention rather than to limit the invention. Therefore, it includes descriptive rather than limiting words. 
     Obviously, it&#39;s possible to modify this invention from what the description teaches and one may practice the invention other than as described.