Patent Publication Number: US-2004042225-A1

Title: Vehicle interior lighting assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
     [0001] This application claims priority from Provisional Application No. 60/407,167, filed Aug. 30, 2002, and entitled “Vehicle Interior Lighting Assembly”. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] This invention relates generally to a vehicle interior lighting assembly for illuminating the interior of a vehicle.  
       [0004] 2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98  
       [0005] Cold cathode discharge tubes, also known as cold cathode fluorescent lights (CCFLs), are known for use as light source throughout. As is described in detail in the Appendix, cold cathode discharge tubes produce light by passing electric current through a gas or vapor. This causes an ionization process in which electrons are separated from their charges and collide with one another to produce a glow. The power supply for a cold cathode tube typically includes a magnetic or electronic ballast. Heating above ambient temperature is not required for a cold cathode tube to produce light. The tubes are made of glass and are therefore comparatively brittle and prone to breakage. The glass tubes may be phosphor coated to emit various color temperatures and can be contoured to a variety of different shapes to suit different applications. So long as cold cathode tubes are not subjected to shocks or bending, torsional or vibration loads sufficient to shatter them, their operational longevity is such that in many applications they can effectively serve as permanent light source.  
       [0006] It is known for lighting assemblies to include cold cathode discharge tubes supported within lamp housings. Typically, in such an assembly, a portion of the housing serves as a reflector and another portion serves as a lens. When energized, the cold cathode tube emits light that either passes directly through the lens or reflects off the reflector portion and passes through the lens. It&#39;s also known for such a lighting assembly to include a receptacle that is permanently fixed to a support structure and removably receives the lamp housing so that the cold cathode discharge tube and lamp housing can be removed and replaced as a unit.  
       [0007] For example, U.S. Pat. No. 4,186,432 issued Jan. 29, 1980 to Martin Hammicker, discloses a vehicle interior lighting assembly including a lamp housing having a translucent lens and a cold cathode discharge tube enclosed within the lamp housing in a position to emit light through the lens. The vehicle interior lighting assembly of the Hammicker patent includes a first set of electrical connectors coupled to electrodes of the cold cathode discharge tube and providing a current path to the tube from external electrodes of the lamp housing. The Hammicker lighting assembly also includes a receptacle that&#39;s supported on a mineshaft wall and that removably receives the lamp housing. As such, the lamp housing and the cold cathode tube within it can be removed and replaced as a unit. The vehicle interior lighting assembly disclosed in the Hammicker patent also includes a second set of electrical connectors disposed in the receptacle and positioned to couple with the external housing electrodes and an outside power source. The first and second sets of electrical connectors provide a current path between the tube and the outside power source.  
       [0008] In addition, U.S. Pat. No. 4,940,921 issued Jul. 10, 1990 to Helling et al., discloses a receptacle that&#39;s supported on a ceiling of a room in a building and removably receives a sealed disposable lamp housing that includes a clear lens. The vehicle interior lighting assembly of the Helling et al. patent also includes a plurality of elongated cold cathode discharge tubes sealed within the lamp housing.  
       [0009] However, a vehicle interior lighting assembly constructed according to either the Hammicker patent or the Helling et al. patent cannot protect a cold cathode tube against torsional, vibration and shock loads applied to the assembly that would be experience in a moving vehicle. Nor can such an assembly support elongated cold cathode discharge tubes end-to-end in an elongated cornice lighting fixture supported longitudinally along the length of a passenger compartment.  
       [0010] What is needed is a vehicle interior lighting assembly that can support and protect elongated cold cathode discharge tubes against torsional, vibration and shock loads. What is also needed is such a vehicle interior lighting assembly that can support elongated cold cathode discharge tubes end-to-end in an elongated cornice lighting fixture supported longitudinally along the length of a passenger compartment of a vehicle.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011] A vehicle interior lighting assembly is provided that includes a lamp housing having a lens and a cold cathode discharge tube carried by the lamp housing. The tube is configured to emit light through the lens when energized by electrical current. The vehicle interior lighting assembly also includes current paths extending from respective electrodes of the cold cathode discharge tube, connectable to an external power source, and configured to deliver electrical current from the source to the tube sufficient to illuminate the tube. The lamp housing is additionally configured to support and protect the tube from breakage in the passenger compartment of a vehicle that flexes and transmits related forces to the assembly causing the housing to flex. Therefore, a vehicle interior lighting assembly constructed according to the invention is able to protect cold cathode discharge tubes in the interior of a vehicle against breakage that might otherwise result due to flexing of the vehicle structure.  
       [0012] According to another aspect of the invention, the housing including a pair of lamp support bushings disposed at opposite ends of the housing and supporting opposite ends of a cold cathode discharge tube. The bushings are configured to limit torsional, shock, vibration and/or bending forces that the housing can apply to the tube as the housing flexes with a vehicle the housing is supported on.  
       [0013] According to another aspect of the invention, each bushing includes a flexible annular cuff that fits around an end of a cold cathode tube to flexibly support the tube.  
       [0014] According to another aspect of the invention, each bushing comprises polyurethane foam.  
       [0015] According to another aspect of the invention, the housing comprises an extruded polycarbonate lens/reflector tube.  
       [0016] According to another aspect of the invention, the tube includes the lens and a reflector portion that is co-extruded with the lens.  
       [0017] According to another aspect of the invention, the lens and reflector are extruded separately, then joined together by sonic weld or other suitable means.  
       [0018] According to another aspect of the invention, the housing comprises a pair of end caps configured to close opposite ends of the tube and to carry the lamp support bushings in positions such that the bushings support the cold cathode discharge tube in a position spaced from a continuous inner wall of the lens/reflector tube. This prevents the lens/reflector tube from transmitting or applying torsional or bending stresses to the cold cathode discharge tube.  
       [0019] According to another aspect of the invention, at least one of the end caps includes a wire shield that extends axially from a wall portion of the end cap. The wire shield is configured to block passenger access to electrical wiring leading from the housing to a vehicle power source.  
       [0020] According to another aspect of the invention, the assembly includes a plurality of tubes and lamp housings arranged end-to-end and longitudinally along an elongated vehicle interior compartment. This arrangement provides an extended line of illumination along the length of such a compartment.  
       [0021] According to another aspect of the invention, the lamp housing is a removable self-contained cartridge and the assembly includes a vehicle lighting fixture that includes a receptacle configured to removably receive the cartridge. This allows the cold cathode discharge tube and cartridge to be removed and replaced as a unit.  
       [0022] According to another aspect of the invention, the cartridge is sealed to prevent contaminants such as dust and insects from inhibiting or otherwise modifying the emission of light from the cartridge.  
       [0023] According to another aspect of the invention, the cartridge is hermetically sealed to prevent water vapor from entering the housing and clouding the lens.  
       [0024] According to another aspect of the invention, the assembly includes a plurality of the cartridges and the vehicle lighting fixture includes a receptacle configured to receive and support the cartridges longitudinally along a vehicle passenger compartment in an end-to-end arrangement.  
       [0025] According to another aspect of the invention, the receptacle is configured to removably receive and support the cartridges longitudinally along a vehicle passenger compartment in an end-to-end arrangement.  
       [0026] According to another aspect of the invention, the current paths each include an electrical contact supported in one of the end caps and coupled to one of two electrodes of the cold cathode discharge tube, and a wire that is coupled to and extends from the contact and is connectable to a vehicle electrical power distribution system  
       [0027] According to another aspect of the invention, a method is provided for installing a lamp cartridge in an existing vehicle lighting system. According to the method, a vehicle is provided having an existing interior lighting fixture comprising a lamp housing for receiving a lamp. A cartridge is then shaped to fit within the lamp housing. The custom-shaped cartridge is then installed in the lamp housing and is connected to an electrical distribution system of the vehicle. 
     
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
     [0028] These and other features and advantages of the invention will become apparent to those skilled in the art in connection with the following detailed description and drawings, in which:  
     [0029]FIG. 1 is an end view of an interior lighting assembly constructed according to the invention and shown incorporated into a cornice lighting fixture of a bus;  
     [0030]FIG. 2 is an end view of a lamp cartridge of the interior lighting assembly of FIG. 1;  
     [0031]FIG. 3 is a cross-sectional view of the lamp cartridge of FIG. 2 taken along line  3 - 3  of FIG. 2;  
     [0032]FIG. 4 is a cross-sectional view of the lamp cartridge of FIGS. 2 and 3 taken along line  4 - 4  of FIG. 3 and with a cold cathode tube of the cartridge removed for clarity;  
     [0033]FIG. 5 is a schematic block diagram of the cold cathode tube of the lamp cartridge of FIGS.  2 - 4 , an inverter ballast of the interior lighting assembly of FIG. 1, a key pad, and associate electrical interconnections between them;  
     [0034]FIG. 6 is a fragmentary perspective view of a series of lamp cartridges constructed according to the invention mounted in a series of receptacles formed in cornice lighting fixtures with the fixtures shown installed in a bus;  
     [0035]FIG. 7 is an end view of an interior lighting assembly constructed according to an alternative embodiment of the invention with a removable cartridge of the assembly shown detached from a receptacle of the assembly; and  
     [0036]FIG. 8 is a fragmentary end view of a bus-mounted interior lighting assembly constructed according to another alternative embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF INVENTION EMBODIMENT(S)  
     [0037] A vehicle interior lighting assembly constructed according to the invention is shown at  10  in FIGS.  1 - 8 . The assembly  10  includes a lamp housing  12  having a lens  14  and a cold cathode discharge tube  16  carried by the lamp housing  12 . The tube  16  emits light through the lens  14  when energized by electrical current. The assembly  10  also includes a current path  18  extending from an external power source  19  to the cold cathode discharge tube  16 . The current path  18  delivers sufficient electrical current from the source  19  to the cold cathode tube  16  to illuminate the cold cathode tube  16 . The lamp housing  12  supports the cold cathode tube  16  in a vehicle compartment  20  and protects the cold cathode tube  16  from breakage due to flexing of a vehicle  22  that the assembly  10  is installed in. The lamp housing  12  does this by protecting the cold cathode tube  16  from the transmission of associated resulting torsional, shock, vibration, and or longitudinal bending forces from the vehicle  22 , through the lamp housing  12 , to the cold cathode tube  16 .  
     [0038] Details regarding the operation, construction, and available models of cold cathode discharge tubes suitable to be employed in an interior lighting assembly constructed according to the invention are included in the following publications that are incorporated herein by reference: National Cathode Corp. Home Page, http://www.lighting-inc.com/manufacturers/nationalcathode/html;  What is Cold Cathode? , http://www.lighting-inc.com/manufacturers/nationalcathode/whatis.html; . Cold Cathode Fluorescent Lamps ; http://www.nelt.co.jp/nhe hp/cfl/cfl.html;  Compact Fluorescent Lamps ; http:/www.eren.doe.gov/consumerinfo/refbriefs/ef2.html;  
     [0039] As best shown in FIG. 3, the housing  12  includes a pair of lamp support bushings  24  supported at axially opposite ends of the housing  12  as shown in FIG. 3. The lamp support bushings  24  support respective opposite ends of the cold cathode discharge tube  16  and limit torsional, shock, vibration, bending, longitudinally compressive, and tensile forces that the housing  12  may apply to the cold cathode tube  16  as the housing  12  flexes with a vehicle  22  the housing  12  is supported on. Each bushing  24  includes a flexible annular cuff  26  comprising polyurethane foam or any other suitable shock absorbing material.  
     [0040] In the embodiment shown in the drawings, the housing  12  includes a self-contained lamp cartridge  28 . As best shown in FIG. 4, the lamp cartridge  28  comprises an extruded polycarbonate lens/reflector tube  30 . The lens/reflector tube  30  includes both the lens  14  and a reflector portion  32  that is co-extruded with the lens  14 . In other embodiments, the lens  14  and reflector  32  may be extruded separately, then joined together by sonic weld or other suitable means.  
     [0041] As is also best shown in FIG. 3, the housing  12  also comprises a pair of end caps  34  that close off opposite ends  36 ,  38  of the lens/reflector tube  30  by being glued to the respective lens/reflector tube ends  36 ,  38  using a suitable cement  40 . The end caps  34  are shaped to include axially inwardly extending cups  42  that support the lamp support bushings  24 . The cups  42  support the bushings  24  in relative positions that allow the bushings  24  to support the cold cathode discharge tube  16  in a position spaced from a continuous inner wall  44  of the lens/reflector tube  30 . This arrangement prevents the lens/reflector tube  30  from contact  46 ing and transmitting or applying side forces directly to the cold cathode tube  16  when the lens/reflector tube  30  is bent.  
     [0042] Each of the current paths  18  includes a contact  46  coupled to one of two electrodes  48 ,  50  of the cold cathode discharge tube  16 . Each current path  18  also includes a wire  52  that is coupled to and extends from one of the contacts  46  and is connectable to a vehicle electrical power distribution system  54 . The wires  52  extend out of the cartridge  28  through respective end wall portions  56  of the end caps  34 .  
     [0043] Each of the end caps  34  includes a wire shield  60  that extends axially from around an outer edge of the end wall portion  56  of each end cap  34 . When abutted axially against a wall or another lamp cartridge end cap  34 , the wire shields  60  block passenger access to the electrical wires  52  that lead from the housing  12  to the vehicle electrical power system  54 . The electrical wires  52  extend through holes  64  in the respective wire shields  60  as shown in FIG. 3.  
     [0044] As shown in FIG. 5, between the vehicle power source  19  and the cold cathode tube  16 , the assembly  10  includes an inverter ballast  66  and a keypad  68 . The inverter ballast  66  converts electric power received from the vehicle power source  19  to whatever current and potential values are compatible with a cold cathode tube  16  to be used in the assembly  10 , and inverts the power to provide alternating current. The keypad  68  is connected between the inverter ballast  66  and the vehicle power source  19  and provides control for each individual fixture, e.g., on-off and dimming.  
     [0045] To receive and support the cartridge  28  in a desired position for illuminating a vehicle compartment  20 , the assembly  10  includes a vehicle interior lighting fixture  70  including a receptacle  72  that receives the cartridge  28 . As shown in FIG. 1, a wall of the receptacle  72  is contoured to complement the shape of the reflector portion  32  of the lens/reflector tube  30  to maximize contact area between the receptacle  72  and the cartridge  28 . In the embodiment shown in the drawings, the cartridge  28  is riveted into the receptacle  72 . Rivets are passed through and hold together the receptacle  72  and the reflector portion  32  of the lens/reflector tube  30 . In the embodiment shown in FIG. 7, the cartridge  28  may be removably received by the receptacle  72  rather than fixed in place by rivets so that the cold cathode discharge tube  16  and cartridge  28  can be removed and replaced as a unit when damaged or rendered inoperative.  
     [0046] The cartridge  28  is sealed to prevent contaminants such as dust and insects from inhibiting or otherwise modifying the emission of light from the cartridge  28  and for ease of maintenance and cleaning. In the present embodiment the cartridge  28  is also hermetically sealed to prevent water vapor from entering the housing  12  and clouding the lens  14 .  
     [0047] As shown in FIG. 6, a plurality of the above-described lamp cartridges  28  may be arranged end-to-end and longitudinally along an elongated vehicle interior compartment  20 . As shown in FIG. 8, the cartridges  28  may be arranged end-to-end and longitudinally along both cornice areas  74  of a vehicle interior compartment  20 . The receptacles  72  of the vehicle lighting fixtures  70  shown in FIGS. 6 and 8 are configured to receive and support the cartridges  28  longitudinally along a vehicle  22  passenger compartment  20  in an end-to-end arrangement. This arrangement provides an extended line of illumination in a desired position along the length of such a compartment  20 . As shown in FIG. 8, the longitudinal arrangement may also be in the form of center strip lighting  75  supported along a longitudinal centerline of the ceiling of a vehicle compartment  20  as shown in FIG. 8.  
     [0048] A lamp cartridge  28  of the type described above may be installed in an existing vehicle lighting system without significant modification to the existing system. According to the method, the cartridge  28  is formed and shaped to fit within a lamp housing  12  of the existing system. The custom-shaped cartridge  28  is then installed in the lamp housing  12  and is connected to an electrical distribution system  54  of the vehicle  22 . The cartridge  28  may be installed using rivets as described above or by any other suitable means known in the art.  
     [0049] This description is intended to illustrate certain embodiments of the invention rather than to limit the invention. Therefore, it uses descriptive rather than limiting words.  
     [0050] Obviously, it&#39;s possible to modify this invention from what the description teaches. Within the scope of the claims, one may practice the invention other than as described.