Patent Publication Number: US-6217190-B1

Title: Lighting assembly for multiple fluorescent lamps

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is being filed concurrently with U.S. patent application Ser. No. 09/158,195, now U.S. Pat. No 6,048,220, issued Apr. 11, 2000 both of which claim the benefit of U.S. Provisional Application No. 60/060,661, filed Oct. 2, 1997, and have the same assignee. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is related to lighting assemblies and is more particularly related to fluorescent lighting assemblies using electronic ballasts. More particularly, this invention is related to a fluorescent subassembly or lampholder including ballast components and integral fluorescent sockets. 
     2. Description of the Prior Art 
     Conventional ballasts used in overhead troffers or luminaires include lamps, ballasts and socket subassemblies or lampholders. The ballast or ballasts are mounted at the center of the troffer and attached to the top of the troffer. Wires extend from the ballast or ballasts to sockets located at opposite ends of the troffer. For a four lamp assembly, wires must be connected to sockets at both ends of the four lamps. When a defective ballast is replaced, often on a trial and error basis, these wires must be disconnected and reconnected. Installation and maintenance of conventional lighting assemblies is therefor time consuming and the manufacturing cost of the lighting assembly is increased. 
     One approach to simplifying and therefore reducing the cost of ballast installation is disclosed in U.S. Pat. No. 5,720,546 assigned to The Whitaker Corporation. This patent discloses an integral ballast that can be mounted at one end of a lighting assembly. A neutral wire is connected to the opposite end of the lighting assembly and this wiring must be completed during assembly of the lighting fixture. U.S. patent application Ser. No. 08/967,534 discloses a lighting assembly in which a ballast subassembly, including a ballast circuit similar to the MULTILITE MUL120 ballast circuit, can be mounted on a single end of a troffer with commoning contacts located at the opposite end. The ballast components are mounted on a printed circuit board positioned in a metal housing with conventional fluorescent sockets mounted on the exterior of the housing and connected to the printed circuit board. 
     U.S. Pat. No. 5,013,253 discloses another approach to simplifying the construction of fluorescent lighting fixtures. This patent discloses a method of wiring an otherwise conventional fluorescent lampholder in which wire leads are positioned in an insulating housing to connect terminals in integrally molded lamp sockets with an external connector block. Conventional external ballasts can then be wired to lamp sockets using this external connector block. 
     SUMMARY OF THE INVENTION 
     The principal objective of the instant invention is to simplify the assembly of fluorescent ballasts and of fluorescent lighting assemblies. By simplifying the manufacture of these assemblies they can be made more cost effective. The instant invention achieves these manufacturing improvements not only by changes to the assembly procedure, but by changes to the components themselves, which permit changes to the manufacturing procedure. 
     According to the invention, a fluorescent lighting assembly includes a ballast lampholder subassembly and at least one lampholder connector. The ballast lampholder and the at least one lampholder connector are located at respective opposite ends of the fluorescent lighting assembly with fluorescent lamps or tubes extending between. In a preferred embodiment, the ballast lampholder subassembly and the lampholder connector are mounted on a fluorescent lighting troffer. Each of the housings for both the ballast lampholder subassembly and the lampholder connector include a molded housing part. In a preferred embodiment, a plurality of lampholders comprise integrally molded extensions of this molded housing part, such as the cover for the ballast lampholder subassemblies. The lampholders include terminal cavities into which fluorescent lamp terminals can be inserted. Wires are crimped to these terminals before insertion into the terminal cavities, and these wires are then used either to attach the terminals to the ballast circuitry on the interior of the housing or to other terminals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described by way of example with reference to the accompanying drawings wherein: 
     FIG. 1 is an exploded view showing the basic components of a fluorescent lighting assembly that can be used with fluorescent lights in a fluorescent ceiling unit; 
     FIG. 2 is an exploded view showing the components of a ballast lampholder subassembly; 
     FIG. 3 is a side view of the housing of the ballast lampholder subassembly; 
     FIG. 4 is a section view of the housing shown in FIG. 3; 
     FIG. 5 is a bottom view showing the interior of the housing shown in FIG. 3; 
     FIG. 6 is a view showing an individual lampholder of the type which can be used on the ballast lampholder subassembly or on the lampholder connector subassembly; 
     FIG. 7 is a view of the components of a lampholder connector subassembly; 
     FIG. 8 is a bottom view of a lampholder connector subassembly; 
     FIG. 9 is a view of a three lamp ballast lampholder subassembly used in another embodiment of the invention; 
     FIG. 10 is a view of a three lamp lampholder connector used with the ballast lampholder subassembly shown in FIG. 9 to form a three lamp fluorescent lighting assembly; and 
     FIG. 11 is a view showing the manner in which fluorescent lamp terminals are attached to a bus wire in the embodiment of FIGS.  9  and  10 . 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     The fluorescent lighting assembly  2  as shown in FIG. 1 is intended to mount four conventional fluorescent lamps in a ceiling. This lighting assembly includes a ballast lampholder subassembly  4  located on a first end  38  of the lighting assembly, fluorescent lamps  30  extending between the first end  38  and the second end  40  of the lighting assembly  2 , lampholder connectors  50  located at the second end  40  and a troffer  80  in which the other components are mounted. The preferred embodiment of this lighting assembly is of the type that could be mounted in a suspended ceiling in an office building. The lighting assembly  2  and the troffer  80  are shown in an inverted position in FIG. 1 so that the surface of the troffer, facing downward when installed, is visible. This lighting assembly  2  can employ conventional fluorescent lamps  30 . In the preferred embodiment the lighting assembly  2  and the ballast lampholder subassembly  4  are of the type that would be used with instant start T-8 fluorescent lamps. The ballast subassembly  4  is an electronic ballast of the type that can energize two eight foot fluorescent lamps or four lamps that are each four feet in length as in this embodiment. 
     The components of the ballast lampholder subassembly  4  are shown in the exploded view of FIG.  2 . Ballast lampholder subassembly  4  is an integral unit or hub comprising a ballast housing  6  (FIG. 1) that includes a housing cover  8  attached to a housing base  10  that encloses the electronic ballast circuitry and components on the interior of the housing  6 . The housing cover  8  is molded from a thermoplastic and the housing base  10  can be fabricated from sheet metal or plastic. In the preferred embodiment, the housing base  10  is a stamped metal plate that serves as a grounding member when connected to the metal troffer  80  (FIG.  1 ). 
     The housing cover  8  is attached to the housing base  10  to form the housing  6  enclosing the fluorescent ballast. With reference also to FIG. 3, the housing cover  8  has opposite sides  8   a,    8   b  and top  8   c  which enclose three sides of the housing  6 . The cover  8  extends between ends  8   d  and  8   e  (FIG. 2) that would be adjacent to the opposite interior surfaces of a lighting assembly  2 . The housing base  10  encloses the fourth side of the housing  6 . 
     As shown in FIGS. 2 and 3, ballast lampholder housing cover  8  includes three protruding housing areas  12  that provide room for the larger components in the power supply circuit and the ballast circuit of the electronic ballast. Four channels  14  are located on the top of the ballast subassembly  4  and extend between and on either side of the protruding housing areas or enclosures  12 . Channels  14  provide space for mounting fluorescent lamps  30  in fluorescent lampholders  15  that have a conventional mounting configuration. A fluorescent lamp lampholder  15  is located in each channel  14  to engage pins on the first base of a fluorescent lamp  30 . These lampholders  15  are integrally molded as part of the housing cover  8 . 
     With reference also to FIGS. 5 and 6, each of the lampholders  15  has a pair of terminal cavities  16  in which fluorescent lamp terminals  17  are positioned. The lampholders  15  have a conventional lamp mounting configuration and are intended to receive one end of a bi-pin fluorescent lamp  30 . The terminal cavities  16  open onto an interior surface of the housing cover  8  so that the terminals can be inserted into the integrally molded lampholders  15 . The fluorescent lamp terminals  17  each include a terminal spring  18  and a crimp barrel  19  that attaches the terminal  17  to the stripped end of an insulated lead wire  20 . Terminal springs  18  of opposed terminals  17  face the center of the lampholder  15  and are deflected outwardly when a bi-pin lamp  30  is rolled into the lampholder  15 . In the preferred embodiment terminals  17  comprise stamped and formed terminals manufactured by AMP Incorporated as Part Number 640483. 
     As shown in FIG. 5, the housing cover  8  also includes splicing terminal mounting pockets  23  molded on the interior of the cover  8 . A conventional insulation displacing splicing terminal can be inserted into each pocket  23  to splice wires spanning the pocket  23 . External power lead wires  26  can be spliced to wires extending from a printed circuit board  27 , shown in FIG. 2, containing ballast circuitry and ballast components. The wires  26  are suitable for supplying external electrical power to the ballast subassembly. The splicing terminal in each pocket  23  comprises a conventional terminal manufactured by AMP Incorporated as part number 62833-1 and the pocket  23  is configured to receive this terminal. The splicing terminal includes parallel insulation displacement slots each having parallel beams which engage the wires  26  to not only establish an electrical connection, but also to establish a redundant termination to the wire to provide an effective mechanical strain relief without additional components. Other leads (not shown) can be attached to a poke-in section of each splicing terminal and these leads are attached to other components in the ballast subassembly. In addition to other components of an electronic ballast, the printed circuit board  27  includes larger components such as output inductors  28  and a choke  29  as shown in FIG.  2 . These larger components are positioned on the printed circuit board  27  so that they can be mounted in the larger enclosure sections  12  between the lampholders  15 . As shown in FIG. 1, the ballast lampholder subassembly  4  is mounted on only one end of the lighting assembly  2  and the troffer  80 . 
     Fluorescent lamps  30  are conventional tubular fluorescent lamps with a first bi-pin base  32  at one end and a second bi-pin base  34  at the opposite end. Two pins  36  at each end are conventional. Fluorescent lamps  30  are instant start lamps with a conventional instant start electrode (not shown) connected to the pins  36  at the ends of the glass envelope forming the lamp  30 . In the preferred embodiment the fluorescent lamps  30  are used with a suitable instant start electronic ballast circuit and power supply circuit such as that used in the MULTILITE MUL120 manufactured and sold by Electrofab, Ltd. The components of this ballast circuitry are included on printed circuit board  27 . The pins  36  fit within the lampholders  15  which are part of the ballast subassembly  4 . The lamps  30  can be rolled into position in the lampholders in a conventional manner. Since the preferred embodiment of this invention employs instant start fluorescent lamps, it should be understood that instant start fluorescent lamps having a single pin on each base could also be employed with suitable lampholdrs. This invention could also be employed with preheat fluorescent lamps and a suitable preheat electronic ballast. 
     In this invention, only the first base  32  of each fluorescent lamp  30  is connected directly to the electronic ballast in ballast lampholder subassembly  4 . The opposite second base  34  and the pins  36  therein are connected to lampholders in a lampholder connector  50 . The preferred embodiment of this invention is intended to be used with multiple fluorescent lamps  30 , and in the four lamp version of this invention, the fluorescent lamps are paired so that for each pair of fluorescent lamps, the respective first base  32  is attached to the ballast and the respective second bases  34  of the two lamps in each pair are electrically commoned in the lampholder connector  50 . In the preferred embodiment of FIGS. 1-8, the pins  36  in the second base  34  of one lamp in each pair of lamps are connected to the corresponding pins  36  in the other lamp of that pair of lamps. For this invention, only the first bases  32  at the first end  38  of the lighting assembly will be energized to start the lamps. No current will flow through the pins  36  in the second bases  34  of the fluorescent lamp pairs until an arc is established between the opposite ends of each lamp  30 . By using an electronic ballast, such as the MULTILITE MUL120 manufactured and sold by Electrofab, Ltd., that is capable of operating fluorescent lamps of twice the length of the lamps  30 , it then becomes possible to common the second bases  34  through one of the lampholder connectors  50 . The electronic ballast used in ballast subassembly  4  is also capable of operating two separate pairs of fluorescent lamps, so the preferred embodiment employs two pairs or four lamps  30 . 
     With reference to FIGS. 9 and 10, ballast lampholder subassembly  104  and lampholder connector  150  are three lamp versions of the lampholder subassembly  4  and lampholder connector  50 , respectively. The ballast lampholder subassemblies  4 ,  104  and the lampholder connectors  50 ,  150  are fabricated and assembled so that the cost of the fluorescent lighting subassembly can be significantly reduced. By molding the lampholder cover  8  and the corresponding cover for the three lamp version  104  with integrally molded lampholders  15 , the cover can be used to simplify assembly. This is best appreciated by referring to FIG.  2 . The fluorescent lamp terminals  17  can be crimped to wires  20  and inserted into the lampholders  15  with the wires extending downward from the cover  8 . Opposite ends of these wires  20  can then be attached to the printed circuit board  27  either by soldering or by inserting terminals crimped to the wire ends onto pins soldered to the printed circuit board. For example, a receptacle, such as AMP Incorporated part number 61291, can be crimped to the end of each wire  20 , and it can be mated to a pin, such as AMP Incorporated part number 61137, previously soldered to the printed circuit board  27 . This approach simplifies hand wiring of the fluorescent lamp terminals to the ballast circuitry on the printed circuit board. Next, the printed circuit board can be positioned on the interior surface of the housing base  10 . If the housing base  10  comprises a stamped metal plate, the ballast circuit can be grounded to this base, which can in turn be attached by screws or other fasteners to the metal troffer  80  (FIG. 1) when the ballast lampholder subassembly  4  is placed in service. Power wires  26  are attached to the ballast circuitry by using a splicing terminal in a pocket  23  in the manner which was discussed previously with reference to FIG.  5 . After the internal components have been assembled in this manner, the housing base  10  can be snapped to the housing cover  8  to complete the assembly of the ballast lampholder subassembly  4 . 
     The integral ballast lampholder subassembly  4  and the lampholder  50  can be mounted on troffer  80  as shown in FIG.  1 . Troffer  80  is generally conventional in construction having a top wall  82 , two end walls  84  at the first and second ends of the lighting assembly and two side walls. Since the ballast lampholder subassembly  4  is mounted at an end of the troffer  80 , the four fluorescent lamps  30  can be mounted in the troffer on substantially equally spaced centerlines without the need for additional space between the two center fluorescent lamps to accommodate a conventional ballast. 
     With reference to FIGS. 1,  7  and  8 , the lampholder connector subassemblies  50  which are located at the opposite end of the troffer  80  include a molded housing with connector lampholders  51  molded to the housing in much the same manner as for the ballast lampholder subassembly  4 . Fluorescent lamp terminals  17  as previously described are inserted into the lampholders  51 . However, the terminals in the lampholder connector subassembly need not be connected to the ballast. These fluorescent lamp terminals  17  merely connect corresponding pins of multiple fluorescent lamps  30 . Therefore these fluorescent lamp terminals  17  can be joined by wires  57  extending between two terminals in different connector lampholders  51 . Each wire  57  joins two corresponding terminals  17  in two lampholders  51 . In the embodiment shown, two connector lampholders  51  are located at opposite ends of a connector base  53 . Terminal cavities  52  in each connector lampholder  51  open onto an open lower surface or trough  54  of the connector housing. The wire leads  57  extending between two spaced-apart lampholders  51  are disposed in this trough  54  on the underside of the lampholder base  53 . The wire leads  57  are held in the trough  54  by molded-in raised nubs that keep the wire leads tucked into the troughs  54  for wire management and to prevent the wire leads  57  from dangling out of the troughs  54 . The same basic approach shown for the two-lamp lampholder connector  50  can be used for a four-lamp lampholder. For both the two-lamp and four-lamp versions the same terminal subassembly comprising two fluorescent lamp terminals  17  connected by a wire lead  57  could be used, because the length of the wire lead  57  would be the same. 
     Lampholder connectors  50  also include mounting tabs  58  extending from opposite sides of the lampholders  51 . These tabs  58  can be inserted into slots (not shown) on the end walls  84  of the troffer  80  to mount the lampholder connectors  50  with connector lampholders  51  in alignment with the lampholders  15  on the ballast lampholder subassembly  4  at the opposite end of the lighting fixture assembly  2 . The two dual position lampholder connectors  50  shown in FIGS. 1 and 7 do not need to be connected to the ballast circuitry in the ballast lampholder subassembly  4  because the electronic ballast circuit used in this embodiment can be used to initiate and power two four foot lamps  30 . One of the dual lampholder connectors  50  connects the opposite ends of two side-by-side fluorescent lamps  30 . 
     A second embodiment of this invention is shown in FIGS. 9 and 10. This embodiment uses a three-lamp ballast lampholder subassembly  104  and a three-lamp lampholder connector  150 . The three-lamp ballast lampholder subassembly  104  includes a ballast circuit for use in a three-lamp lighting fixture, but in most other respects is constructed in the same manner as the four-lamp version. The principal difference is that the three-lamp ballast lampholder subassembly  104  includes a wire  105  that connects the three-lamp ballast lampholder subassembly  104  to the three-lamp lampholder connector  150  located at the opposite end of the fluorescent lamps in a three-lamp lighting fixture. This wire  105  is connected to the ballast lampholder subassembly  104  in substantially the same manner as to the lampholder connector  150 , and attachment of this wire will be discussed with reference to the lampholder connector  150 . The three-lamp lighting fixture thus can operate in much the same manner as that described in U.S. Pat. No. 5,720,546 which is incorporated herein by reference. 
     As shown in FIG. 10, lampholder connector  150  includes three lampholders  151  with two terminal cavities  152  in each lampholder  151 . The same terminals  17  are used in this three-lamp lampholder connector  150 . The lampholder connector  150  also includes two pockets  160  located adjacent to the terminal cavities  152  in each lampholder. In addition to the six pockets  160 , a seventh pocket  155  is located adjacent to the central lampholder. Each of these molded pockets is configured to receive a splicing terminal  56 , shown in FIG. 11, which in a preferred embodiment comprises a conventional terminal manufactured by AMP Incorporated as part number 62833-1. As shown in FIG. 10, a single bus wire  157  extends between opposite ends of the three-lamp lampholder  150 , and this single bus wire  157  extends through all of the pockets  155  and  160 . Each pocket includes slots on either side so that the bus wire  157  can be laced through the slots so as to span the corresponding pockets  155  and  160 . After the bus wire  157  has been inserted into each of the pockets, a splicing terminal  56  is inserted into each pocket. Each splicing terminal  56  includes two insulation displacement slots defined by opposed metal edges which engage the bus wire  157  to form a gas tight permanent electrical connection to the bus wire  157  in a conventional manner. In addition to the insulation displacement slots, each splicing terminal  56  also includes a poke-in terminal portion which can engage the stripped end of a wire when the stripped end is inserted into the poke-in terminal portion. Alternatively, a spade terminal may be attached to the stripped end of the wire and inserted into the poke-in terminal portion. 
     The poke-in terminal portion of each splicing terminal  56  is accessible through the open end of its corresponding pocket  160 . As shown in FIG. 11, fluorescent lamp terminals  17  located in the cavities  152  are each connected to the common bus wire  157  by a respective lead wire  161 . The stripped end of each lead wire  161  is inserted into the poke-in terminal portion of a corresponding splicing terminal  56  located in a pocket  160  adjacent to a corresponding lampholder cavity  152 . All of the fluorescent lamp terminals  17  in the three-lamp lampholder connector  150  are thus electrically connected to the single bus wire  157 . Therefore, all of the fluorescent lamp terminals  17  in the three-lamp lampholder connector  150  are electrically connected to each other. 
     The splicing terminal  56  in the seventh pocket  155 , which is also connected to the single bus wire  157 , is used to connect all of the fluorescent lamp terminals  17  in the three lampholders  151  to the ballast subassembly  104  located at the opposite end of the troffer in a three-lamp lighting assembly. A stripped end of wire  105  is inserted into the poke-in terminal portion of the splicing terminal  56  in the pocket  155 , and in this manner the wire  105 , extending the length of the lighting assembly, is connected to the bus wire  157  in the three-lamp lampholder connector  150 . The opposite end of the wire  105  can be connected to the ballast in the ballast subassembly  104  by using a similar splicing terminal  56 , not shown. 
     Each three-lamp lampholder connector  150  also includes slots  162  on opposite ends. These slots permit the bus wire  157  to extend beyond the ends of the lampholder connector  150 . These slots  162  are aligned with the bus wire  157  and facilitate efficient assembly of the three-lamp lampholder connector  150 . A series of three-lamp lampholder connector housings can be positioned end to end with slots  162  in alignment. A continuous wire can then be laced through troughs on the bottoms of the housings with the continuous wire extending through the slots  162 . A portion of the wire extending between each pair of adjacent housings can be cut, thereby severing the wire connection between the adjacent housings. In this way, separate lampholder connectors can be wired in an efficient manner. 
     The three-lamp version of this lighting assembly shown in FIGS. 9-11 differs from the two or four-lamp version because all of the fluorescent lamp terminals  17  in the three-lamp version of the lampholder connector  150  are electrically connected. Therefore, two terminals  17  connected to two pins in the same fluorescent lamp are electrically commoned in the three lamp version. For the two-lamp lampholder connector  50  of FIGS. 7 and 8, the terminals  17  which are connected to the same lamp are not electrically commoned. Instead, each fluorescent lamp terminal  17  in one lampholder  51  of the lampholder connector  50  is connected to corresponding terminals  17  having the same relative position in the other lampholder  51 . In other words, terminals on the right side of each lampholder are electrically connected together and terminals on the left side of each lampholder are electrically connected together, but right-side terminals are not electrically connected to left-side terminals. It should be understood, however, that all of the terminals  17  for the two-lamp version  50  could be connected to a single bus in the same manner as for the three-lamp lampholder connector  150  because the ballast need not be connected directly to an individual pin on lamps connected to the lampholder connectors. 
     The use of integrally molded lampholders  51  simplifies the assembly of the lampholder connectors  50  which are assembled in much the same manner as the lampholder connectors  150 . Terminals  17  previously connected to wires can be inserted into lampholder terminal cavities on the lower surface  53  in the same manner as for the ballast lampholder cover  8 . The use of splicing terminals with the three-lamp lampholder connector  150  has been previously discussed. 
     Although the use of integrally molded lampholders greatly simplifies assembly of both the ballast lampholder subassemblies and the lampholder connectors, it should be understood that some, though not all, of this improvement can be achieved by attaching separately molded lampholders to a molded cover or to the lampholder connector base. Although this variation adds an assembly step, it still uses the same basic approach to achieve the other advantages of this invention. This is but one of the minor changes that can be resorted to without departing from the scope of the invention defined by the following claims.