Abstract:
Lampholders to be used with cold cathode fluorescent lamps of the type that do not require heated internal filaments. A lamp pin contact to engage one of the two lamp pins at each end of the lamp provides the electrical circuit between a high voltage ballast and the gas within the lamp. A lamp retainer device engages one of the lamp pins and cooperates with one lamp pin contact to support the lamp. The device may take the form of one or more cantilever mounted insulating or conductive arms, a flat or spring wire form or may be made of compressible material. A further form of lampholder uses a spring loaded contact to engage the lamp pins of a fluorescent lamp and to make contact with a single power conductor.

Description:
This application is a continuation-in-part of U.S. application Ser. No. 09/026,077 filed Feb. 19, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to lampholders for electrical lamps, and more particularly to lampholders to mechanically support and provide electrical power to fluorescent lamps. 
     2. Description of the Prior Art 
     Originally, fluorescent tube lamps were cylindrical glass enclosures or envelopes which contained an ionizable gas. A tungsten filament located at each of the two tube ends required a low voltage from a ballast or “starter” to heat the filament to incandescence to create thermionic emissions so that enough ions were created to ionize the gas. The voltage from the ballast was applied to the filaments via two metallic lamp pins which extended out of each end of the glass tube envelope. The two lamp pins at each end were engaged by lampholders at each end which provided mechanical support and electrical power to the fluorescent lamps. 
     Later, fluorescent lamps called “cold cathode” lamps were developed that eliminated the need to heat the filament. Instead, a voltage, in the order of 1300 volts, produced by a high-voltage ballast, was applied to the filament to force a sufficient number of tungsten ions from the filament to ionize the gas for ignition However, since the pins also serve with the lampholders as mechanical supports for the fluorescent lamp, and in view of the large number of installed double-contact fluorescent lampholders, a need for fluorescent lamps with two lamp pins at each end continues to exist. Some manufacturers applied an electrical shunt across the two lamp pins at each lamp end, in the belief that the high energizing voltage would need to be evenly distributed across each of the filaments to cause an even dispersion of ions. 
     FIGS. 1 and 2 show a prior art fluorescent lampholder  10  and the manner in which it was connected to an electrical source. A body  12  fabricated of phenolic, rubber or a suitable plastic is arranged to be placed in a housing, at the ends of a reflector or other similar mounting (not shown). Body  12  has a channel  14  with an entry slot  16  leading from outside body  12  into channel  14 . Placed in the open back of body  12  are two lamp pin contacts  18  each intended to engage one of the fluorescent tube pins (not shown) in their notches  22  in the upper portion  20  of lamp pin contacts  18 . The lamp pin contacts  18  are assembled to the interior wall of body  12  by fasteners (not shown) extending through an aperture  24  in each of the lamp pin contacts  18 . A shunt bar  26  is coupled between the lamp pin contacts  18 . The bottom portion  28  of lamp pin contacts  18  are bifurcated as at  30  and provide two coupling tongues  32  which make contact with the bared end of an insulated conductor (not shown). Tongues  32  act as one-way clutches allowing the conductor ends to be inserted but not withdrawn while making electrical contact with such bare conductor ends. A cover  34  of insulating material covers the back of the body  12  and is held in place by a staple  36 . 
     A ballast  40 , coupled to the lines  38  from a 120 Volt AC supply  37  at one end, is coupled to shunt  26 A which spans lamp pin contacts  18 A,  18 B and shunt  26 B which spans lamp pin contacts  18 C,  18 D as shown in FIG.  2 . Within the fluorescent lamp  42  tube, at one end thereof is a filament  44  connected across lamp pin contacts  18 A,  18 B and at the other end is a filament  46  connected across lamp pin contacts  18 C,  18 D. 
     To use the lampholder  10 , a fluorescent lamp (not shown) would be turned so that its lamp pins at one end are positioned one above the other and the lamp pins made to enter slot  16  and moved towards the bottom of body  12 . Once the lamp pins are aligned with the channel  14 , the lamp is rotated until each of the lamp pins enters the notch  22  of its associated lamp pin contact  18 . The tapered lead-ins to each of the notches  22  from above and below assure that the lamp pins enter the notches  22 . The resilience and shape of the portion  20  allows the portion  20  to be deflected as the lamp pins move into position in the notches  22  and return to grip the lamp pins once they are in their associated notches  22 . A similar lampholder  10  is positioned at the opposite end of the lamp to engage the lamp pins thereat. 
     With further improvements to the lamp and electronic ballast no filament is needed. Currently, fluorescent lamps are manufactured to work in either a hot cathode mode or a cold cathode mode. 
     SUMMARY OF THE INVENTION 
     The instant invention overcomes the difficulties noted above with respect to prior art cold cathode fluorescent lamp lampholders by eliminating the shunt and by eliminating one electrical lamp pin contact in the lampholder while retaining the ability to mechanically support the fluorescent lamp and couple it to a source of AC electrical power. This further negates the belief of evenly dispersed voltage across the filament. To retain the fluorescent lamp in place one of the customary lamp pin contacts is replaced in each of the lampholders with one or more resilient retaining arms to engage one of the fluorescent lamp pins. The other of the two lamp pins is engaged by the notch of an associated lamp pin contact. The resilient retaining arms also insure that the other lamp pin will remain seated in the notch of the lamp pin contact. The retaining arm may be made of an insulating material or fabricated of a material and in a form such that it provides its own spring forces or is provided with suitable spring members. It may also be fabricated of metal strips or metal spring stock to provide the desired spring forces. However, the retaining arm is not connected to a source of AC power. 
     A compression spring member may also be used to urge an electrical contact member into contact with both of the lamp pins of an inserted fluorescent lamp; This spring member is coupled to a contact to which an electrical conductor may be fastened to provide electrical power to the lamp. The compression spring may be compressed to initially place the lamp in the lampholder and thereafter allowed to expand to maintain the contact between the lamp pins of the lamp and the contact. It is an object of the invention to provide a lampholder for fluorescent lamps. 
     It is an object of the invention to provide a lampholder for cold cathode fluorescent lamps. 
     It is an object of the invention to provide a lampholder for cold cathode fluorescent lamps which operate with high-voltage electronic ballasts. 
     It is still a farther object of the invention to provide a lampholder for cold cathode fluorescent lamps which is simpler and has fewer parts than prior art fluorescent lampholders. 
     It is yet another object of the invention to provide in one form a lampholder for fluorescent lamps which eliminates the shunt member and replaces one conductive pin engaging assembly with a lamp retaining device which carries no current and in another, uses a spring operated plunger to retain the lamp. 
     Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principles of the invention, and the best mode which is presently contemplated for carrying them out. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings in which similar elements are given similar reference characters: 
     FIG. 1 is an exploded, lower left front perspective view of a fluorescent lampholder constructed in accordance with the teachings of the prior art. 
     FIG. 2 is a schematic, wiring diagram of the device of FIG.  1 . 
     FIG. 3 is an upper left, perspective view of the front of a lampholder housing of the instant invention. 
     FIG. 4 is an upper left, perspective view of the back of the housing of FIG. 3 with the back cover removed so that the details of a lamp retaining device therein can be appreciated. 
     FIG. 5 is an upper left, perspective view of the back of the housing as shown in FIG. 4 showing a different form of lamp retaining device. 
     FIG. 6 is an upper left, perspective view of the back of the housing as shown in FIG. 4 showing yet another form of lamp retaining device. 
     FIG. 7 is an upper left, rear perspective view of the back of the housing as shown in FIG. 4 showing still a further form of lamp retaining device. 
     FIG. 8 is an upper left, perspective view of the back of the housing as shown in FIG. 4 showing yet another form of lamp retaining device. 
     FIG. 9 is an upper right, perspective view of the lamp retaining device of FIG.  8 . 
     FIG. 10 is an upper left, perspective view of the back of the housing as shown in FIG. 4 showing another form of lamp retaining device. 
     FIG. 11 is an upper left, perspective view of the back of the housing as shown in FIG. 4 showing a further form of lamp retaining device. 
     FIG. 12 is a lower left, perspective view of the lamp retaining device of FIG.  11 . 
     FIG. 13 is an exploded, lower left front perspective view of a further form of fluorescent lampholder constructed in accordance with the concepts of the invention. 
     FIGS. 14 to  18  show alternative forms of the contact member shown in FIG.  13 . 
     FIG. 19 is a fragmentary, side elevational view, partly in section, showing the assembled components of FIG. 13 in a position to install or remove a fluorescent lamp. 
     FIG. 20 is a fragmentary, side elevational view, partly in section, showing the assembled components of FIG. 13 once a fluorescent lamp has been properly seated in the lampholder. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to FIGS. 1,  3  and  4 , the details of the fluorescent lampholder  110  can be described. Body  112  is similar to body  12  except that lower body portion  111  has only one wire lead entrance  13  as compared to the two wire lead entrances  13  of the lampholder  10  of FIG.  1 . Bodies  12  and  112  are fabricated by molding or casting from insulating materials such thermosetting or thermoplastic materials, Bakelite or the like. Each wire lead entrance  13  receives the two cantilever tongues  32  of a single lamp pin contact  18 . The ends of the tongues  32  rest against the floor  15  of the wire lead entrance  13  and act as one way clutches. The bared end of an insulated conductor (not shown) is advanced along the floor  15  of wire lead entrance  13  and displaces the tongue  32  away from floor  15  and thus establishes electrical contact. Any attempt to withdraw the conductor causes the edge of tongue  32  to bite into the bared metal of the conductor and prevent withdrawal of such conductor. The two tongues  32  permit multiple conductors to be used, as in daisy-chain wiring of multiple lampholders. The second position in body  112  for a wire lead entrance is covered as at  117  (see FIG.  3 ). A set of slots  123 , one on each side of lower body portion  111  permits the lampholder  110  to be mounted in a fixture, housing or the like (not shown). 
     Upper body portion  121  has a central cavity  25  which contains a central hub  27  to define the channel  14  thereabout. The diameter of the central hub  27  is slightly less than the spacing between the two lamp pins at each end of the fluorescent lamp. Central hub  27  has a medial slot  29  in line with slot  16 . The installation of a fluorescent lamp (not shown) to the lampholder.  110  would proceed as follows. The lamp is rotated until both of its lamp pins are aligned with slots  16  and  29 . The lamp is now lowered into the lampholder  1   10  until the lamp pins are positioned in diametrically opposed positions just beyond the periphery, of central hub  27 . The lamp is now rotated to a position where the lamp pins of the lamp are transverse to the slot  29 . In the prior art device of FIG. 1, the lamp pins each come to rest in the notches  22  of one of the lamp pin contacts  18 . The same thing occurs at the opposite end and the fluorescent lamp is now connected and supported. 
     In the lampholder  110  of FIG. 4, one of the lamp pins engages a lamp pin contact  18  and is seated in its notch  22  (not visible) as is true of the prior art devices of FIG.  1 . Thus, there is the desired electrical contact between the bared end of an electrical conductor (not shown) inserted in wire entrance  13  and one lamp pin of the fluorescent lamp at each end. The support of the fluorescent lamp at each end may be provided by the device of FIG. 4 or the other devices disclosed herein and described below. Two cantilever mounted arms  150  are mounted adjacent the outer periphery of the left segment of hub  27  at each end of the fluorescent lamp to grip the other lamp pin between the rounded leading edges  152  of the arms  150 . The displacement lobes  153  when engaged by the fluorescent lamp pin as it is turned in the channel  14  causes the outward defection of the arms  150  to permit the lamp pin to be positioned between the rounded leading edges  152  as the arms  150  return to their initial position after the lamp passes the lobes  153 . FIG. 5 shows a lampholder  130  which employs a single cantilever mounted arm  154  with two displacement lobes  156  and  158  which causes the outward deflection of arm  154  as the lamp pin is rotated into position adjacent the outer surface of hub  27  and permit the arm  154  to return to its initial position once the lamp pin is positioned in recess  159 . Thus, the fluorescent lamp pins are held between notch  22  of a lamp pin contact  18  and recess  159  of arm  154 . 
     FIG. 6 shows a lampholder  160  which also employs a single cantilever mounted arm  162  which engages a lamp pin of an inserted fluorescent lamp in a recess  161  between two displacement lobes  164  and  166 . The leading edge  168  when engaged by a lamp pin deflects the arm  162  outwardly away from hub  27 . The engagement of a lamp pin with the portion  169  of the arm  162  similarly deflects the arm  162 . The arm  162  returns to its initial position once the lamp pin is within recess  161 . The arm  162  has a base  163  with slots  165  in its sides which engage the tabs  167  formed on the inside surface  170  of the wall defining upper body portion  121  and a central interior wall  172 . 
     In FIG. 7, a lampholder  180  is shown which uses a single cantilever mounted arm  182  similar to arm  162  but made of metal spring stock instead of molded of a plastic or rubber material. Arm  182  has displacement lobes  184  and  186  with a recess of  187  therebetween. Depending upon the direction in which the fluorescent lamp is turned as the lamp pins are moved into channel  14 , the engagement between a lamp pin and one of the lobes  184  and  186  causes the arm  182  to be outwardly deflected away from the surface of hub  27 . When the lamp pin is positioned in the entrance to recess  187 , the arm  182  is permitted to return to its initial position with the lamp pin fully in recess  187 . The lead-in  188  and the arm  182  itself provide for the displacement of the-arm  182  by engagement with a rotating lamp pin. The end section  183  of arm  182  is positioned between raised pad  190  and tab  192  on the interior surface  170  of the wall defining upper body portion  121 . Adjacent the knee  185  of arm  182  is a pad  194  on the central interior wall  172 . Since the arm  182  is not connected to a power supply conductor, it does not electrically affect the fluorescent lamp inserted into the lampholder  180 . 
     A substantially closed spring metal band  202  (see FIGS. 8 and 9) is used in place of the cantilever mounted displaceable arms  162  of FIG. 6 and 182 of FIG.  7 . Metal band  202  has two linear, inclined sections  204 , 206  whose end portions are bent inwardly with radiused bends to form displacement lobes  208  and  210 , respectively, with a recess  209  between them. The ends of the lobes  208  and  210  grip the lamp pin in the recess  209 . The band  202  is placed on a shelf  212  on interior wall  170  and against a block  214  on the roof of chamber  25 . The lamp pin displaces the ends of the band  202  by contact with displacement lobes  208 , 210  until the pin rests in the recess  209  and is engaged by the ends of the band  202 . 
     A length of resilient wire is used as the lamp retaining arm  222  in the lampholder  220  shown in FIG.  10 . The arm  222  has a first linear portion the end portion  232  of which is wound about a post  234  and the other end of which is bent at an acute angle to give a displaceable lobe  228 . A second linear portion  226  has an end  236  wrapped about a post  238  and a second end bent to form a displacement lobe  230 . A pin recess  227  is formed between lobes  228  and  230 . Arm  222  is displaced by the lamp pin engaging either of the lobes  228 , 230  and returns to its initial condition once the lamp pin enters recess  227 . 
     A different type of lamp retainer device is shown in FIGS. 11 and 12. The lampholder  240  makes use of a lamp retaining device  242  made of a compressible material which is compressed when the lamp is installed and expands thereafter to grip the lamp pins. The device is generally K-shaped and has slots  244  and  246  in it shorter marginal faces to leave a vertical bar  245  along its back face. A V-notch  248  is formed in the front face providing a pin recess  247 . The remaining portions of the front face provide lead-in surfaces  250 , 252 . The inner wall  170  is formed with two L-shaped arms  254 , 256  the shorter member of each  258 , 260 , respectively, facing one another. The device  242  is positioned with member  258  in slot  244  and member  260  in slot  246 . The lamp pin when it contacts lobes  250  and  252  compresses the lobe until the pin enters recess  247  at which time the compressed lobe  250  and  252  expands to hold the lamp pin in the recess  247 . 
     Thus, there have been shown resilient lamp retainer devices which cooperate with lamp pin contacts to support a fluorescent lamp in a lampholder. These devices may be cantilever mounted arms of plastic or spring metal, flat spring metal or spring wire forms or compressible material. The devices are displaced in some manner as the lamp is installed and then return to securely grip a lamp pin. 
     Turning now to FIGS. 13 to  20  a further form of lampholder  300  for fluorescent lamps and employing a single element to engage both lamp pins contact is disclosed. The body  302  has bore  304  from front face  306  to a generally open parallel rear face  308 . The bore  304  is enlarged from a point between front face  306  and rear face  308  and extending to rear face  308 . The transition from bore  304  to the enlarged bore portion. 310  provides a step  312 . Placed within bores  304  and  310  is a plunger member  314  having a generally cylindrical shape extending from a front surface  316  to a rear surface  318 . Adjacent rear surface  318  is an external annular ring  320  which can engage step  312  to prevent plunger member  314  being drawn out of body  302  through front face  306 . Plunger member  314  has a first diameter bore  322  and a larger second diameter bore  324  concentric with the first diameter bore  322  and in communication with it. The transition from bore portion  322  to bore portion  324  produces a step  326 . 
     A rear housing member  330  is joined to body  302  as with threaded fastener  332  to complete the housing of lampholder  300 . Rear housing member  330  has an inside surface  334 , an outside surface  336 , a bottom wall  338  and a side wall  340 . A hub  342  projects inwardly from inside surface  334  and is positioned in the upper portion of rear housing member  330 . A boss  344  having an aperture  346  allows fastener  332  to pass through rear housing member  330  to mate with a boss on inner surface  309  of body  302  (not shown). A first rib  348  extends between hub  342  and boss  344  and a second rib  350  extends between boss  344  and bottom wall  338 . A cantilevered extension  352  of second rib  350  extends at an angle to the longitudinal axis of the rear housing member  330 . A second hub  354  extends between the main portion of second rib  350  and the extension  352 . An opening  356  in bottom wall  338  provides access to the region of the rear housing member adjacent extension  352 . 
     A first electrical contact  360  is made of a resilient, flexible metal such as copper, a copper alloy such as beryllium copper or the like. A first contact portion  362  is bent at an acute angle from the longitudinal axis of first electrical contact  360  for engagement with a portion of the outer surface of hub  342  and with the last turn  374  of compression spring  370 . A bridge portion  364  of contact  360  permits the contact  360  to pass around a portion of the surface of boss  344 . Tongue  368  is formed by bending contact  360  as at  366  to an acute angle to the longitudinal axis of contact  360 . When contact  360  is assembled to rear housing member  330 , the bend  366  will extend between hub  354  and the joiner of second rib  350  and extension  352 . Tongue  368  will operate in the same manner as tongues  32  described above with respect to FIG.  1 . An insulated conductor  380  having a portion of the insulation removed to expose the central conductor  382  is inserted through opening  356  in bottom wall  338  and between the free edge of tongue  368  and the inside of side wall  340 . 
     A second electrical contact  390  in the form of a thin metal disk is proportioned to fit within bore portion  324  in plunger  314  and comes to rest against step  326 , thus bridging bore  322 . In this manner the two lamp contact pins  274  of an end cap  272 , on either end of fluorescent lamp  270  can be engaged at the same time. 
     A compression spring  370  extends from a first turn  372  to a last turn  374 . The last turn  374  fits over a portion of the outer surface of hub  342  and engages first contact portion  362  of first contact  360 . The first turn  372  engages the second contact  390 . Accordingly, a current path is established from a power supply conductor  380 , whose bared central conductor  382  engages tongue  368  of first contact  360 , through first contact  360  to the last turn  374  of compression spring  370 , the compression spring  370  itself to the second contact  390 , because of the engagement of first turn  372  with second contact  390 , to the lamp pins  274  of an inserted lamp  270 . 
     In order to use lamp holder  300 , the contact pins  274  of one end of the lamp  270  must be placed in a fixed lampholder (not shown). The plunger  314  is depressed into the body  302  so that the lamp pins  274  at the opposite end of lamp  270  can enter bore  322 . The compression spring  370  is compressed. Once the lamp pins  274  are in place, the plunger  314  is released and the expanding spring  370  pushes the front face  316  of plunger  314  towards end cap  272  and causes second contact  390  to engage the lamp pins  274 . To remove lamp  270 , the plunger  314  must be depressed. 
     The second contact  390  shown in FIGS. 13,  19  and  20  is a thin, flat circular disk but may take other shapes and dimensions. FIG. 14 shows a second contact  400  which is thin, flat, circular disk with a central aperture  402  therethrough. The aperture  402  has a width such that remainder of disk  400  can engage both lamp pins at one end of a lamp. The second contact can be a thick, flat, circular disk  404  as shown in FIG.  15 . The faces of disk  404  are plane but may have a pocket or indentation extending inwardly from one face as shown by indentation  408  in contact  406  shown in FIG. 16 or conical indentation  412  in contact  410  as shown in FIG.  17 . The lamp pins  274  will seat on the inclined or flat surfaces of the disks based upon their relative dimensions due to spring  370 . FIG. 18 shows a conical contact  414  with a triangular recess  416 . 
     While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred embodiments, it will be understood that various omissions and substitutions and changes of the form and details of the devices illustrated and in their operation may be made by those skilled in the art, without departing from the spirit of the invention.