FIELD OF THE INVENTION 
   The invention pertains to adapters for allowing fluorescent lamps to be used with light fixtures designed for incandescent bulbs, and in particular to an adapter that is not removable by a consumer after it has been installed in an incandescent fixture. 
   BACKGROUND OF THE INVENTION 
   Incandescent lamps have been in use for over a hundred years, and remain in widespread use. They are relatively inexpensive to purchase and easy to replace. Fluorescent lamps use less energy than incandescent lamps. They are, however, initially more expensive to purchase than incandescent bulbs and more expensive to replace, and may not be as readily available as incandescent bulbs, which can be found at many retail locations. 
   Although fluorescent lamps are more energy-efficient, many light fixtures are designed only for standard incandescent light bulbs. To use a fluorescent lamp in such fixtures requires an adapter. Adapters for allowing fluorescent lamps to be used in place of incandescent lamps in such fixtures are known. Typically, such adapters include a housing that contains or can receive a fluorescent ballast, a socket for receiving the contact pins of a fluorescent lamp, and a threaded ring contact and a tip contact similar or identical to those on the base of a standard incandescent bulb, which allows the adapter to be simply screwed into a standard incandescent socket. 
   Typically, known fluorescent adapters can be removed from a standard incandescent socket just as easily as they can be installed. That is not normally a problem, but in some cases it is desirable to prevent the adapter from being removed after installation. For example, some manufacturers of fluorescent lamps are partners in ENERGY STAR®, a program sponsored by the U.S. Environmental Protection Agency to promote energy efficiency. Many manufacturers of electrical appliances are ENERGY STAR® partners, and many of the ENERGY STAR® partners offer rebates on qualified products. In those cases, it would defeat the purpose of the ENERGY STAR® program, and subject manufacturers to payment of unnecessary rebates, if the fluorescent adapter could be removed and the consumer could revert to incandescent bulbs. 
   There is a need for a fluorescent adapter that can be installed as easily as an incandescent light bulb but that cannot be removed after installation. The present invention meets that need. 
   SUMMARY OF THE INVENTION 
   In one of its embodiments, the present invention encompasses a fluorescent adapter, comprising a housing including a tip contact compatible with an electrical socket, a threaded ring contact compatible with the electrical socket, the ring contact surrounding the housing and rotatable with the housing when the housing is rotated in a first direction and not rotatable with the housing when the housing is rotated in an opposite direction, and a fluorescent ballast supported by the housing and having input electrodes in electrical contact with the tip contact and the ring contact, respectively, and output electrodes for removably receiving the contact pins of a fluorescent lamp. 
   In another embodiment, the invention encompasses a compact fluorescent lamp assembly, comprising a fluorescent lamp having contact pins, a housing including a tip contact compatible with an electrical socket, a threaded ring contact compatible with the electrical socket, the ring contact surrounding the housing and rotatable with the housing when the housing is rotated in a first direction and not rotatable with the housing when the housing is rotated in an opposite direction, a fluorescent ballast supported by the housing and having input electrodes in electrical contact with the tip contact and the ring contact, respectively, and output electrodes for removably receiving the contact pins of the fluorescent lamp, and an enclosure removably attached to the ballast for enclosing at least the fluorescent lamp. 
   In still another embodiment, the invention encompasses a fluorescent adapter, comprising a housing including a tip contact compatible with an electrical socket, a threaded ring contact compatible with the electrical socket, the ring contact surrounding the housing and rotatable with the housing when the housing is rotated in a first direction and not rotatable with the housing when the housing is rotated in an opposite direction, a fluorescent ballast supported by the housing and having input electrodes in electrical contact with the tip contact and the ring contact, respectively, and output electrodes for removably receiving the contact pins of a fluorescent lamp, and a drive member on the housing for engaging the ring contact when the housing is rotated in the first direction during insertion of the adapter into the electrical socket and for disengaging from the ring contact when the housing is rotated in the opposite direction, wherein the drive member comprises a disc having at least one tooth and the ring contact includes at least one arcuate slot for receiving the tooth when the housing is rotated in the first direction. 
   In a further embodiment, the invention encompasses a fluorescent adapter, comprising a housing including a tip contact compatible with an electrical socket, a threaded ring contact compatible with the electrical socket, the ring contact encircling the housing and freely rotatable relative to the housing when the housing is rotated in a first direction, and means for preventing relative rotation between the ring contact and the housing when the housing is rotated in a second direction opposite the first direction to insert the adapter into the socket. 
   In another aspect of the invention, the invention encompasses a method of non-removably inserting a fluorescent adapter into an electrical socket comprising the steps of providing a threaded ring contact surrounding and freely rotatable on an adapter housing, preventing relative rotation between the ring contact and the housing when the housing is rotated in a first direction to insert the adapter into the socket, and permitting free relative rotation between the ring contact and the housing when the housing is rotated in a second direction opposite the first direction. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. 
       FIG. 1  is a perspective view of an adapter according to the invention, in combination with a fluorescent ballast and a fluorescent lamp with an optional cover shown in phantom. 
       FIG. 2  is an exploded view of the combination of  FIG. 1 . 
       FIG. 3  is an exploded view of the adapter. 
       FIG. 4  is a cross-sectional view of the adapter according to the present invention, taken along the lines  4 — 4  in  FIG. 1 . 
       FIG. 4A  is a partial top plan view, taken along the lines  4 A— 4 A in  FIG. 4 . 
       FIG. 5  is a section view of the adapter, taken along the lines  5 — 5  in  FIG. 4 . 
       FIG. 6A  and  FIG. 6B  are partial section views, taken along the lines  6 A,B— 6 A,B in  FIG. 5 . 
   


   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, in which like numerals indicate like elements, there is shown in  FIG. 1  a compact fluorescent lamp assembly  10  comprising a fluorescent lamp  12 , a ballast  14 , and an adapter  16  according to the present invention. Fluorescent lamp  12  may be a fluorescent lamp in any of numerous configurations, including conventional helical, spiral, and U-shaped fluorescent lamps. An optional enclosure  18 , for enclosing at least the fluorescent lamp  12 , is also shown. Enclosure  18  may be clear or frosted, as desired. 
   As best seen in  FIG. 2 , fluorescent lamp  12  may be inserted in conventional fashion into ballast  14 , which includes two receptacles  20  for receiving contact pins  22  of fluorescent lamp  12 . In another embodiment, lamp  12  includes four contact pins  22 , and ballast  14  includes four matching receptacles  20 . Ballast  14 , receptacle  20 , and contact pins  22  may be conventional. Ballast  14  also includes a pair of contact pins  24  and receptacles  26  to connect ballast  14  to adapter  16 . The contact pins  22 ,  24  and receptacles  20 ,  26  serve to provide an electrical path from adapter  16  to lamp  12 . The number of contact pins  22 ,  24  and receptacles  20 ,  26  may be varied without departing from the scope of the invention. 
   Adapter  16  is shown in more detail in  FIG. 3 . Adapter  16  comprises a housing  28 , which is preferably made of plastic or other non-conducting material. Housing  28  is surrounded by a conductive ring contact  30 , which is free to rotate circumferentially around the barrel portion  32  of housing  28 . Housing  28  has a top plate  34  which supports receptacles  26 . Top plate  34  is inserted into the top opening  36  of housing  28  and may be held in place by friction fit, adhesive, or the like. 
   At the bottom of housing  28  is a drive member  38  in the form of a toothed disc. Drive member  38  has two projecting teeth  40 ,  42 , which project upwardly from its top surface and engage slots  56  in ring contact  30 , as will be explained more fully below. 
     FIG. 4  shows the elements of adapter  16  in cross section. Ring contact  30  is threaded on its outer surface  46  in the same manner as a conventional incandescent bulb. Similarly, at the bottom end of housing  28  is a tip contact  48 , also as found on a conventional incandescent bulb. Wires  50  and  52  provide an electrical path from ring contact  30  and tip contact  48 , receptively, to receptacles  26  in top plate  34 , which receive contact pins  24  of ballast  14 . 
   As seen in  FIG. 4A , the contact pin  24  and the receptacles  26  may be arranged in a keyhole slot configuration so that a slight twist releasably locks the ballast in place on housing  28 , and so that a slight twist in the opposite direction allows ballast  14  to be removed. The ballast input electrodes  24  include a shaft portion and a head portion, as shown in  FIG. 4A . When the ballast  14  is locked to the adapter  16 , the head portions engaae the receptacles  26  to prevent the ballast  14  from being separated (along a longitudinal direction) from the adapter  16 . It will be appreciated that one advantage of this locking “bayonet” style connection between the pins  24  and receptacles  26  is that it allows greater weight to be supported by the ballast  14  with the lamp assembly  10  in an inverted position (that is, with the lamp  12  and ballast  14  positioned below the adapter  16 ). For example, if a lamp shade (not illustrated) or other component were connected to the ballast  14 , the bayonet style connection would allow the ballast  14  to support the weight of the lamp shade while in an inverted position, while remaining firmly connected to the adapter  16 . In contrast, a conventional straight contact pin received in a conventional straight receptacle would be less capable of supporting substantial weight in an inverted position. 
   Drive member  38  may be fixedly attached to housing  28 , such as by eyelets  54 , adhesive, and the like. In this manner, while housing  28  is free to rotate inside ring contact  30 , drive member  38  will rotate with housing  28 . Optionally, drive member  38  may be integrally molded into housing  28 . 
   As best seen in  FIG. 5 , the bottom of ring contact  30  is provided with a plurality of arcuate slots  56 , which are arranged circumferentially around the bottom. Slots  56  may be holes through ring contact  30 , or may be notches or depressions in ring contact  30 . Slots  56  engage teeth  40 ,  42  in drive member  38 . 
   Referring together to  FIGS. 5 ,  6 A and  6 B, adapter  16  may be turned either clockwise, as represented by arrow  58 , or counter-clockwise, as represented by arrow  60 . When adapter  16  is rotated in the clockwise direction, housing  28  rotates freely within ring contact  30  until the edge of tooth  40  contacts the wall  62  of slot  56 . Continued movement of housing  28  in the clockwise direction will thereafter cause ring contact  30  to rotate with housing  28 . Thus, adapter  16  can be screwed into a conventional incandescent socket in the same manner as a conventional incandescent bulb. 
   However, when housing  28  is rotated in the counter-clockwise direction, in an attempt to remove adapter  16  from the socket, tooth  40  will not engage any of the slots  56 , but will move freely past slots  56 . Thus, once adapter  16  has been threaded into a socket, it cannot be removed. Instead, rotation of housing  28  in a counter-clockwise direction, as though to remove it, will simply result in movement of housing  28  within ring contact  30  while adapter  16  remains in place. 
   Drive member  38  may be punched or stamped to create projecting teeth  40 ,  42 , or the teeth  40 ,  42  may be integrally molded into drive member  38 . In one embodiment, drive member  38  and ring contact  30  may be conventional parts available from Well Sun Co., Ltd., of Taipei, Taiwan. 
   Optionally, additional pairs of projecting teeth  40 ,  42  may be circularly arranged on drive member  38  to engage additional slots  56  in ring contact  30 , providing increased stability and protection against breakage of one or more teeth. 
   In an alternative embodiment, the projecting teeth  40 ,  42  may be disposed on ring contact  30  to engage slots  56  circularly arranged on drive member  38 . 
   It should be understood that other techniques for permitting the ring contact to be threaded into a socket into one direction but not in the opposite direction can be used without departing from the scope of the invention. Thus, for example, instead of a drive member having projecting teeth and slots in the bottom of the ring contact, an eccentric drive technique could be used, whereby the barrel portion  32  and ring contact  30  engage each other only when the housing  28  is rotated in the clockwise direction, but do not engage each other when the housing is rotated in the counter-clockwise direction. Numerous other one-way drive and ratchet-type drive techniques can be used without departing from the invention. 
   The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.
A fluorescent adapter having a housing including a tip contact compatible with an electrical socket, a threaded ring contact compatible with the electrical socket, the ring contact surrounding the housing and rotatable with the housing when the housing is rotated in a first direction and not rotatable with the housing when the housing is rotated in an opposite direction, and a fluorescent ballast supported by the housing and having input electrodes in electrical contact with the tip contact and the ring contact, respectively, and output electrodes for removably receiving the contact pins of a fluorescent lamp. The adapter is easily inserted into the socket but is not removable after insertion.