Abstract:
A housing has an internally-threaded opening that opens through an external surface. A support has external threads that engage the internal threads. Radiation-emitting structure on the support emits a beam of radiation that propagates to a location remote from the housing. At the location, the beam has a width that is a function of the position of the support within the housing. According to a different aspect, a housing has an internally-threaded opening that opens through an external surface, the housing including thermally-conductive material with the internal threads thereon. A support has external threads that engage the internal threads, the support including thermally-conductive material with the external threads thereon. Radiation-emitting structure is provided on the support, and the thermally-conductive material of the support carries heat from the radiation-emitting structure to the external threads.

Description:
FIELD OF THE INVENTION 
     This invention relates in general to light fixtures and, more particularly, to thermal and optical control techniques for light fixtures. 
     BACKGROUND 
     Over the years, a variety of different types of light fixtures have been developed. Within a light fixture, radiation is emitted by a light bulb or some other type of radiation generator. Most light fixtures involve considerations of optical control of this radiation. In addition, most light fixtures involve considerations of thermal control relating to dissipation of heat emitted by the radiation generator. Although existing techniques for optical and thermal control have been generally adequate for their intended purposes, they have not been entirely satisfactory in all respects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention will be realized from the detailed description that follows, taken in conjunction with the accompanying drawing FIGURE, which is a partly exploded, sectional perspective view of a light fixture that embodies aspects of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The drawing FIGURE is a partly exploded, sectional perspective view of an apparatus that is a light fixture  10  embodying aspects of the invention. The light fixture  10  includes a base  12  and a housing  13 . The base  12  has a cylindrical opening  16 , and the housing  13  has a cylindrical projection  17  that is rotatably received within the cylindrical opening  16 . The housing  13  can pivot about a not-illustrated axis with respect to the base  12  through rotation of the projection  17  within the opening  16 . 
     The base  12  has a member  21  with the opening  16  at one end thereof. In the disclosed embodiment, the member  21  is made of aluminum, but it could alternatively be made of any other suitable material. The member  21  is generally cylindrical, except that a portion near opening  16  is tapered, and the outer end of that portion is rounded a cylindrical recess  22  extends axially into the member  21  from an end thereof remote from the opening  16 . The opening  22  has internal threads  23  near its outer end. 
     The base  12  also has a further member  26  with a generally cylindrical portion that is disposed within the recess  22  of the member  21 , and that has external threads  28  engaging the internal threads  23  on member  21 . In the disclosed embodiment, the member  26  is made of an electrically insulating material, such as a commercially-available plastic, but it could alternatively be made of any other suitable material. A cylindrical recess  27  extends axially into the member  26  from an inner end thereof. The outer end of the member  26  has a base or connector  31  of a type known in the art as an E26 or E27 type connector, or a medium “Edison” connector. In a known manner, the connector  31  has external threads  32  that are made of an electrically conductive material, as well as a button  33  that is made of an electrically conductive material. The button  33  is electrically isolated from the threads  32 . The connector  31  can thus be screwed into a standard socket for a standard light bulb. Although the disclosed connector  31  is a medium “Edison” connector, it could alternatively have any of a variety of other configurations, including but not limited to those known as a candelabra connector, a mogul connector, or a bayonet connector. 
     The housing  13  includes a member  42  that has the cylindrical projection  17  thereon. In the disclosed embodiment, the member  42  is made of aluminum, but it could alternatively be made of any other suitable material. The member  42  also has a further cylindrical projection  43  with external threads  44  thereon. The housing  13  includes a cylindrical sleeve  51  with a central cylindrical opening therethrough, and with internal threads  52  within the opening. The sleeve  51  is thermally conductive. In the disclosed embodiment, the sleeve  51  is made of aluminum, but it could alternatively be made of any other suitable material. At one end of the sleeve  51 , the internal threads  52  engage the external threads  44  on the member  42 . The housing  13  has a bezel  56  at an outer end remote from the member  42 . In the disclosed embodiment, the bezel  56  is made of aluminum, but it could alternatively be made of any other suitable material. The bezel  56  has a cylindrical projection  57  with external threads  58  thereon. The external threads  58  engage the internal threads  52  of sleeve  51  at a location near an outer end of the sleeve. The bezel  56  has a cylindrical opening  61  extending axially therethrough, and has a radially-inwardly extending annular flange  62  at the outer end of the opening  61 . 
     A lens  63  is mounted within the opening  61 , adjacent the flange  62 . In the disclosed embodiment, the lens  63  is a an optically transparent window made of glass with no optical power. However, the lens  63  could alternatively have some optical power. The lens  63  is made of a known type of durable glass, but it could alternatively be made of any other suitable material. 
     A resilient O-ring  67  is provided between the sleeve  51  and the cylindrical projection  43  on member  42 , and a further resilient O-ring  68  is provided between the sleeve  51  and the cylindrical projection  57  on bezel  56 . The O-rings  67  and  68  help to seal the housing  13  against moisture, so that the light fixture  10  can be used in outdoor applications. A cylindrical support  76  is disposed within the sleeve  51 , and has external threads  77  that engage the internal threads  51  of the sleeve. The support  76  is thermally conductive and, in the disclosed embodiment, is made of aluminum. However, the support  76  could alternatively be made of any other suitable material. 
     The support  76  has two spaced recesses  81  and  82  therein, on a side thereof facing the bezel  56 . If the bezel  56  is unscrewed and removed, a not-illustrated tool with two spaced prongs can be inserted into the sleeve  51 , and positioned so that the prongs each engage one of the recesses  81  and  82 . The tool can be rotated in order to rotate the support  76  with respect to the sleeve  51  of the housing. When the tool rotates the support  76  with respect to the sleeve  51 , the cooperating threads  52  and  77  cause the support  76  to move axially within the sleeve  51 . After adjustment of the position of the support  76 , the tool is removed, and the bezel  56  is re-installed on the sleeve  51 . 
     A light emitting module  86  is supported on the side of support  76  nearest the bezel  56 , between the recesses  81  and  82 . In the disclosed embodiment, the light emitting module  86  includes a semiconductor radiation generator and, more specifically, a light emitting diode (LED) that emits visible light. However, the light emitting module  86  could alternatively be any other suitable type of radiation generator, and could emit radiation in a spectrum other than the visible spectrum. When the support  76  is rotated in order to adjust its axial position within the sleeve  51 , the light emitting module  86  is moved closer to or further away from the opening  61  through the bezel  56 . This in turn increases or decreases the width of the light beam emitted through the bezel  56 , as measured at a location spaced outwardly from the light fixture  10 . 
     During normal operation, the light emitting module  86  produces heat. Most of this heat flows into the thermally-conductive support  76 , and through the support  76  to the sleeve  51 . Then, this heat flows through the sleeve  51  and is emitted into the ambient air surrounding the light fixture  10 . The cooperating threads  52  and  77  facilitate this transfer of thermal energy by providing a relatively large surface area of physical contact between the support  76  and sleeve  51 . In contrast, for example, if the engaging surfaces on the support  76  and sleeve  51  were purely cylindrical, the amount of surface area in direct contact between these two parts would be less than in the disclosed embodiment. 
     A power supply unit  91  is provided in the recess  27  within the base  12 . The power supply unit  91  is a type of device known in the art. For example, the power supply unit  91  can be a device of the type disclosed in U.S. Ser. No. 11/449,138 filed Jun. 8, 2006. The power supply unit  91  includes a flexible circuit board  92  that has electrical components mounted thereon, and that is bent to form a cylindrical sleeve. The flexible circuit board  92  can optionally be embedded in a cylinder of a thermally-conductive potting material, as indicated diagrammatically by a broken line  93  in the FIGURE. The power supply unit  91  has a one pair of wires  96  that projects from one end and that are respectively electrically coupled to the threads  32  and the button  33  of connector  31 . 
     The power supply unit  91  also has a further pair of wires  97  that projects from the opposite end. The wires of the pair  97  extend through openings in the members  21  and  42  and the support  76 , and are each electrically coupled to the light emitting module  86 . The wires of the pair  97  each have a length that is sufficient to accommodate rotational and axial movement of the support  76  within the sleeve  51 . In the disclosed embodiment, the power supply unit  91  is designed to receive 120 volt, 60 Hz alternating current (AC) power through from the connector  31 , and to convert this power into a suitable signal for driving the light emitting module  86 . The signal supplied to the light emitting module  86  may be a direct current (DC) voltage, or may be a pulse width modulated (PWM) signal of a type known in the art. 
     Although a selected embodiment has been illustrated and described in detail, it should be understood that a variety of substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the claims that follow.