Abstract:
A heated lamp is provided having a lamp housing, a lens, a thermal reflector, a heating wire, at least one insulator, a light bulb, and a thermostat. The lens is affixed to the housing defining a chamber there between. The thermal reflector is provided in the housing and is spaced from the lens. The heating wire is provided between the reflector and the lens. The at least one insulator is associated with the reflector and is configured to support the heating wire circuitously about the reflector and operative to heat the lens responsive to electrical current being delivered through the wire. The light bulb is carried by the housing between the lens and the reflector. The thermostat is electrically coupled with the heating wire operative to regulate temperature of the heating wire responsive to electrical current being delivered through the wire. A heated light bulb assembly is also provided.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure pertains to heated lamps and heated light bulb assemblies for lamps. More particularly, this disclosure relates to apparatus for melting snow and ice and removing condensation from lenses of lights and lighting systems for mobile and stationary applications. 
       BACKGROUND OF THE INVENTION 
       [0002]    Techniques are known for heating lamps and lighting systems. One technique involves providing a heating wire on a back surface of a cover element provided over a vehicle light. However, such a system does not necessarily provide thermal protection for overheating. Secondly, such a system does not necessarily provide a lens heater contained within a lamp housing spaced proximate a thermal reflector. Thirdly, such a system does not necessarily provide an ability to modify an existing lamp by merely replacing an existing lamp bulb with a bulb assembly that heats the lens sufficient to melt snow and/or ice from the lens. Finally, the recent adoption of LED lighting systems, which generate very little heat, increases the problem of snow and ice accumulating on the lens of such a lighting system. Accordingly, improvements are needed to better enable removal of ice, snow and condensation from lenses of lights and lighting systems. 
       SUMMARY OF THE INVENTION 
       [0003]    Lamps, lights and bulbs are provided with a heating wire that heats a lens provided between a respective bulb and an environment including inclement weather that can cover the lens with snow, ice, or vapor. By heating the lens, accumulation of snow, ice, or vapor is mitigated or eliminated from a surface of the lens, thereby enabling light to transmit through the lens. Applications include lamps and bulbs on conveyance devices, including vehicles, boats, planes, and trains, as well as sedentary structures, such as lamp posts, street lights, railroad crossing markers and lights, and airport ground and runway lighting systems. 
         [0004]    According to one aspect, a heated lamp is provided having a lamp housing, a lens, a thermal reflector, a heating wire, at least one insulator, a light bulb, and a thermostat. The lens is affixed to the housing defining a chamber there between. The thermal reflector is provided in the housing and is spaced from the lens. The heating wire is provided between the reflector and the lens. The at least one insulator is associated with the reflector and is configured to support the heating wire circuitously about the reflector and operative to heat the lens responsive to electrical current being delivered through the wire. The light bulb is carried by the housing between the lens and the reflector. The thermostat is electrically coupled with the heating wire operative to regulate temperature of the heating wire responsive to electrical current being delivered through the wire. 
         [0005]    According to another aspect, a heated light bulb assembly is provided having a bulb, a thermal reflector, a heating wire, and a thermal resistor. The bulb has a base configured to be received in a socket of a light fixture. The thermal reflector is carried by the base. The heating wire is provided along an inner surface of the reflector having end portions received within the base and electrically coupled with bulb contacts provided in the base. The thermal resistor is electrically coupled with the heating wire operative to regulate temperature of the heating wire responsive to electrical current being delivered there through. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Preferred embodiments of the disclosure are described below with reference to the following accompanying drawings. 
           [0007]      FIG. 1  is an exploded perspective view from above of a heated vehicle tail light assembly according to one aspect. 
           [0008]      FIG. 2  is a front elevational view of the heated vehicle tail light assembly of  FIG. 1  with the lens removed for viewing and not showing the electric cable wiring. 
           [0009]      FIG. 3  is side elevational view of the heated vehicle tail light of  FIGS. 1 and 2  with the lens removed. 
           [0010]      FIG. 4  is a perspective view from above of a heated light bulb assembly according to another aspect. 
           [0011]      FIG. 5  is a side elevational view of the heated bulb assembly of  FIG. 4 . 
           [0012]      FIG. 6  is a plan view of the heated light bulb assembly of  FIGS. 4-5 . 
           [0013]      FIG. 7  is a side elevational view of the heated bulb assembly of  FIG. 7 . 
           [0014]      FIG. 8  is an exploded perspective view from below of the heated light bulb assembly of  FIGS. 4-7 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
         [0016]    In  FIG. 1 , a representation of an illustrative heated lamp in the form of a heated tail light assembly is shown and identified by reference numeral  10 . More particularly, heated light assembly, or lamp  10  in one implementation is realized by a heated tail light assembly that is affixed to a rear surface or bumper of a vehicle, such as a truck or trailer (not shown). An electrical wiring harness (not shown) from the vehicle provides power to operate the light and heat the light assembly in an effort to remove presence of ice in the form of snow, graupel, hail or frost from a lens surface on the tail light assembly. Optionally, heated lamp  10  can be any of a number of lamps or lights, including side marker lights, head lights, cab lights, brake lights, or any other form of light on any type of conveyance or vehicle including ATVs, snowmobiles, boats, planes, cars, trucks, trains and other forms of transportation requiring a lens heater for removing accumulated snow and/or ice on operating lights associated with the conveyance. Furthermore, heated lamp  10  can be used on other lighting systems including sedentary structures, such as lamp posts, street lights, railroad crossing markers and lights, and airport ground and runway lighting systems. Furthermore, the embodiment depicted in  FIGS. 4-8  can also be used on such lighting systems. 
         [0017]      FIGS. 1-3  show a tail lamp implementation for heated lamp  10  suitable for use on the rear bumper of a tractor trailer, a vehicle bumper, or a rear body surface. As shown in  FIG. 1 , a lens heater  12  is provided within a chamber, or cavity  15  and is operative to heat a lens  16  in order to remove snow, ice or condensation that has accumulated on lens  16  and might otherwise obstruct light transmission through lens  16 . A thermal, or radiant reflector  18  is received within a lamp housing, or body  20 . A lamp assembly  14 , including a lamp socket  22  and a lamp bulb  24 , are then mounted to housing  20 , in front of reflector  18 . A heating wire  28  of lens heater  12  is then mounted to reflector  18  and lens  16  is secured to housing  20 , encasing respective components therein. In assembly, face portion  26  of lens  16  transmits light from bulb  24 , as well as heat from bulb  24  and heated wire  28 . Lens  16  is secured to housing  20  with a pair of snap-fit complementary flanges  34  and  36 , respectively. Lens  16  and housing  20  can optionally be secured to housing  20  with a plastic weld, or using complementary threaded rim portions on lens  16  and housing  20 . Optionally, a lens retainer ring (not shown) can be used to secure lens  16  to housing  20 . Further optionally, fasteners can be used to secure lens  16  to housing  20 . 
         [0018]    As shown in  FIG. 1 , lamp socket  22  includes a pair of wings, or arms  38  and  40 , each having a respective aperture  42  and  44 . Wing arms  38  and  40  are made from a rubber material. Integrally molded bosses  64  and  66  are provided on back wall  32  of housing  20 , each including an integrally formed stud, or post  68  and  60 , respectively. According to one construction, housing  20  (including bosses  64  and  66  and pins  68  and  70 ) are formed from injection molded plastic. Optionally, any suitable structural material can be used including metal or composite materials. In assembly, pins  68  and  70  are received through apertures  42  and  44  with an interference fit, wherein the rubber of wings  38  and  40  is urged open to receive pins  68  and  70  in a tight fit-up, as shown in  FIGS. 1 and 2 . In assembly, an aperture  46  in reflector  18  provides clearance for boss  64 . Likewise, a cutout portion  48  in reflector  18  provides clearance for lamp socket  22  when received within housing recess  62 . 
         [0019]      FIGS. 1 and 2  show heating wire  28  configured in a serpentine, or circuitous pattern within lamp  10  and affixed in spaced-apart and fixed relation to a front reflective surface  30  (see  FIG. 1 ) of reflector  18 . More particularly, an array of spaced-apart thermal insulating studs, or isolators  50 ,  52 ,  54 ,  56 ,  58  and  60  are mounted to reflector  18 . In one case, each stud is made from ceramic material and has a stepped-down diameter (not shown) on a proximal end abutting with reflector  18 , and reflector  18  has a complementary aperture through which the stepped-down diameter of the stud is received and secured with a threaded faster (within a complementary threaded bore in the stud). Optionally, each stud can be affixed with adhesive or cement to surface  30  of reflector  18 . Each stud  50 ,  52 ,  54 ,  56 ,  58  and  60  includes a slot, or wire slit  61  in a distal end and oriented to support a segment of heating wire  28  in the depicted serpentine configuration. Heating wire  28  comprises a circuitous wire carried in conformably spaced and proximate relation from a thermally and optically reflective surface  30  of the reflector  18 . 
         [0020]    Lamp socket  22  and lens heater  12  of  FIG. 1  receive a supply of DC electric current from an electrical cable  71  led from a vehicle wiring harness (not shown). Cable  71  has an insulated outer cover with three conductive wires  73 - 75  comprising respectively a ground wire, a positive charge (+) tail light wire, and a blinker wire  75 . Ground wire  73  electrically couples with thermistor  29  on wire  28  and lamp socket  22  via a y-splitter. Tail light wire  74  electrically couples with an opposite end of heating wire  28  (than thermistor  29 ) and lamp socket  22  via a y-splitter. Blinker wire  75  electrically couples with lamp socket  22 . In one case, an insulating cover of cable  71  is stripped back and individual wires  73 - 75  are fed through three individual ports in an integrally molded port  72  of housing  32 . An end portion of insulating cover for cable  71  (and neighboring portions of wires  73 - 75  are then affixed to port  72  by inserting epoxy into cavities provided on both sides of port  72 , capturing cable  71  and wires  73 - 75  therein. 
         [0021]    Reflector  18  of  FIGS. 1 and 2  is a reflector of both light and thermal (radiant) energy. In one case, reflector  18  is made from injection molded plastic that receives a layer of chrome plating on surface  30 . Optionally, reflector  18  can be made from one or more thin pieces of steel, stamped steel, or chromed steel. Other suitable reflective materials can also be used optionally. As shown, reflector  18  comprises a parabolic reflector configured to focus light emanating from bulb  24  for delivery through transparent or translucent lens portion  26  of lens  16 . Lens portion  26  may include one or more prisms in portion  26  configured to further concentrate and direct transmission of light from heated lamp  10  pursuant to a desired output pattern. 
         [0022]    In one case, heating wire  28  of  FIGS. 1 and 2  comprises a Nichrome heating wire (or Nichromium wire) with a thermistor physically crimped to one end of the wire to provide an electrically conductive connection. Optionally, a PTC thermistor alloy resistance wire can be substituted for wire  28  and thermistor (or thermal resistor)  29 . Further optionally, one or more conductive traces made from Indium Tin Oxide (ITO), a heat resistant film, can be deposited as a thin film directly onto surface  30  of reflector  28  (or on surface  130  of cone  118  of  FIGS. 4-8 ), or is deposited onto a layer that is subsequently adhesively affixed onto such surfaces. One suitable optional wire is sold as PTC Thermistor Alloy Resistance wire, sold by Senphus, Jiangyin Senphus Electrical Material Co., Ltd., No. 8, Taoyuan Rd., Chengchang Industrial Park, Huangtu Town, Jiangyin City, Jiangsu Province, China. Optionally, thermistor  29  can be replace with any form of thermostat, or with a thermocouple, or resistance temperature detector (RTD) and associated control circuitry, or other thermostat capable of limiting maximum heat output and providing thermostatic control to activate heat delivery from wire  28  to lens  26 . 
         [0023]    As shown in  FIG. 3 , heated lamp  10  is affixed to a vehicle with fasteners, such as fasteners that secure into structural recess  62  of housing  20 . Optionally, housing  20  can be formed in a vehicle body, or contained within the body where it is mounted. 
         [0024]      FIGS. 4-8  depict another aspect comprising a heated light bulb assembly  123  usable in an existing vehicle, structure, conveyance, or lamp post/fixture for melting snow or ice, and removing vapor from a lens through which the bulb is radiating visible (or other forms of) light. More particularly, an existing incandescent lamp bulb or heat lamp bulb is modified with the addition of a frustoconical thermal (or radiant) reflector  118  in which a helical heating wire  128  is supported along an inner thermally (and optically) reflective conical surface  130 . As shown in  FIGS. 4 ,  5 , and  7 , electric current is delivered from the base  129  of bulb through conductive metal leads  134  and  136 , up through wire  128  and thermistor  132 . A pair of small notches are formed in a top edge of base  129  to facilitate passage of leads  134  and  136  inside of base  129  where they are electrically coupled with respective conductive contacts on base  129 , such as via brazing or mechanical affixation. Insulation (not shown) is provided about leads  134  and  136  where they pass through such notches in order to prevent leads  134  and  136  from shorting out across base  129 . In operation, thermistor  132  limits and prevents overheating of wire  128  resulting from current flow. In combination, bulb  124  is a heat-lamp-type bulb which further delivers heat to a lamp fixture having a lens on which snow and/or ice is otherwise accumulating. In one case, conductive lead  134  is formed from two discrete segments joined together by thermistor  132  which is crimped onto both segments, thereby joining them together electrically and mechanically. 
         [0025]    Although shown on a typical vehicle light bulb, it is understood that lamp base  129  can take on any of a number of alternative configurations including bayonet, threaded, or other suitable mechanical couplings that also provide electrical contacts with a light socket or fixture provided on a vehicle or conveyance, or stationary support structure, such as a lamp post. The depiction in  FIG. 8  illustrates one typical form of bayonet lamp base  129  with a conical, or frustoconical reflector  118 . In one case, reflector  118  is made from an insulating material, such as a plastic, and has a reflective inner coating, such as chrome, on surface  130 . Optionally, reflector  118  can be made from any suitable material, including metal or steel, and can take on other suitable shapes including parabolic, or dish-shaped configurations. Optionally, thermistor  132  can be replaced with any other suitable device that limits or prevents overheating when electric current is applied continuously to heating wire  128 . Heating wire  128  has an inherent resistance when current flows through, thereby generating heat output. Wire  128  can be constructed from the same materials as wire  28  in  FIGS. 1-3 . 
         [0026]    Although the embodiments depicted in  FIGS. 1-3  and  4 - 8  use incandescent (or halogen) bulbs, in is envisioned that such heated lamp systems can be incorporated on lamps and lighting systems using lower heat output lights (or bulbs), such as fluorescent bulbs, Light Emitting Diode (LED) bulbs, and other forms of energy efficient light output devices. Snow accumulation on such devices is exacerbated due to use of these low energy (and heat) output forms of lighting. For example, the usage of LED lighting on railroad crossing indicator lights and airport runway lights greatly increases the risk of snow and/or ice obstructing the lights during inclement (or winter) weather. Such embodiments help overcome this problem. 
         [0027]    In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.