Headlamp assembly for removing water based contamination

A headlamp assembly having a mechanism for reducing water based contamination is disclosed. The mechanism includes a lens assembly having an outer lens and an inner lens. A heating element may be disposed between the inner and outer lenses. Alternatively, inner and outer lenses may be spaced apart having a passage formed therebetween thorough which fluid may travel. Heat from light emitting diodes and a circuit board may be directed toward the outer lens through passages formed in the headlamp assembly.

SUMMARY

Embodiments disclosed herein relate generally to a lighting system which comprises a means for removing and/or preventing water based contamination from forming or accumulating on areas of an optical lens used in conjunction with a light emitting diode (LED) lamp.

A mechanism for reducing water based contamination in a headlamp assembly is provided. The mechanism uses some of the heat created by a LED emitter or other heat-generating devices within the headlamp assembly, to heat the lens area of a LED lamp. Thus, the heat prevents build-up of water-based contamination in the form of snow or ice on the lens, and heat is drawn away from the heat-generating devices, thereby extending the useful life of a LED circuit and emitter which may deteriorate prematurely when exposed to elevated temperatures generated by the LED and associated components.

In addition, one or more resistive heating elements, in the interior of the headlamp may be utilized in conjunction with heat radiating from the LED in order to remove water-based contamination from a LED lamp assembly. An optically-clear thermal transfer fluid may be utilized in the interior of a LED lamp to heat the lens structure in order to prevent accumulation of water-based contamination on the LED lamp.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

For purpose of promoting an understanding of embodiments described herein, references are made to embodiments of a vehicle light emitting diode (LED) headlamp assembly and method of making only some of which are illustrated in the drawings. It is nevertheless understood that no limitations to the scope of any embodiments disclosed are thereby intended. One of ordinary skill in the art will readily appreciate that modifications such as the component geometry and materials, the positioning of components, type of heating and control devices, and the type of electrical connections do not depart from the spirit and scope of any embodiments disclosed herein. Some of these possible modifications are mentioned in the following description. Furthermore, in the embodiments depicted, like reference numerals refer to identical structural elements in the various drawings.

A headlamp assembly10in accordance with an embodiment of the invention is illustrated inFIG. 1. In the embodiment illustrated, headlamp assembly includes a plurality of light emitting diodes, one of which is indicated at12. Those of skill in the art will appreciate that the quantity of Light emitting diodes depicted should not be construed as limiting, in that more or less Light emitting diodes may be utilized depending on the application of the headlamp. Headlamp assembly10includes a lens assembly15and a housing20. Lens assembly15is formed of a material that prevents Light emitting diodes12from being exposed to the outside environment. For example, lens may be formed of polyester, polycarbonate, or glass. In addition, lens assembly15may be a single or dual lens structure, which will be described in detail below. In the embodiment shown inFIG. 1, heating elements25are incorporated into lens assembly15for assisting in the removal of water based contamination.

FIG. 2Ais an exploded view of a lens assembly9for a headlamp assembly10. An inner lens layer14and an outer lens layer15, which includes side perimeter16terminating at ledge22, are shown along with sealing element31. A resistive element25is installed between inner lens layer14and outer layer15using an optically clear acrylic based pressure sensitive adhesive as a filler and bonding agent. Inner and outer lenses (14,15) may be formed of polycarbonate, polyester, polyester, or glass.

FIG. 2Bis an exploded view of a headlamp assembly10, of one embodiment which comprises a circuit board, light emitting diodes12, housing26, an inner and outer lenses joined by adhesive to form lens assembly. The lens assembly ofFIG. 2Aattaches to housing26to form headlamp assembly10.

FIG. 3ais an exploded view of an embodiment of lens assembly15for use with headlamp assembly10. As depicted, lens assembly15is a composite lens including inner lens50and outer lens55with resistive heating element60positioned therebetween. Inner and outer lens layers50and55may be formed of an optical grade material, such as polycarbonate or glass. An adhesive material of an optical grade, i.e. an acrylic based adhesive, is applied on upper and lower sides of heating element60, which is an electrically resistive element having a small enough diameter that it does not interfere with the optical performance of lens assembly15. By way of example, suitable alternative adhesives include thermally-activated or thermosetting adhesives, hot melt, chemically-activated adhesives such as those utilizing cross-linking agents, UV-activated light curing materials (LCM), encapsulated adhesives, and the like. Thus, lens assembly15is manufactured to fit together with sufficient precision as to have the same effect as a single layer lens. To accomplish this, the index of refraction of each material used in the lens assembly must be known in addition to the geometry. Then, modifications to the geometries of each lens layer may be considered to ensure starting and ending light path of light rays passing through lens assembly15matches that of a single layer lens that lens assembly15is replacing. The index of refraction for all points of interest across the lens surfaces may be determined using the following equation:

Wherein:□resulis the angle between a ray that has passed through a surface from one media to another and the normal line at the point on the surface where the ray passes through□incidis the refractory index of the material that the ray is traveling within as it approaches an interface surface between two media.□resulis the refractory index of the material that the ray passes into once it crosses the interface surface between two media.□incidis the angle between a ray as it approaches a surface between one media and another and the normal line at point on the surface where the ray passes through.

Heating element60may be formed of copper or other base material that would operate within the voltage and current limitations necessary for removing water based contamination from lens assembly15. For example, heating element60may operate at a voltage of 12-24 VDC/VAC. A maximum power of 0.1255 Watts/cm2lens area may also be applied. More particularly, heating element60may have specific resistance as determined by the required power density, operating voltage, and specific lens area in order for heating element60to be capable of removing an average of 3.095 milligrams of ice/cm2of lens area/minute over a maximum 30 minute duration when headlamp assembly10has been held at −35 C for a period not shorter than 30 minutes in an environment chamber with the environment chamber fully active for both 30 minute durations. The total power (in watts) can be determined by multiplying the effective area of lens assembly15required to be cleared of water based contamination (in cm2) times the power per lens area. Thus, resistance of the heating element60is dependent upon the type of material used to make resistive heating element60, as well as its diameter.

In some embodiments resistive heating element30may be formed by depositing a layer of indium tin oxide (ITO) metal film on a polyester sheet, such as manufactured by Minco®. The diameter of heating element60may be in the range of 10 to 20 microns. In one embodiment, heating element60is configured in a pattern and disposed between two sheets of polyester, such as Thermal-Clear™. In some alternate embodiments heating element60may be formed by depositing a layer of indium tin oxide (ITO) metal film on a polyester sheet, such as manufactured by Minco®. In addition, the material used to make heating element60may be copper or a transparent conducting oxide such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and doped zinc oxide or other similarly conductive and optically transparent materials.

Lens assembly15is shown in an assembled configuration inFIG. 3b. In one embodiment, lens assembly15is formed by laying heating element60in a pressure sensitive adhesive material using a robotic fixture device or other controllable/repeatable means capable of placing heating element60. Heating element60, containing adhesive, is then sandwiched between lens layers,50and55, which are pressed together using a clamp, ram, vice, or other means of applying a clamping force to lens assembly15by contacting an inner surface62of inner lens50and an outside surface63of outer lens55with compliant interfaces (rubber blocks, etc). The compliant interfaces may be shaped such that they contact center portions of inner and outer lenses,50and55, prior to deforming to make contact with the remainder of inner surface62and outer surface64for the purpose of dispelling air and other entrapped gases.

Alternatively, heating element60or wire may be embedded within a lens via an ultrasonic procedure. Essentially, the procedure begins with determining a mounting location in the lens substrate. Next, a wire is threaded onto an embedding tool known as a sonotrode. The sonotrode aids in pressing the wire against the lens substrate, and comprises an ultrasonic transducer, which heats the wire by friction. The molecules of the polycarbonate substrate simultaneously vibrate very quickly, so that the lens material melts in the area of the aperture. Accordingly, the wire is embedded into the polycarbonate substrate by use of pressure and heat. A final step in the process entails connecting ends of the wire that are not embedded, to terminals on the lens substrate.

FIG. 3cshows a view of a circuit70used in one embodiment providing power to heating element60. Circuit70comprises a resistive heating element60made from a thin wire, comprising any of various materials including copper, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and doped zinc oxide. Preferably, materials selected for heating element60should be optically transparent, and be capable of resisting fluctuations in current flow direction. Heating element60is configured as a pair of metallic or metallic oxide loops connected in parallel. A first loop72is connected to leads A and B. A second loop74is connected to leads B and C. The circuit construction allows for the use of either 24 volt or 12 volt systems at the same power level. Thus, for 24 volt operation, only leads A and C are utilized. For 12 volt operation, leads A and C are connected together to one pole and lead B to the other pole.

A simple control system100may be used to allow heating element60to operate automatically. Automatic or manual control logic would dictate that as long as the ambient temperature local to lens assembly is within temperature range wherein water based contamination may occur, heating element60is active (powered on). An automatic control system could be constructed of a comparator that switches heating element60on or off based on the resistance value of heating element60(which would vary with temperature). The resistance value may be compared to a set threshold resistance associated with a maximum temperature of the range wherein water based contamination may occur. Then, if the resistance value is at or below the threshold, the comparator switches to close the circuit providing power to heating element60and remains in that state. Conversely, if the resistance value is above the threshold resistance, the comparator switches to open the circuit disrupting power to the mechanism, which remains in an off state. The threshold value could be determined by calculation using the material properties of the resistive element, adhesive, and lens material and geometries and verified through empirical testing or just determined through empirical testing. Alternatively, the control system may use a separate electronic temperature indicating device. The control system could simply be a switch that is operated manually, it could be controlled by a programmable logic controller, or other means of switching the device on/off, or the device could be left on all the time.

FIG. 4Ais a schematic representation of another embodiment of a mechanism110for reducing water based contamination from a headlamp assembly10. Mechanism110includes inner and outer lenses120and121and an energy source that dissipates energy in the form of heat. The energy source may be light emitting diodes125, or any other part that dissipates energy in the form of heat either by mechanic or electrical principles. An optically clear fluid, in gaseous or liquid form, is directed past energy sources (Light emitting diodes125) with a mechanically or electrically operated pump, fan, compressor or the like. In the embodiment shown, a fan122is used to circulate the fluid. Free convection may also be used to transfer heat energy from energy sources125to mass particles contained in the fluid, which is then directed through a channel128between inner lens120and outer lens121. Heat energy is then transferred from the fluid mass particles to lenses120and121such that accumulation of water based contamination cannot occur. The heat energy also removes any previously accumulated water based contamination from lenses120and121. Mechanism110may be used alone or in conjunction with another device, such as a heating element, in order to provide sufficient energy to lenses120and121. The fluid may be channeled using existing geometries within lens assembly15and additional geometries may be added to provide passages for the fluid. The fluid may be partly or completely encapsulated or free flowing against lenses120and121. In the embodiment illustrated inFIG. 4a, channel128facilitates the transfer of cool air originating from outer lens121, which is exposed to the outside of the headlamp, toward light emitting diodes125in order to decrease the temperature of light emitting diodes125. Thus, mechanism110provides a means of distributing heated and cooled fluid within headlamp assembly10. It will be appreciated by those of skill in the art that the “fluid” as used herein may comprise liquid, gaseous substances, including air or other vapors, free-flowing polymeric fluids, partially or completely encapsulated fluids, as well as fluids comprising mass particles. Representative heat transfer fluids known in the art may also include polyolefins, polyalphaolefins, diphenylethanes, and the like, manufactured and sold by Radco®.

FIG. 4Bis schematic representation of an embodiment of a mechanism210for reducing water based contamination from a headlamp assembly10. Similar to the embodiment described in conjunction withFIG. 4a, mechanism210includes inner and outer lenses220and221having a channel128therebetween, a fan222and light emitting diodes225that dissipate energy in the form of heat. In addition, mechanism210includes a heat sink230having fins232. A solid state heat pump235, such as a Peltier device, may be inserted between heat sink230and light emitting diodes125. When energized solid state heat pump235acts to reverse the direction of energy transfer to cause energy to flow from heat sink230to light emitting diodes125, as indicated by arrow237, under controlled conditions wherein light emitting diodes125would not become damaged due to overheating.

The transfer of heat towards light emitting diodes125may be used when the temperature local to mechanism210and light emitting diodes125is sufficiently low that the conditions are correct for water based contamination to develop or accumulate on outer lens121. Heat pump235also increases the energy that is transferred from light emitting diode to the fluid, thereby more effectively providing energy to outer lens121for the purpose of removing water based contamination. Additional solid state heat pumps, or other types of heat pumps, may be used at other locations anywhere surrounding a fluid channel that is being used for the purpose of transferring energy as described above.

As is known in the art, Peltier heat pump235, operates based on the Thomson Effect, which is based upon the principle that electric potential difference is proportional to temperature difference. Specifically, a thermal gradient is created when a temperature difference along a conductor is present such that one part of the conductor is warmer, while the other is colder. Thermal energy in the form of electrons, will inherently travel from the warmer portion of the conductor to the colder portion.

In terms of polarity, electrons normally travel from positive to negative. The Peltier Effect involves the discovery that when current flows through a circuit comprising two or more metals of varying electronic properties (ex, n-type vs. p-type), the current drives a transfer of heat from one junction to the other. However, when the polarity is reversed as is the case under an applied voltage, electrons will travel in the opposite direction (i.e., from negative to positive). Similarly, heat transfer will also occur in the opposite direction. Thus, the direction of heat transfer may be controlled by manipulating the polarity of current running through Peltier heat pump235.

Heat created by light emitting diodes125, circuit board (not shown inFIG. 4b), or other heat generating devices may be absorbed by heat sink230. In order to prevent absorbed heat from being exhausted to the atmosphere via fins232, heat pump235may be activated in order to transport heat from heat sink230to a channel located below the heat sink. In one embodiment, sensors may be utilized to monitor when the temperature of the fluid drops below a certain level, at which time a control circuit may activate heat pump235in order to transport stored heat from heat sink230to thereby promote circulation of heated fluid within mechanism210. Heat sink230, which collects and stores heat originating from heat generating devices. These heat generating devices may include Light emitting diodes, resistors, fans or air pumps, power electronics including but not limited to linear and switch mode current regulators, which may be required to drive or regulate power within the lamp. Essentially, heat sink330may collect heat from any device that creates heat within the lamp, whether or not it is the device's primary function to do so. Subsequently, heat collected by heat sink330may be exhausted to the atmosphere via fins332.

FIG. 5illustrates a cross-sectional view a mechanism310for reducing water based contamination from a headlamp assembly10. Mechanism310includes an inner lens320and outer lens321and heat sources, including light emitting diodes and a circuit board325. A channel326is located below circuit board325for allowing the passage of fluid. As discussed above, heat generated by light emitting diodes and associated circuitry on circuit board325is transferred to channel326via a convection process. A channel328for transferring fluid is also located between inner and outer lenses320and321. Subsequently, a portion of the heat transferred to channel326, exits mechanism310via heat sink330having fins332.

More specifically, a free-convection process may be utilized to circulate fluid between inner and outer lenses320and321in order to maximize melting of snow and ice from outer lens321. In this embodiment, heat is transferred to fluid by use of geometries within the lens structure. The initial temperature of channel328is cold. Second fluid-flow channel326is located below circuit board325and facilitates absorbance of heat originating from circuit board325. Thus, the initial temperature of channel326is hot. As illustrated inFIGS. 6aand6b, side channels327,327′ located in opposite side-walls of mechanism310connect channels326and328. The channels may be formed at an angle in the range of 10 to 30 degrees, as inFIG. 6a, to an angle of approximately 120 to 150 degrees, as inFIG. 6b. Angled side channels327,327′ as well as channels326and328represent a system of channels enabling heated fluid to flow within mechanism310via a free convection process enhanced by gravity, density, and buoyancy. This process optimizes fluid flow within the dual lens structure, brought about by absorption and desorption of heat as discussed infra.

Heated fluid located in channel326, is inherently less dense than colder fluid located in channel328. Gravitational acceleration creates a buoyant force causing colder, heavier fluid in channel328to move down to displace the warmer fluid in channel326. As the cold fluid collects in channel326, it absorbs heat from circuit board325, light emitting diodes, and other heat-generating devices. As the fluid becomes warmer, viscous forces of the fluid are decreased and buoyant forces which encourage fluid flow are increased. Buoyant forces thus overtake the viscous forces of the fluid, and flow is commenced toward channels328. Pressure within the side channels is minimized by optimizing the cross-sectional area of the channels so that cross-sectional area increases in the direction of desired fluid flow. Accordingly, fluid flow within the side channels is promoted in the direction of channel328, and resisted in the direction of channel326. Once the fluid reaches channel328its heat is desorbed by snow and ice accumulating on outer lens321. This steady state process repeats itself continuously, until outer lens321is free from water-based contamination caused by cold outdoor temperatures.

FIG. 7ais a cross-sectional view of another embodiment of a mechanism410for reducing water based contamination from a headlamp assembly10. Mechanism410includes an inner lens420and outer lens421and heat sources, including light emitting diodes and a circuit board425. A channel426is located below circuit board425for allowing the passage of air. As discussed above, heat generated by light emitting diodes and associated circuitry on circuit board425is transferred to channel426via a convection process. A circulation device such as fan427is provided to further encourage circulation of air within mechanism410. A channel428for transferring fluid is also located between inner and outer lenses420and421. Subsequently, a portion of the heat transferred to channel426, exits mechanism410via heat sink430having fins432.

FIG. 7bis a cross-sectional view of mechanism410′ wherein a liquid is circulated within channels426′ and428′. As discussed above the liquid may be a heat transfer fluid known in the art such as polyolefins, polyalphaolefins, diphenylethanes, and the like. A pump427′ is provided to circulate the liquid within mechanism410.

FIGS. 8a,8b, and8care cross-sectional view of a mechanism510for reducing water based contamination from a headlamp assembly10including a solid state heat pump512.FIG. 8aillustrates mechanism510with a single lens521. Heat sources, including light emitting diodes and a circuit board525are also provided. In the embodiment ofFIG. 8a, heat is transferred by way of solid state heat pump512. As discussed above, heat pump512transfers heat from a heat sink530towards circuit board525. Thus, heat from heat sources, including circuit board525is directed towards lens521to heat lens521for reducing water based contamination from a headlamp assembly10.

The embodiment shown inFIG. 8bis also a mechanism510′ for reducing water based contamination from a lens, wherein a heat pump512′ is employed. Mechanism510′ includes inner lens520′ and outer lens521′. As discussed with respect toFIG. 5, heat generated by light emitting diodes and associated circuitry on circuit board525′ is transferred to a channel526′ via a convection process. A channel528′ for transferring fluid is also located between inner and outer lenses520′ and521′. Heat sources, including light emitting diodes and a circuit board525′ are also provided. In the embodiment ofFIG. 8b, a solid state heat pump512′ is positioned below circuit board525′ and acts to draw heat from circuit board525′ and the light emitting diodes. The heat is then transferred to from heat pump512′ to channel528′ to heat the fluid within the channel. The heated fluid then travels up channels formed in the sides of mechanism to channel528. The heated air may then heat lens521for reducing water based contamination from a headlamp assembly10. Transferring heat away from circuit board525′ and light emitting diodes also reduces the temperature of the circuit elements and light emitting diodes, thereby preventing degradation due to heat.

FIG. 8cdepicts a mechanism510″ for reducing water based contamination from a lens, wherein a first heat pump512″ and a second heat pump513″ employed. Mechanism510″ includes inner lens520″ and outer lens521″. Heat generated by light emitting diodes and associated circuitry on circuit board525′ is transferred to a channel526″ via a convection process. A channel528″ for transferring fluid is also located between inner and outer lenses520″ and521″. First solid state heat pump512″ is positioned below circuit board525″ and acts to draw heat from circuit board525″ and the light emitting diodes. The heat is then transferred to from heat pump512″ to channel526″ to heat the fluid within the channel. In addition, a second heat pump513″ is positioned adjacent to heat sink530″ for transferring heat from heat sink530″ towards channel526″. The heated fluid then travels up channels formed in the sides of mechanism510″ to channel528″. The heated air may then heat lens521for reducing water based contamination from a headlamp assembly10.

FIGS. 9aand9brepresent alternative embodiments of a mechanism610,610′ for reducing water based contamination from a headlamp assembly10utilizing a single lens structure. As shown, a device that moves air, such as a fan or air pump,612,612′, is positioned in a compartment613,613′, below circuit board625,625′ and in close proximity to a channel626,626′. Heat from circuit board625,625′ is drawn into channel626,626′ and through passages627,627′ toward compartment613,613′. Fan,612,612′ acts to force the air into a chamber628,628′ within mechanism610,610′ to circulate in order to prevent warm air from becoming trapped in one particular area. Warm air radiating from the Light emitting diodes and circuit board625,625′ rises up to lens630,630′. If snow or ice has accumulated on lens630,630′, this heat will aid in melting the snow and/or ice. If, however, the temperature of lens630,630′, is the same or warmer than the air inside chamber628,628′, heat will tend to build up in the area below lens630,630′ and above circuit board625,625′ causing a risk to the Light emitting diodes and other circuitry. Fan612,612′ pulls cooler, more dense air, which naturally migrates toward the bottom portion of the headlamp, up to the portion between lens630,630′ and circuit board625,625′, thus facilitating a replacement of warmer air trapped within the this area. As shown, one or more holes632,632′ may be provided in circuit board625,625′ to facilitate transfer of air from the bottom portion of mechanism610,610′, through holes632,632′ and into chamber628,628′, thereby circulating air throughout mechanism610,610′, and particularly circulating warm air generated by the Light emitting diodes and circuitry to facilitate reducing water based contamination from a headlamp assembly10. The embodiment ofFIG. 9bincludes a solid state heat pump or thermal slug635to further included to assist in reducing water based contamination from a headlamp assembly10. Heat pump635draws heat from circuit board625′ and light emitting diodes down into a channel626′ where the heat is transferred, via fan612′, to air within channel628′ in the manner described above.

As illustrated in each ofFIGS. 10-13a resistive heating element may be embedded the outer lens of any of the previously discussed embodiments. With respect toFIG. 10, a mechanism710for reducing water based contamination from a headlamp assembly10is shown with resistive heating element712. Heating element712is powered by circuit board725and provides heat to lens730when snow and ice accumulate on the lens, to thereby clear the lens from water-based contamination which can act as a filter decreasing transmittance of light through lens730.

FIG. 11illustrates an alternative embodiment to that disclosed inFIG. 10. A mechanism810for reducing water based contamination from a headlamp assembly10is shown with resistive heating element812embedded in an outer lens830. An inner lens831is also shown with a channel836formed therebetween. Fluid within channel836flows through side channels and through channel839, which is formed between circuit board845and heat sink850. Once heated, resistive heating element812provides heat to outer lens830in order to facilitate the removal of water-based contamination such as snow and ice from the outer lens. In addition, resistive heating element812provides a means of promoting circulation of fluid within channels836and839by transfer of heat to the fluid causing the molecules of the fluid to move rapidly to thereby increase flow of fluid.

FIG. 12represents a modified version of the embodiment disclosed inFIG. 10. A mechanism910for reducing water based contamination from a headlamp assembly10is shown with resistive heating element912embedded in a single lens930. The resistive heating element912is powered by circuit board945and provides heat to lens930when snow and ice accumulate on the lens, to thereby clear the lens from water-based contamination which can act as a filter decreasing transmittance of light through lens930.

In addition, as shown by the arrows, warm air originating from Light emitting diodes and circuit board945and associated circuitry is transferred to lens930via heat pump948. Heat from heat sink946is also transferred toward lens930. Thus, lens930is provided with heat both by a resistive heating element912as well as transfer of heat radiating from the Light emitting diodes and circuit board945by way of heat pump948. This creates a two-fold advantage, in that water-based contamination is melted from lens930thereby increasing optical transmittance, and heat is reduced in the area of the Light emitting diodes and associated circuitry thereby extending the useful life of the headlamp. Heat pump operates in the manner described in relation toFIG. 8a.

The embodiment shown inFIG. 13is a mechanism1010for reducing water based contamination from a headlamp assembly10is shown with resistive heating element1012embedded in a lens1013. As described with respect to the embodiment ofFIG. 9b, mechanism1010includes a solid state heat pump or thermal slug1035to further assist in reducing water based contamination from a headlamp assembly10. Heat pump1035draws heat from circuit board1045and light emitting diodes down into a channel1046where the heat is transferred through passages1048to chamber1050. A fan1052directs air through openings1055and into chamber1060towards lens1013in the manner described above.

A control system may be utilized in any one of the embodiments discussed supra. The system includes temperature sensor which monitors the temperature in and around the lens structure. Sensor520may comprise a Resistive Temperature Detector (RTD), Positive Temperature Coefficient Thermistor (PTC), or any other type of temperature sensor known in the art including variable resistors, thermistors, bimetal circuits, bimetal switches, as well as linear and switch mode current regulators. The temperature read by the sensor is converted to a signal and transferred to a comparator. The Comparator compares the actual temperature reading to a threshold temperature value stored within the device. If the actual temperature is below the threshold value, the comparator sends a signal to a switch in order to activate the heating element, thermal transfer fluid circulating device, or Peltier heat pump to thereby heat the dual or single lens structure in order to melt water-based contamination accumulating on the LED lamp. Similarly, when the actual temperature read by the sensor is above the threshold temperature value, comparator will send a signal to the switch in order to deactivate heating element, thermal transfer fluid circulating device, or Peltier heat pump and heat will thus be stored by the heat sink and eventually exhausted to the atmosphere if necessary via fins.

It will be understood by those skilled in the art that the above disclosure is not limited to the embodiments discussed herein and that other methods of controlling heating element, thermal transfer fluid circulating device, or Peltier heat pump may be utilized. These methods may include manual activation and deactivation of heating element, thermal transfer fluid circulating device, or Peltier device via an on/off switch. Other alternative embodiments include continuous activation of the elements so that LED lamp temperature is high enough to prevent accumulation of water-based contamination but low enough to prevent inadvertent thermal deterioration of the LED lamp and its components.