Abstract:
A passive cooling lighting fixture that includes a light diffusing lens. The fixture is self-contained and self-cooled in order to maximize the life span of the light source. The passive cooling system utilizes vented end caps that circulate cool air into the lighting fixture while venting hot air out of the lighting fixture. The light diffusing lens produces a light that is soft enough for use indoors.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention generally relates to lighting apparatuses. The incandescent light bulb has been the light bulb standard in both commercial and residential lighting applications for more than one hundred years. The incandescent light bulb was invented in the early 1800&#39;s, but it did not become commonly used until the late 1800&#39;s. The incandescent light bulb creates light when an electric current is passed through a filament that is suspended in a vacuum. The resistivity of the filament causes the filament to heat up and glow as the electric current passes through it. Incandescent light bulbs are relatively inexpensive and easy to manufacture in a variety of shapes and sizes. Despite this, incandescent light bulbs are falling out of favor because of the energy required to power them. There are laws in place in the United States that will cause the use of incandescent light bulbs to be slowly phased out in coming years. Additionally, incandescent light bulbs can become very hot if left on for long periods of time, and they burn out and have to be replaced every 1000 to 2000 hours of use. 
         [0002]    Fluorescent light bulbs have also become very common over the last several decades. Fluorescent light bulbs are generally constructed out of long glass tubes. The tube is filled with a gas containing mercury vapor and argon, xenon, neon, or krypton under pressure. The inner surface of the tube is coated with a fluorescent material. The tube also contains a coiled electrode that emits electrons which in turn excite the mercury vapor. The excited mercury atoms produce short-wave ultraviolet light which causes inner coating of the tube to fluoresce, producing visible light. Fluorescent light bulbs last longer than incandescent light bulbs (typically 10 times longer) and require less energy to operate. Additionally, fluorescent light bulbs do not get as hot as incandescent light bulbs. Despite these advantages, fluorescent lights are not universally favored. Fluorescent lights take longer to turn on, and tend to flicker as the tube gets old. Also, the light produced by a fluorescent bulb is often considered to be glaring and not ideal for use by those with sensitive eyes. 
         [0003]    The newest light source to come into use in recent years is the Light Emitting Diode, commonly called an LED. LEDs are miniature semi-conductors that produce light when electrons are allowed to recombine with electron holes within the device, releasing energy in the form of photons. Different colors of light are created by changing the type of semi-conductor, as well as changing the color of the plastic housing of the LED. LEDs are attractive as a light source because they emit more light per watt than incandescent light bulbs and their efficiency is not affected by shape or size like a fluorescent light bulb. LEDs last much longer than both incandescent and fluorescent light bulbs. LEDs light up very quickly and are ideal for frequent on-off cycling. Also, LEDs are made of solid-state components, so they are very shock resistant unlike incandescent and fluorescent light bulbs which are extremely fragile. 
         [0004]    Despite the advantages of LEDs lights, LEDs still have some problems. First, the light produced by an LED is very bright and often too harsh for use in-doors. Additionally, LED performance is largely dependent on the ambient temperature of the environment where it is operating. If the LED is operating in a warmer environment, the device will fail due to overheating. For this reason, LED lights require adequate heat sinking in order to maintain long life. A heat sink is a separate device that transfers heat generated within the LED to a fluid medium, usually air. The most efficient heat sinks are ones that move air across a heated area in order to cool it down. But including a fan in an LED assembly is impractical because of size and power restrictions. 
         [0005]    Accordingly, there is a need for an LED lighting apparatus that creates a softer light source that is more appropriate for indoor use. Additionally, there is a need for an LED lighting apparatus that effectively sinks the heat away from the LED light so that the lifetime of the LED can be maximized. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is a passive cooling lighting fixture that utilizes an LED light source. This passive cooling lighting fixture provides a filtering lens that diffuses the harsh LED light source creating light that is appropriate for indoor use. The passive cooling lighting fixture also features an innovative heat sinking system that allows the LED light source to stay cool. The heat sinking system includes double walled, vented end caps that fit over the ends of lighting fixture as well as a double walled portion of the lighting fixture that draws heat away from the LED lights. Some of the vents in the end caps are oriented at the base of the end cap, nearest the base of the lighting fixture where the LED lights are situated. The rest of the vents in the end caps are oriented at the distal end of the end cap. The end caps also feature inner ports toward the base end of the end cap. The lighting fixture is also partially double walled so that the heat generated from the LED light source is sinked away from the LEDs by air held in an inner chamber created by the double walled portion. The double walled, vented end caps ends of the lighting fixture are positioned such that the inner ports are over the ends of the inner chamber. With the double walled, vented end caps in place, cool air from outside the lighting fixture is circulated through the inner chamber. This cools and moves the hot air away from the LED light components. The heat sink is reminiscent of human sinuses, which heat incoming air to body temperature, in that it uses air to conduct heat away from a heat producing source. The heat sinking system of the present invention does not include any moving parts so it does not require any extra power. Additionally, it does not create any noise. 
         [0007]    Other features and advantages of the present invention will become apparent from the following more detailed description, when taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The accompanying drawings illustrate the invention. In such drawings: 
           [0009]      FIG. 1  is a side view of the present invention; 
           [0010]      FIG. 2  is an exploded perspective view of the present invention of  FIG. 1 ; 
           [0011]      FIG. 3  is an environmental view of the present invention; 
           [0012]      FIG. 4  is an environmental view of the present invention illustrating a frame from which the lighting fixture can be suspended; 
           [0013]      FIG. 5  is an environmental view of the present invention illustrating the lighting fixture fitted into a panel with multiple apertures; 
           [0014]      FIG. 6  is a further environmental view as in  FIG. 5  illustrating how the lighting fixtures are fit into the panel with multiple bracketed apertures; 
           [0015]      FIG. 7  is a perspective view of the present invention illustrating air flow through the innovative heat sinks featured therein; 
           [0016]      FIG. 8  is a cut-away perspective view along line  8  of  FIG. 7  illustrating the direction of air flow through the inner chamber and end caps of the present invention; 
           [0017]      FIG. 9  is a top perspective view along line  9  of  FIG. 7  illustrating the direction of air flow through the end caps of the present invention; 
           [0018]      FIG. 10  is a bottom perspective view along line  10  of  FIG. 7  illustrating the direction of air flow through the end caps of the present invention; and 
           [0019]      FIG. 11  is a side perspective view along line  11  of  FIG. 7  illustrating the direction of air flow through the end caps of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    The present invention is a passive cooling lighting fixture that overcomes the negative aspects of LED lights by providing a fixture with a lens that diffuses the harsh light created by an LED. Additionally, the present invention solves the heating problem common to LED lights by providing a passive heat sink that is silent and requires no extra power considerations. These and other features of the present invention will be described in more detail below. 
         [0021]      FIG. 1  is a side view of the passive cooling lighting fixture  10  of the present invention. Here it can be seen that the various parts and pieces of the lighting fixture  10  are all contained within the lighting fixture  10 . The size of the lighting fixture  10  as shown in the preferred embodiment is small enough to fit within a standard panel of a drop-down ceiling, but in other embodiments, the lighting fixture  10  can be larger or smaller. 
         [0022]      FIG. 2  is an exploded side view of the passive cooling lighting fixture  10  of  FIG. 1 .  FIG. 2  illustrates more particularly the various parts that are included in the lighting fixture  10 . First, the main body of the lighting fixtures  10  is made of a rigid channel  12 . The rigid channel  12  is made of aluminum in the preferred embodiment, but in other embodiments the rigid channel  12  can be made of other materials. Ideally, the rigid channel  12  is made from a material that will hold its shape even when heated. The rigid channel  12  in the preferred embodiment is also double walled along the outside of the base of the channel  12 . This double walled portion of the channel  12  creates an inner chamber  14 . The inner chamber  14  does not open into the channel  12  at any point, but is open at both ends of the channel  12 . 
         [0023]    Next, the light source  16  is shown. In the preferred embodiment, the light source  16  is a series of surface mounted LEDs  20  that are placed along a strip  18 . A plurality of LEDs  20  are mounted to the strip  18 . The strip  18  is long enough to run the length of the channel  12 , but not longer than the channel  12 . In the preferred embodiment, the strip  18  is mounted into the channel  12  along the side of the channel  12  that that is double walled. This is essential to the heat sinking function of the present invention in that the heat created along the strip  18  from the plurality of LEDs  20  is transferred into the inner chamber  14  of the double walled portion of the channel  12 . The light diffusing lens  22  is the same length as the channel  12  so that it fits over the channel  12 . In the preferred embodiment, the light diffusing lens  22  is rounded, but in other embodiments the light diffusing lens  22  can have any cross-sectional configuration (i.e. flat, concave, etc). The panel  22  can attach to the channel  12  with clips, clamps, screws or adhesive, but in the preferred embodiment, the panel  22  attaches to the channel  12  by sliding along a c-shaped concourse  58  (SEE  FIG. 8 ) that allows the panel  22  to be inserted and removed horizontally, but holds the panel  22  in place vertically. In the preferred embodiment, the light diffusing lens  22  is made from opaque plastic, but in other embodiments, the panel  22  can be made from other light diffusing materials such as frosted glass. 
         [0024]    Also featured in  FIG. 2  are the double walled end caps  24  that function as heat sinks in the present invention. The end caps  24  are comprised of an inner wall  26  and an outer wall  28  that when put together create a hollow air passage  30 . The end cap outer wall  28  features a series of base vents  32  located at the base of the channel, and distal vents  34 . These vents function with the hollow air passage  30  to increase air flow through the end caps  24 . The end cap inner wall  26  features two ports  36  that are positioned over the open ends of the inner chamber  14  created by the double walled portion of the channel  12 . When the assembled end caps  24  are in place over the ends of the channel  12  such that the end cap inner ports  36  are over the ends of the inner chamber  14  created by the double walled portion of the channel  12 , the heated air that accumulates inside the inner chamber  14  flows out of the inner chamber  14  through the ports  36 . Once the heated air exits the inner chamber  14 , it is circulated out of the end caps  24  by cooler air that passes through the end caps  24  via the base vents  32  and the distal vents  34  that are oriented along the end cap outer wall  28 . Thus, the heat created by the LED light source  16  is successfully sinked away from the lighting fixture  10  without requiring the use of a fan or other noisy moving parts that would require extra power. The air flow pattern described above is specifically laid out in  FIGS. 7-11  below. 
         [0025]      FIG. 3  is an environmental view of the present invention. Here, the passive cooling lighting fixture  10  is shown in its preferred embodiment with the length of the lighting fixture  10  being approximately the same as the length of a panel from a standard drop-down ceiling. This type of ceiling is common in commercial real estate such as office buildings and retail spaces.  FIG. 3  shows that the lighting fixture  10  can be clipped onto the ceiling cross pieces  38 . This makes the lighting fixture  10  particularly ideal for installation in spaces where a minimum amount of alteration to existing structures is desired. 
         [0026]      FIG. 4  is yet another environmental view of the present invention. Here, the passive cooling lighting fixture  10  is attached to a frame  40  that allows the lighting fixture  10  to be suspended below the ceiling. The frame  40  attaches to the ceiling cross-pieces  38  via clips, clamps, screws or adhesive. In the preferred embodiment, the frame  40  attaches to the ceiling cross-pieces  38  with clips to allow for easy installation and removal of the lighting fixture  10 . Likewise, in the preferred embodiment, the lighting fixture  10  attaches to the frame  40  with a clip that allows for the lighting fixture  10  to be easily removed. In other embodiments, the lighting fixture may be attached to the frame with clamps, screws or adhesive as well. Although the embodiments described here are meant for indoor use, the present invention can also be configured for outdoor applications. Additionally, the present invention can be used in conjunction with various mounting systems besides the mounting system described here. 
         [0027]      FIG. 5  is still another environmental view of the present invention. Here, the passive cooling lighting fixture  10  is shown in a series fitted into a spacing panel  42  that features multiple apertures  44 . In this embodiment, the spacing panel  42  is approximately the same size as a ceiling panel tile from a standard drop-down ceiling that is common in commercial real estate. In other embodiments (not shown), the spacing panel can be any size as long as the spacing panel is large enough to fit the passive cooling lighting fixture. The apertures  44  of the spacing panel  42  are illustrated more particularly in  FIG. 6 .  FIG. 6  shows how the lighting fixtures  10  fit inside the panel apertures  44 . Also shown in  FIG. 6  are the aperture brackets  46 . These brackets serve to snap the lighting fixtures  10  in place so that they will not fall out of the panel  42 . Each aperture  44  also features a guard  48 . Each guard  48  is located at one end of each aperture  44  and functions to keep the lighting fixture  10  from being pushed too far into the aperture. 
         [0028]    The air flow described in  FIG. 2  is further illustrated in  FIGS. 7-11 . In  FIG. 7 , air flow along the entire length of the lighting fixture  10  is illustrated. First, cool air from outside the lighting fixture enters the end caps  24  through the end cap distal vents  34  along lines  50 . Next, air along the inner chamber  14  created by the doubled walled portion of the rigid channel  12  is heated when the LED light source  16  is powered on. This air becomes heated because the LED light source  16  is attached to the outside of one of the walls of the inner chamber  14  created by the double walled portion of the rigid channel  12 . The light source  16  gives off energy in the form of heat as it produces light, and this heat is transferred through the wall that the light source  16  is attached to. The direction of the flow of heated air along the inner chamber  14  is indicated by lines  52 . This heated air moves toward the end caps  24  located at both ends of the rigid channel  12  and exits the inner chamber via the end cap ports  36 . Finally, the heated air is drawn out of the lighting fixture through the end cap base vents  32  along lines  54  and  56  along with the cool air that entered from the distal vents  34 . The angled placement of the end caps  24  relative to the rigid channel  12  assists with the flow of the cool air from the distal vents of the end cap  34  to the base vents of the end cap  32 . 
         [0029]      FIG. 8  is a cutaway perspective view taken from  FIG. 7  along line  8 . Here, it can be seen that hot air can flow in both directions along the inner chamber  14 .  FIG. 8  also better illustrates the c-shaped concourse  58  that allows the light diffusing lens  22  to slide into place over the rigid channel  12  and remain in place without falling off.  FIG. 9  is another cutaway perspective view taken from  FIG. 7  along line  9 .  FIG. 9  shows a top-down view of the end cap  24  showing the directions of air flow through the lighting fixture  10 . As described above, the cool air enters the end cap  24  along lines  50 . The cool air draws out the hot air taken along lines  52 . The air is finally vented out of the lighting fixture along lines  54  and  56 . 
         [0030]      FIG. 10  shows a bottom-up view of one end of the lighting fixture  10  taken along line  10  of  FIG. 7 .  FIG. 10  illustrates how the placement of the distal end cap vents  34  and the angle of the end cap  24  help to direct cooler air taken along lines  50  from outside the lighting fixture  10  into the end cap  24  so as to circulate hot air away from the LED light source  16 .  FIG. 11  is a side view of one end of the lighting fixture  10  taken along line  11  of  FIG. 7 .  FIG. 11  more closely shows how air circulates into and out of the inner chamber  14 .  FIG. 11  also shows how the circulated air leaves the lighting fixture  10  either horizontally or vertically out of the base end cap vents  32 , as shown by lines  54  and  56 . 
         [0031]    The present invention is a passive cooling lighting fixture that overcomes several of the shortcomings that have been common to lighting fixtures in the past. First, the passive cooling lighting fixture includes a light source that features a plurality of LED lights. These LED lights require less energy than both incandescent and fluorescent light bulbs. LED lights cycle on and off quicker than fluorescent light bulbs, and they do not generate as much heat as incandescent light bulbs. Despite their advantages, LED lights produce a light that is very bright and oftentimes very glaring. Additionally, LED lights produce some heat. If that heat is not sinked away, the LED light will experience a shorter life span as well as possible unexpected failure. The present invention houses its plurality of LED lights in a rigid channel that is covered by a light diffusing lens. The light diffusing lens creates a light from the LEDs that is more appropriate for indoor use because it is softer and not glaring. The light fixture of the present invention also solves the heating problem common to LED lights by providing a passive cooling system that sinks the heat away from the LED lights. The cooling system operates by circulating air through a chamber that heats up as the LED lights are powered on. The circulation of the air through the chamber is accomplished by a pair of end caps that include both distal and base vents. As cool air enters the end cap through the distal vents, it circulates through the chamber drawing hot air out through the base vents of the end cap. The angle of the end caps in relation to the rigid channel helps create the upward draft necessary to circulate the cool air into the lighting fixture and the hot air out. 
         [0032]    Although several embodiments have been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.