Abstract:
This light emitting diode (LED device provides a 360 degree lighting angle in the horizontal plane and a 300 degree lighting angle in the vertical plane while simultaneously addressing LED die thermal management, which is critical to high lumen output LEDs. This LED lighting device is comprised of the LED lens, the LED holder and the heat sink stem. Light produced by at least one LED die traveling vertically is diffused by the top refractive portion of the lens. Light rays directed towards the pointed elements are totally internally reflected downwards then refracted out of the lens, thus resulting in a spherical light pattern. This technology is designed as a replacement for conventional light sources, such as incandescent light bulbs, halogen bulbs, CFLs (compact fluorescent lamps) and metal halide lamps.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    This invention relates to light emitting diode (LED) devices and more specifically, to an improved LED lens and heat sink stem for emitting a spherical light pattern and dissipating heat. 
         [0003]    2. Description of Related Art 
         [0004]    All light sources convert electrical energy into radiant energy and heat in various proportions. Light emitting diode (LED) devices generate little or no IR (infrared) or UV (ultraviolet) light, but convert only 15% to 25% of the electrical power to visible light, the remainder is converted to heat that must be conducted from the LED die to an underlying circuit board, heat sink, etc. 
         [0005]    In order to maintain a low junction temperature to keep good performance of an LED, heat generated by the LED must be dissipated. A build up of heat inside the LED device leads to color shift, reduced light output, shortened life and ultimately device failure. In addition, drive current, thermal path and ambient temperature also affects the junction temperature. Furthermore, high-flux LEDs, which are needed for conventional light illumination, require higher drive currents which further increases junction temperature. 
         [0006]      FIG. 1  illustrates a sectional view of a conventional 360 degree lighting angle LED  100  having one or more LED dies  101  which sits atop the first electrode  104 . A bonding wire  102  connects the LED die  101  to the second electrode  103 . Light emitted by the LED die  101  exits the transparent encapsulate  105  in all directions. The upper surface  106  acts as a partial reflector, reflecting some of the light downwards. In another 360 degree LED prior art example, the encapsulate  105 , takes the shape of a sphere  107 . 
         [0007]    If such LED devices are to be used as conventional lighting, then high-flux LEDs must be incorporated. High-flux LEDs produce more heat, and heat must be moved away from the die  101  in order to maintain expected light output, life and color. Unfortunately, the prior art example contains a critical flaw; it neglects to address LED thermal management; as it does not contain any significant heat sink to draw out the heat via conduction. Electrodes  103  and  104  may draw out some heat; though the majority of the heat generated is trapped inside by the insulating plastic resin encapsulate  105  or  107 . Such LED lamps are thus relegated for use with only lower flux LEDs, which would not be suitable for conventional lighting needs. Retrofitting this LED lamp with a sufficient heat sink, beneath the LED die  101  would revert the 360 degree lighting angle back to typical 30 to 140 degree lighting angles. 
         [0008]    A need therefore exists for an LED device designed to emit a spherical light pattern while successfully managing the heat generated. Such a device would be advantageous for use as a replacement to current conventional light sources or other applications where spherical light patterns are desired. 
       SUMMARY OF THE INVENTION 
       [0009]    This LED lighting device is comprised of an LED lens, an LED holder and a heat sink stem. The crown of the LED lens features twin convex peaks; other iterations may include a convex or concave crown. Circumscribing the lens are 5 pointed, reflective and refractive elements. This LED lens is attachable or fixed to the LED holder. The LED holder houses the LED die, the positive and negative terminals, and the heat sink slug. The holder is attached to the heat sink stem. In the preferred embodiment, the holder and the heat sink stem are one entity. In another embodiment, the LED holder has a hollowed out cylinder base with positive and negative contact patches. In another embodiment, the LED holder has a hollowed out cylinder base with positive and negative contact points. In yet another embodiment, the LED holder has a hollowed out cylinder base with a screw type pattern on the inner walls with positive and negative contact areas. 
         [0010]    The LED lens and each of the various embodiments of the LED holder are attached or fixed atop their individually related heat sink stem. The heat sink stem performs the critical task of drawing heat out of the device. The stem is also used as a means of conveying power to and from the LED Device. Finally, the stem provides an elevated and unobstructed platform for light propagation. 
         [0011]    Light produced by an LED die is diffused upwards and outwards by the top refractive crown portion of the lens. Light rays directed towards the pointed elements are totally internally reflected downwards then refracted out of the lens. The result is a spherical light pattern. Heat produced by the LED die is conducted by the Heat sink slug and is then absorbed by the heat sink stem via an intermediate thermal material. 
         [0012]    The foregoing, and other features and advantages of the invention, will be apparent from the following, more particular description of the preferred embodiments of the invention, the accompanying drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    For a more complete understanding of the present invention, the objects and advantages thereof, reference is now made to the ensuing descriptions taken in connection with the accompanying drawings briefly described as follows: 
           [0014]      FIG. 1  illustrates a sectional view of a conventional 360 degree lighting angle LED; 
           [0015]      FIG. 2  illustrates an example of a spherical light producing lens in accordance with one embodiment of the invention; 
           [0016]      FIG. 3  is another iteration of the lens featuring a convex crown; 
           [0017]      FIG. 4  is another iteration of the lens featuring a convex crown; 
           [0018]      FIG. 5  is an iteration of the lens shown in  FIG. 2  attached to its corresponding heat sink structure; 
           [0019]      FIG. 6A  is a sectional view of the lens shown in  FIG. 2 , featuring contact points and heat sink stem; 
           [0020]      FIG. 6B  is an iteration of the lens shown in  FIG. 2 , forming a lens, LED and holder attachment with contact points; 
           [0021]      FIG. 7A  is a sectional view of the lens shown in  FIG. 2 , featuring contact patches; 
           [0022]      FIG. 7B  is an iteration of the lens shown in  FIG. 2 , forming a lens, LED and holder attachment with contact patches; 
           [0023]      FIG. 8A  is a sectional view of the lens in  FIG. 2 , featuring a screw connection and heat sink stem with a screw connection; 
           [0024]      FIG. 8B  is an iteration of the lens shown in  FIG. 2 , forming a lens, LED and holder attachment with a screw connection. 
           [0025]      FIG. 9A  is a sectional view of the lens shown in  FIG. 2 , featuring positive and negative leads and heat sink stem with positive and negative contact pads; 
           [0026]      FIG. 9B  is an iteration of the lens shown in  FIG. 2 , forming a lens, LED and holder attachment with positive and negative leads; 
           [0027]      FIG. 10  features an LED device package of  FIG. 5  adopted for use in a conventional incandescent Edison bulb package; and 
           [0028]      FIG. 11  features an LED device package of  FIG. 5  adopted for use in a conventional incandescent bulb with an indexed double contact bayonet style base. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0029]    Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying  FIGS. 2-11 . 
         [0030]      FIG. 2  illustrates an example of a spherical light producing lens in accordance with one embodiment of the invention. Light rays A through G emanating from an LED die  201 , with a focal point  202 , are totally internally reflected then refracted out of the lens  200  by the pointed elements  203  through a 90 degree angle. The top surface of the pointed elements  203  may be coated with a reflective material such as aluminum (AL) or nickel chrome (NiCr). Light rays G through J are refracted out of the double crown lens portion  204  through a 60 degree angle. Collectively, all the light rays emitted by the LED die  201  radiate around a 300 degree lighting angle  205  in the vertical plane and a 360 degree lighting angle in the horizontal plane. Surface  207  may be shaped to direct more light rays emitted from the LED die  201  towards a particular section of the lens, such as the pointed elements  203 . 
         [0031]    The length of the die  201  is directly proportional to the size of the lens  200 . The lens length (L) is 5.472 times the die length, whereas the lens height (H) is 2 times the die length. Thus, the lens  200  size may be scaled up or down in proportion to the die length  201 . 
         [0032]    The lens  200  may be manufactured by a variety of process including but not limited to injection molding, casting and diamond etching. The lens  200  is made of a transparent material including but not limited to acrylic; also known as Polymethylmethacrylate (PMMA), polycarbonate (PC), polyetherimide (PEI) and cyclic olefin copolymer (COC). The optimal refractive index range of the lens  200  is between 1.4 and 1.6. 
         [0033]    The volume  206  between the lens and the LED die  201  may be used to house a lens (not shown) mounted to the LED die  201  and employed to direct more light emitted from the LED die  201  towards a particular section of the lens, such as the pointed elements  203 . This volume  206  may also be filled with a transparent material including but not limited to silicone, epoxy or any other material with a refractive index of 1.4-1.6. 
         [0034]    The lens  200  may also act as a color filter. 
         [0035]      FIG. 3  illustrates another iteration of the lens  300  which features a convex crown  304 . 
         [0036]      FIG. 4  illustrates a version of the lens  400  featuring a concave crown  404 . 
         [0037]      FIG. 5  illustrates a sectional view of an LED device  500  where a lens  200  may be attached, fused or bonded to the top of the heat sink stem  503 . The LED die  201  is mounted on a silicon substrate  501  (though other substrates may also be used). Electricity powers the device by traveling from the positive lead  504  through the heat sink stem  503 , across the bond wire  502  to the LED chip  201 . The negative lead  505  emerges from the heat sink slug  506 . Besides the light that is produced (the propagation of which is described in  FIGS. 2-4 ) a significant amount of heat is also generated by the LED die  201 . Heat H 1  is initially absorbed by the heat sink slug  506  and then transferred to the heat sink stem  503 . The heat sink stem radiates heat away from the outer stem walls by convection H 2  and conducts the remainder of the heat H 3  to a prospective device. The heat sink stem  503 , which can vary in length and width, may be made of a non-electrically conductive plastic material. This high thermal conductive plastic may be injection molded. Another iteration of the heat sink stem is made of metal. 
         [0038]      FIG. 6B  illustrates a lens  200  and LED lens holder  602  which jointly form the lens and holder attachment  601 . 
         [0039]      FIG. 6A  shows a sectional view of an LED device  600  which illustrates the means by which the lens and holder attachment  601  is joined to the heat sink stem  603 . The lens and holder attachment  601  is attached by means of two contact points  604  and  605 . The lens and holder attachment  601  is mounted atop the heat sink stem  603  and then rotated through a clockwise or a counterclockwise rotation (depending on the design) until the positive contact point  604  and negative contact point  605  are locked into the positive contact terminal  606  and negative contact terminal  607  respectively. A thermal interface material  608  reduces the thermal resistance and increases the heat flow between the two bordering surfaces; the heat sink slug  506  and the heat sink stem  603 . The thermal interface material  608  may include; thermally conductive paste, thermally conductive compounds, Phase change material, thermally conductive elastomers and thermally conductive tape. 
         [0040]      FIG. 7B  illustrates a lens  200  and LED lens holder  702  which jointly form the lens and holder attachment  701 . A positive  704  and a negative contact patch  705  protrude from the base of the attachment  701 . 
         [0041]      FIG. 7A  shows a sectional view of an LED device  700  which illustrates the means by which the lens and holder attachment  701  is joined to the heat sink stem  703 . The lens and holder attachment  701  is attached by means of two contact points  708  and  709 . The lens and holder attachment  701  is mounted atop the heat sink stem  703  and then rotated through a clockwise or a counterclockwise rotation (depending on the design) until the positive contact patch  704  and negative contact patch  705  are locked onto the positive contact terminal  706  and negative contact terminal  707  respectively. A thermal interface material  608  may be used as a heat conduit between the heat sink stem  703  and the heat sink slug  506 . 
         [0042]      FIG. 8B  illustrates a lens  200  and LED lens holder  802  which jointly form the lens and holder attachment  801 . A positive contact patch  804  circumscribes the base of the attachment  801 . 
         [0043]      FIG. 8A  shows a sectional view of an LED device  800  which illustrates the means by which the lens and holder attachment  801  is joined to the heat sink stem  803 . The lens and holder attachment  801  is attached by a screw connection. The lens and holder attachment  801  is mounted atop the heat sink stem  803  and rotated through a clockwise or a counterclockwise rotation (depending on the design) until the positive contact patch  804  and the heat sink slug  506  are tightened and may be locked onto the positive contact terminal  805  and the negative center pad  806  respectively. 
         [0044]    An electrically conductive, thermal interface material may be used as an interface between the negative center pad  806  and the heat sink slug  506 . 
         [0045]      FIG. 9B  illustrates a lens  200  and LED lens holder  902  which jointly form the lens and holder attachment  901 . A positive  904  and a negative lead  905  extend out from the base of the attachment  901 . 
         [0046]      FIG. 9A  shows a sectional view of an LED device  900  which illustrates the means by which the lens and holder attachment  901  is joined to the heat sink stem  903 . The positive LED lead  904  and the negative LED lead  905  are soldered to the positive solder pad  906  and the negative solder pad  907  respectively. A thermal interface material  608  may be used as a heat conduit between the heat sink stem  903  and the heat sink slug  506 . 
         [0047]      FIG. 10  illustrates one variation of the LED device  500  adopted for use in a conventional incandescent Edison bulb package. LED device packages  600  through  900  may also be used. 
         [0048]      FIG. 11  illustrates another variation of the LED device  500  adopted for use in a conventional incandescent bulb with an indexed double contact bayonet style base. LED device packages  600  through  900  may also be used. 
         [0049]    The above described embodiments of the present invention are meant to be illustrative and not limiting. It will thus be obvious to those skilled in the art that various changes and modifications may be made without departing from this invention in its broader aspects. Therefore, the appended claims encompass all such changes and modifications as falling within the spirit and scope of this invention.