Spherical Light Output LED Lens and Heat Sink Stem System
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.
1. Field of Invention
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.
2. Description of Related Art
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.
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.
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.
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 INVENTIONThis 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.
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.
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.
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.
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:
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
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.
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.
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.
The lens 200 may also act as a color filter.
An electrically conductive, thermal interface material may be used as an interface between the negative center pad 806 and the heat sink slug 506.
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.
Claims
1-10. (canceled)
11. A heat sink stem comprising:
- a body includes a means for coupling to a lens or lens holder;
- a thermally conductive material;
- a stem length used as a platform for light propagation lead wires traveling the length of the stem to an LED light source.
12. The heat sink stem of claim 11, wherein the heat sink stem comprises:
- a cylindicular body;
- a protruding cylindicular center section with twist and lock channels;
- positive and negative contact points;
- A twist and lock attachable lens and holder with positive and negative contact points.
13. The heat sink stem of claim 11, wherein the heat sink stem comprises:
- a cylindicular body;
- a protruding cylindicular center section with twist and lock channels;
- positive and negative contact patches;
- A twist and lock attachable lens and holder with positive and negative contact patches.
14. The heat sink stem of claim 11, wherein the heat sink stem comprises:
- a cylindicular body;
- a protruding cylindicular center section with a screw type pattern on the walls of the perimeter; positive and negative contact points; a screwable lens and holder with positive and negative contact points
15. The heat sink stem of claim 11, wherein the heat sink stem comprises:
- a cylindicular body;
- positive and negative contact pads;
- an attachable lens and holder with solderable positive and negative contact leads.
16. The lens and holder package of claim 11, wherein the holder is made of metal.
17. The heat sink stem claim of 11, wherein the stem is made of a thermally conductive plastic.
18-21. (canceled)
Type: Application
Filed: Jul 22, 2011
Publication Date: Sep 20, 2012
Inventor: Malek Bhairi (Claremont, CA)
Application Number: 13/189,419
International Classification: H01J 7/24 (20060101);