BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
FIG. 1 is a cross-sectional view of an embodiment of the present invention;
FIG. 2 is an exploded cross-sectional view of an alternate embodiment of the present invention;
FIG. 3 shows a flow chart of a manufacturing process; and
FIG. 4 is a is a cross-sectional view of a prior art light source.
DETAILED DESCRIPTION OF THE INVENTION
A brief discussion of a prior art light source may be useful. FIG. 4 shows an embodiment 40 of a prior art light source having a plurality of differently colored LED dice 41 arranged on light source body 42. Light source 40 utilizes multiple colored LED dice 41 to create white light. Encapsulant 44 may be used to protect LED dice 40. LED dice 40 may include LED dice for producing red, green, and blue light. Light guide 46 having walls 47 for controlling light emission is coupled to body 42 and receives light emitted from LED dice 40. Insufficient light mixing may result in a nonuniform colored light. Colored blotches may appear (shown by broken lines) at the base of light guide 46 as a result of insufficient light mixing. These colored blotches or hot spots typically reduce the quality of light produced by the LED light source.
FIG. 1 shows a cross-sectional view of one embodiment 10 of a light source having an array of LED dice 11 arranged on light source body 12. LED dice 11 may be arranged in a particular pattern and produce various colored light. In the embodiment shown, a generally transparent first encapsulant layer 14 is provided directly upon LED dice 11. A light diffusing element 15 is embodied as a second encapsulant layer provided over first encapsulant layer 14. Second encapsulant layer 15 includes a generally transparent substrate 16 containing a plurality of air bubbles 17. Bubbles 17 are, in effect, discontinuities between one medium and another which serve to diffuse the light, resulting in a better mix of the colors. Light guide 18 is connected to body 12 and receives light emitted from LED dice 11. Bubbles 17 of second encapsulant layer 15 effectively diffuse light from dice 11 to yield a white light source with improved uniformity. In another embodiment of the invention (not shown), first and second encapsulant layers 14, 15 can be combined into a single encapsulant layer having a plurality of air bubbles contained therein.
FIG. 2 shows an exploded cross-sectional view of another light source embodiment 20 having grooved substrate 21. In the embodiment shown, grooves 22 are defined upon a surface of substrate 20. With substrate 20 overlaid upon first encapsulant layer 14, grooves 22 create medium discontinuities, here embodied as air gaps, which diffuse and redirect light emitted from LED dice 11. Grooves 22 may be considered elongated bubble elements and may be closed at ends of substrate 20.
In operation, LED dice 11 (FIG. 1) produces colored lights, typically red, green and/or blue which are used to create a white light for communication into light guide 18. Discontinuities, such as air bubbles 17 or grooves 22, effectively diffuse colored light emanating from LED dice 11 prior to introduction into light guide 18. Consequently, embodiments of the present invention can produce a well-mixed white light, preferably devoid of color blotches.
FIG. 3 shows a manufacturing process flow chart 30 in accordance with an embodiment of the invention. In an initial step 31, LED dice are arranged on a body in a pattern which enhances color mixing and minimizes heat build up. At step 32, the first encapsulant layer is placed over the LED dice. The first encapsulant layer is of clear resin, epoxy or silicon material. The first encapsulant layer may be a curable liquid resin which flows into intimate contact with individual LEDs and which is subsequently hardened. At step 33, a second encapsulant layer containing discontinuities (such as bubbles) is placed over the first encapsulant layer. The second encapsulant layer may be a sheet laminate which overlays the first encapsulant layer. The sheet laminate may be a cured resin, such as an epoxy or silicone. At step 34, the body is connected at a light entry edge of the light guide.
In another embodiment, the second encapsulant layer may be manufactured by introducing water into a laminate resin. The resin may then be cured at appropriate temperatures and pressures to create and/or maintain water and/or air bubbles within the cured resin. An alternative method of creating the second encapsulant layer may include vigorously stirring a resin to entrain air bubbles, forming the resin into a sheet form, and quickly curing the sheet, for example, in a heated vacuum chamber. Bubbles within the encapsulant layer may be generally spherical or may assume alternative configurations or shapes. The bubbles need not necessarily be air bubbles, but may be defined by other fluids, for example by introduction of bubble-generating fluids within the second encapsulant layer.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter,
Patent Application
20080079014
