Abstract
Surface emission concentric shells that can emit both light rays and a large amount of heat from the whole outer surface are proposed here for a large globe light-emitting diode (LED) bulb. The concentric shells are composed of an outer total internal reflection (TIR) shell and an inner metallic shell adjacent to the outer shell. The TIR shell can guide light rays emitted from LEDs owing to the TIR and emits illuminating light from the outer surface. Assuming that the thickness of the TIR shell is sufficiently small, the TIR shell can also emit heat of the inner shell to the outside. It is theoretically predicted based on the heat transfer theory that the larger the concentric shells are, the larger the amount of heat that can be emitted to the outside. A large globe LED bulb prototype having the concentric shells with an outermost diameter of about 95 mm is therefore designed and fabricated, with which it is shown that an illuminating light flux of about 1064 lumens and heat of about 12.2 W can both be emitted to the outside. The prototype also shows to have a large hollow structure in which several kinds of devices can be accommodated.
Highlights
The replacement of traditional incandescent light bulbs with light-emitting diodes (LEDs) has been progressing rapidly owing to the high efficiency and long life of LEDs
Concentric shells composed of the total internal reflection (TIR) shell that encloses a metallic inner shell are applicable to LED bulbs, enabling heat generated by the LED to be released through both the inner shell and the TIR shell to the outside
The large globe LED bulb prototype is fabricated, which shows that an illuminating light flux of about 1064 lumens and heat of about 12.2 W can both be emitted to the outside
Summary
The replacement of traditional incandescent light bulbs with light-emitting diodes (LEDs) has been progressing rapidly owing to the high efficiency and long life of LEDs. Several solutions have been developed to produce wideangle light distributions.[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28]. A total internal reflection (TIR) shell with LED light sources has been developed, which can emit illuminating light from its surface.[29] Concentric shells composed of the TIR shell that encloses a metallic inner shell are applicable to LED bulbs, enabling heat generated by the LED to be released through both the inner shell and the TIR shell to the outside. In Ref. 29, a standard pear-shape light bulb having the concentric shells with the outermost diameter of about 60 mm is fabricated, which is shown to emit an illuminating light flux of about 600 lumens
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