FIGURE 4.1 An LED equivalent of a screw-base A-lamp showing the component parts. Courtesy of Philips Lighting.

and linear fluorescent, and metal halide lamps. This is an appealing market segment for several reasons. The large number of available sockets appeals to the manufacturing community, and the lower investment required to try these products by directly replacing the older lamp in the existing luminaire appeals to the consumer. Although the LED chips themselves are manufactured by a small number of multinational companies, the assembly of an LED lamp resembles that of any electronic equipment. The investment needed to set up an assembly line is relatively modest, and therefore a very large number of companies can and have entered the industry. The approximately 4 billion medium screw-base sockets in U.S. households represent a very attractive potential market, so the industry development has happened very quickly, in the span of only a few years. At the same time, the industry1 is scrambling to develop meaningful safety and performance standards, and product quality varies over a wide range.

FIGURE 4.3 through Figure 4.5 illustrate examples of LED replacements for incandescent A-lamps, PAR lamps, and linear fluorescent lamps. The lamp on the left of Figure 4.3 uses the remote phosphor concept where the blue LEDs excite the orange phosphor cover (which emits white light), and the lamp on the right uses two phosphor white LEDs2 placed within an envelope that mimics an incandescent A-19 lamp.


FIGURE 4.2 Two types of LED luminaire: (a) with integrated LED light source; (b) with replaceable LED module. Courtesy of Toshiba.


FIGURE 4.3 Sample LED replacement lamps for incandescent A-19 lamps. Courtesy of Philips Lighting.


1 Primarily the National Electrical Manufacturers Association ( and the Zhaga Consortium (

2 See the discussion of white phosphor LEDs in the subsection of Chapter 3, “Use of Phosphors.”

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