Because of the increasing cost of electrical energy, the substitution of initially costlier but more energy efficient lamp types in place of incandescent lamps has become practical. A prime candidate for this substitution is the fluorescent lamp, primarily because of its high luminous efficacy.
Compact fluorescent lamps are known in which the envelope includes at least two longitudinally extending leg members joined together by a transversely extending envelope portion. One example of such a lamp which is commercially available is the "Twin-Tube" fluorescent lamp manufactured by GTE Sylvania, Danvers, Massachusetts. Other examples are disclosed in U.S. Pat. No. 4,374,340, which issued to Bouwknegt et al on Feb. 15, 1983; U.S. Pat. No. 4,426,602, which issued to Mollet et al on Jan. 17, 1984; and U.S. Pat. No. 4,481,442, which issued to Albrecht et al on Nov. 6, 1984.
In lamps of the above type, in which a plurality of spaced-apart leg members are employed, the light output resulting from the lamp is generally non-uniform (i.e., the silhouette of the individual leg members is clearly distinguishable) and may be aesthetically displeasing in particular lighting applications in which the lamp envelope is exposed.