Compact fluorescent lamp having convoluted tubular envelope of tridimensional configuration, method of making such envelope, and lighting unit incorporating such lamp

摘要

A fluorescent lamp of high brightness and compact size is provided by forming the envelope from vitreous tubing that is bent upon itself in such a manner that the envelope has either five or seven U-shaped sections which are disposed in tridimensional array and define a single convoluted discharge channel. The U-shaped sections are so oriented that the tubular legs of the U's are positioned in side-by-side columnar relationship with each other and the sealed ends of the tubing are located adjacent one another. The lamp thus has an arc length that is more than six or eight times as long as the overall height dimension of the convoluted envelope and generates light in a very efficient manner. The retrobent fluorescent lamps are combined with a protective housing, a base structure and operating circuits of various types to provide convection-cooled lamp units that are small enough to be used in table lamps and similar lighting fixtures but have light outputs in excess of 1,500 lumens and efficacies in the order of 60 lumens per watt. Various arrangements for including the ballast and other circuit components either as integral parts of the lamp unit or as separate components which are housed in the lighting fixture and thus permitting the lamp units to be used as direct replacements for incandescent type lamps are disclosed. Method of manufacturing the various multi-U-bent envelopes from a single piece of glass tubing employing arcuate molding components and sequential bending operations are also disclosed.