Fish & Richardson P.C.
Spiral fluorescent tube and method and device for manufacturing the same
 A fluorescent tube which is used for bulb-type fluorescent lamps is spirally wound, so that the effective length of the tube is increased. While a fluorescent tube is kept vertical, it is rotated and heated evenly at the part to be wound to a glass softening temperature or above by a heating device. The rotation of the fluorescent tube is stopped, and the part which is not facing a rod are heated. Then, the tube is clamped from a horizontal direction by a pair of clamps, and is wound around the rod at least 2.5 times by rotating the clamp arms in opposite directions while the arms gradually shift away from each other. 
Matsushita Electronics Corporation
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Masaru Toshiyoshi Shunji
Saito Oga Asai