Manufacturing method of an arc tube formed from a glass tube and having a spirally wound section within one plane
AssigneePanasonic Corporation
InventorsShiro Iida, Noriyuki Uchida, Hidezoh Akutsu
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Abstract
An arc tube is composed of an arc tube body that is formed by winding a straight glass tube. Two portions of the straight glass tube are spirally wound around an imaginary conical surface. The spiraled portions of the glass tube are sandwiched between a pair of movable fixed plates. The spiraled portions of the glass tube are heated to a temperature equal to or higher than a point at which the glass tube is deformable and yet lower than the softening point of the glass tube. The spiraled portions are flattened by the movable plate moving downwardly under its own weight.
Claims9
A manufacturing method of an arc tube, comprising:
- a winding step of spirally winding a glass tube around an imaginary conical surface;
- and
- a deforming step of heating a spiraled portion of the glass tube to a temperature equal to or higher than a point at which the glass tube is deformable and lower than a softening point of the glass tube, and deforming the spiral so that the spiraled portion has a tube axis substantially within one plane, wherein
- when seen from an axis of the imaginary conical surface, a minimum gap between adjacent turns of the spiraled portion before the deforming is not smaller than 0.5 mm and not greater than 0.4 times an outside diameter D1 of the glass tube.
Dependencies are inferred from the claim text.