Patent · US Expired

Method of making a unitary tubular generally U-shaped discharge vessel, particularly for compact fluorescent lamps

US4830648A · kind A · utility

4Cited by

5References

7Claims

0Family size

Assignee

Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH · DE

Inventors

Lutz Klein · Scheuring, DE
Ernst Panofski · Augsburg, DE

Key dates

Filing date	Aug 30, 1988
Grant date	May 16, 1989
Priority date	—
Expiry date	Aug 30, 2008

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC03B23/207
WIPO fieldOther special machines
WIPO sectorMechanical engineering

Abstract

To prevent weakened corners when forming a U-shaped discharge tube with sharp corners (28, 29) during a bending operation from a straight tube, two glass tubes (1, 3) having a wall dimension suitable for a compact fluorescent tube are fused to a central tubular glass element (2) of thicker wall dimension so that, upon bending into U-shape with sharp corners (28, 29), the thicker wall portion can stretch and form the essentially right-angle corners of requisite wall thickness. Preferably, during the heating steps for forming the glass, the initially straight glass portions (1, 2, 3) are rotated.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.