Electric lamp with an envelope seal designed as pinch seal, and a device and method for its manufacture

US4469983A · kind A · utility

Assignee

• Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH · DE

Inventors

• Helmut Grahmann · Friedberg, DE
• Dieter Hofmann · Augsburg, DE
• Alfred Wacker · Friedberg, DE

Key dates

• Filing date: Feb 18, 1982
• Grant date: Sep 4, 1984
• Expiry date: Feb 18, 2002

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J5/32
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

The lamp has a pinch seal which surrounds a mounting structure carrying l-in wires of the filament; PA0 the front face (7) terminating the lamp envelope end forms substantially a plane, and is arranged at right angle to the generated surface of the lamp envelope (1) with the transition of these two surfaces to one another being substantially in the shape of a circumferential edge, PA0 the length of the pinch seal (2) extending from the front face (7) on the axis of the lamp envelope is from 0.2 to 0.4 times the external diameter of the lamp envelope (1), PA0 and the width of the pinch seal is close to the external diameter of the lamp envelope. To form this shape, the lamp is introduced into a die, with the envelope softened and, during execution of the pinch operation, excess gas pressure is applied to the interior of the lamp envelope so that the lamp envelope will accurately follow the shape of the pinch jaws similar to a blow-molding operation. The excess gas can be introduced into the lamp envelope for example through an exhaust tube forming part of the mounting structure, which is later on used for exhaustion and filling of the lamp and then sealed off.