Method for manufacturing an incandescent lamp
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorKazuo Maeda
Life of this patent
Estimating the term…
Abstract
A method for manufacturing an inexpensive lamp, which suppresses distortion of a bulb and prevents decrease in commercial value and breakage of the bulb. In a glass bulb having one end thereof communicating with an exhaust tube, an assembly of a filament, metal foils and lead wires is disposed. In this state, the whole glass bulb is heated by a burner. The end opposite to the exhaust tube of the glass bulb is pinch-sealed to form a pinch-sealed portion. Subsequently, an expanded portion is formed by charging a protective gas from the exhaust tube into the glass bulb.
Claims4
A method for manufacturing a lamp comprising a bulb containing a filament and having an expanded portion and a pinch-sealed portion, the lamp manufacturing method comprising:
- softening a bulb communicating at one end thereof with an exhaust tube with the filament located inside the bulb;
- pinch-sealing the end opposite to the exhaust tube of the bulb;
- and
- forming the expanded portion by charging a protective gas from the exhaust tube, wherein
- by pressing dies each having a predetermined shape against the bulb, a narrowed portion is formed between the expanded portion and the pinch-sealed portion, simultaneously with the formation of the expanded portion, so that 0.5≦S/d≦1,
- wherein the outside diameter of the bulb is d (mm) and the outside diameter of the narrowed portion is S (mm).
Dependencies are inferred from the claim text.