Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
1999-02-12
2001-01-16
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S573000, C313S634000
Reexamination Certificate
active
06175187
ABSTRACT:
INCORPORATION BY REFERENCE
This application incorporates the subject matter of Japanese Patent Application 10-30168 filed Feb. 12, 1998 as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dual tube fluorescent lamp and a lighting device using the dual tube fluorescent lamp. The dual tube arrangement includes an inner luminescence tube contained within an outer tube.
2. Description of Related Art
Although it is known to use a dual tube type fluorescent lamp, there is a perceived need to provide a dual tube fluorescent lamp which is bent to a predetermined shape that may include one or more bent or nonlinear portions.
The manufacture of a dual tube type fluorescent lamp having a nonlinear portion by known methods is rather complicated. After manufacturing a substantially linear dual tube type fluorescent lamp, a portion of it must be bent. The portion to be bent into some nonlinear shape is heated over a gas flame or by an electric furnace. The outer glass tube and the inner luminescence tube are softened and then bent into the desired shape.
During this heating and bending it becomes difficult to control both the inner luminescence tube and the outer tube such that they do not come into contact with one another. If they do, either or both of the tubes will become mis-shaped or ruined. Also, cracks may form in one or both of the tubes. There has been a need to find a better way of manufacturing dual tube type fluorescent lamps having non-linear portions.
SUMMARY OF THE INVENTION
Accordingly, a primary object of the present invention to provide a dual tube type fluorescent lamp having one or more bent or non-linear portions and a lighting device using such a lamp. The dual tube type fluorescent lamp includes an inner fluorescence tube and an outer glass tube containing the inner fluorescence tube.
Another object of the invention is to provide a method of manufacturing a dual tube type fluorescent lamp that does not cause the tubes of the lamp to crack during manufacture and which does not allow defects to occur by virtue of the inner and outer tubes coming into contact with one another during the manufacturing process.
The dual tube type fluorescent lamp according to the invention has an inner fluorescence tube and an outer tube containing the inner fluorescence tube. It has at least one non-linear or bent portion. A pair of electrodes, one located near each tube end, provide a means for applying electric power to the lamp. A phosphor layer is formed in the inside of the inner fluorescence tube. There is a gap between the inner and outer tubes. The inner luminescence tube contains mercury and a rare gas providing an electric discharge medium. An important aspect of the invention is the use of a layer of material that has a softening point higher than the softening point of glass. This layer of material is applied either to the outer surface of the inner tube or to the inner surface of the outer tube or both, at least at portions of the inner and outer tubes that are to be bent or formed into non-linear portions.
Various embodiments of the invention will be described in detail with reference to the following drawings.
REFERENCES:
patent: 5753999 (1998-05-01), Roozekrans et al.
patent: 5804914 (1998-09-01), Ozawa et al.
patent: 6008567 (1999-12-01), Aizawa et al.
Patel Ashok
Pillsbury Madison & Sutro LLP
Toshiba Lighting & Technology Corp.
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