Electric lamp and discharge devices – With gas or vapor – Envelope with particular structure
Patent
1985-02-26
1987-02-24
DeMeo, Palmer C.
Electric lamp and discharge devices
With gas or vapor
Envelope with particular structure
313493, H01J 6134, H01J 6170
Patent
active
046459723
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a low pressure discharge lamp having an inner tube to restrict a discharge path in an outer bulb forming a discharge space.
BACKGROUND ART
A variety of proposals have been made for this kind of discharge lamp to substitute it for an incandescent lamp because the discharge lamp allows its size-reduction into a compact form. The discharge lamp disclosed in Japanese Unexamined Patent Publication No. 44956/1982 is shown in FIG. 1 as an example, in which there are provided two electrodes 3 passing through an end plate 2 closing the lower opening portion of an outer bulb 1, extending in the outer bulb 1 and each one end of inner tubes 4, formed into a U-shape, is fitted to each projection 11 through which each of the electrodes 3 passes, on account of which cross-talk discharge possibly occurring between the electrodes 3 is prevented. The other open end of the inner tubes 4 is in contact with the upper surface of the end plate 2 and a recess 5 for causing bridge of electric discharge is formed in the vicinity of each of the open ends. On the other hand, the inner tubes 4 are held by a pressing plate 10 fitted to the upper end of a supporting rod 9 secured to the end plate 2 so that both the open ends are in contact with the end plate 2. A reference numeral 7 designates a layer of fluorescent material.
In the discharge lamp having the construction described above, since the supporting rod 9 and the pressing plate 10, both needed to secure the inner tubes 1 are incorporated in the lamp as additional parts, there are problems of increasing the number of parts; causing additional management for these parts, complicated structure of the lamp and increasing manufacturing steps.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a low pressure discharge lamp having double tube structure comprising an outer bulb and inner tubes, in which each open end part at the side of covering an electrode of the inner tubes is bonded with an adhesive to an end plate at a position facing the outer bulb and the other each open end part, which does not cover the electrode, of the inner tubes is made in contact with the end plate thereby eliminating problems of complicated management of parts; complicated manufacturing steps and increase in weight of the discharge lamp, all resulting from use of additional parts to secure the inner tubes, in view of the circumstances as described above.
It is another object of the present invention to provide a low pressure discharge lamp having double tube structure, in which an outer bulb, inner tubes and a fine pipe for air discharge are bonded with an adhesive on a surface of an end plate facing the outer bulb whereby manufacturing work can be simplified, damage of parts to be bonded or bonding portions can be prevented and reliability on airtightness can be increased.
BRIEF DESCRIPTION OF DRAWING
FIG. 1 is an exploded perspective view of a conventional low pressure discharge lamp in contrast to the present invention;
FIG. 2 is an exploded perspective view of an embodiment of the low pressure discharge lamp according to the present invention;
FIG. 3 is a diagram showing the preparation of an inner tube shown in FIG. 2;
FIG. 4 is a diagram showing the preparation of the inner tube in FIG. 2;
FIG. 5 is a diagram showing the preparation of the inner tube in FIG. 2;
FIG. 6 is an exploded perspective view of another embodiment of the low pressure discharge lamp according to the present invention;
FIG. 7 is a cross sectional view partly omitted of the other embodiment of the discharge lamp of the present invention;
FIG. 8 is a cross sectional view of an important part of still another embodiment of the present invention;
FIG. 9 is a cross sectional view showing another embodiment of the present invention; and
FIG. 10 is a cross sectional view of a separate embodiment of the discharge lamp of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with refe
REFERENCES:
patent: 4199708 (1980-04-01), Lauwerijssen et al.
patent: 4208618 (1980-06-01), Heine
patent: 4524301 (1985-06-01), Cohen et al.
Hiroshi Ito
Hitoshi Yamazaki
Jun Imai
Kouzi Yamamoto
Shizuo Nakano
DeMeo Palmer C.
Mitsubishi Denki & Kabushiki Kaisha
O'shea Sandra
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