Electric lamp and discharge devices – With gas or vapor – Envelope with particular structure
Patent
1985-04-12
1987-10-27
Levy, Stewart J.
Electric lamp and discharge devices
With gas or vapor
Envelope with particular structure
H01J 6130
Patent
active
047032278
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to a low pressure mercury vapor discharge lamp provided with a bulb for forming an electric discharging path and preparation thereof.
BACKGROUND OF ART
There has been known a fluorescent lamp such as a low pressure mercury vapor discharge lamp provided with a U-shaped bulb formed with bending or connecting processes, from a publication such as Japanese Unexamined Patent Publication No. 155675/1979 (FIG. 1) or Japanese Unexamined Patent Publication No. 133744/1980 (FIG. 2). The fluorescent lamp having such construction is advantageous because a lamp is made in a compact form. However, the U-shaped bulb 1 as shown in the figure has a space of gap 31 between both legs 1a, 1b. Therefore, in manufacturing steps, when the legs 1a, 1b of the bulb 1 are gripped from their outer sides so that a force is applied in its central direction, a connecting part 2a between the both legs 1a, 1b is apt to cause breakage. Accordingly, a device A is generally used to grip the both legs 1a, 1b of the bulb 1 in a plan passing through the legs 1a, 1b, as shown in FIG. 3 which is disclosed in Japanese Unexamined Patent Publication No. 124928/1980. On the other hand, the fluorescent lamp in a compact form which is substituted for an incandescent lamp generally has the legs 1a, 1b of the bulb 1 of about 100-150 mm in height, on account of which the bulb has to be supported in only one direction in the manufacturing steps. This means that it is necessary to prepare the device A used for various manufacturing steps at a high accuracy thereby to cause problems of complicated maintenance and inspection.
Further, there has been proposed a fluorescent lamp in which a U-shaped bulb 1 is further bent into two parts (hereinbelow referred to as a double U-shaped bulb) aiming at further compactness of the lamp. FIG. 4 shows a lamp, as an example, disclosed in Japanese Unexamined Patent Publication No. 108162/1980. In this case, two U-shaped bulbs 1, 1 are arranged so that there remain spaces of gap 31, 32, 33 and 34 between all adjoining legs among the legs 1a, 1b, 1c and 1d. Therefore, when the two U-shaped bulbs have to be supported by a supporting device A without causing breakage of the connecting parts 2a, 2b, the structure of the device A must be complicated in comparison with the device for a single U-shaped bulb 1, this prohibiting a large scale production. The same condition applies to a fluorescent lamp of a double tube structure in which a U-shaped bulb is placed inside an outer bulb.
DISCLOSURE OF THE INVENTION
The present invention has been attained in view of the above-mentioned circumstances and it is an object of the present invention to provide a low pressure mercury vapor discharge lamp enabling a bulb to be easily gripped by a supporting device in manufacturing steps, simplifying a manufacturing device, rendering maintenance and inspection to be easy and allowing a large scale production, by arranging legs of a U-shaped bulb in a contacting state.
It is another object of the present invention to provide a low pressure mercury vapor discharge lamp reducing quantity of material to be used for sealing a bulb to an end plate through glass frit at an open end of the bulb in which the glass frit is arranged corresponding to the inner wall of the open end of the bulb, whereby sealing between the end plate and the open end of the bulb is established at inner wall of the bulb at the open end.
It is still another object of the present invention to provide a low pressure mercury vapor discharge lamp which reduces coating time of glass frit in a fitting groove and makes molding of an end plate easy by constructing the lamp so as to attach both ends of a U-shaped bulb to the end plate so that the both ends of the bulb is received in a common fitting groove for the glass frit, formed in the end plate.
It is further object of the present invention to provide a low pressure mercury vapor discharge lamp which is able to withstand an external force without pushing up manufacturing cost and imp
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patent: 3501662 (1970-03-01), Plagge
patent: 4298822 (1981-11-01), Fukuda
patent: 4524301 (1985-06-01), Cohen et al.
patent: 4527088 (1985-07-01), Bouchard et al.
patent: 4530710 (1985-07-01), Dullea et al.
Patents Abstracts of Japan, vol. 7, No. 62 (E-164) (1207), Mar. 15th 1983; & JP-A-57 210 559 (Mitsubishi Denki K.K.) 12-24-1982.
Patents Abstracts of Japan, vol. 7, No. 103 (E-173) (1248), May 6th 1983; & JP-A-58 25 066 (Mitsubishi Denki K.K.) 02-15-1983.
Imai Jun
Ito Hiroshi
Takeda Takao
Tanaka Norihiko
Taniguchi Yoshiteru
Levy Stewart J.
Mitsubishi Denki & Kabushiki Kaisha
Roskos Joseph W.
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