JPH0117227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-pressure discharge lamp in which an inner tube for regulating a discharge path is disposed within an outer bulb forming a discharge space, and a method for manufacturing the same.

Since this type of discharge lamp can be made compact in shape, various specific proposals have already been made as a substitute for incandescent light bulbs. One of them is disclosed in Japanese Patent Application Laid-Open No. 57-44956.
Figure 1 shows this. That is, two electrodes 3 are provided on the stem 2 that closes the lower end opening of the outer tube 1 so as to protrude into the outer tube 1, and one end of the U-shaped inner tube 4 is attached to a protrusion 11 that passes through the electrodes 3. are fitted into each other to prevent crosstalk discharge between the electrodes 3. The other open end of the inner tube 4 is brought into contact with the upper surface of the stem 2, and a discharge hole 5 is formed near the open end. On the other hand, the inner tube 1 is held by a press plate 10 attached to the upper end of a support rod 9 fixed to the stem 2 so that both open ends are pressed against the stem 2. Reference numeral 7 denotes a fluorescent layer. In a fluorescent lamp with such a structure, the support rod 9 and presser plate 10 for fixing the inner tube 1 are installed as separate parts in the lamp, so the number of parts increases. It has problems such as complicated management, complicated structure, and increased manufacturing process.

This invention was made in view of the above circumstances,
The edges of the openings formed at one end of each inner tube are welded together to reduce the complexity of parts management, the complexity of the manufacturing process, and the weight of the lamp due to the use of separate parts for fixing the inner tubes. It is an object of the present invention to provide a low-pressure discharge lamp that eliminates all the problems that increase the number of problems caused by the problem, and a manufacturing method suitable for this low-pressure discharge lamp.

Hereinafter, one embodiment of the present invention will be described based on FIG. 2.

1 is a cylindrical glass outer tube with a domed tip and an open bottom; 2 is a metal or ceramic stem that airtightly closes the bottom opening of the outer tube 1; A discharge medium made of a predetermined amount of mercury and a rare gas such as argon gas is sealed in the airtight space formed. Reference numeral 3 denotes two electrodes sealed to the stem 2 so as to project into the outer tube 1, and 4 is an inner tube made of glass that is disposed within the outer tube 1 and regulates the discharge path. The inner tube 4 is formed by welding one leg of two glass tubes bent into a U-shape to one another. That is, the free end side end of the inner tube 4 is fixed to the stem 2 surface by the glass frit 8 in an airtight manner so that crosstalk discharge does not occur between the electrodes 3 with the electrodes 3 inside. has been done. On the other hand, the other end is in contact with the surface of the stem 2, and a substantially semicircular opening 5 cut out from the end surface is formed on the side surfaces facing each other, and furthermore, at the top of this opening 5, The glass constituting the inner tube 4 is melted, and the tops of the openings 5 are welded together to form a bridged connecting portion 6.

The inner tube 4 shown in this example was manufactured as follows. FIG. 3 is a diagram explaining the manufacturing method. Two glass tubes A, A bent into a U-shape, with their respective two legs A ₁ , A ₁ and A ₂ , A ₂ facing each other closely and with their end faces facing upward, The end portions of the leg portions A ₂ and A ₂ are simultaneously heated and melted using gas burner C from the end portions of the leg portions A ₂ and A ₂ . When left in this state for a while, the leg portions A ₂ and A ₂ form a semicircular opening 5 as if cut out from the end surface side due to the wind pressure of the flame of the burner C. The peripheral edge 51 of the opening 5 has a bulge 52 formed of molten glass. Then, pinch the thickening at the top of the opening 5 (the center of the arc forming the opening periphery 51), and then pull the glass tubes A, A apart slightly, so that the pinched part becomes the predetermined connecting part 6. By forming it into
The fabrication of the inner tube 4 is completed. Note that it is advantageous to form the phosphor layer 7 deposited inside the inner tube 4 after the inner tube 4 is molded, as this facilitates the processing of the connecting portion 6.

In the fluorescent lamp formed in this way, the two inner tubes 4 can be treated as one inner tube 4 having substantially two U-shaped curved portions due to the connecting portion 6. Therefore, the stem can be erected on the two surfaces of the stem by the four end surfaces without using any supporting members. Therefore, the work of fixing the inner tube 4 to the stem 2 with the frit 8 can also be done with an inner tube holding jig (not shown), which is used when fixing the inner tube 4 as a single U-shaped tube as in the past. ) is not necessary, and the fixing work is extremely simplified. Moreover, since all four end surfaces are in contact with the two stem surfaces, the inner tube 4 itself will not collapse even if it is subjected to external force such as impact force during the post-fixing process or when handled as a product. I will not invite such a situation. Therefore, even after the inner tube 4 is fixed, there is no need to use the inner tube support as shown in FIG. 1, so the number of parts can be reduced, and the number of man-hours for assembling the parts can also be reduced, making parts management easier. Moreover, it is possible to prevent the manufacturing process from becoming complicated. Furthermore, although the support rod 9 and the presser plate 10 shown in FIG. 1 are made of metal, the support rod 9 and the presser plate are The weight advantage of not using plate 10 is not negligible.

Further, when manufacturing the inner tube 4, the connecting portion 6 is formed at the same time as the opening 5, which becomes the hole for crossover discharge, is formed, so that the number of heating and annealing steps for the glass tube can be reduced. Furthermore, with this reduction in the number of steps, the manufacturing yield of the inner tube 4, which uses fragile items such as glass tubes, can be greatly improved.

Note that, as shown in the above embodiment, the opening 5 formed in the inner tube 4 is not limited to a semicircular shape cut out from the end surface, but may be formed in a circular shape in the middle of the leg of the inner tube 4. You may. In this case, the opening 5 can be easily formed by blowing a high temperature flame such as an oxygen-gas flame from an obliquely outward direction of the intended opening location.

As explained above, the present invention provides two inner tubes with both ends in contact with the bottom surface of the outer tube within the outer tube that forms the discharge space, and one end of the inner tube that does not have an electrode. Since an opening is formed in the tube and a portion of the periphery of this opening is welded together, no supporting member is required to support the inner tube, and therefore,
The number of parts is reduced and parts management becomes easier. Furthermore, since assembly of the inner tube support member is also omitted, the manufacturing process can be simplified. In addition, when manufacturing the above-mentioned low-pressure discharge lamp, two glass tubes bent into a U-shape are placed close to each other, and then a gas burner is applied to the opening location of the glass tube to melt the opening location and increase the flame pressure. Since the apertures are made using the method described above and the peripheral edges of the apertures are immediately pinched and connected, there is an advantage that a low-pressure discharge lamp can be manufactured extremely easily and without reducing the manufacturing yield.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing a conventional low-pressure discharge lamp in comparison with the present invention, FIG. 2 is an exploded perspective view showing an embodiment of the low-pressure discharge lamp of the present invention, and FIG. 3 is an exploded perspective view showing an inner tube according to the present invention. FIG. In the figures, 1 is an outer tube, 2 is a stem, 3 is an electrode, 4 is an inner tube, 5 is an opening, and 6 is a connecting portion. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. An outer tube made of a transparent material with a discharge medium sealed inside and a pair of electrodes sealed at the bottom; disposed within the outer tube, with both ends abutting the bottom of the outer tube, and one end is fixed with an adhesive so as to enclose the electrode in an airtight manner, and is provided with two U-shaped inner tubes made of a transparent material and having an opening connected to the outer tube at the other end. A low-pressure discharge lamp characterized in that the inner tube is integrated by welding parts of the edges of the opening to each other. 2 Arrange two U-shaped glass tubes so that their legs face each other, then heat and melt one of the opposing legs with a gas burner and use the flame of the burner to make a notch-shaped opening in the glass tube. A method for manufacturing a low-pressure discharge lamp, comprising the steps of: forming an opening, and then pinching together parts of the edges of the opening in a softened state and welding them together.