JPH0449819Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a halogen incandescent lamp having a tungsten filament.

[Prior art and its problems]

Halogen incandescent light bulbs are widely used for a variety of purposes, but recently there has been a demand for compact, high-output bulbs, such as in VRT handlights. Therefore, although these devices generate a large amount of heat, they are small in size, and because they are placed in a narrow device, heat dissipation is low and the temperature becomes quite high.

Incidentally, in an incandescent light bulb, a molybdenum metal foil is embedded in the sealing part of the envelope, one end of an internal lead wire connected to a filament inside the envelope is welded to this metal foil, and an external lead rod made of molybdenum is welded to the metal foil. One end is welded to the metal foil and the other end extends outside the enclosure. A fuse wire made of nickel or the like is then welded to this external lead rod, and the tip of this fuse wire is connected to a pin of a ceramic lamp. Therefore, since the external lead rod protruding from the envelope is surrounded by a lamp base that is small and has low thermal conductivity, it is exposed to a high temperature of about 500° C., for example, and is easily oxidized. In particular, since the fuse wire is welded, it deteriorates during welding, and the welded portion is easily oxidized, resulting in a very short lifespan of the incandescent light bulb.

[Purpose of invention]

Therefore, an object of the present invention is to provide an incandescent light bulb that has a simple structure, prevents oxidation of the external lead rod, and has a long life.

[Structure of the idea]

The structure of the present invention is an incandescent light bulb in which one end is connected to a metal foil embedded in the sealing part of the envelope, and the other end is connected to an external lead rod extending outside the envelope, and a fuse wire, The external lead rod is characterized in that a thin film layer of low-melting glass is formed on the surface, and the top is further covered with a cement layer.

〔Example〕

The drawing shows an example of a halogen incandescent light bulb with a rating of 650W used in VTR hand lights, etc., and the quartz glass envelope 1 is small with an outer diameter of about 21φ. A tungsten filament 2 is supported within the enclosure 1 by a pair of internal lead rods 3,3. Two molybdenum metal foils 4, 4 are embedded in the sealing portion 11 of the enclosure 1, and one end of the internal lead rod 3 is welded to each of the metal foils 4. One end of a pair of external lead rods 5, 5 made of molybdenum is similarly welded to the metal foil 4, and the other end protrudes from the sealing portion 11 to the outside. A fuse wire 6 made of nickel is welded and fixed to this protruding portion via a nickel sleeve 61.

In this way, the metal foil 4 to which the inner lead rod 3 and the outer lead rod 5 are welded is pressure-sealed to the sealing part 11 at high temperature, but due to the difference in thermal expansion between quartz glass and molybdenum, it is cooled to room temperature. When it becomes external lead rod 5
A slight gap is created between the sealing part 11 and the sealing part 11. Therefore, low melting point glass is injected to fill this gap, but in the present invention, low melting point glass is adhered not only to this gap but also to the entire surface of the external lead rod 5 to form the thin film layer 7. do. And on top of that
It is completely covered with a cement layer 8 such as Al ₂ O ₃ -SiO ₂ .
Here, when forming the thin film layer 7 on the surface of the external lead rod 5, the surface of the external lead rod 5 protruding from the sealing part 11, especially the part where the fuse wire 6 is welded, is coated uniformly with the thin film layer 7. difficult to form;
There will inevitably be areas where low melting point glass will not adhere. However, since that part is also completely covered with the cement layer 8, the contact of this part with air can be delayed, and a large oxidation prevention effect can be obtained. Next, the lamp base 9 made of ceramic is placed over the sealing part 11, and the fuse wire 6 is inserted into the inside of the pin 91.
are welded and bonded with adhesive 92 to complete the process.

When an incandescent lamp with such a configuration is turned on, the external lead rod 5 also becomes hot due to heat generation, but this external lead rod 5 is completely covered with a thin film layer 7 of low melting point glass and a cement layer 8. Because of this, oxidation is almost completely prevented, and the lifespan of an incandescent light bulb is determined by the lifespan of the filament. Incidentally, if the protruding part of the external lead rod 5 from the sealing part 11 is not covered with anything as in the past, oxidation will progress significantly after about 10 hours of lighting and the protruding part will become unusable. The covered item became unusable in about 20 hours. On the other hand, if it is double covered with a thin film layer 7 of low melting point glass and a cement layer 8 as in the present invention, approximately
The life of the filament was reached after 40 hours of lighting, but
It has been found that the external lead wires have not yet been oxidized, and that this oxidation prevention is highly effective.

[Effect of idea]

As explained above, in the incandescent light bulb of the present invention, the part of the external lead rod protruding from the sealing part is completely covered with a thin film layer of low melting point glass and a cement layer. Oxidation of this part is prevented and the lifespan of the incandescent light bulb can be extended. Therefore, it can be suitably applied to cases where a small, high-output incandescent light bulb is placed in a narrow device, such as a hand light for a VTR.

[Brief explanation of the drawing]

The drawing is a sectional view of an embodiment of the present invention. 1... Envelope, 2... Filament, 3... Internal lead bar, 4... Metal foil, 5... External lead bar,
6...Fuse wire, 7...Low melting point glass thin film layer,
8...Cement layer, 9...Lamp base, 11...
... Sealing part, 61 ... Sleeve, 91 ... Pin, 9
2...Adhesive.

Claims (1)

[Scope of utility model registration request] An incandescent light bulb having one end connected to a metal foil embedded in the sealing part of the envelope and a fuse wire connected to the other end to an external lead rod extending outside the envelope,
This incandescent light bulb is characterized by forming a thin film layer of low melting point glass on the surface of this external lead rod, and further covering the top with a cement layer.