JPS5847642Y2 - Tungsten halogen lamp with improved seal - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a tungsten halogen lamp.

Such lamps have a quartz or high silica glass enclosure and a halogen-containing fill gas.

The high silica glass used in tungsten halogen lamps cannot be easily hermetically sealed with low melting point glasses such as the so-called soft-hard glasses commonly used in lamp manufacture.

Therefore, tungsten halogen lamp enclosures are generally sealed by press seals.

Such a seal is created by heating the open end of the tubular envelope to a softening point and crimping the end between the two openings to form a press seal.

Because such lamps operate at high temperatures, molybdenum ribbon connectors are commonly embedded within the press seal to provide electrical connections to the lamp and to prevent seal failure due to thermal expansion.

Examples of such lamps are shown in US Pat. Nos. 3,497,753 and 3,466,489.

Such press seals are generally satisfactory if the seal temperature is not extremely high during lamp operation.

However, at sealing temperatures above about 350 DEG -400 DEG C., the external lead wire becomes oxidized, and the degree of oxidation increases with temperature and causes premature seal failure.

Since the external lead wire cannot be completely hermetically sealed within the press seal, air can penetrate the press seal around the lead wire and cause oxidation of the heated wire.

The increase in wire diameter due to oxide formation causes excessive stress on the press seal, leading to premature seal failure.

Such conditions are particularly likely to occur if the lead-in wire is made of molybdenum.The tungsten halogen lamp of the present invention has a tungsten filament within a high silica glass enclosure, which enclosure is also known in the prior art. It contains a halogen-containing filler gas that serves to regenerate the filament as shown in the figure.

The enclosure has a press seal at one or both ends thereof, and a thin molybdenum ribbon connector is completely embedded within the press seal.

An internal lead-in wire connects the ribbon connector to the separated end of the filament.

An external molybdenum lead-in wire is attached to the end of the ribbon connector and projects outside the press seal to electrically connect the filament to an external power source.

A molybdenum aluminide coating is applied to the surface of the lead-in wire to prevent oxidation of the external molybdenum ribbon.

A molybdenum aluminide coating is preferably formed in correspondence with the molybdenum wire so that the coating is chemically adhered to the molybdenum, i.e. the coating is integral with the wire and will not separate or fall off therefrom. .

Preferably, the coating is very thin, about 1 mil (0.0254 mm) or less, so as not to compromise the connection of the conductor to the molybdenum ribbon by welding or the like.

In operation, the aluminum in the aluminide coated wire is oxidized to aluminum oxide in the presence of air, and the aluminum oxide thus formed prevents further oxidation of the metal underneath.

When forming a press seal around a molybdenum ribbon connector and its lead-in wire, small air passages often form between the wire and the embedded silica glass.

Such passages often extend from the end of the press seal to the molybdenum ribbon connector.

Such passageways allow air to gradually enter the interior and cause oxidation of the molybdenum ribbon connector.

Such results indicate that the press seal is heated to approximately 400°C during operation.
This is especially true in a miniaturized lamp of the type shown in the figure, where the temperature is above 100%.

To prevent the ingress of air into the passageway and thereby protect the ribbon connector from oxidation, the passageway is substantially sealed with fused soft glass near the termination of the lead-in wire at the end of the press seal. Ru.

Soft glasses have lower melting points than high silica glasses.

That is, soft glass has a melting point of about 500-600°C, and high silica glass has a melting point of about 1500-1600°C.

Thus, the crack between the soft glass and the silica glass can flow into the eye to some extent.

Furthermore, the soft glass fuses to the silica glass and adheres well to the conductive wire.

As shown in the figure, a tungsten halogen lamp 1 has a high silica glass enclosure 2 having a press seal 3 at one end thereof.
have.

A tungsten filament 4 is arranged inside the enclosure 2.

Two spaced apart molybdenum ribbon connectors 5 are completely embedded within the press seal 3.

The filament 4 has two legs 6 which are connected to separate ribbon connectors 5.

The external lead-in wire 7 is welded to the opposite ends of the ribbon connector 5 and projects to the outside of the press seal 3.

The lead-in wire 7 consists of a straight 25 mil (0,635 mm) molybdenum wire and has an approximately 0.3 to 0.5 mil (
0.0.076 to 0.0127) thick molybdenum aluminide coating.

Molybdenum aluminide coatings consist of 90 parts aluminum powder, 10 parts inert material (such as powdered silica), and 1 part halide activator (such as sodium fluoride). Wrap the conductor in the mixture and heat at 1038°C (1900°C) for 2 hours in a hydrogen atmosphere.
'F) was formed by heating.

Around the lead-in wire 7 the fissure channel was sealed by a soft glass bead 8 applied in the manner described below.

That is, after the lamp 1 is evacuated, filled and sealed,
Length approximately 1/2mm, inner diameter 40mil (1.02mm),
A soft glass tube with an outside diameter of 100 mils (2.54 mm) was placed on the side of the press seal 3 of each feedthrough 7 protruding from the end of the press seal 3.

Then, heat the glass tube (melting point approx. 50
0-600°C) was melted.

The melted portion of the glass tube penetrated into the eye, welded to the press seal 3 and stuck to the lead-in wire 7.

A life test was conducted on two groups of 650 Watt lamps with a rated life of 25 hours.

This lamp had an operating temperature of 625°C in the middle of the press seal.

This temperature is significantly higher than any conventional tungsten halogen lamp rating.

The first group of lamps has a conducting wire coated with aluminide according to the present invention and is sealed with soft glass, while the second group of lamps is of a conventional type, and the aluminide coat is also made of soft glass beads. It is not sealed by.

The first group of lamps actually operated for 25 hours, their rated life, but became unusable due to normal conditions, ie tungsten evaporation from the filament.

The second group of lamps failed in about 5-10 hours.

The cause of the failure was the destruction or cracking of the press seal.

Although the invention has been described with reference to a particular embodiment of a tungsten halogen lamp, other lamps with a press seal having a thin ribbon connector embedded therein and an external lead-in wire or ribbon thereof may also be used. It can also be applied in locations where oxidation of the connectors causes premature lamp failure.

A quartz infrared heating lamp is one example.

The conventional lamp is similar to a tungsten halogen lamp except that it does not contain halogen as its lamp fill gas.

Although the above has been described based on one embodiment of the present invention,
It is noted that the present invention is not limited thereto, and that those skilled in the art will be able to make numerous modifications and changes without departing from the spirit and scope of the present invention.

[Brief explanation of drawings]

The accompanying figure is an elevational view of a single terminated tungsten halogen lamp on which the present invention is based. The relationship between the raw components and reference numbers in the figure is as follows. 1: Tungsten halogen lamp, 2 glass enclosure,
3 nibless seal, 4: tungsten filament, 5
: Ribbon connector, 6: Leg, 7: External lead-in wire, 8 Ni glass bead.

Claims (1)

[Scope of utility model registration request] A quartz glass enclosure having a press seal portion, a filling gas containing halogen filled in the enclosure, a tungsten filament disposed within the enclosure, and a molybdenum ribbon connection embedded in the press seal. a tungsten halogen lamp having a molybdenum external lead wire connected to the ribbon connector within the press seal, means for electrically connecting the filament to the ribbon connector, and a molybdenum external lead wire connected to the ribbon connector within the press seal The wire projects outwardly from the press seal portion and has a thickness of 0.3 to 0.5 mil (0.0076 to 0.012 mm) on its outer surface.
A tungsten halogen lamp, characterized in that the lamp is coated with a molybdenum aluminide coating up to 7 mm in thickness, and has a soft glass bead hook provided at the outlet of the press seal portion of the external lead-in wire.