US1317492A

US1317492A - Htjrger

Info

Publication number: US1317492A
Authority: US
Publication date: 1919-09-30
Anticipated expiration: 1936-09-30

Description

L. HAMBURGER AND 0. LE LY. In.

ELECTRIC INCANDESCENT LAMP APPLICATION FILED IAN-11.1917.

I Patented Sept. 30, 1919.

INVENTORS I WITNESS Q? By A ilorneys,

UNITED STATES PATENT OFFICE.

' nonnwnx riniummenn. AND max LELY, .13., or EIN'D-HOVEN, nnrnnnnanns.

C ELECTRIC INGANDESCENT LAMP.

I To all whom it ma concern:

Be it known that we, LODEWIJK HAM- BURGER and DIRK LELY, Jr., subjects of the Queen of the Netherlands, residing at Eindhoven, Kingdom of the Netherlands, have invented new and useful Improvements in or Relating to Electric Incandescent Lamps; and We do herebydeclare the following to be a full, clear, and exact description of the same.

In many electric incandescent lamps, for instance, those having a tungsten filament, the temperature to which the filament may be raised under high vacuum, is not limited by the melting point of the metal, but by its vapor pressure,'because under such conditions of temperature and vacuum the Va porized metal condenses upon the bulb and obscures it. It has been proposed to prevent this obscuring of the bulb by introducing substances into the lamp which durin its burning evolved gases which reacted with the vaporized or atomized particles of the filament, to form compositions which do not obscure the light as much as the condensed filament vapors. In the case of tungsten filament lamps this may be ef-' fected, for instance, by halogen or oxygen compounds. The aforesaid substances have been placed in the lamp in locations of greater or less heat in accordance with their volatility or decomposability.

It has been found however that many substances which even at high temperatures do not give off any reacting vapor, such as oXid of sodium Na U, sodium phosphate Na PO the fiuorids of the metals'of the alkaline earths and silica, SiO nevertheless may have a beneficent influence upon the duration of the useful life of the lamp. This has proven to be the case and in like degree even when a lamp, containing said substances only upon the inner walls of the bulb, was burnt while being immersed in liquid air. Ihe same action, the retarding of the obscuring of the bulb, was also found when in lieu of a tungsten filament, filaments of other elements, for instance, carbon, molybdenum, platinum, iron, silver, zinc or copper were used in the lamp. It follows clearly from these and other experiments that in the said cases the action cannot be ascribed to any active vapor, but only to the action of the introduced sub:

\ stance in a solid state. The present invention is based upon this conclusion.

Specification of Letters Patent.

Application filed January 11, 1917. Serial ii'o. 141,840.

- to the invention Patented Sept. 30,1919.

The action of the solid substances upon the atomized particles from the incandescent Wire striking their surface is probably due primarily to the formation of a solid (colloidal) solution in the solid layer. Ap-

plicants however do not wish to bind themselves to this explanation. A favorable action of such substances is best realized When they are applied to the incandescent lamp in such a place that they are struck by the particles e ected from the wire. Preferably therefore the surface of the substance in the bulb should be large. When however the stable substance is placed in a glass tube or the like, genids which dissociate 'by heat, it cannot act because the articles ejected from the wire will not stri ie it. a

It is known that even small quantities of Water have a detrimental effect in 'a tungsten filament lamp. Therefore it is advantageous to choose non-hygroscopic sub.- stances, because smaller precautions are then necessary. As all soluble substances must be considered hygroscopic, it is preferablev to use substances which are insoluble in water.

In practice it has proven difficult to employ halogen or oxygen delivering substances in incandescent lamps burning under a high voltage of about 200 volts or higher, because arcing readily takes place between the feed wires. In the. process according however no active vapor pressure is necessary, but on the contrary would have a deleterious effect, especially in high voltage lamps, because it furthers arcing. Therefore it is preferable to use only slightly volatile and highly stable substances.

So for example calcium fluorid CaF which is only slightly volatile and which is known to have a large degree of stability even at the temperature of the electric arc, is especially fit for high voltage lamps. It has also the already mentioned advantage of being practically insoluble in water, in consequence of which this substance has no tendency to retain water or to absorb water from a moist atmosphere.

An embodiment of the invention is illus trated in the accompanying drawing wherein a conventional type of electric lamp with the bulb in section, is shown. a designates the filament supported in suitable manner within the glass bulb b. On the inner walls as has been proposed for haloits of bulb b is a coating 0 of the substance, as calcium fluorid, which is used to counteract the blackening of the bulb. The thickness of the material 0 is shown much exaggerated in the drawing, this layer being in fact of little thickness and invisible.

It has been proposed (U. S. Patent No. 406,130) to coat the inner surface of carbon filament lamps with a thin film of a substance mixed with more or less water, the substance being so chosen that the film becomes a good conductor of electricity, whereby the whole inner surface of the bulb is brought to the same potential as the filament in order to prevent the electrical carriage of material. The present invention, however, refers to an action obtained with a non-conducting film; all incandescent lamps in which a conducting film is applied upon the surface of the globe, are expressly disclaimed.

It has been proposed (U. S. Patent No. 1,252,372) to coat the inner surface of the lamp bulb with a material, containing an oxidizing agent, which at the temperatures encountered under operating conditions, is able to combine with the dark deposit, the resulting material being transparent. In this case the temperature of the active material is much higher than the temperature of the bulbs of ordinary lamps of the vacuum type, because the active material is put on a surface, working as an economizer that is reducing tie heat losses by the hot gases in a gas-filled lamp. The present invention, however, refers to an action, obtained with a non-oxidizing substance, which does not reach a temperature hlgher than the bulb of an ordinary lamp of the vacuum type, all incandescent lamps in which an oxidizing agent is applied upon the surface of the globe, being expressly disclaimed.

What we claim is:

1. An incandescent electric lamp of the vacuum type comprising a bulb and a thin non-conducting layer on the inner surface of the bulb of a non-oxidizing substance which during the burning of the lamp does not evolve an active or measurable vapor pressure of an gas, but prevents the obscuring of the ulb while solid.

2. An incandescent electric lamp of the vacuum type comprising a bulb and a thin non-conducting layer on the inner surface of the bulb of a non-oxidizing substance which is practically insoluble in water and which during the burning of the lamp does not evolve an active or measurable vapor pressure of any gas but prevents the obscuring of the bulb while solid.

3. An incandescent electric lamp of the vacuum type comprising a bulb and provided on the inner surface of the bulb with a thin layer of fluorid of calcium.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

LODEWIJK HAMBURGER. DIRK LELY, JUNIOR.

Witnesses:

J. J, HELSDON RIX, ANN NAG'I'IANZEE.