Electric lamp with resilient base

FIELD OF INVENTION

This invention relates to electric lamps of the type having an enclosing envelope and a base to which the envelope is attached by adhesive. In particular it relates to lamps of this type which will resist shock pulses and vibration.

BRIEF SUMMARY OF PRIOR ART

At present there are commercial lamps designed to be vibration resistant and others designed to be shockproof. A special mount design is used in each case, and the designs are not only widely different from each other but also different from the mount used in standard incandescent lamps of equivalent size. The socalled C-9 mount is ordinarily used for resistance to vibration and the C-22 for resistance to shock. In certain applications special filament materials are required which are substantially more expensive than the standard tungsten; for example, thoriated tungsten and rhenium tungsten. The necessity of stocking several types of lamps increases the amount of bookkeeping, handling and storage necessary.

BRIEF SUMMARY OF INVENTION

The present invention reduces the above disadvantages because it permits the use of a single type of lamp which will resist both vibration and shock when such vibration and shock are transmitted via the base. Moreover, the direct cost of the lamp is reduced because a standard lamp construction such as used in incandescent lamps for more general use can be used. In addition, my invention permits a higher base operating temperature to be tolerated for a longer period of time than is now possible with standard cements.

This is attained by using a resilient or flexible cement to hold the base to the lamp envelope and by using it in sufficient thickness to damp any vibration or shock which might otherwise be transmitted from the base to the filament inside the bulb. The resilient cement may be, for example, a di-methyl silicone rubber.

Other features, objects and advantages of the invention will be apparent, taken with the drawing, which shows a cross-section view of a lamp according to the invention.

In the drawing the sealed glass envelope 1 contains the glass stem 2 through which lead-in wires 3, 4, extend to support the filament 5. A coiled coil filament is one in which a wire is coiled once to a small diameter, then this coil is itself coiled at a larger diameter. This can be a Class “C” lamp, which generally has its envelope filled with inert gas, such as the rare gases or nitrogen, at a pressure generally slightly below atmospheric although a higher pressure is often used; or 5 it can be a Class “B” lamp, which has an envelope from whose interior all or nearly all of the gases have been removed, producing a nearly perfect vacuum inside.

The usual sealed exhaust tube 10 extends from the lamp.

The base is of the customary screw type, having a cylindrical metal shell 7 with screw threads 8 thereon, and a glass insulating plug sealed to the bottom of the shell and supporting an eyelet contact 9. One lead wire 3, is connected to the top of the shell 7, and the other 4 to the eyelet contact 9. , ... ... .

The base 6 is held to envelope 1 by the resilient cement 11 between the base 6 and the lamp envelope 1, the cement being about three thirty-seconds inch thick, and the cement must extend out of the shell to support 2q the envelope 1 out of direct mechanical contact with shell 7.

The resilient cement can be a di-methyl silicone rubber, such as the Dow-Corning Co.’s materials 95-047, CF-171 and S-2288.

Tests on a group of lamps show that lamps with the resilient base of my invention have as long a life under vibration as lamps with the previous standard base have without any vibration. The transmission of shock through the base is found to be considerably dampened ₃₀ by the resilient cement.

Although a particular embodiment of the invention has been described, various modifications and alterations of the invention will be apparent to a worker skilled in the art, without departing from the spirit and 35 scope of the invention, which is set forth in the claims.