US2459789A - Electrode construction for neon signs - Google Patents

Description

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ELECTRODE CONSTRUCTION FOR NEON SIGNS Filecl- Aug. 21, 1946 HTE-ENTOR.

Z 12 BY Patented Jan. 25, 1949 UNITED STATES PATENT OFFICE ELECTRODE CONSTRUCTION FOR NEON SIGNS Thomas H. Briggs, Jr., Norristown, Pa., asslgnor to Superior Tube Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 21, 1946, Serial No. 692,099

2 Claims.

This invention relates to an electrode construction for neon or similar signs illuminated by electrical discharge through gases.

The usual electrode construction involved in these signs comprises a tube of metal held in an end of the glass sign tube by means of a pair of wires sealed through the pinched end of the glass tube. The tubular metal electrode is held spaced from the glass tube by means of mica and ceramic spacers and the end of the tube is provided with a base member cemented to the glass and soldered to the electrode supporting wires. This construction has numerous disadvantages which will be brought out hereafter in comparison with the improved construction. In accordance with the present invention a simple electrode construction is attained which has many advantages.

The general object of the invention is the production of an electrode construction of improved type. This general object of the invention as well as other objects relating to details will become apparent from the following description read in conjunction with the accompanying drawing in which:

Figure 1 is an elevation showing the improved electrode construction, the figure corresponding to one end of a neon or similar sign;

Figure 2 is an axial section through the same construction; and

Figures 3, 4 and 5 are fragmentary sections similar to Figure 2 showing alternative constructions.

Referring first to Figures 1 and 2 the construction in its preferred form comprises a cap indicated generally at 2 and provided with a flange 4 sealed to the glass tubing indicated at 5. If desired the glass tubing may be of long length forming a component of the sign when sealed at both ends. Generally, however, an electrode assembly is provided in which case the assembly is marketed with only a relatively short length of tubing 6 which may be joined to the main tubing of the sign by the sign manufacturer.

A central portion 8 of the cap 2 formed as indicated is arranged to be welded to the electrode l0 taking the form of a metal tube. The electrode assemblies are provided in pairs, one member of each pair being arranged for exhaustion and gas filling of the sign. Figure 2 shows specifically the construction adopted at the exhausting end. The center of the cap 2 is provided with a hole l2 about which the exhaust tubulation i4 is sealed. A snap-on cover l6 enters the hollow in the cap 2 and serves to protect the sealed portion of the exhaust tribulation.

The completed construction just described may be formed as follows:

The cap 2 is a standard cap of a type used at the present time for the formation of the ends of socalled cartridge-type photocells. This cap is formed of an alloy adapted to seal satisfactorily to glasses having the same coeificients of expansion' over useful ranges of temperature. It may, for example. be formed of the so-called No. 42 alloy or No. 52 alloy, these alloys being chromium alloys on the surfaces of which chromium oxide may be produced for the proper sealing to glass.

The cap is degreased and there is then welded to the center portion 8 thereof the electrode tube ID of suitable type, the material being any one of those commonly used for electrodes in neon signs.- This tube is of a material resistant to positive ion bombardment and sputter. Since the tube is of simple form, for example, the simple cylinder illustrated in Figure 2, it may be easily produced to close tolerances with a minimum of tooling costs and may be furnished in any desired size.

The combined welded cap and tube are then subjected to the usual firing in wet hydrogen to produce on the cap 2 a chromium oxide surface suitable for glass sealing.

The exhaust tubulation of proper glass is then sealed about the opening I! in the cap through which exhaustion is to take place. The assembly for the other end of the sign is, of course, not necessarily provided with the opening l2 or the tribulation.

Following this there is sealed to the flange l of the cap the glass tubing 6 which may be either a short length or a complete sign. If a short length is used the sealing may be readily accomplished by automatic machinery.

- The assembly thus provided is ready for sale to or use by the neon tube manufacturer. The manufacturer may, if the glass tube length 6 is short, seal this to the glass tubing to form the body of the sign. Following the assembly of the two electrode constructions with the sign, exhaustion and filling of the sign with the proper gas through the tubulation I4 is accomplished and the tubulation is sealed off leaving the tip in the form illustrated at M. The protective cap [6 may then be snapped into place to cover the glass tip.

There are numerous advantages in the electrode construction just described. The cost of manufacture is very considerably reduced. The number of parts required for each end of the sign is also reduced as are the labor operations in- 3 volved, especially at the time of assembly and after exhaustion.

The ruggedness of the electrode construction is far superior to that of the usual constructions in which there is always some play due to the support of the electrode tube by means of wires and loose fit in the glass tube.

Any electrode material may be adopted which is desired for a particular application.

The length of the assembly is very substantially reduced, for example to the extent of approximately an inch at each end of the sign.

Automatic equipment may be used for sealing when short lengths of glass tubing are used.

There is avoided the difficulty of maintaining the opening of an exhaust tubulation in a pinched seal. The electrodes are permitted to operate at lower temperatures to reduce evaporation. This end is secured by reason of the welding to the end caps which serve to radiate or conduct heat from the electrodes. In contrast with this in prior constructions the only metallic conduction path for heat has been through small supporting wires with the result that cooling occurs substantially only through the portions of the glass tubing surrounding the electrodes and since the glass is a relatively poor conductor of heat the electrodes operate at temperatures which result in substantial shortening of life.

Additionally the parts used are available as standard parts on the market.

As is indicated by Figures 3, 4 and 5, the particular electrodes used are subject to considerable varlation. If it is desired to provide an electrode of small diameter such as indicated at 20 a. flange 22 thereof may be welded to a fiattened portion of the end cap it. In Figure 4 there is illustrated a tube 26 of larger diameter I provided with an internal flange 28 welded to the cap 24. In Figure 5 a tube 32 is provided with an enlarged portion 34 which fits over the central part of the end cap 32 to be welded in position in essentially the same fashion illustrated in Figure 2.

It will be clear that other variations in the embodiment of the invention may be made Without departing from the scope thereof as defined in the following claims.

What I claim and desire to protect by Letters Patent is:

1. An electrode construction for gas discharge signs comprising a length of glass tubing, a cap of an alloy having substantially the same expansion characteristics as the glass tubing, said cap having a depressed central portion, and a tubular electrode within said glass tubing and having a portion of its inner surface secured to the depressed central portion of the cap.

2. An electrode construction for gas discharge signs comprising a length of glass tubing, a cap of an alloy having substantially the same expansion characteristics as the glass tubing, said cap having a depressed central portion, a tubular electrode within said glass tubing and having a portion of its inner surface secured to the depressed central portion of the cap, and a glass tube secured to an opening in the depressed central portion of the cap.

THOMAS H. BRIGGS, JR.

REFERENCES (CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,852,020 Metcalf Apr. 5, 1932 2,146,579 Inman Feb. 7, 1939 2,222,669 Kurtz Nov. 26, 1940 2,237,184 Lemmers Apr. 1, 1941 2,238,277 Miller Apr. 15, 1941 2,267,318 Aicher Dec, 23, 1941

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