US2023558A - Neon tube and method of making the same - Google Patents

Description

A. P. TALLMAN NEON TUBE AND METHOD OF MAKING THE SAME Filed Dec. 17, 1934 PatentedDec. 10, 1935 PATENT OFFICE NEON TUBE AND METHOD OF MAKING THE SAME

Allen P. Tallman, Toledo, Ohio V Application December 17, 1934, Serial No. 757,943

6Claims.

This invention relates to an improvement in ary to use tubes containing neon, argon krypton or the like rendered luminescent by high 10 tension current. The glass tubes employed for this purpose are bent into the shape of various letters, figures and designs and lend themselves very readily to such shaping.

The light emitted from the tube escapes in a1 directions but ordinarily the sign is viewed from only one side. If the tube'is mounted in front of a board or backing as is generally the case,

the light emitted in the direction of the board is partly absorbed and partly reflected by the backing boardQand in neither case does it have any beneficial efiect from the standpoint of rendering the sign visible. This invention has for its object the reflection of a large part of the light rays from the back of the tube so that they may be directed to the side from which the sign will be seen, and also contemplates the absorption of any rays which are not reflected so that they will not illuminate the background. Accordingly, the lighted tubes stand out more disw tinctly both because of the reflected light and because of the relatively dark background. Details and further features of the invention will appear as the description proceeds.

In the accompanying drawing forming a. part of this specification, Figure l is a section through a tube showing one form of the invention and also showing a portion of a backing behind the tube. Figure 2 is a view similar to Figure l, but showing an alternative form of construction. 4 Figure 3 is an isometric view of a section of a tube such as disclosed in Figure 2.

In the form shown in Figure 1 there is a glass tube ill, such as is commonly used for this purpose, and it is shown located in front of a back-- ing board it, which may be of any desired construction. On the rear of the tubethere is shown a reflecting layer l2 and an absorbing layer 83. The reflecting layer is generally white,

although it may be colored or tinted in any desired manner to accord with the tint of light which is desired, where such tinting of the reflector is found helpful. The layer i3 is ordinarily black, although good absorptive material of another color might be employed.

The preferable construction of these layers is to make them of a coating material which may be baked in place on the surface of the glass, and will withstand the radiations and emanations from the tube. One suitable coating material comprises resins, commonly referred to as glyp- 5 tal or alkyd, with fatty acid dissolved in coal tar hydrocarbons or other suitable solvents, such as hydrogenated naptha, petroleum naptha, and various combinations of them. The resins are condensation products formed by the combining of polyhydric alcohol with dibasic acid. For the white layer, titanum oxide has been found particularly suitable, although other suitable pigments maybe employed for coloring the reflecting layer, and any suitable pigment, pref- 1 erably black, may be employed in the absorptive layer. r

A convenient way of making the tube is to paint the coatings thereon and thereafter bake them on during the customary bombardment of the tube, at which time suflicient heat is generated to produce the necessary baking of the coating. This has the advantage of producing the coated tube merely by coatingit with the proper materials at. the proper time without requiring 25 any separate baking operation.

A coating of the material suggested has been found suitably resistant and durable under the normal conditions of use of such a tube, although it will be understood that the broader scope of so the invention is not dependent upon the particular coating material employed.

In the construction shown in Figures 2 and 3 the front half IQ of the tube is of clear glass similar to that employed in tube l0, but the rear 35 portion or the tube is formed of two layers of glass, an inner white layer l5 and an outer black layer it. While the colors white and black are preferred for the reflecting layer I5 and absorptive layer i6, respectively, it will be understood that other colors are permissible as indicated in connection with the description of layers 12 and I3, A backing board Ha, similar to backing board i i, is indicated on the drawing.

In making a tube such as shown in Figures 2 4 V 3 may operate very satisfactorily, it will obviously involve more expense in its manufacture than will the simple coating of the tube during the bombardment step, as discussed in connection with Figure 1, and while other suitable resistant materials may be employed in place of those suggested for use in coatings I2 and I3, it must be understood that ordinary paints and varnishes are aflected by the radiations and emanations from the tube to such an extent that their useful life is brief. Accordingly, if materials are used in place of those suggested, care must be taken to select those which will withstand the conditions to. which they are subjected in use on such a tube. The use of the reflective and absorptive coats, as described above, has a number of important ad-- vantages. Of course, it is readily understood that by reflection of the light towards the front, the waste of the light, which would otherwise occur, is avoided. It may not so readily appear that the apparent breadth of the tube is approximately doubled, but this will be understood if it is taken into consideration that the light directly transmitted results in an apparent column of light which is smaller than the actual column of gas, while the use of the reflector results in light being so directed that the entire tube to thelighting up of 'the back board is avoided, the

sign stands out against the relatively dark background and is additionally distinct because of this reason. As a consequence tubes become :much more clearly and readily visible and at the same time the form, into which the tubes are bent so as to make the desired characters or designs, is much more clear cut and distinct. A small tube thus coated is as clearly visible as one -about three times the capacity without the coat- Having set forth the principles of this invention and disclosed two specific forms thereof, it will be understood that the specific disclosures are by way of illustration and the appended claims are not limited thereby, except so far as stated in the claims It will befurther under- 5 stood that whereas for the sake of brevity reference is made in the claims to a neon tube, this expression is intended to cover a tube of this type regardless of the particular-gas employed whether neon, argon, krypton, or other gases or 1 vapours that may be used in a like manner, or a mixture of such gases, reference being made to the type of light rather than to the particular gas employed.

1 What I claim is:

' 1. A neon tube having a reflecting coat around its rear half, said coat having incorporated therein titanium oxide.

2. A neon tube coated on its rear sidewith a composition comprising a resinous condensation 20 product formed from polyhydric alcohol and dibasic acid and dissolved in a suitable solvent, baked in place upon the tube, and containing a suitable pigment. 1

3. A tube in accordance with claim 2 and in 25 which the pigment comprises titanium oxide.

4. A tube in accordance with claim 2, and the coat containing white pigment next to the glass and black pigment in its outer portion.

5. The method of making a coated neon tube, 0 I

which comprises coating a portion of the tube with a suitable reflective enamel composition and baking the enamel ontothe tube during thebombardment of the tube in the process of making the same. 5-

as a pigment.

' ALLEN P. TALLMAN.

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