US3200280A - Decorative light source - Google Patents

Description

1965 M. THAU ETAL DECORATIVE LIGHT SOURCE Filed Dec. 13, 1960 United States Patent 3,20tl,2$0 DECORATIVE LIGHT SQURCE Marcus Than and Frances Krasnow Than, New York, N.Y. (both Universal Gratings Inc., Ave. C, Newark 5, NJ.)

Filed Dec. 13, 1960, Ser. No. 75,554 SCiaims. (Cl.313--110) This invention relates to decorative light effects, and more particularly to lamps provided with a transparent decorative finish.

Decorative electric light bulbs are a staple article of commerce. Their decorative effect may be due to the overall shape of the glass envelope which encloses the actual light source, such as an incandescent filament, or to the texture of the glass envelope. Fluted glass bulbs have been previously employed, and plain glass envelopes have been coated to produce special effects.

This invention in its more specific aspects is concerned with a coated transparent envelope for a light source. The known decorative coatings on electric light bulbs rely on selective transmission of light. The selection may be made among the light waves of different wave lengths so as to transmit only light of selected colors, or different areas of the bulb surface may be coated with material of different opacity so as to transmit light of different intensity. It is a common feature of the known decorative coatings for electric light bulb envelopes that they reduce the light output of the bulb to a significant extent. It is an object of this invention to provide a decoratively coated light bulb the light output of which, if so desired, is not significantly smaller than the output of the bulb without the coating.

We aim specifically at a decorative light source the effect of which i produced by varying the refractive properties of the lamp envelopes over the surface thereof whereby the intensity of the light emitted varies over the surface of the bulb, but the overall light output may remain virtually unchanged.

Lenses arranged about a light source have previously been employed to produce an effect somewhat related to that produced by this invention, but a lens arrangement is of necessity so costly as to preclude its application in most cases. Also we are concerned more specifically with a decorative bulb which produces an effect not readily duplicated by lenses unless they be numerous and very small.

We have found that a decorative incandescent light bulb obtained when the clear glas enevelope of an ordinary bulb is coated with a substantially transparent wrinkle-textured organic coating of essentially uniform composition. The terms wrinkle-texture and wrinklecoating have'acquired specific meanings in paint technology, and will be employed in this specification and the appended claims as they are understood by paint technologists.

The decorative lamp obtained shows very bright surface areas or spots separated by darker areas For lack of a more descriptive term, the decorative effect will be referred to hereinafter as sparkle to express the brilliance of the individual light spots which normally exceeds the average brightness of the bulbv surface when not provided with the wrinkle textured coating. It will be understood that there cannot be any effect comparable to that of sparks which would imply a variation of light intensity in time.

Wrinkle finishes are generally produced by applying a layer of a suitable liquid coating'composition to a sur face. The layer .is permitted to dry with or without the application of heat. Internal stresses developing during the drying operation cause small ridges to form on the previously smooth surface of the coating. When the coating composition is substantially transparent in the dry condition and is deposited on a transparent carrier through which light is transmitted, the individual ridges have been found to act as minute lenses and to produce a sparkling effect.

The configuration of the ridges and the resulting overall pattern of the wrinkle textured coating depends partly on the chemical nature of the coating composition in a manner which is not fully understood as to its theoretical basis, but a large amount of data based on practical experience is now available which permits those skilled in this art to influence the fineness of the pattern, and to some extent also the shape of the ridges. An even greater influence on the appearance of the wrinkle pattern is exerted by the shape of the coated surface. Substantially cylindrical surfaces favor the establishment of a pattern in which fairly uniform elongated ridges extend parallel to the cylinder axis. On a spherical or otherwise threedimensionally curved surface, the same coating composition will produce a pattern of small unit areas. In each area the ridges follow an approximately parallel course, but the directions of main longitudinal extension of the ridges in adjacent areas are angularly offset in a random pattern. The overall appearance of a spherical bulb coated with a wrinkle finish is quite uniform. On a flat surface the pattern of ridges may approach more closely a honeycomb structure in which the ridges are connected and are of somewhat irregular polygonal shape.

Regardless of the specific configuration of the ridges, a transparent wrinkle textured organic coating intersecting a beam of light produces the decorative sparkle effect desired. It will be understood that quantitative differences in the decorative effect will be brought about by varying the spacing of the ridges and their height. As the ridges are flattened by reducing their height and increasing their spacing, the differences in refractive properties between the ridges and the intervening furrows are reduced and the sparkle effect is diminished.

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which the sole figure shows a conventional light bulb having a standard screw socket 1 providing two terminal connections for a fila- 'ment 2. The filament is enclosed in a gastight clear glass envelope 3 of substantially spherical shape which is shown partly broken away to reveal the filament.

The glass envelope 3 is completely coated on the outside with a layer 4 of transparent wrinkle textured organic coating composition. The light bulb is shown full scale and its spherical portion ha a diameter of approximately 2- /2 inches. The wrinkle pattern is composed of unit areas having each a main dimension of less than /8 inch. The spacing of individual ridges in each area is less than inch, but it will be understood that the size of the individual unit areas varie appreciably over the bulb surface and the spacing of the ridges is quite irregular. The figures cited are merely representative average figures.

The coating is produced, for example, by dipping the clear glass envelope of the bulb in the coating composition described hereinafter in more detail in Example I, draining off an excess of coating material, and baking the coated bulb for 15 minutes at 300 F.

We have found that the sparkle effect which becomes apparent when the filament 2 is connected to a suitable source of electric current does not depend on the nature of the transparent coating composition, on the manner in which it is applied, nor on any specific wrinkle configuration. Actually, it appears reasonable to assume that a similar effect could be produced by imparting a wrinkle texture to the glass surface of the bulb itself.

The following examples of coating compositions are merely illustrative of those which will lend themselves to the purposes of this invention.

Example I A wrinkling varnish base is prepared from a mixture of 100 pounds of rosin-modified phenol formaldehyde (85% rosin, 15% B-stage phenol formaldehyde) with gallons of raw China-wood oil by heating the mixture to 540 F. After two hours, a sample is withdrawn from the batch, cooled, and diluted with an equal amount of xylol. 5% by weight of the resin solids of a cobalt napthenate drier is added and a sample metal panel is coated with the varnish. After drying, the coated panel is heated for one hour to 275 F. while the developing wrinkle pattern is inspected. If it is not considered satisfactory, heating of the main body of resin mixture to 540 F. is continued until the varnish reaches proper wrinkling properties after 5 /2 hours.

The batch of varnish is permitted to cool and is then diluted with an equal weight of xylol to form a stock solution. To prepare a bulb coating solution, the stock solution is mixed with 2 /2% of a cobalt naphthenate drier containing 6% cobalt, and diluted with a solvent to the desired viscosity.

Blown China-wood oil may be substituted in 'the coating composition for raw China-wood oil, and other wrinkling oils, that is, oils known to impart wrinkling properties to otherwise non-wrinkling varnishes may be substituted for the China-wood oil without basically affecting the results achieved although China-wood oil gives most consistently satisfactory results. Examples of such wrinkling oils are bodied oiticica oil, the blown forms of perilla oil or linseed oil, also Poyok oil. The proportions of wrinkling to non-wrinkling constituents may be altered to suit specific operating conditions and to vary the wrinkle pattern produced in a manner well known in itself.

Example 11 An alkyd resin solution is prepared in a basically conventional manner by heating a mixture of Percent Phthalic anhydride 28.4 Glycerol 17.7 China-wood oil fatty acids 34.6 Linseed oil fatty acids 19.3

for several hours to 500 F. until the test described in Example I indicates that the alkyd varnish produced has the desired wrinkling properties. The time required may vary between approximately three and six hours. The varnish is then cooled and mixed with an equal weight of xylol or a mixture of xylol and toluol.

To produce a wrinkle coating composition, the alkyd stock is further compounded as follows:

Alkyd stock "percent" 66 Blown China-wood oil ozs. per gal 2 Cobalt naphthenate drier do 3.2 A solvent mixture of equal parts of xylol and toluol Balance This coating composition is further adjusted by additions of xylol-toluol mixture (1:1) to a viscosity of 22 to 32 seconds on a No. 4 Ford Cup, and sprayed on clear glass bulbs from a spray gun.

The coated bulbs are dried to remove most of the solvent, and then baked at 275 F. for one hour, 300 F. for minutes, or in any approximately equivalent manner as is well known in itself.

Those skilled in paint technology will understand that the method of application will largely govern the viscosity of the coating composition employed. It is also well known that the viscosity of the liquid material as applied influences the wrinkle pattern that becomes apparent on drying or curing of the coating. A coating composition of higher viscosity usually forms a coarser wrinkle pattern, and vice versa.

We consider a fine wrinkle texture most pleasing, and therefore prefer to apply coatings by spraying of compositions having a viscosity near 22 seconds. Dipping compositions will generally produce a fine-textured wrinkle finish from a viscosity of approximately 32 to 35 seconds, but a serviceable coarse-textured wrinkle coating can be formed by dipping a clear glass bulb in a varnish having a viscosity of to seconds, and others may prefer the appearance of a light source in which a rather coarse wrinkle-textured film is interposed between a filament or the like and the eyes of the viewer.

If desired, the coating composition may be colored to obtain particularly pleasing effects at some sacrifice in light output. The coloring matter must be transparent or substantially transparent. An opaque coating will interfere with the sparkle effect. Many dyes and pigments are available which lend themselves readily to coloring the varnish bases described above. The following dyes are merely illustrative of suitable coloring materials:

Auramine (Colour Index 655) Methylene Blue (Colour Index 922) Methylene Green B (Colour Index 924) Bismarck Brown R (Colour Index 332) Auramine is classified as a spirit soluble dyestuff, the others belong to the class of basic dyestuffs. All are soluble in a mixture of 80% acetone and 20% methanol in a concentration of 12 ozs. per gallon. The solution of coloring matter is added to the varnish composition otherwise ready for application to a light bulb in quantities sufficient to produce the desired effect. A light blue coating is produced by adding 0.15 gram of the 12 oz. per gallon solution of Methylene Blue in acetone-methanol to one gallon of the varnishes of Examples I and II, and similar minute amounts of the other dyestuffs will produce decorative color effects.

The proper selection of the coloring material will be influenced by the wattage output of the bulb to be coated, and by other properties of the bulb which influence the temperature reached by the glass envelope in service. As a group, dyes are more susceptible to fading under heat than pigments which will be discussed presently.

The appliction of the dyes enumerated will generally be limited to evacuated bulbs of low wattage, 25 watts being the approximate upper limit of lamp output with which the fading of the dyes will be reasonably slow. On the other hand, the varnish described in Example I tends to yellow under the influence of excessive heat, and this yellowing to some extent may be balanced by the fading of Bismarck Brown, so that a combination of Bismarck Brown with the varnish of Example I will be found to have a stable color under conditions of intermediate wattage. Neither dyes as a class, nor the varnish of Example I will generally be recommended for use with gas filled lamps the glass envelopes of which operate at fairly high temperatures.

Data on heat resistance and solvent solubility of organic dyes are available and those skilled in the art will have no difiiculty in securing suitable dyes for most applications. Under severe operating conditions, we prefer to color a heat resistant varnish such as the alkyd varnish of Example H with transparent pigments of which the following are illustrative:

Thioindigo Fast Red Phthalocyanine Blue (Copper) (Prototype 481) Phthalocyanine Green (Prototype 483) Hausa Yellow (Prototype 103) Quinacridone Red These pigments are not listed by the Colour Index,

but several of them have recognized prototypes. They are distinguished by excellent resistance to heat and light and are virtually transparent in thin layers or when finely ground.

To incorporate a pigment in a wrinkling varnish, we grind the pigment with three to four times its weight of varnish stock until a macroscopically homogeneous smooth mixture is obtained and add a suitable amount of the resulting paste to the varnish. The depth of color desired will determine the amount of pigment paste used. 3 ozs. of a Phthalocyanine Blue paste containing of pigment will produce a medium blue coating when added to one gallon of the varnish of Example II.

The transparent wrinkle varnishes employed for coating light bulbs according to this invention may be further modified by the addition of natural or synthetic pearl essence. A commercial pearl essence, whichis either derived from fish scales or synthetic, consists of guanine crystals suspended in a vehicle usually containing a resin and amyl acetate or other solvent. Approximately 4 to 8 ozs. per gallon of pearl essence, corresponding to 1 to 3 ozs. of guanine per gallon may be incorporated into the varnishes of Examples I and II without materially affecting the wrinkling properties of the coatings produced. If preliminary tests should show that a commercial product is not adequately compatible with the wrinkle coating, guanine crystals may be ground with varnish base to form a paste containing guanine.

Depending on the amount of pearl essence employed and/or the fineness of the wrinkle structure, the appearance of the bulb filament is more or less accentuated. The amount of pearl essence added must be less than that commonly employed to produce an actually pearlescent, more or less opaque surface.

We prefer to use a synthetic pearl essence prepared by grinding lead hydwrogen phosphate (PbHBO crystals with a varnish base to produce a paste of approximately 40% lead hydrogen phosphate content. The paste is then admixed to a wrinkle varnish having the same base in amounts of up to approximately 24 ozs. per gallon. There is no lower limit to the amount of lead hydrogen phosphate paste that may be incorporated in a wrinkle varnish, but the elfect produced with amounts of less than about 12 ozs. per gallon is so small as not to be of value in most instances. Quantities of more than 24 ozs. per gallon of lead hydrogen phosphate paste do not show an increased effect commensurate with the larger amounts added, and will usually be unnecessary.

A portion of the lead hydrogen phosphate may be replaced by crystalline basic lead carbonate at a saving in cost without a significant loss in efficiency. A pigment mixture which produces effects comparable to guanine when employed in small amounts consists of 40% lead hydrogen phosphate and 60% basic lead carbonate crystals.

It will be appreciated that dyestuffs, pigments, and pearl essence may be added to the wrinkling varnishes in any conventional manner other than specifically described without departing from the spirit and scope of this invention, and that the methods of mixing specifically described, which are conventional in themselves, are merely intended to be illustrative. The quantities of these addition agents also are not critical in any manner, and the several addition agents may be used separately or jointly as desired. A wrinkling varnish may thus be prepared to contain simultaneously a dye or dye mixture, a pigment or pigment mixture, as well as pearl essence of natural or synthetic origin, or both. The addition agents will modify tthe basic sparkle effect produced by the transparent wrinkle textured coating, and their modifying eifects are basically additive.

The following basic varnishes have also been found to produce transparent wrinkle finishes on glass bulbs suitable for the decorative light effects of this invention but the wrinkles produced with the following compositions are relatively shallow and widely spaced.

Example Ill lbs. of rosin modified phenol formaldehyde resin are heated with 8 gallons of liquefied oiticica oil to a temperature of 500 to 510 F. until a homogeneous dispersion is obtained. The mass is permitted to cool to a temperature of less than 350 F. whereupon five gallons of xylol and 12 gallons of light gravity petroleum naphtha are added with stirring. The resulting mixture is cooled to a temperature not substantially above room temperature and is mixed at a ratio of 19:1 with a 6% solution of manganese octoate in a mixture of aromatic solvents.

Upon further dilution with a mixture of xylol and petroleum naphtha in an approximate proportion of 1:2 to give the desired viscosity, there is obtained a wrinkling varnish ready for application to a light bulb and drying in the afore-described manner.

Example IV .A mixture of 4 lbs. polyvinyl butyral with 4 gallons of butanol and 1 gallon of water is prepared by thorough blending at room temperature. The mixture which contains air bubbles-is permitted to stand until the entrapped air escapes and is then ready for spraying. If desired, it may be diluted by-further additions of aqueous butanol. Electric light bulbs sprayed with the polyvinyl butyral lacquer obtained may be air dried or force dried at elevated temperature.

After drying, the bulbs arefound to be coated with a relatively shallow-ridge wrinkle finish in which the wrinkles are spaced almost A" apart. The sparkle effect observed when the bulb is connected to a source of electric current is correspondingly poor.

Example V Chlorinated rubber of 5 centipoise viscosity is dissolved in xylol in an amount of one pound per gallon. 6 lbs. of the resulting solution are mixed at room temperature with 2 lbs. of blown China-wood oil and 0.22 lb. of a commercial cobalt drier containing 6% cobalt. There is obtained a wrinkle coating composition which may the applied in any desired manner. Its viscosity may be adjusted with xylol if so desired.

A wrinkle finish of good texture is obtained by air drying a coating deposited on a light bulb, but a better wrinkle eilect is produced when the coating is force dried at elevated temperature, for example, at 250 F. for approximately one hour.

The substantially colorless transparent wrinkle textured coatings deposited from these compositions in a manner analogous to that of Examples I and II may be further modified by incorporating therein substantially transparent coloring matter and nacreous substantially transparent pigments. The transparency of the addition agents is generally improved, if necessary, by grinding them to a small particle size. Lead hydrogen phosphate thus is preferably ground very fine since it produces pearlescence and opacity by its crystalline structure when not so ground. Lead hydrogen phosphate is most effective when employed in varnishes of relatively low refractive index, that is, lower than the refractive index of lead hydrogen phosphate. All the examples of varnishes enumerated in Examples I and II satisfy this requirement.

The strongest sparkle eifect is produced when the film of wrinkle textured transparent material transmits light that includes a substantial proportion of aligned light rays, and as small as possible a proportion of diifuse light. Best results are thus obtained with a point light source spaced from the wrinkle textured film or by any other source of parallel light rays. Virtually no sparkle effect is produced when the film is directly applied to a source of diffuse light, such as an externally frosted bulb or a conventional fluorescent tube. When a wrinkle coating is deposited on a flat glass carrier and a distant light source of any nature is viewed through the carrier, the decorative sparkle is clearly observed. Generally then, sparkle can be produced with a source of diffused light by spacing it from the film.

The term varnish as employed in this specification and the appended claims is to be construed broadly and it is not limited to any specific class of organic coating compositions nor to any specific curing reaction of the composition. The term wrinkle varnish will thus be understood to designate any organic finishing composition from which a wrinkle textured coating can be produced by the usual methods of application, such as spraying, brushing, dipping, roller coating, knife coating, or the like, followed by drying and/or heating.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically disclosed.

What we claim is:

1. A decorative electric light bulb comprising a light transmitting rigid envelope; a substantially transparent coating of wrinkle textured organic material of uniform composition on said envelope, said coating having an outer surface formed with a plurality of spaced integral ridges, said ridges being elongated in substantially parallel alignment; and a light source within said envelope.

2. A bulb as set forth in claim 1, wherein said coating is colored.

3. A bulb as set forth in claim 1, wherein said coating includes a nacreous pigment.

4. A decorative light source comprising, in combination:

(a) a light emitting member adapted to produce a beam of light including at least a major portion of substantially aligned light rays, and not more than a minor portion of diffuse light rays;

(b) a substantially transparent carrier intersecting said beam; and

(c) a wrinkle-textured substantially transparent coating of uniform composition on said carrier, said coating having an outer surface formed with a plurality of spaced integral ridges, said ridges being elongated in substantially parallel alignment.

5. A light source as set forth in claim 4, wherein said member is an incandescent filament, and said carrier is a transparent portion of a substantially gas tight envelope enclosing said filament, said transparent portion being spaced from said filament.

DAVID J. GALVIN, Primary Examiner.

ARTHUR GAUS S, JAMES D. KALLAM, GEORGE N.

WESTBY, Examiners.

Claims (1)

1. A DECORATIVE ELECTRIC LIGHT BULB COMPRISING A LIGHT TRANSMITTING RIDIG ENVELOPE; A SUBSTANTIALLY TRANSPARENT COATING OF WRINKLE TEXTURED ORGANIC MATERIAL OF UNIFORM COMPOSITION ON SAID ENVELOPE, SAID COATING HAVING AN OUTER SURFACE FORMED WITH A PLURALITY OF SPACED INTEGRAL RIDGES, SAID RIDGES BEING ELONGATED IN SUBSTANTIALLY PARALLEL ALIGHMENT; AND A LIGHT SOURCE WITHIN SAID ENVELOPE.

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