US2676114A - Method of producing graded coatings - Google Patents

Description

April 20, 1954 D. w. BARKLEY 2,676,114.

METHOD OF PRODUCING GRADED COATINGS Filed June 8, 1951 4 Sheets-Sheet l April 20, 1954 D. w. BARKLEY 2,676,114

METHOD OF PRODUCING GRADED COATINGS Filed June 8, 1951 4 Sheets-Sheet 2 qttomegi April 20, 1954 D. w. BARKLEY METHOD OF PRODUCING GRADED COATINGS 4 Sheets-Sheet 3 Filed June a, 1951 5. M w m m o m m 4 Z M Ma Q I I o w W e l .m S .9 W w 2 0% n0 D J .o M I e O o o o o o o o T 6 w 9 6 7 w .5 a 5 M. w 0 /u muz imz u 9402.2 Nu uwqvzuuauu U. mm Aw April 20, 1954 x p w BARKLEY 2,676,114

METHOD OF PRODUCING GRADED COATINGS I Filed June 8, 1951 I 4 ShetS-Shtit 4 3nnentor /5@a% an I 720%56 fiiJUd/le Gttornegs Patented Apr. 20, 1954 METHOD OF PRODUCING GRADED COATINGS.

Dwight W. Barkley, New Kensington, Pat, as-

signor to Libbey-Owens-Ford GlassGompany, Toledo, Ohio, acorporation 01: Ohio= Application June}, 1951, Serial.N0.=.2.i0, 5 83v 6 Claims.

The present invention relates broadly to the surface coating of" glass or plastic, and more par-- ticularly to an improvedmethod of producing a graded coating, upon a base orsupport body-bythermal evaporation.

It is an aim of this invention to provide such a method wherein coatings of predeterminedwidth and gradation can be deposited upon theglass or other support-bodyby thermal evaporationwithout'the useof movable shields as has been customary in the past;

Another object of the invention is the provision of" such a'method wherein the depositing of a coating oi predetermined width graduation upon the glass OrothersuppQItt body is effectedina single evaporation cycle and is controlled by the use of one or more stationaryshields positionedat" a predetermined location between thesupport bodyv-andjthe source of evaporation of' the material" to be laiddown.

Generally stated; the method of thisinvention comprises locating the support body of glassor other material to be coated'in' a vacuum chamber facing a plurality of independent'sources of materialize be evaporated spaced from one another and corresponding in number to the detheticalline is then drawn diagonally betweenthe other endof the series of 'material'evaporation sources and the diagonal; opposite endiof the graded area on said support body andjwhichsecondline intersects the first line at a point between the support body to be coated and A stationary shield isthenlocatedat the point of intersection of "the sources of evaporationtwo hypothetical. diagonal lines, I after which the material from the, Several, sources of'evaporation are evaporated preferably simultaneously to pro-.

when "taken in connection, with the accompany-- g;-drawi-ngs',- wherein Fig.1 1 illustrates"diagrammatically'thedeposit ing of a uniform coatingupon a support-body from a single source;

Fig. 2 illustrates diagrammatically the deposits ing of two coatings of uniform; thickness upon two; support bodies also-from a-singlesource;

Fig. 3 illustrates diagrammatically the deposit 7 ing of graded coatings upon twosupport bodies from two sources of "evaporation and employing the method'of' this invention to; effectthe grading" of the respective-coatings;

Fig; 4' isr'an enlarged" view showing a' method: of: producinga gradedfcoating having ffour different-thicknesses; r

Fig. 5 is a vertical sectionaliview, through an" evaporation chamber used" for carrying out the method-of'Fig.-4;*'

Fig. 6' is a diagrammatic View illustrating the" depositing of a; coating. on a support body in which the graded areas are, of: relatively narrow Width? Fig. 7' illustratesdiagrammatically the'laying down- 0fagradedfcoating from a continuouslinef source of evaporationmnd in which the* line source is: disposedat -an" angle: with respect" to tion' ofacoating-of relatively I greaten thickness at the center 'and graded outwardly therefromemploying a perforatedshield;

Fig, 11 is-a graph of. the luminoustransmittance of a glass sheet having a' continuous graded T coating of a. character similar. to thatjiproduced" Eig; 1311s: a, crossesectional iew taken!- substantiallyet DQ111116; Hie- 43 QfijE gIi. 2.3:

Fig;v 14;..is; arsimilanrcrosmsentionm viewtaken substantially l;4 -l-4. of E -SJL- 12 Fig: 15" illustrateswdiasrammatieally theiformae admin 3 tion of graded coatings upon a plurality of lenses;

Fig. 16 is a front view of a lens having a graded coating thereon; and

Fig. 17 illustrates diagrammatically the formation of graded coatings from three sources of evaporation to produce artistic and decorative effects upon bottles, jars, and the like.

With reference now to the drawings, and particularly to Fig. 1, there is shown diagrammatically a support body 20 which may consist of a sheet or plate of glass or plastic and a single source of evaporation 2| from which the material is evaporated upon the support body to form a coating 22 of uniform thickness throughout the entire width of said coating. The efiective width of the coating 22 is controlled by the position of the stationary shield.23 located at a predetermined point between the support body 20 and source of material evaporation 2|.

As'is ordinarily true in producing thermally evaporated coatings, the degree of vacuum employed in performing the invention is such that the evaporated material travels out radially from the evaporation source in straight lines as indicated at 24 and 25 in Fig. 1 until it contacts the surface to be coated. Therefore, by moving the shield 23 to the left, the width of the coating 22 will be reduced whereas movement of the shield to the right will result in an increase in the width of said coating,

In Fig. 2 is illustrated the manner in which a second support body 26 can be provided with a separate coating 2? simultaneously with the coating of the support body 26; Coatings of respective uniform thickness can thus be obtained on two separate and properly arranged support bodies 29 and 25- from the single source of evaporation 2|. The efiective area of the material evaporated from the single source 2| is increased to effect the coating of the two glass bodies 20 and 28 by arranging the two bodies at an angle to one another and employing separate shields 23 and '28 respectively. The material evaporated from the source 2| is deposited upon the support bodies as coating 22 between lines and 25 and coating 21 between similar lines 29 and 30 As in Fig. 1, the width of these coating may be selectively varied by moving the shields 23 and 28 inwardly or outwardly. I

It will be appreciated that the coatings laid down in either Fig. 1 or Fig. 2 are substantially uniform in thickness, particularly when the article being coated is located at a considerable distance from the evaporation source or filament carrying the material to be vaporized such that all points of the surface to be coated are substantially at the same distance away from the filament. In the following description and accompanying drawings, it is assumed that such conditions prevail and that the variation in thickness in the various. areas or segments of graded films produced are in no way produced by variation in the distance of the article to be coated away from the filament. On the other hand, thegraded films of this invention are produced by the employment of stationary shields associated with the filament and surface to be coated in a novel and improved manner.

Fig. 3 illustrates diagrammatically one form of the invention in which two spaced evaporation sources or filaments 3| and 32 are employed in connection with separate stationary shields 33 and 34 to deposit graded coatings 35 and 36 51- multaneo'usly 'on the two support bodies 31 and 38 respectively. As will be evident, the material evaporated from source 3| covers the area between lines 39 and 46, while the material from source 32 covers the area between lines 4| and 42. Thus, as will be seen from an inspection of Fig. 3, the material evaporated from the two sources 3| and 32 combines and overlaps so as to jointly deposit upon the inner marginal portion of each support body 37 and 38 the graded coatings 35 and 36 respectively, each having a relatively thick portion 43 and a contiguous relatively thinner portion 44.

,In Fig. 4 is shown a method of producing upon the undersurface of a horizontally disposed support body 45 a graded deposit of four diflerent thickness areas 45, 41, 48 and 59 by the use of a stationary shield 50 and four evaporation sources or filaments 5|, 52, 53 and 54. As herein shown, the four filaments are arranged in alignment and each is spaced from the adjacent filament or filaments' a' distance which corresponds proportionately to the width of the coated areas in the graded film.

The shield 50 is placed at the intersection of a hypothetical line 55 drawn through the end filament 5| diagonally to the extreme outer edg of the coated area 46, with a similar line 56 drawn from th next adjacent filament 52 to the other end of the first graded area 46 and the beginning of the secondgraded area 41. The diagonal arrangement of these lines will be through the same coextensive intersection or loci of similar hypothetical lines 51 and 58 drawn through the other evaporation sources 53 and 54 to the successive limiting borders of the graded coated areas 41, 48 and 49 of progressively greater thicknesses.

The shield 50 is located at the intersection of hypothetical lines 55 and 58 drawn diagonally from the two extreme evaporation sources 5| and 54 to the limiting borders of the graded coated deposits, as for example the coated deposit in graded area 45 and the similar deposit in graded area 49. Specifically, the shield 50 is located at the intersection of a hypothetical line 55 drawn from an end evaporation source, such as filament 5|, to the extreme ed e of the thinnest coated area 46, with a similar line 58 drawn from the evaporation source most distant or fartherest awayfrom the first evaporation source, such as the filament 54, and to the margin between the thickest coating 49 and the next thinnest coating 48.

Examination of Fig. 4 will show that where the plane of the surface being coated and the plane of the evaporation sources are substantially parallel that a simple geometric relationship is immediately apparent in that similar triangles can be envisioned by the use of the hypothetical lines. Thus, a hypothetical line X,Y considered as taken normal to both the plane of the surface to' be coated and to the line of the evaporation sources provides immediate geometrical principles of similar triangles, such as triangles OAB and 00D. Thus, the portions CY and OX of the line X-Y are perpendicular to the bases of the triangles and are related to each other in a proportional manner the same as the bases of the two triangles are related proportionately, namely, as the distances A-B and CD. Expressed simply, this is as follows:

12 0Y-OD i It -is also apparent that the sum of the two normals or perpendiculars is equal to the total dis-' serene tance-from'the plane ofthefilaments to the plane of'the object to be coatedythat is OX+OY-=XY By solving for thedistanee at which the shield is to belocated-away from th -objecttape-coatedand substituting in the. first equation, it is appa entthat AB'('X'Y0X 2 AB(.XY), A B.+CD

Thus, by suclrcalculation, employing the dimensions CD of'the grading to be produced and the dimensions AB" of er-filament arranged to define the loci,the'shields may be-properly located. The shields'may also be located verysimply in practice by actually sightingalong the suggested hypothetical lines.

In Fig. is'illustrated one' type' of apparatuswhi'ch may be employed to' carry out the method illustrated in Fig". 4, and the same numerals are used'to designate thesame-parts. This apparatus includes a conventional evaporation chamber or bell jar 59 mountedupon" abase 60 and being connected with a suitable source of vacuum through conduits 61. The "four filaments or sources of evaporation are shown at 5|, 5-2, 5%

and 54 and each carriesa charge of material to be evaporated. The 'supportbody 45 to be'coa-ted' is carried in a horizontal position above the sources of evaporation in any desired manner such as by supporting upon posts 62. The shield" 50 can be secured-tea bracket 63 slidably carried-by one'oi the'posts 62 for vertical adjustment and securedin place by thumb screw 64. The shield 50 may also be carried on thebracket 63' in such" a manner that by-means of a thumb screw 65" it can be adjusted laterally in'a horizontal plane. The *materialto be evaporated may be a metal or it'may'be a non-metal such as to produce the desired properties in the coated product; Examples are aluminum, chromium, magnesium fluoride, and quartz.

' "In'Figi. 6 is diagrammaticallyshown theuse of the samefon'r -filaments '51 to 54 inclusive, spaced from one another "and-positioned with respect to the stationaryshield 50 to produce on the under-- surface of the support body'iiSacoating'Sl-having a rather small graded area 68 along the inner marginal portion thereof in-which the grading drops sharplythrough the layers 69 of different thicknesses. 'It will be'seen that the only difference in the arrangement of parts to produce this type of coating as against widely spaced graded segments produced in Fig. 4 has been to move the shield 5t further away-from the filaments! t'oi54 inclusive and closer to the plate 66 being coated, so that the coated'area from the filament 51 will bebetween lines'lfi and H while the gradings through the layers 69 will be produced accordingto the intersection ofthe lines 12,13 and H at the shield 58 with the line 11 It is therefore apparent that given a definite distance between extreme filaments, a desired Width of grading, and a distance of evaporation from the evaporation sources to the object to be coated that there is only one locus at which the shield can be located. Thislocus can be determined as alreadydescribed.

- In Fig. 7 is shown-diagrammatically a means of producing on the-undersu'rface of the support body a graded coating'lB' which-the areas not slightly-different thickness are of relatively narrow width :and such gradual change inthickness as to produce-apontinuous graded-area or sloping surface18.- This-is accomplished by introducing a large numberof evaporation sources 19 which are closel y adjacent one another or preferably the use of an evaporation source of a continuous line type in which evapora-- tion is occurring-from all: points-along such line. i This can. be I easily accomplished by the use ofiarr electroplatedfilament-wire coated with the-de-- siredv material to be evaporated, or it can be provided by the use of a filament towhich a materialis applied which, when molten,-is stronglywetting and spreads out-over the entire-surface and-thus evaporates irom all points on the: filament such, for example, as aluminum or inconel on 9. tong-- sten filament.

While itis usually preierredthat the li'ne of the filamentor filaments extends parallel. to the plane of the surface of the support body .being' coated, this is not-always necessary asshownsin Fig. '7. The location of the shielded can be d'eted: mined as before byth'e intersection.of the hypw thetical lines 8 carried through the filaments to the extremeedges of the gradedlarea to be pro duced.

Wherev it is desired 1 to produce deposits .oira coating in graded areas-which. will haveconsiderable width as in Fig;-4 ,the:shield Elli-may :be positioned closer-to'the filaments and: the deposits in such step gradedareas willebviously be-oia materially wider area-than those shown, for example, in Fig 6. However, :where..adistinct. diiference in area width iste'beobtained,..thefila-= ments 82 and 83, as-shown in' Fig.'3,.may bezmcre widely spaced and the shield 84 positioned so:- that it will cutofi agreateramountof theicoat ing material directed-toward the support'bodyrtd. Thus, the effective'coatingarea.86 of the filament- 82 is determined by 'the position of the shield and. as between lines 8'5 and 88:, while the effective coating area of the filament 8 3 is sdefined-Jby-lines B9 and 90 toform thecoat 8|. YA graded coating is thus obtai'nedwhereinthe thinner :areaBB will be of substantial "width in. comparison. to thethicker marginal area 91 It will thus be apparent. thatthe spacing, .b8-' tween the adjacent evap'oration sources: and/or the total number of said sources willdirectly de-; termine to a proportionatedegree the sspacingzorwidth of the gradediarea.

In Fig. 9 isshown the production of a graded deposit having areas of difiering width and 0011- sequently somewhat irregular although. progres sively controlled and of predetermined thicknesses, which graded areas may be produced. by the use of two shields interposed between the evaporation sources and 'thesupport body to be coated. As willbe noted, the filaments. 92. to 9.1 inclusive are substantially equally spaced from each othenwhile the end filament fitspaced a relatively greater distance from the adjacent filament 91 As 'hereinbefore disoussed the effective width of the coating deposited on the support body 99' from the filamentsill to 9 1 will,.by" reason of the equal spacing oi these filaments. result in a seriesof graded areas'of proportion-'- ately equal width. The first filament 9:2 would: then normally'deposit' a coating between the I00 and I01, since the edge: of the coated areav would be established by'therelative position or. the shield 1'02- to the"first"filament "-92. However, by interposing- 'a -secondor -auxiliary shield. Hi3 between the shield tofzi andsupport body 99, the

edgeof the area *I-M normally determined by the line IOI will'actually be cut off by the auxiliary shield I03 and consequently the edge of the area I04 will be as produced along the line I05. This will result in an area I04 of perceptibly narrower rated material at the first shield I02 and, secondly, according to the position of the shield I03 which will directly act to establish the edge of the coated areas along lines I06 and I] such as indicated at I08 and I09. As will be noted, the filaments 95, 96 and 91 are equally spaced with relation to each other and the previous filaments and will, by reason of their relative spaced positions to shield I02, produce coated areas H0 and III of substantially equal width. More specifically, the line II2 from filament 95 will intersect with similar lines H3 and H4 from filaments 96 and 91 at the shield I02. If the filament 9! produced a graded deposit II5 between the lines I00 and H4, the thickness of the deposit H5 would be uniform from line H4 to the edge of the support body. However, in accordance with the arrangement of the filament 98 relative to filament 9?, there is produced a relatively thicker graded area H6 along the marginal portion of the support body or between lines I00 and I II.

It will therefore be seen that use of the second shield I03 determines the hypothetical limiting lines at or in the vicinity of the innermost edge of the graded area and particularly at the edge where the grading desired would be the thinnest. Location of this second shield and resultant width of coated areas, however, operates in the same manner as the first shield I02, and the location of the shield I03 may be determined in exactly the same way as previously described, by sighting hypothetical lines through certain limiting evaporation sources to the support body and locating the shield at the intersection of such l'mes.

In Fig. 10 is shown a diagrammatic arrangement of a shield I I3 having a perforation or circular opening I I0 in combination with two evaporation sources I and I2I to produce a coating which is thickest at the center I22 and grades downwardly in a thinner-coated area I23 towards the edges. Obviously, more than two filaments might be used to increase the total thicknesses through which the grading is produced, and it is apparent that the perforation may be circular, square, or any other shape. Thus, as shown in Fig. 10, the particular shape and size of opening IIS will control the coating from filament 420 between lines I24 and I25 and likewise from the filament I2I between lines I26 and I21.

The shields employed in the practice of the invention are of solid materials capable of supporting their own weight and are preferably made from aluminum or other metals, particularly those which are free of sputtering.

It will be more apparent from the followingexamples that the invention is concerned not alone with coating of fiat plates but is particularly useful in connection with a coating of shaped articles such as lenses, and decorative ware such as bottles, jugs, etc. In the coating of such materials, it will be apparent that the edges of the shields need not be straight but may be of a curved, serrated or other shape so as to produce. the graded patterns in definite desired limited areas of somewhat similar contour.

Example 1 ,An automobile windshield 14" a 30" was produced which had a-graded coating along the toponly and starting with the most dense area-at the top and graduated downwards in thickness for a distance of three and one-half inches from the top edge of the windshield. The product actually produced hada luminous transmittance as shown by the curve inFig. 11 in the upper three and one-half inches, no coating being appliedto; the glass beyond the three and one-half inches down from the top.

In producing this windshield with the graded deposit at the top, the same was arranged at a distance of twenty-two inches from a tungsten filament formed by twisting three strands of .020" tungsten wire together. The filament was further coiled into a spiral so as to provide over a distance of eight inches, ten or more turns. Upon each of the ten equally spaced turns, there was applied a small hook of inconel wire. This inconel wire (approximately nickel, 13% chromium, and ti iron) was .060" in diameter and a one-half inch piece of such wire was.

used to form the hooks. Molten inconel wets tungsten well and evaporation from the filament was thus secured all along the entire eight inches as a continuous line source.

Between the filament and the windshield to be coated, a fiat, rectangular metal shield was. placed at a distance of fifteen inches away from the filament and arranged in front of the Wind'- shield so as to obscure most of its surface and protect the same from receiving any deposit. Preferably, the shield was of approximately the same size and shape as the windshield. The.

shield was then moved into position and arranged according to hypothetical lines by sighting along the extreme ends of the filament tothe upper edge of the windshield and to a point three and one-half inches down from the upper edge, or to the extremes of the area which was to be coated with the grading. The shield edge was thus definitely located at the intersection of these hypothetical lines which placed the shield at the distances as previously indicated from the filament and from the windshield. The bell jar was then closed and evacuated to approximately 10- mm. and the filament was heated, the inconel melted and wetted the entire tungsten surface. As a result, the grading secured upon the windshield was extremely uniform in nature and the eye could not discern any definite breaks or lines of difiering transmission in the coating. This is more clearly shown by the smoothness of the graph in Fig. 1'1 which shows how gradually the light transmission varies with the distance from the top of the windshield. That is to say, at the upper edge of the windshield, the transmittance of light was substantially zero and as the distance increased toward three and one-half inches, the curve defining this transmittance rose slowly in the upper marginal areas and then gradually in a smooth upward course toward approximately luminous transmittance or more.

With reference now particularly to Figs. 12, 13 and 14, the windshield I28 therein illustrated as an example of another form of the invention has a graded coating I29 composed of a plurality I33, and I34 which are formed by the deposition of material evaporated from three sources of evaporation I35, I36 and I3'I- arranged in line amen 14 with-one; another and spaced a predetermined distance from one: another as described above. will-be. apparent, material evaporated from all filament I35 will be'deposited upon the glass to form the still thinner deposit or band I32.

Due to the curved edge I3I of the shield I30 and the relative positions of the evaporation sources I35, I36 and I31, the bands I32, I33 and I34 will not be in the form of straight, continuous bands of uniform width across the top portion of the windshield I28 but will conform withthe curvature of the edge I'3I of the shield. Thus, the curved edge I3I o'fthe shield will con trol the extent'of'the coating from the evaporation source I35 downwardly'from the top edge of the windshield to the innermost edge of the area I 32 to be coated as" indicated by lines I38 and I39. 'Ihus, the material evaporated from filament I35'will produce a coating of uniform thickness over the unshielded area of the windshield, the'innerm'ost edge of said coating being curved to conform with the curved edge I3I of said shield as indicated by line I40.

Likewise, the curved edge I3'I of' the shield I30 will 'control'the application of the coating iromthe evaporation source I36 upon the windshield from the top edge downwardly to the inner edge ofthebandI33 as indicated by lines I and I42 that intersect with the lines I33 and I39 from evaporation source I35 at the curved edge 131 of the shield. The curved-character oi theband I33, as controlled by the edge of the shield, is also indicated by the line I43 which intersects with the line I40 at said curved edge The heaviest areas I34 of the coating I29 are formed in -a-'-similar -manner along lines I44 and I45 from the evaporation source I3"! and since these lines intersect with lines I38I4I and 'I39'-I42 respectively at the curved edge of the shield; the width of the band I34 will be determined loy the unshielded portion of the evaporated materia'l-from the source I31. Also, since the curved line establishin'g thewidth oi the band r I33 will be controlled by the curved edge I3I of the shield, the actual areas. or bands I34 coated from the source I31 will substantially disappear 'at'the top of thewindshield as indicated by lines I46 and I4? from said source, along the edge of the shield and to the windshield.

, As will be noted in Fig. 13, the central area of the windshieldwillthus have only the two bands 'I32jand i33'while, as shown in Fig. 14, the opg posite 'upperfcornerareas "will carry the combined' deposits I32, I33 and I3 41fro m the three evaporation sources I35, I36 and" I31.

Ecuample 2 j With reference ct Fig. 16, several lenses I48 were produced havingtheir upper half carrying a graded coating I49 of inconel of varyingthick nesses and densities upon one surface thereof. In producing this coating, the lenses were mounted, as shown in Fig. 15, upon a support I50 in definite alignment at a distance of 17.3 inches away from a tungsten filament wound spirally of .040""wire so as to produce some ten loops within adistance of two inches of coil. As h'eremshown-fthere was thus provided a con? tinuous' evaporation source I'5"I two inches long,

the two ends of which are indicated in the drawing. This filament arrangement is capable of producing deposits of varying thicknesses and, more especially, a thin :area I52 adjoining a materially thicker area I53.

In front of the support I carrying the lenses and between such support and the evaporation source I 5I, a solid, rectangular shield I54 was arranged at a distance-of 14.2 inches away from the evaporation source. The'shield was such as to cover completelythe lower halves I55 of the lenses so as to prevent any deposition on such surface. The position of theshield I54 will thus determine and control the coating from the .evaporation source I5I and progressive thick 'nesses of deposit will be applied as between the lines I56 and I51. to the innermost edge of the coated area,vwhich line I51 strikes the edge I 54' .of the shield I54 and the line I58 from the opposite end of "the continuous source I 5I. The intersection of'lines- I51 and I58 'at the'edg'e of the shield'will thus determine the over-all width of the coating I49 and also the progressive increase in thickness of the coating between the area I52 and the area I53.

The shield was such as to produce a graded coating on the upper half of the lenses by, reason of the evaporated'ma-terial being laid down by various portions of the source or filament I5I. Upon each of the coils of the filament there was hung a small piece of inconel wire weighing .069 gram. When the vacuum chamber was closed and the filament heated, the inconel evaporated from all portions of the coil and deposited upon theupper half of'the lenses in the definite graded type deposit which varied in light transmission from 10% at the upper edge'down to 60% atthe lower edge of the coating, and the lower half of the lenses were completely uncoated and showed the normal transmission of glass of something over The continuous filament I51 wasarranged in this work in a direction such that it was parallel to the direction inwhich the grading I49 was to be produced upon the lenses I48, and the arrangement of the shield I54 and support I50" carrying the lenses was substantially as shown in Fig. 15.

Example 3 'As a furtherillustration of the uses of the invention, .there was produced a decorative jar I59 which had areas of different colors and of difierent reflectivities. The method of producing the decorations upon this jar is. illustrated diagrammatically in Fig. 17 in which is shown -evapora tion of material .from three evaporation sources I50, I6I and 52.. Thesesources were tantalum filaments and each was loaded with a material which. would provide a transparent coating, the material actuallyused being magnesiumfluoride to the amount of 0.5 gram in the two extreme filaments and. 0.3 gram in themiddle filament. The filaments were. located approximately two inches apart. Between the filaments and the jar which was to receive the coating, there was arranged in the vacuum chamber a shield I63 of suflicient width and. height to generally protect the jar. from receiving any coating other than above the upper serrated edge of the shield. In the center of the shield, there was a perforation I64 in the shape of a roundhole. This hole was one-half inch in diameter and through'it a deposit was formed upon the sides of the bottle in the shape of circles as indicated at'I65. Toobtain other andvaried effects on the upper portion l l or'neck I66 of the'jar, the upper edge I 61 of the shield was suitably crenelated, serrated or otherwise formed. Simultaneously with the deposition through the perforation I64, a portion of the evaporated material was accordingly also directed toward said jar neck I66.

The jar I59 was preliminarily coated all over with a reflective coating of chromium in a separate operation. The precoated, highly reflective jar was then placed in a vacuum chamber at a distance of twenty inches away from the filamerits I69 to I62 inclusive, and the shield I63 was moved into proper position at a distance of seventeen inches away from the filaments or three inches away from the jar, the shield being arranged so that deposits I68 were formed upon the neck I66 of the jar through the shadowing effects of the serrated edge I 51 of the shield while the circular deposits I65 were formed upon the side of the jar. As shown in Fig. 17, three definite sharp graded steps I69, I18 and I H of decreasin thicknesses of deposit of jmagnesium fluoride were thus produced depending upon the action of the shield and the various weights of magnesium fluoride applied to the fil-' aments. That is, from the filament I 60, the graded step or band IN on the neck of the jar I59 will be effected between lines I12 and I13 and a simultaneous coating in one of the circular deposits I65 between lines I14 and I15 which indicate the range of the circular pattern established by the round opening I64 in the shield I 63. The band I18 likewise will be created as between the lines I12 and I16 from the filament I BI .and the unshielded portion of the evaporated material along the line I16 will intersect with line I13 at the serrated edge I61 of the shield I63 and determine the actual width of the band IN. A second circular deposit will also be formed from the filament I6I between lines I 11 and I18. From the filament I62, the heaviest area of deposited material I69 will be formed as between lines I12 and I19, the shielded portion of the material along line I19 also creating the opposite edge of the coated area I19, since the line I 19 will intersect with lines I13 and I 16 at the upper serrated edge I61 of the shield. From this filament I62, the third circular deposit will be formed by the unshielded portion of the material through the round opening I64 of the shield I63 between lines I80 and I8I. The three bands or segments I69, I18 and HI upon the neck I66 of the jar each had a margin of saw-tooth pattern and each of the segments was of a different color due to lightinterference effects produced by the magnesium fluoride deposit upon the reflective coated bottle, since each of the graded deposit sections was of a difierent thickness of magnesium fluoride.

In a similar manner, the circular deposits I65 of magnesium fluoride on the center of the bottle provided areas I82, I83 and I84 of three different contrasting colors and diiferent reflectivitesdue to the three different thicknesses in the areas as shown in the figure. which. were secured through the combined action of the hole I66 in the shield I63 and the different loadings upon the three filaments. Thus, the central area I83 coming from the central filament IN and between lines I11 and I18 primarily was of a different color than the areas I82 which came from the two extreme filaments of different loadings I 60 and I62 and between .the respective line I14I15 and I8IlI 8I. The two areas I were of a third color, duevto a still greater thickness of deposit, since in such areas material was received from the central filament and from an extreme filament in each such area. Accordingly, the areas I82, I83 and I84 were of progressively greater thickness and of entirely diiferent colors from each other. The method of employing the shield has thus permitted the deposition of coat ings of transparent materials such as'magnesium fluoride and other semi-transparent materials such as zinc sulphide, quartz, aluminum oxide, or metals such as aluminum, chromium, etc. for the purpose of securing vari-colored and decorative effects.

It is apparent that the three circular areas produced on the bottle might have been arranged in some other decorative design rather than asingle vertical arrangement of circles. Thus, a pyramid arrangement of the three circles would result if the three filament sources were definitely not in a linear alignment but disposed with re spect to each other in a triangular arrangement. It is thus apparent that the evaporation sources may be arranged with respect to each other in various ways other than in direct linear-arrangement whenever the grading desired need not be of a type where the grading is of a single linear nature.

The term graded area or area to be coated with the grading, as employed in the claims, means the area coated with deposits ranging in thickness from a margin of no coating or thickness to a margin between a coating of maximum thickness and the next thinner coating, 1. e., be-

tween CD in Fig. 4. In fact, the invention is not concerned with the area having the thickest coating since such coated area receives deposits from all evaporation sources without any limiting efiects from the shields employed. Thus, the term graded area covers that area in which the gradings are controlled by the cooperative effects of the shield or shields with the filaments and the location of such filaments and the object to be coated.

I claim:

1. The method of producing a graded coating upon a support body by thermal evaporation, which comprises arranging the support body in position to be coated in a vacuum chamber, providing a linear source of evaporation in said chamber, projecting a hypothetical diagonal line between one end of the evaporation source and. the opposite end of the area on the support body to be coated with the grading, projecting a sec- 0nd hypothetical diagonal line between th other end of the evaporation source and the opposite end of the area on the support body to be coated with the grading and which second line intersects the first line at a pointbetween'the sup port body and evaporation source, placing a shield between said support body and evapora tion source at the intersection of the two hypothetical diagonal lines, and evaporating coating material from the evaporation source as said shield is held stationarily at said intersection to produce a graded coating.

2. The method of producing a graded, coating upon a support body 'bythermal evaporation as defined in claim 1, wherein the shield is of platelike form having one of its edges located at the intersection of the two hypothetical lines and the body portion thereof covering the area of the support body to be left uncoated.

3. The method of producing a graded coa ing upon a sup-port body' by thermal evaporation,- which comprises arranging the support body i i position to be coated in a vacuum chamber, providing a plurality of sources of evaporation spaced from one another in said chamber, projecting a hypothetical diagonal line between one extreme evaporation source and the opposite end of the area on the support body to be coated with the grading, projecting a second hypothetical diagonal line between the other extreme source of evaporation and the opposite end oi the area on the support body to be coated with the grading and which second line intersects th first line at a point between the support body and the sources of evaporation, placing a shield between said support body and evaporation source at ti e intersection of the two hypothetical diagonal lines, and evaporating coating material from the several sources of evaporation as said shield is held stationarily at said intersection to produce a graded coating.

4. The method of producing a graded coating upon a support body by thermal evaporation as defined in claim 3, wherein the shield is of platelike form having one of its edges located at the intersection of the two hypothetical lines and the body portion thereof covering the area of the support body to be left uncoated.

5. Th method of producing a graded coating upon a support body by thermal evaporation, which comprises arranging the support body in position to be coated in a vacuum chamber, providing a plurality of independent sources of evaporation in said chamber spaced from, one another and corresponding in number to the number of graded areas to be produced, projecting a hypothetical diagonal line between one extreme source of evaporation and the opposite end of the area on the support body to be coated, projecting a second hypothetical diagonal line cetween the other extreme source of evaporation and the opposite end of the area on the support body to be coated and which second line intersects the rirst line at a point between th support body and the sources of evaporation, placing a shield between said support body and evaporation source at the intersection of the two hypotheticai diagonal lines, and simultaneously evaporating coating material from the several sources of evaporation as said shield is held stationarily at said intersection to produce a graded coating having areas of predetermined width and gradation dependent upon the number of sources of evaporation and the spacing thereof.

6, The method of producing a graded coating upon a support body by thermal evaporation as defined in claim 5, wherein the shield is of platelike form having one of its edges located at the intersection of the two hypothetical lines and the body portion thereof covering the area of the support body to be left uncoated.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,107,784 Gardner Feb. 8, 1938 2,123,706 Biggs July 12, 1938 2,160,981 OBrien June 6, 1939 2,351,536 Osterberg et a1 June 13, 1944 2,384,209 Sukumlyn Sept. 4, 1945 2,433,635 Sukumlyn Dec. 30, 1947 2,463,986 Pride Mar. 8, 1947

Claims (1)

1. THE METHOD OF PRODUCING A GRADED COATING UPON A SUPPORT BODY BY THERMAL EVAPORATION, POSITION TO BE COATED IN A VACUUM CHAMBER, PROVIDING A LINEAR SOURCE OF EVAPORATION IN SAID CHAMBER, PROJECTING A HYPOTHETICAL DIAGONAL LINE BETWEEN ONE END OF THE EVAPORATION SOURCE AND THE OPPOSITE END OF THE AREA ON THE SUPPORT BODY TO BE COATED WITH THE GRADING, PROJECTING A SECOND HYPOTHETICAL DIAGONAL LINE BETWEEN THE OTHER END OF THE EVAPORATION SOURCE AND THE OPPOSITE END OF THE AREA ON THE SUPPORT BODY TO BE COATED WITH THE GRADING AND WHICH SECOND LINE INTERSECTS THE FIRST LINE AT A POINT BETWEEN THE SUPPORT BODY AND EVAPORATION SOURCE, PLACING A SHIELD BETWEEN SAID SUPPORT BODY AND EVAPORATION SOURCE AT THE INTERSECTION OF THE TWO HYPOTHETICAL DIAGONAL LINES, AND EVAPORATING COATING MATERIAL FROM THE EVAPORATION SOURCE AS SAID SHIELD IS HELD STATIONARILY AT SAID INTERSECTION TO PRODUCE A GRADED COATING.

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