US2560117A - Sign - Google Patents

Description

July 10, 1951 R. w. MALLARY 2,560,117

SIGN

Filed Jan. 31, 1947 2 Sheets-Sheet 1 5i i I I: M f

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INVENTOR ROBERT W. MALLARY ATTORNEY July 10, 1951 R. w. MALLARY SIGN Filed Jan. :51, 1947 2 Sheets-Sheet 2 ww g I l I r 7/ ///H/ INVENTOR ROBERT W. MALLARY ATTORNEY Patented July 10, 1951 UNITED STATES PATENT OFFICE SIGN Robert W. Mallary, Los Angeles, Calif.

Application January 31, 1947, Serial No. 725,497

4 Claims.

This invention relates generally to illuminated signs, and relates more particularly to signs of the edge-lighted type utilizing transparent and translucent materials such as plastics.

It is an object of the invention to provide devices of this character wherein great diversity and control of optical effects may be produced.

Another object of the invention is to provide a panel of suitable characteristics in which sign characters, such as letters, numerals and the like, may be variously embedded to produce various effects. For example, the sign characters may be wholly embedded in the panel. Ihus, by removing the sign characters or decorative features from contact with the air, and embedding them within a substantially transparent block or panel, the basic means is provided for the control and exploitation of differences in color, degree of translucency and refractiveindex, for the purpose of developing a great many different optical eifects. The advantages of embedding the sign characters and figures results in a high degree of control of the optical effects desired, particularly as regards those effects resulting from the combination of materials of different as well as identical indices of refraction.

Further advantages reside in the economical utilization of the light entering the panel from the edge resulting from the property of total internal reflection, a more even illumination of the sign characters, also owing to the effects of the total internal reflection of light, and the enhanced effect on the appearance of the sign characters when seen through a refractory transparent medium. Other eifects'may also be secured by but partially embedding the sign characters or figures in the panel.

Still another object of the invention isthe provision of a device of this character wherein addiitional effects may be produced by roughening certain surfaces of either the panel or the sign characters, or both.

A further object of the invention is to provide a device of this character wherein still additional effects may be produced by special treatment of certain surfaces such as the rear surface of the panel, so as to provide a back drop for the sign characters and the like.

A, still further object of the invention is to provide a device of this character wherein an attractive three-dimensional spacious effect is produced.

One of the advantages Of embedding the sign characters in the panel is that it isolates such characters from dirt and the like, so that the Sign is easily cleaned and polished, and may be 2 rebufied should that be necessary after a period of use.

In many edge-lighted signs now in use the illumination is intense over the lower portion of the sign characters but is weak over the upper portion, or vice versa, and it is therefore another object of the invention to provide a device of this character wherein there is relatively even illumination of the sign characters. One factor in securing such even illumination is the characteristics of the sign characters themselves which readily transmit light to all parts thereof. Another feature of the invention which aids in effecting even illumination of the sign characters is the use of a plurality of light sources. For example, the panel is illuminated from a plurality of sides, as from the top and bottom, and the panel is provided with rearwardly extending portions having the top and bottom edges curved so as to illuminate the sign characters evenly.

Still another object of the invention is to provide a device of this character wherein the illuminated parts of the device differ optically from each other in some respect, so as to afford contrast and variety.

A further object of the invention is to provide a device of this character wherein the sign characters are fully visible throughout a wide range of viewing positions.

A still further object of the invention is to provide a device of this character wherein sign characters and the like, havingvarious different optical characteristics may be employed within the same sign.

A still further object of the invention is to provide a device of this character wherein sign characters may be so disposed that some of said characters are in front of others, while all said characters are visible in their entirety.

A still further object of the invention is to provide a device of this character, wherein actual objects, or facsimile objects, may be embedded in the panel, such as, for example, bottles, etc.

Further objects and advantages of the invention will be brought out in the following part of the specification.

Referring to the drawings, which are for illustrative purposes only,

Fig. 1 is a perspective view of a sign embodying the present invention;

Fig. 2 is a sectional view taken on line 22 of Fig. 1;

Fig, 3 is a fragmentary sectional View showing an alternative arrangement of the panel and sign characters;

Fig. 4 is a perspective View of a sign embodying an actual object embedded in the panel; and

Fig. 5 is a perspective view of an alternative arrangement of the invention.

Referring to Fig. 1, reference numeral it indicates a housing for supporting a transparent enclosing block or panel, indicated generally at H, which is illuminated by One or more suitable surfaces of light within the housing, as will be more fully described hereinafter.

The housing comprises a front wall l2, side walls is, a top wall 14, a back wall l5, and a bottom wall it, the latter extending forwardly at ll, of the front Wall G2, to prevent forward tilting of the sign.

The panel II has rearwardly turned portions l8 and it at the top and bottom respectively, said portions extending through openings provided therefor in the front wall l2. It is to be understood, of course, that the panel or block H is of transparent material such as, for example, a clear plastic, or at least is substantially transparent.

Means for securing the free ends of the flanges or parts is and I9 within the housing comprise brackets 28 and El located above and below the upper extension l8, and brackets 22 and 23 disposed above and below the lower extension [9. These brackets extend longitudinally of the housing and are secured to the interior thereof by any suitable means such as welding, soldering, or the like.

As shown in Fig. 2, there is a source of light for each of the extensions, there being a source of light 24 aligned with the upper extension, and a second source of light 25 aligned with the lower extension. These sources of light may be of any suitable character, although they are shown as fluorescent tubes, which extend longitudinally of the housing behind the respective extensions I8 and [9. These light sources are usually white but can be of any other desired color, or one may be of one color and the other of a different color. If desired, in order to intensify the light reflected into the panel I i, reflectors 26 and 27 may be provided about the tubes 24 and 25 in such a manmay as to reflect the light from said tubes into the adjacent tubes of extensions 18 and id. The reflectors may be of an suitable type, and are secured within the housing by any suitable means, not shown.

The light enters the respective extensions through the surfaces 28 and 29 respectively, and is deflected from the curved longitudinal edges 3! and 3| respectively, so as to direct said light throughout the panel. edges 36 and 3| are such as to internally reflect the light and not allow it to escape, and the illuinination within the panel I! is the result of the total internal reflection of light from said sources.

The rear surface of the panel may be treated in a variety of ways, but in Figs. 1 and 2 said surface is polished-and buifed. Likewise, the face 32 of the panel is buffed and polished to a high degree so that it Will be as invisible as possible, will internally reflect the light, and will pass the light reflected from the sign characters. When the Sign is seen in complete darkness, the face of the panel is completely invisible. However, when the The radii of the curved ters, numerals, emblems, sculpture, objects dart, decorative figures, facsimile objects, actual objects, and all other usages where the principles enumerated herein find application. The purpose of the above Wording is to emphasize the fact that the essence of this inventionlight reflecting, transmitting and absorbing materials embedded within a substantially transparent panel and illuminated-is applicable in many different fields.

As shown in Figs. 1 and 2, certain of the sign characters, indicated generally at 35, and comprising the letters 0R0 extend in relief from the rear surface of the enclosing panel H in the direction of the face 32, that is, the rear surfaces of these characters share a common plane with the rear surface of said panel. These letters possess optical properties different from the optical properties of the panel, and such properties may relate to color, degree of transparency, and/0'1- refractive index, so that they will be distinguishable when the device is illuminated. Embedded completely Within the panel are additional sign characters, indicated generally at 36 and comprising the words For quality. These words are located in front of the letters 0R0. The words For quality are set off from the characters behind them and also from the rear surface of the enclosing panel so that they appear to be suspended in space. Thus the illusion of spaoiousness Within the panel is heightened. The words For quality can, if desired, be more transparent than the letters 0R0 so that the latter may be seen in their entirety simultaneous= 1y with the former.

It is to be understood that the sign characters 36 possess optical properties which are of such character as to make them readily distinguishable in connection with the optical properties of the panel (which is essential to the invention) and the characters 35 (which is desirable though not necessary).

Embedded within the panel is also a base for the characters 0R0, said base being indicated generally at 3'1. This base has no structural purpose in the sign because in fact all sign characters are held firmly in place by virtue of being embedded in the panel. Rather its function in this sign is decorative in seeming to support the letters CR0 and providing a front face 36 which has the words Why not try the best? inscribed thereon, as indicated at 38. That is,

' the base is non-functional from the structural sign is seen in semi-darkness or in light. the face reflects a certain amount of external light. However, these reflections can be substantially eliminated by the application of one of the glare and reflection-killing micro-films of known character.

It is to be understood that the term sign characters as used herein, is intended to mean letpoint of view, but has an aesthetic function. The base 3? should be extremely transparent so as to permit the maximum passage of light therethrough from the lower source of light 25. This is desirable in View of the fact that the base 31 is located adjacent the lower end of the panel H and in the path of light passing through the extension iii and into said panel.

The characters 33 are on the front surface of the base 3'! and, in contrast to the other sign characters above described, the effect is two-dimensional rather than three-dimensional, They may be applied in the manner commonly used in the coloring of indicia or instrument dials. The differences between these sign characters and those found in ordinary dials is that the former are completely embedded and insulated from the air, whereas the latter are not.

In the present arrangement the sign characters Why not try the best? are illuminated mainly by conventional transmitted light and only partially by edge lighting. This is due to the fact that the source of'light enters the panel directly behind these letters and they are seen 1 against said source of light. This type of illumination gives a distinctly different appearance to the sign characters than where they are edgelighted.

It is to be understood that in a sign of the present character the enclosing panel II should, in general, be more transparent than the most transparent sign character or figure within it, otherwise it would mask out some or all of said characters. Moreover, for the most striking results, sign characters superimposed in front of other characters should be more transparent than the latter.

Of course, the sign characters may be of various types and may have various characteristics. For example, there may be various optical char: acteristics which the materials may have for the purposes of this invention. These optical characteristics can :be listed as color, degree of translucency, refractive index and an important fourth characteristic representing combinations of the former three to form patterned, textured and mottled eifects. These latter in most cases result from the mixing and incomplete fusion of materials of different colors, and/or degrees of translucency, and/or indices of refraction. The materials which are used and the manner in which they are mixed determine the particular pattern, or texture, in any given instance.

Regarding the material embedded within the enclosing block, several categories have been established. The first is best described as constituting a thin interlayer, or what can be conceived as an embedded surface. This embedded surface is (1) disposed two-dimensionally (on a plane) within the panel, or (2) extends three-dimensi-onally within it. Whether disposed two-dimensionally or three-dimensionally within the panel, it is always a thin interlayer of non-transparentalthough preferably near-transparent light reflecting material. In the second category the material delineating the sign character extends three-dimensionally through the'mass of the sign character. these distinctions clear. If a transparent methacrylate letter is surface dyed and then embedded within a methacrylate block, there is a visible interlayer; this represents the first category. On the other hand, the letter may be formed from a sheet of methacrylate which, in manufacturing has been caused to be dyed all the way through its mass; this represents the second category.

Taking the sign characters 35, the surfaces 4 may be colored and they are then seen as an interlayer of color; or if they are colored all the way through their mass, they are seen by virtue of such coloring. Or they may have their surfaces 40 slightly more opaque than the panel II and are rendered visible by virtue of such degree of opacity. Further, these characters may be more opaque than the panel through their mass, and rendered distinguishable in this way.

A further alternative arrangement is'to' have the interlayer 40 of a different refractive index than that of the enclosing panel I I; or it may be comprised of a material of a different refractive index than that of the panel and extending three-dimensionally through the mass of said character. Or the same purpose (i. e., distinguishing the sign character from the panel and rendering it visible) can be achieved by a mottled interlayer at 40, or this same mottled effect can be translated into a three-dimensional form and Some examples will make '6 extend, through the mass of the sign character. It is, of course, to be understood that the coloring,.translucency and other characteristics above through differences in color, translucency or refractive index, either singly or in combination.

For example, if the sign characters are red in color it is difficult for the spectator to ascermixed together.

tain whether this coloring matter extends only over the surface of the characters or whether it extends through their massthis in spite of the fact that there exists an actual difference in effect between the one and the other (i. e. a sign character colored through its mass absorbs more light). Where mottled effectsare resorted to, however, the case is different. Mottled effects,

it will be recalled, are the result of mixing materials of different optical characteristics in such a way that complete fusion does not result. In

I this instance it is normally not diflicult for the spectator to ascertain whether the mottled effect is an interlayer within the panel or extends through the mass of the sign character. The importance of these mottled eifects to the present invention justifies the emphasis which has been assigned to the differences between the aforementioned categories. Three-dimensional textures and mottled patterns are among the most beautiful effects characteristic of this sign.

' Let us say, for, instance, that two transparent materials of different indices of refraction are One might suppose, because both materials are transparent, that they will remain invisible within the panel. However, this is not the case, at least when mixed in such a way that complete fusion is not the result. In this instance discrete minute areas of one material are adjacent to the other. At the interface where the two materials conjoin a reflection' is established. Multiply these points of refiection by manythousands, insure there is a correct density of these reflections per unit area, and the result is a flowing, apparently homogeneous, mass of luminous material. When utilized this effect accounts for the special luminosity of the sign characters in the present sign. Moreover, it represents the principal means whereby white and all color tints deriving from white are achieved.

It has been previously said that the sign characters, even though colored, should preferably remain as transparent as possible. There are several reasons for this. For one thing, a sign character which is dark in color is correspondingly more opaque. In other words, the ratio of light absorption to light reflection and transmission is weighted on the side of absorption, 1. e. the sign character is reduced in luminosity. Because light transmission and reflection are so preferred over absorption dyes are normally, though not invariably, used in preference to pigments as coloring matter. Unfortunately, there is no such thing as a white dye. This explains theimportance of the special luminous effect described in the previous paragraph.

,It .is not sufficient simply to create a threedimensional, mottled texture using transparent eet-tan materials (if-different indices* of refraction-"tool:- "tain the aforesaid luminous effect '(which might be described as a multiplied micro-point reflection'e'ffect), at least if the most intense lumi- -nosi'tyis to be had. Themat'erials chosen must be-right, not only asregards respective indices of refraction but also as regards the surface tension-establishedbetween 'the' two, The'number, "size and positioning of the 'niinute areasror "points within the enclosing vehicle must be correctly "calculated for maximum reflection. 'For'examp'le, if the sign character is "too densily "pa cjiied with' these refiectmgpoints'oriareas most bf the 'lig'ht is'reflected fback "out before "it 'jpen'e- "tratesthe sign character; 1. e. it -is 'ex'cessively opaque. *In"thisinstanc'e the sign ic'haracter is luminous around "the "edges but "dull in the "middle portions. "Onthenther liand,'if "thereare not'a'sufficientnumber'nf these reflecting areas is comparable to that of scatt'eredfstars against adark field. 'Thenagain, the 'smallerth'e points 'or areas of reflection the more conducive to "a What has been said 'in "preceding paragraph pertaining to the "word "O'R'O" also applies to 'thewords For quality, it being understood that in determiningthe i-specific treatment of these "sets of "sign charactersthe two at leastdiffer "optically" in some respected as to afford contrast and variety. For example, the words "For quality "may be very transparent so that "the word ORO'can 'be'seen throughthem "allowing an letters to he seensimultaneously. It i might .be suggested that only the surfaces be colored. in contrast to coloring through their mass because the latter arrangement tends to "absorb more-light. Thus, 'thesi'gn characters comprising the words For quality may "be" unsaturated in color (very little color, i.'e. a li'ghtsh'ade) and therefore would be very transparent (as "opposed "'to' translucent or opaque) and of the "samere- "fractive index 'as that of the enclosing'panel "ll so there would'be no "glare or reflections lto cut down transparency. .In contrast, the word 0R0 *may be deeper'in color, luminous owing to the micro-point reflection 'e'fie'ct .described in 'the previous paragraph (perhaps combined with 'a three-dimensional texture) relatively jtransluc'ent,;and comprised lof'materials of different refractive indices than that of the panetl 1,

One of the 'sub 'c'ategories previously .de-

scribedan'emb'edded interlayer disposed on a plane'applies to'th'e sign characters Why not try the best?"because these are two-dimensional "in every sense. However, like the'threeediinensional sign characters these two-dimensidnalletters can be saturated or unsaturated in respect to color; transparent, translucent or .opaquefiof the same or different indices of refraction'from the panel I I or they may be mottled in the aforesaid. manner.

.By removing the sign characters or decorative figures from contact with the air and embedding them within a substantially transparent block the basic means is provided to control and exploit differences in color, translucency :and .re- .fractiveindex for thepurp'ose' of developing an indefiniterepertory of optical effects. The sadvantages of 'embedding 'can lee-summarized as 1) "resulting in-azhighdegreeof control otthebptical efiects desired, particularly as regards ithose effects (reflections and their absence) resulting ifrom' -the combination-of materials of dissimilar J .-.sure":thatzthe colorcis notso darkcthat. it absorbs too :much-ofthe illumination or masks out the sign characters. If it is desired that the sign ets-*wllas identical'indicesof refraction, 2) ;an "economicalutilization or the light en'tering the block from the edge resulting from'the property oftotalinternalreflection, (3) a more even illumination-of the 'sign characters also owing to the effects of the total internal reflection of light, (4) .a'more .even illumination of the sign characters'owing to the control which is exerfcised over the indices of refraction of the embedded sign characters and the panel, (5) the desirable eifect on the appearance of the "sign characters when seen through the refractory,

"transparent medium, (6) providing a transparent, invisible superstructure, or support, .for the sigircharacters holding them in a proper position'relative to the source of illumination and to ,the other'elcm'ents constituting the over-all -Sign-.a subject which has not previously been mentioned. To .an uninformedobserver it would appear that the sign characters are manufactured apart from the. enclosing panel and only subsequently embedded within. it. But as ainatter of fact theprocedure may involve molding the enclosing .panel .first with the :sign char- .acters (or moreprecisely, the shapes of the sign characters) already apart ,of-the panel as deep recessesin its-rear surface. Then, with-a subsequent molding operation, the recesses are filled .in solid tozproduce-the result seen by 'theobserver. When this, method is followed the panel is rightly conceivedasa necessary antecedent to the manufacture of the sign characters themselves. vl-nzeiiect the panel itself is a illOldf-ih which-the lightrefiecting materials comprising the signcharacters arev formed.

.While the transparent panel could; if desired, be made of almost any transparent material,

eplastiesgsuch as epolystyrene and methacrylate havebeen. found highly desirable. .Where'ther- -Without going 'into detail turing the sign, some discussion of thesubject 'Will-serve'to clarify-certain features of the'sign itself.

For eXam-ple,= if it::is intended that thevenclosingwpanelabeslightly coloredplet us say'tinted .throughoutrits mass, molding powde'ris selected of "the :proper: color; care being exercised 'to incharacters are'seen byvirtue of a light reflect- "The: panel is then inserted in a mold and sameztoharacteristics as those of the panel itself.

-A's an alternative the recesses can be left uncoated-and"fille'd'in with a colored plastic; or as =a' fu'rther 'alternative the two methods can be "combined.

Let us say, on the-other hand, that the sign cliaracters are to be rendered visibleby virtue of a three-dimensional interlayer which is mottled. In this case the recesses are sprayed with a special mixture consisting of two or more light reflecting insoluble, incompatible materials. The failure of these materials completely to merge results in patterns and. mottled effects which are very effective, especially when seen under the conditions of edge lighting. By combining materials of diiferent chemical composition, colors, degrees of translucency, and refractive indices a great variety of effects can be secured.

Or let us say that the recesses are sprayed with a special mixture consisting of minutely granulated transparent particles of a given refractive index immersed in a vehicle of a different refractive indexa vehicle, moreover, in which they are insoluble. Being insoluble in said vehi cle the surface irregularities of these minute granules are preserved and being immersed in a surrounding medium of a different index of refraction they are light reflecting. The recesses being filled in with a material of optical characteristics identical with those of the panel, and thepanel being edge lighted, the sign characters are, rendered visibleby virtue of this encased frosted effect (which, be it said in passing, is in effect the interlayer counterpart of the micropoint reflection effect). Somewhat the same result may be obtainedby roughening the recesses with sand blasting apparatus, coating them with a material of adiiferent refractive index from that of the panel and in which the material comprising the panel is insoluble, and filling in the recesses are previously described. The above are methods of achieving whiteness and,luminos-,

ity inthe sign characters and in this respect have the same function as the micro-point reflection fie t- Where it is desired. that a mottled effect extend three-dimensionally through the mass of the sign character a different procedure is followed. In this instance the recesses in the rear surface of the panel are left uncoated and a plastic compound with which the recesses are filled isof a special character. In other words, the mixture which is fed into the hopper of the injection molding machine consists of at least two different materials, or if the mixture consists of the same plastic material there must at least be a difference as regards color and/or degree of translucency. For instance, a given mixture might consist of three constituents, all of them the same methacrylate plastic: (1) 50% transparent powder, (2) 30% colored powder and (3) 30% a powder which is somewhat more opaque than both of the preceding. Whenthe granules are'heated in the heating cylinder of the molding machine they soften and by action of a ram are forced into the mold cavity and finally into the recesses in the rear surface of the panel. Complete mixture of the three constituent materials does not occur, however, because they never become sufiiciently liquid to fuse. Rather, the result is a three-dimensional mottled effect comprised of transparent, translucent and colored areas. By varying the composition of the mixture as regards the type, size, proportion and number of the constituent granules an infinite number of effects can be obtained.

The micro-point reflection effect, as regards technique ofmanufacture and in other respects as well, is' related to the immediately preceding. What is required in this instance, however, is a mixture of at least two substantially transparent materials'of different indices of refraction. It

will be recalled that the micro-point reflection effect results where minute areas, or points, of a given index of refraction are surrounded by a vehicle of a different refractive index and are illuminated. While a certain amount of luminosity will always result from this combination maximum reflection is contingent upon (1) the nature of the materials comprising respectively the embedded minute areas and the surrounding vehicle, (2) the respective indices of refraction of the embedded areas and the vehicle, (3) the size of the embedded areas, (4) their position, and (5) their density relative to the surrounding vehicle. Control of these in the molding operation is obtained by a correct determination of (1) the types of materials making up the mixture, (2) the proportion, or ratio, by weight of these constituent materials, (3) the size of the granules of the respective constituent materials, and (4) general molding conditions.

For example, as regards the types of materials used, one might be a transparent, thermoplastic material of a given index of refraction and the other a transparent thermosetting. plastic of another index of refraction, keeping in mind that the granules of thermosetting material are to comprise the minute, light reflecting areas within the vehicle which is made up of the thermoplastic material. Because the thermosetting granules do not soften under the effect of heat they maintain their identity and shape during the injec-v tion operation. This introduces an added element of control into the molding operationa control which is apt to'be materially lessenedv when two thermoplastic materials are used. Then again, because a correct density of the reflecting points, or areas, within the vehicle is necessary if maximum reflection is to result, the

, proportion, or ratio, in which the respective sets 7 however, at the interface between a gas and a of granules are mixed is of utmost importance.

Importance must also be attached to the absolute and relative sizes of the granules comprising the mixture. It will be recalled that the micro-point reflection effect is most efiective where the reflecting surfaces are extremely minute and contribute to an effect of a glowing such as neon gas. These reflecting surfaces can be no smaller than the granules of which they are comprised.

In the preceding the micro-point reflection effect is described as resulting from the comolding of two or more tpyes of. granulated plastic materials. When this method is followed any given reflection results from the conjoining of two solid materials of. different refractive indices,

said reflection taking place at the interface between these materials. Reflection can alsoresult,

solid, let us say, for example, where air and a plastic material conjoin. This can be achieved by heating transparent plastic granules of homogeneous composition in a mold and compressing them, insuring that the pressure is not so excessive that all the air is driven out. In other words, if the exact amount of heat and pressure areapplied minute pockets of air remain trapped within the sign character. Reflections are established where the air pockets and surrounding plastic vehicle conjoin. The effect-is substantially the same as that previously described. While it is possible to exercise this pressure control where compression molding technique is utilized, it is less feasible when injection or. transfer molding operations are used. The desired effect may also be secured by having reflecting areas consist of minute pockets of a liquid mate rial. embedded. within a. solid vehicle, or. even that. the reflecting. areas: might consist. of discrete solids immersed in a liquid, or solids immersed'ina gas. An example ofv the latter. migi: be. something onthe order. of spun glassstuiied or blown into the recesses. of the transparent panel g It. was previously said that embedding the sign. character within the enclosing panel permitscontrol of the refractive index. of the. sign character relatire to that of the panel, Theserefractive indices may or. may not bethe same. If, they are identical. no. glare. effects emanate at. the interface between. the sign character and. the enclosing panel. Qn the other. hand,.if the re.-- fractive. indices. vary the. contrary holdstrue.

Whenithetwo. refractiveindices are diiferentiandl resultin g1are.effects,-. these latter are not. uni..- formly distributed over the entire. surface or" the sign character; rather they are. localized atcertainpoints. Thisis. held to be a limitation characteristic of. many plastic. illuminated signs now in usea limitation which resultsfrom the fact that the. light does. not approach every part of the surface of the sign character with the. same 2:.

angle of' incidence. In these. cases, any particiu lar pattern. of light. reflection is. determinedby the conformation. of the interface. (1. e. th.5p:= ciflc shape of the signcharacter) relative to the. angle. of; incidence of the illumination. In so far as. the manufacturer ofthe sign character. determines its. Shape it. indirectly determines.v the. pat-.- ternofli'ght reflections which result. In.v actual practice, however, the latter is largely an un foreseen result and essentially. accidental.

Taking, for instance, the letter R in the. word. R0: if this letter is, comprised of a material of a different refractive index from that of the panel certain parts of its. surface will be subject to glare and will thus. be rendered visible; the. remaining, parts. however,. will remain, invisible. when the sign character and panel are of different indices of refraction, total internal reflection takes place within the sign character as well as within the enclosing. panel; In other words,.the interface between the sign character and'thepanelexerts the same actionon theimpinging. light 'asthe interface between the panel and. the surrounding air. Assuming. theTrned-i'um in which-the. sign character is immersedisof a different refractive index than that of the sign character it is more or less irrelevant, considered from: the standpoint of appearance, whether this.

medium be a solid, such as the plastic of the enclosing panel, or a gas, such as the atmosphere. This is. assuming, of course, that illumination in both instances is by total internal reflecti cn.

When a sign character is comprised of the micro-point reflection eifect extending substantially. through its mass. itis again-more or less irrelevant, from the. standpoint of appearance. Whether said sign character is immersed? in a solid or gaseous medium. Assuming, at least, that the mediumis of adifferent refractive indexthan. the predominant material of thesign. character, with the resulting localizedlglareeffects, the latter are overwhelmed. by the. prevails ing high luminosity of the letter as. a whole. In other words, the reflections at the interface con joining. the sign character. and. the. panel are invisible and thus neither augment nor lessen the. clear definition of. the sign character. Considered from this point of view a sign character comprised of the micro-point reflection effect, or

This is. owing to the fact that,

. embody. the micro-point reflection efiect.

sign characters comprising the micro-point rcflection effect, and its variations, are considered within the scope of this invention even when disassociated from. the enclosing panel as shown. in. Fig. 5. In. this figurereference numeral 58. indicates the housingcontaining the illumination unit. Abase 5|, for. the sign. characters or letters. 0R0 indicated generally at 52,. is shown disposed. on. the housing, said sign characters 030 being shown mounted on the base M which, if. desired. may be. so. constructed as to The words.l?or quality may be provided'cn the front. face of. the. base 5i in the mamier described in connection with the. words Why not. try, the best? on thebase 31 in Fig. 2.

Unlike other optical effects characteristic of and. important to the. present invention, the. micro-point eifect does not depend on the enclosing panelfor its success.-

While the panel is typically transparent it,. too, may be treated in various Ways as regards color, translucency and'mottl'ed effects. For in.- stance. the enclosing panel. can. often be made. more attractive by being. tinted with color,. either over its surface or through its mass. This. can. be done if. the degree of color saturation. is not. so excessive. as. to cancel out too large aportionof. the light. emitting. from: the. interior thereof; Moreover, it should be remembered that thesum. total-effectshouldbe no more. opaque than. the. most transparent. portion. of. the. material. em? bedded Within the block which. is. meant; to. be seen -by the observer. Thenagain, the. enclosing-. panel can be mottled, for instance, three-dimem sionallytextured through its. mass. Needless to say, the caution. exercised in. respect. to. color. is exercised in. respect to. these mottled. effects as well.

A variation or alternative arrangement ofthe. invention pertains to the. use: of luminescent (fluorescent andphosphorescent). dyes. and pigments as a substitute for the normal. coloring matten. For these purposes. the illumination source shouldbe. rich. in ultra-violet energy and filters 61 used. These filters. are. mounted in" grooves provided therefore inv the. respective brackets-22,. 2-3 which are of such character as to absorb the visible light and pass the ultravioletlighti There exists the" further possibility of a sign which combines the'feature of avisible, aswell as: a luminescent sign. This-can/be done by using coloring matter whichis suitable for illumination by visible light, but which also possesses luminescent properties. Needless to say, the appearance of the sign under the two different sources of. illumination is-markedly diiferent. It is. also 'to be understood that the filter M- may beused to determine the character and color of. visible light and if desired one 'filter'may be used toprov-ide one color and the. other used to the other letters; the letters are incompletely seen and the vision is confused. This is not the case with the present sign. When the. person viewing the letters moves from a position directly in front of such sign, refraction causes the letters apparently to shorten, but the whole of any letter can still be seen (within reasonable limits). Thus, the sign characters are seen in their en.- tirety as clearly from the side as from the front. Combined are the depth and substantiality of a thick letter seen from the front and the legibility of a shallow letter seen from the side. This special characteristic results from embedding the block letters in a refracting medium.

An additional feature of the invention is the provision for the embedding of a real object, or a facsimile object, as shown in Fig. 4 wherein said object comprises a bottle 42, although other objects may be used, depending upon what is being advertised; and, of course, written or other material may be used in connection with such object.

Moreover, the shape of the panel can be made surface and then forcing this pattern on to it using the original grained material itself or a metal die. Or, the rear surface can be silvered so as to function like a mirror. In this way the thickness of the sign characters ORO can be apparently doubled owing to the reflection set up.

I claim:

1. An illuminated sign comprising:' a one-piece solid molded panel of light transmitting material, said panel having a cavity therein in which a sign character comprising a solid substance of optical characteristics different from said panel is molded so as to be fully embedded within said p a nel and united thereto by molding whereby no interlayer of air exists between the contacting surfaces of said sign character and said panel,

none of the surfaces of said sign character being coplanar with any surface of said panel thereby creating the appearance of being unattached to to conform to the general shape of said bottle or other object. 1

Another possible variation provides for the bottle or other object partly enclosed and partly outside of the panel ll, interpenetrating it as it were, and even further variations are possible.

In summary, the characteristics of the enclosing block or panel ll need not exactly conform to those shown in the drawing. In general, however, it can be said that its face should be highly polished and that it should be of such a shape as to reflect the light internally with a high degree of efficiency directing the rays to the sign characters. For specific effects the face of the enclosing panel can be given a contour which, owing to the effects of optical refraction, results in an optical distortion of the sign characters within the block. For certain applications, i. e. decorative figures such as flowers, etc. the shape of the enclosing block may be cylindrical. Here again, however, it should be noted that the nonplanar shape of such a surface gives rise to pronounced refractory elfects. Such effects, however, can be highly illusory and intriguing. The panel, while normally transparent, can, as has been pointed out above, be treated in various ways, i. e. it can be three-dimensionally textured, colored, etc.

While the panel H may have its rear surface highly polished, and thus invisible to the observer, another method of treating said surface is shown in Fig. 3 wherein an appropriate material such as paper or cloth, on which is printed or otherwise reproduced a texture, design or pattern, is impregnated with a-transparent plastic material and under heat and pressure the material is forced against the rear surface of the enclosing panel so as to become physically and optically united to it, as indicated at 63. The light rays traveling through the panel are reflected from this layer to the observer and enable the design to be seen. An advantage of this method is that the effect of almost any material or texture-cloth, metal, wood, etc.can be reproduced. The process involved is one of lamination.

It is also to be noted that an actual material, such as a monks cloth or a velvet, can be impregnated and then laminated to the rear surface of the enclosing block.

' A grain duplicating that of coarse wood or other appropriate material can be given to the rear surface by heating and softening the rear any surface of said panel and of being freely suspended therein, and means for illuminating said sign.

2. An illuminated sign comprising: a onepiece molded panel of light transmitting material, said panel having two cavities therein in which sign characters comprising solid substances of optical characteristics different from said panel are molded so as to be embedded within said panel and united thereto by molding whereby no interlayer of air exists between the contacting surfaces of said sign characters and said panel, one sign character having its rear surface coplanar with the rear surface of said panel and being substantially opaque relative to the other sign character, and the other sign character having none of its surfaces coplanar with any surface of said panel and positioned substantially in front of the first sign character thereby creating the appearance of being unattached to any surface of said panel and of being freely suspended therein, the sign character in front being substantially transparent and allowing the sign character in the rear to be seen simultaneously with it, and means for illuminating said sign.

3. An illuminated sign comprising: a onepiece solid molded panel of light transmitting material, said panel having a cavity therein in which a sign character of optical characteristics different from said panel is molded so as to be fully embedded within said panel and united thereto by molding whereby no interlayer of air exists between the contacting surfaces of said sign character and said panel, said sign character comprising a vehicle of transparent material in which are embedded minute particles of a transparent material of a different index of refraction from that of said vehicle, the size, number and distribution of said particles in said vehicle producing a reflection effect of great depth and intensity, none of the surfaces of said sign character being coplanar with any surface of said panel thereby creating the appearance of being unattached to any surface of said panel and of being freely suspended therein, and means for illuminatin said sign.

4. An illuminated sign comprising: a onepiece solid molded panel of light transmitting material, said panel having a cavity therein in which a sign character of optical characteristics different from said panel is molded so as to be fully embedded within said panel and united thereto by molding whereby no interlayer of air exists between the contacting surfaces of said sign character and said panel, said sign character comprising a vehicle of transparent material in which are located minute cavities of a gaseous transparent material of a different index of refraction from that of said vehicle, the size, numher and distribution of said cavities in said vehicle producing a reflection effect of great depth and intensity, none of the surfaces of said sign character being coplanar with any surface of said panel thereby creating the appearance of being unattached to any surface of said panel and of being freely suspended therein, and means for illuminating said sign.

ROBERT W. MALLARY.

REFERENCES CITED UNITED STATES PATENTS Name Date Holfert Jan. 31, 1893 Number Number Number Great Britain July 19, 1940

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