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Publication numberUS1902440 A
Publication typeGrant
Publication dateMar 21, 1933
Filing dateJan 15, 1932
Priority dateJan 15, 1932
Publication numberUS 1902440 A, US 1902440A, US-A-1902440, US1902440 A, US1902440A
InventorsJr Edwin R Gill
Original AssigneePrismo Holding Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
US 1902440 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

March 21, 1933.



Filed Jan. 15 1932 2 Sheets-Sheet l Invenfiar:

7&1: My.

March 21, E R LL R SIGN Filed Jan. 15, 1932 2 Sheets-Sheet 2 Patented Mar. 21, 1933 v UNITED STATES PATENT OFFICE EDWIN R. GILL, JR., OF YONKERS, NEW YORK, ASSIGNOR TO PRISMO HOLDING CORPORATION, A CORPORATION OF NEW YORK SIGN Application flled January 15, 1932. Serial No. 586,827.

The invention relates to signs when that itself may not be perceived much in advance term is used in its broadest aspect and inof the approach of the vehicle. One purpose eludes any marker, signal device or mechaof the present invention is to produce a sign nism which may be employed to attract attenfor such use as well as other uses.

5 tion or convey information. Little difficulty It has been discovered that if a sign or the has been found in producing devices of this significant portion thereof is not merely recharacter which will be substantial, relativefleeting but is reflex reflecting the light ly cheap, more or less permanent and satisthrown thereon will to a considerable factory for use in the day time or under orextent be returned toward the source 1@ dinary lighting conditions. \Vhile the presof the light. A single reflex reflecting C3 ent invention is adapted for such use, it is medium in order to be of material use more especially adapted to meet the unusual must be large. It is expensive to make, difconditions which have not been satisfactorily ficult to protect and likely to be removed, inmet up to the present time. jured or destroyed. It has been found that a 15 In order that such a device be satisfactory brilliant reflex reflection may be procured C5 in all places and under any circumstances it by providing a number of small reflex reisv highly desirable that it be especially refleeting elements which are preferably arsponsive to light thrown upon it and this is ranged substantially in contact with each especially desirable when the device or its other so as to avoid the appearance of blind 29 surroundings may be in the dark. or dark spots. To

It is well known that a sign provided with It has been found that small, regularly a reflecting surface may be illuminated and shaped pieces of transparent material such as to some extent made visible in the dark. glass, preferably in the form of spheres, cubes Ordinarily reflecting surfaces throw out light or cylinders whose height equals the diam- 25 at an angle opposite to that at which the light eter and the like, may be conveniently emis received so that their visibility is not high ployed for this purpose especially when assofrom the direction of the source of light. Such ciated with a reflecting medium, and the a reflecting sign is not satisfactory for use, present 1n vention is based at least in partfor instance, as a roadside sign where ordiupon this ldea.

narily the light of a vehicle on the road In Order to explain fully the invention, 3

reaches the sign at an angle and Where it is the accompanying drawings have been prehighly desirable that the light be reflected pared in which Figure 1 is a face plan view b k t th v hi l Att t have b n of a fragment of a sign embodying the inmade to improve such signs by providi vention. Fig. 2 is a vertical transverse fraglight dispersion or light diffusion means on mentary section through a portion thereof. the signs so that when illuminated they Fig. 3 is a fragmentary plan view of an opglow to some extent and throw out light in tional arrangement. Figs. 4, 5 and 6 are seeall directions. Such an arrangement obvioustional views of details. Fig. 7 is a diagramly is uneconomical and may let so little light matic illustration showing the effect of light go toward its source as to be unsatisfactory. upon a sign embodying the invention. Fig. 99

' The intensity of the light returned toward 8 is a face plan view of one form the inventhe source in a way determines the visibility tion may take. Fig. 9 is a transverse vert of the sign. If the intensity of the returned calsection of 8. Figs. 10. 11, 12, 13, 14,

light can be increased, the distance at which 15 and 16 are detail views of optional arthe sign may be visible or legible can be in langements.

creased. In present times when motor cars A sign may consist of a rigid base or back usingroads habitually operate at high speeds, 20 which in practical use will preferably be it is highly desirable that signs be visible for a sheet of metal. On this,-for its protecton, great distances and this is especially importmay be a layer of enamel 21 which may be ant at night when characteristics of the road reflecting and may be cloudy, clear or colorering the insignia 22 are provided reflex refleeting elements 23 which ma be spheres, cubes or other regularl shape geometrical devices and which pre erably may be clear, transparent, colorless glass. As indicated in Fig. 2 the spheres 23 will each be embedded in the enamel preferably to substantially one half the depth of the sphere. Such embedding insures the spheres being permanently held in place. It will be remembered that the enamel is reflecting and when the sphere is properly embedded therein there is produced a reflex reflecting medium of such character that substantially any ray of light falling uponit will be reflected ack in a line parallel to the approaching light. For instance, the ray A of Fig. 5 pass ng diametrically through the center of the sphere 23 will be reflected directly back upon its own path. The ray B in approaching on a diameter will berefracted and reflected back upon the line B which is parallel to and in the same direction as the line B. Likewise the ray C will be reflected back upon the parallel line C and the ray D will be reflected back upon the parallel line D". It will be apparent that in order to produce a reflex reflection at a considerable angle to the face 22 of the sign the reflecting medium 21 should cover nearly the lower half of the sphere which correspondingly should be embedded in the reflecting enamel l yer 21 to the extent of substantially one half of its diameter or possibly somewhat less since if, for instance, the incoming ray D did not meet a reflecting surface at the point E it would tend to pass through the sphere and out and there might be little or substantially no light returned along the path D It will be clear that the maximum distance between an entering ray such as B and its reflex reflected ray B will be something less than the diameter of the sphere so that the most advantageous arrangement for the reflex reflection of the light may be by the use of a very small reflex reflecting elements 23. As a practical matter it may be found conven ent to employ spheres of clear glass which may be somewhat less than of an inch in diameter. One advantage of using such very small spheres is that when they are properly positioned, more or less closely in contact with each other, only very small and very inconsiderable spaces may be left between them. Thus no blind, black or Ydead spaces may appear in the reflex reflecting area. Another advantage of the small elements is that they may be readily embedded a suflicient d stance in the enamel layer 21 and the amount they project therefrom will be so small as to not produce a materially irregular surface, thus leavin little opportunity for the accumulation 0 dirt to foul or blind the sign-and at the same time leaving very little projecting matter to be cracked or broken off to destroy or deform the reflex reflecting elements. While there is a material advantage in using small reflex reflecting elements their use is not essential to all phases of the invention.

To make the device a practical satisfactory reflex reflecting sign or signal it is desirable that the small glass spheres be as small as possible so as to form a multiplicty of lights as each sphere, regardless of size, is comparatively ineflicient in itself and a great number of these lights are required to furnish the requisite illumination. A single bead is hardly discernible. Large sized balls would leave many dark dead spots which may not be distinguishable if a multiplicity of minute beads are employed.

While the reflex reflecting elements embedded in the enamel may be stable and not subject to undesirable results from exposure, to the elements, etc. they may be left uncoated. It may, however, be desirable under some circumstances to place a protective covering or coating on the elements or on the signas a whole. In Fig. 5 such a coating 24 is illustrated. This may consist of a layer of enamel, varnish or the like. In order not to interfere with the efficiency of the sign it should be transparent and it may be colorless, although if it is colored it will cause its color 1t o fie carried by the reflexly reflected rays of While for some purposes it may be sufficient to have the enamel layer 21 and the reflex reflecting elements 23 and the layer 2&1 colorless any one or more of these three elements may be colored and so produce a corresponding colored effect in the reflected rays of light. While the insignia are shown on a base 21, it is obvious that the base might be omitted and the insignia alone employed. Likewise as illustrated in Fig. 3 the insignia 22 may be omitted or left blank and the reflex reflecting elements 23 applied to the main surface or back of the sign. For some purposes in order to emphasize the presence of the sign or the insignla or to produce other I efl'ects portions of the base, in addition to the insignla, may be provided with reflex reflecting elements 23 as indicated in the lower transverse strip 25 in Fig. 1. A transparency may be placed before such a solid field.

As indicated in Fig. 5, the optical structure of the sphere 23 is such that the reflex reflected ray B is further from the parallel diameter A of the sphere than the incoming ray B. In Fig. 6 is illustrated a reflex refleeting element which will have less tendency to spread the rays and will produce an outgoing ray F which is an equal distance from the parallel diameter G as the incoming ray F. Such a structure may be made up of two hemispheres 26 and 27 which may be constructed by calculatin the focal length of the curve of the surface 0 the hemisphere 26 and then describing the hemisphere 27 having a diameter equal to the focal length of 26. While such a form might be the ideal reflex reflecting element to employ, from a practical commercial standpoint it may be diflicult and expensive to manufacture and also difficult and expensive to properly place and embed in the enamel layer. The small diameter of the spheres actually used may approach very Elosely to the theoretical ideal indicated in Fig. 6 since as the sphere gets smaller the difference in diameter between 26 and 27 becomes less.

The characteristics of a sign made in accordance with the present invention may be indicated b such an arrangement as is illustrated in ig. 7 in which a sign 20 may be mounted upon a vertical wall 28 with which is associated a wall 29 at right angles. Light thrown from the source 30 will reflect from the plain enamel portion 21 of the sign 20 and illuminate the wall 29 at the area 2113. Likewise light from the source 30 will reflect from the enamel portion 21A and illuminate the area 216 on the wall 29. Light, however, from the source 30 striking the reflex reflecting elements 23 on the sign 20 will be returned substantially to the source 30, substantially none of the light being reflected to the area 23A on the wall 29. The result will be that an image of the sign will appear on the wall 29, the portion correspondin to the reflecting enamel surface 21 being bright and the portion corresponding to the reflex 'reflection portion 23 being dead or blank.

. to single rays of light, it is understood that ordinarily light travels, not as a single ray, but as a pencil of rays which is more or less conical in shape. Consequently the actual operation of the sign is not actually represented by the ray phenomena indicated and described but will more or less closely approach that operation in general.

It must be understood that due to lack of theoretically perfect transparency, reflection and refraction and due to the use of colors. a certain small amount of spreading of the beam cannot be prevented especially when commercial glass must be employed for practical purposes. In other words, the beam from the moment it is. refracted into (or enters) the reflexing crystal will begin to cone out and the reflected beam will leave the crystal not at a point without area but as an oval or circle with more 'or less actual although minute diameter. The lines in the drawing representing reflected beams therefore really delineate the axes of truncated cones of light. This is not diffusion in a true sense. Diffusion as generallg employed contemplates reflecting and re racting a mass of incident li ht heterogeneously in all directions at once but this is foreign to the present lnvention.

The reflex refraction of the impinging light, substantially all of which is returned toward the source, is to be clearly distinguished from the usual opposite reflection of a plane surface and the general diffused glow of the usual rough heterogeneous surace.

With the invention thus described before him one versed in the art will have no difficulty in manufacturing a sign. The metal sheet may have applied to it the coating to make the enamel layer 21. A cut-out of the insignia desired, preferably made of thin material, may then be placed upon the material and the reflex reflecting elements 23 scattered thereon. The reflex reflecting elements may be embedded the proper distance in the enamel material by hand or by running a roller or the like thereover and then the surplus loose elements may be brushed off. It is highly desirable that the reflex reflecting elements be placed as close together as possible and that there be but a single layer of them. This may be accomplished in any suitable way. The prepared sign may then be baked and the reflex reflecting elements into the enamel by which process they will be rigidly and permanently held in place. hen desired the enamel for that portion of the sign other than the insignia may be separately baked as preliminary step or a second layer of enamel for the insignia may be applied after the first baking.

Since the shape of the under side of the reflex reflecting elements, that is that side toward the base plate 20 or embedded in the enamel 21 or the like, is important to carry out the functions hereof, it is desirable that the heat used to bake or finish the enamel be not high enough to melt or deform thethe glass spheres or the like in the materials of which the main covering coat is to be made and then subject the entire sign to a temperature sufliciently high to melt, bake and 195 finish the enamel without melting or deforming the glass reflex reflecting elements. A heat high enough to deform the reflex refleeting elements or to allow them to run into each other or become welded together may interfere with the efliciency of the device and decrease or limit the light effectively reflected. The baking may be done in one or more steps. 4

In general any binder may be used which fulfills the requirements of the invention, that is, it should be light reflecting, not absorbing, and it should not be transparent nor objectionably translucent. It should be also able to stand up under the anticipated conditions of use. For outdoor work, of course, resistance to weather is essential. This gives a wide choice of materials and variations available. Pottery, concrete, wood plastic, cellulose solutions, glue, colodion etc. are not desirable nor are most varnishes, lacquers, etc. except for coating the final surface.

It may be desired to have the general surface of the sign of dull, dead or not reflecting material or it may be desired to have the reflex reflecting elements on the surface or only slightly embedded therein. In Fig. 4 is illustrated an arrangement in which the back 20 may be provided with a suitable coating 211.). To this may be afiixed, or in this may be embedded, a plurality of reflex refleeting elements 23 which have previously been silvered or coated with a layer of reflecting material 31 such as mercury or other bright metal. Such a coated reflex reflecting element is shown toward the bottom of Fig. 4. \Vhen the elements have been fixed in place on the back or on the layer 21D, they may be rubbed, polished or treated in any other way to remove the reflecting layer 31 from their outer sides leaving the reflecting coating only on substantially half their in-' 'ner sides as indicated at the upper part of Fig. 4. This figure is intended to be a fragmentary illustration of two of the reflex reflecting elements in place on a sign during the process of manufacture in which the re flecting coating 31 of the upper one of the elements is removed and that of the lower one is about to be removed. In Fig. 4 a space is indicated between the two reflex reflecting elements 23 for purposes of clearness of illustration. In practice a space may exist if I the two elements are in different insignia on a sign but if they are in the same insignia the space preferably will be reduced to a minimum and elements 23 will be in substantial contact with each other.

The glass reflex elements may be coated with mercury or silver-ed. They may then be dipped with a paint solution similar, to the protective coating on the back of mirrors, or the silvered surfaces can be copper plated instead of painted. A sign being laid out on any suitable back plate the coated reflex agents are then afiixed in an orderly layer to those parts of the sign which it is intended to render luminous, by any sort of enamel, glue, paste, cement, or adhesive whatsoever consistent with the anticipated usage and duration of the sign. The enamel, adhesive or cement can be transparent or non-transparent, reflecting or non-reflecting in this form, the qualities of permanence and resistance to deterioration only being considered. The mercury coating in this case is the reflecting agent.

Another way of constructing my sign or signal is to partially embed the glass reflex elements in a layer of solder, or preferably an alloy, such as type metal, that expands on cooling for binding. In this case spheres or reflex elements may be embedded to about half their diameter in the alloy layer. A metal back plate is used to which the alloy adheres and acts as retaining and reflecting element for the reflexing elements.

Another method. is to use reflex elements,

silvered and copper plated as described above and to sweat these onto a back plate and then clean the silver oil the face as indicated above.

' Instead of silvering the reflex crystals they can be coated with flake'metal paint, such as the common aluminum paint or the socalled gold paint of flake brass.

Figs. 8 and 9 show a sign similar to Figs. 1 and 2 in which instead of the spherical reflex reflecting elements 23, reflex reflecting elements 32 in the shape of cubes are used and they may be applied as are the spheres in the previous figures. In Fig. 9 is shown the base 20 on which is a complete layer of enamel or the like 21 upon which has been placed a second layer of enamel or the like 21E in the form only of the insignia desired and on this are aflixed or embedded the reflex reflecting elements 32. An ideal arrangement of the cubes over a surface in perfectly regular ranks and files is illustrated. This may not be attained in commercial work but in practice the layout of the cubes will be an approximation of this ideal as closely as practicable.

That the majority of the light rays falling upon a cube will be reflexly reflected is indicated in Figs. 10, 12, 13 and 14. In Fig. 10 is illustrated a ray H approaching the cube at the point h. This is reflected from the point z to the point is to the point Z and goes out at the point 972. in the line H parallel to the incoming ray H. A ray K indicated in Fig. 12 normal to the surface of cube 32 returns on its own path. A ray L at such a small angle to the surface of the cube 32 that it does not meet a side of the cube is reflected from the base of the cube along the line I at something of an angle to the incoming ray L and rays of this character will be somewhat diffused. A ray M, however, striking the cube at a slight angle but near enough to a side wall to be affected thereby will return along the line M substantially parallel to the incoming ray M. Likewise rays N, O,

. Fig. 11.

P and Q illustratedin Figs. 13 and 14 will be refracted and reflected to return along the lines N 0 P Q parallel to the incoming rays and this will be so whethe'i' t'he cubes are set flatly on their bases or tipped to a slight extent as indicated in Fig. 14 or actually-fall and rest on a corner as'illustrated in As illustrated in Figs. 11, 12 and 14', the cubes 32 will preferably be substantially embedded in the reflecting enamel 21. Since the sides of the cubes perform important functions in the reflection, it is highly desirable that they be enclosed in the reflecting enamel. Q

As indicated in Fig. 13 the enamel or other coating if it is transparent and colorless may entirely cover and enclose the cubes" 32 giving additional protection and possibly with only slightly reduced eificiency. In Fig. 14 is illustrated a coating of colorless transparent enamel, varnish or the like 24A corresponding to the coating 24 of Fig. 5.

Fig. 16 shows an arrangement of cubes corresponding to the arrangement of spheres in Fig. 4. Each cube 32 may be covered with a coating of a reflecting material 31A and after they have been put in place the exposed surfaces may be cleaned'of the refleeting material. As in Fig. 4 the elements have been shown separated but they may be in contact. I

The reflex reflecting elements may consist of various regular geometrical forms each being used separately or mixed with others. In addition to the spheres and cubes described in detail above, there is illustrated in Fig. 15 a cylinder which preferably will have its diameter equal to its height. As illustrated, substantially any rays striking it at an angle will be reflexly reflected when it is embedded in a layer of reflecting enamel 21.

The legibility of the sign is very high. As there is no concentrated glare the message it is intended to convey can be read at a great distance; much further than the present sign using comparatively few lenses of large size to dot out cymbals, letters and figures.

The luminous sign being hardly more costly than any ordinary non-luminous sign can be used extensively, adequately, or even profusely, as circumstances in each case may require without burdening the taxpayers of the community unduly and thereby giving the authorities of our states, counties, and municipalities a free hand to promote the safety of the American motoring public by adequate Warnings and directions plainly visible at all hours of the day or night. Night traific on our highways, especially at intersections, and congested centers, is one of the great hazards of the American citizen. A road fully posted with luminous signs and signals would remove a great part of the danger and therefore the present invention will confer an incalculable benefit to society.

Variations from the exact things here shown and described may be made in many 'ways as the invention is not confined to specific details.

I claim as my invention:

'1. A sign the significant portion of which is covered with a plurality of reflex reflecting elements, and a reflecting substance covering at least about the lower half of the surfaces of the elements but leaving the upper portions of the surfaces unaffected.

2. The method of making a sign comprisin" applying a layer of unbaked enamel to a ase, embedding a layer of glass spheres in the enamel to at least about one half their depth, and' baking at a temperature which will melt and fix the enamel and cause it to adhere to the spheres without affecting their shape.

3. The method of making a reflex reflecting surface comprising substantially completely coating a plurality of reflex reflecting elements with a reflecting coating, affixing said elements to a base, and removing the exposed reflecting coating.

4. A sign comprising a base and insignia, a reflecting coating on the base and a reflex reflecting coating on the insignia made up of a plurality of substantially contacting inute reflex reflecting elements each provided with a reflecting back throughout substantially its lower half.

5. A sign comprising a rigid base, a layer of reflecting fused enamel on at least the significant portion thereof and small, substantially contacting clear glass spheres in a substantially single layer embedded into the enamel on the significant portion of the sign, the fusing temperatures of the spheres being somewhat above that of the enamel.

6. A sign a significant portion of which is covered with a plurality of substantially symmetrical reflex reflecting elements each of which is less in its largest dimension than the smallest dimension of the'significant portion of the sign and each of which is internally reflecting to about half its depth on the side toward the sign.

7 In a sign a portion covered with a reflecting layer and a plurality of relatively small substantially symmetrical reflex re- .flecting elements embedded to about half their depth in the reflecting layer.

8. In a sign a portion covered with a refiecting layer and a plurality of relatively small substantially symmetrical reflex refleeting elements embedded to about half their depth in the reflecting layer so as to seal the contacting surface of the elements and the layer from the weather.

9. A one-piece sign comprising a base of a metallic plate, zi coating of fused reflecting enamel therein, having a plurality of relan tively small substantially symmetrical and substantially contacting reflex reflecting units embedded in at least a portion of the enamel to about one half their depths.


Referenced by
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US2422256 *Aug 12, 1944Jun 17, 1947Minnesota Mining & MfgFlexible reflex reflecting film
US2432928 *May 4, 1943Dec 16, 1947Minnesota Mining & MfgTransparent pressure-sensitive lenticular sheet
US2440584 *Jun 19, 1944Apr 27, 1948Minnesota Mining & MfgLenticular reflex reflector sheet and method of making the same
US2518938 *Oct 19, 1945Aug 15, 1950Paul RosenbergSupersonic training device
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U.S. Classification40/583, 404/16, 362/812, 359/541, 359/540, 362/327
International ClassificationG09F13/16, G02B5/126
Cooperative ClassificationY10S362/812, G09F13/16, G02B5/126
European ClassificationG09F13/16, G02B5/126