US 3510976 A
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Description (OCR text may contain errors)
May 12, 1970 R. F. PAULINE ETAL 3,510,976
SAFETY ROAD SIGN Filed March 20, 1968 INVENTORS RONALD F. PAULINE 8 ALLAN D. PARRY \w. LQ Flec- K4 ATTORNEY United States Patent ABSTRACT OF THE DISCLOSURE A flat, clear acrylic sign which has glass spheres dropped on the outside face thereof. Approximately 50% of these spheres are mirror coated. A message is screened on this face. A translucent phosphorescent coating is sprayed on the back of the acrylic plate. A source of light behind the sign shines through revealing the message,
while the sign remains reflectorized to headlights and the phosphorescent coating provides a built-in safety factor in case the light behind fails.
The present invention relates to a road sign, and, more particularly, to a transparent sign having a three-way built-in safety factor.
A variety of signs, particularly highway and road signs, have been provided in the prior art. Particularly in recent years, with the advent of the high speed super highway, it has been necessary that such road signs, such as for giving directional or safety information, be capable of being seen at a substantial distance and from a fast moving vehicle. Among the signs conventionally in use are those which are electrically illuminated at night, those which use retro-reflective beads and those which are provided with luminescent coatings. However, while these signs are very useful under a variety of conditions, none are entirely adequate under all conditions and, particularly, those which are electrically illuminated depend upon the consistency of the light source, i.e., if the light source fails, the sign loses its visibility thereby placing the motorist under considerable hazard. The luminescent signs, on the other hand, are often subject to deterioration from the elements such as rain, snow, etc. and such signs do not always last as long as is desirable. Those signs which depend solely on retro-reflectance are often not always as clearly visible during daylight hours as is desirable, and such signs are not readily visible to pedestrians at night. In addition, many of the signs of the prior art are too expensive.
Accordingly, it is an object of the present invention to overcome deficiencies in the prior art, such as indicated above.
It is another object of the present invention to provide a tripple-safe highway sign.
It is another object of the present invention to provide a new and improved readily visible highway sign which is inexpensive, yet completely reliable, and which provides for the continuing visibility of the sign indicia.
These and other objects and the nature and advantages of the instant invention will be more apparent from the following detailed description, taken in conjunction with the drawings wherein:
FIG. 1 is a perspective view of a sign in accordance with the present invention;
FIG. 2 is a vertical sectional view taken along line 22 of FIG. 1, partly broken away; and
FIG. 3 is a sectional view taken along line 3--3 of FIG. 2;
In the embodiment shown in the drawings, a sign housing 12 is provided having suitable walls including a 'ice bottom wall 14 and a front Wall 16, such walls providing the generally closed housing 12. Within the housing 12 is provided a source of light, such as the electrical outlet .18, which passes through the bottom wall 14 and provides power for, recessed therein, an electric bulb 20. Suitable wire means 22 pass through a sign support 24 to the outlet 18 for powering the outlet 18 and the bulb from a suitable outside source, if desired, it being understood that the housing may contain a storage battery for powering the light source 18, 20. The housing 12 may be formed of any suitable material such as metal or plastic.
The front wall 16 of the housing 12 comprises a transparent plate 26, preferably placed in a generally vertical position as illustrated, such transparent plate 26 being coated on its back surface with a suitable luminescent coating 28. The luminescent coating, preferably a phosphorescent material and preferably in a suitable binder, may be transluscent or transparent. It should not, however, be opaque. The plate 26 is preferably formed of suitable plastic, for example, an acrylic plastic such as Plexiglas, or it may be of any suitable transparent plastic such as a polyester or a polycarbonate; or the plate 26 may be formed of glass.
Provided on the front face of the plate 26 is a suitable transparent adhesive layer 30 containing, either mixed therewith or deposited on the surface thereof as schematically illustrated, a quantity of small glass beads 32, which glass beads are retro-reflective, i.e. they reflect light at the same angle at which such light is received. Any suitable transparent plastic binder may be used for adhering the beads 36 to the front face of the plate 26;
and among such suitable binders may be mentioned the acrylic binders, the polyesters and the epoxies; the only requirements being that the binder be relatively transparent and be capable of strongly and permanently adhering the beads 32 to the plate 26.
The beads 32, well known per se in the prior art, are preferably of relatively small size, e.g. 0.0025 to 0.00 37 inch in diameter, although smaller and larger beads may be used. The glass beads may be formed of glass from such a high index of refraction that such beads are internally reflective or, preferably, the beads may be given a reflective surface coating 34 to provide retro-reflectance from their silvered surfaces. It is preferred, that only about half of the beads used be retro-reflective, although the ratio of transparent to reflective beads may, within the preferred embodiment, range from 1:3 to 3: 1.
Coated over the front of the bead containing adhesive layer 30, are suitable opaque indicia 36 providing the sign message. The opaque layer 36 may comprise an opaque screening ink of conventional composition.
A sign 10 in accordance with the present invention is simple and inexpensive, and it is entirely reliable to provide a traflic or warning sign which can be viewed by a motorist with car headlights on, or a pedestrian walking at night. The reflective face 30 including the beads 32 makes the sign visible to a motorist driving with headlights on by retro-reflectance. The light 20 behind the face of the sign shines through revealing the message to a pedestrian at night by outlining the opaque indicia 36. The built-in safety factor utilizing the phosphorescent backing 28 continues to shine through the face revealing the message in case the light 20 should fail, and the sign continues to be visible to either pedestrian or driver with no headlights. In addition, the phosphorescent coating 28 being protected from the elements, such phosphorescent coating is maintained for extended periods of time.
The following specific example is presented by way of illustration and not by way of limitation, so that those skilled in the art may better understand how the present invention may be practiced.
A one-eighth inch thick Plexiglas (acrylic) sheet 28 is first sprayed with a 20% solids, clear acrylic binder 30 to provide a thickness of 1.8 to 2.0 mils. The binder 30 is made of 40% solids Acryloid B72 from Rohm & Haas Co. and xylol mixed in a 1:1 ratio. The binder is then dried in air for fifteen to twenty minutes. Glass spheres 32 of size 0.0025 to 0.0037 inch in a 50% clearsilvered ratio are dropped onto the clear binder and adhere thereto. The coated sheet 28 is then baked for fifteen to twenty minutes at a temperature of 150200 F. to effect curing of the binder 30 and strong adherence of the beads 32 to the binder. The Plexiglas sheet, with the'beads approximately 50% embedded in the binder, in immersed in a chemical bath which dissolves the exposed upper halves of the silvered coatings on the 50% of the beads which were originally coated; thereby providing a brilliant light return.
A clear .acrylic top coat (not shown) is then sprayed on the complete sign face and the sheet is baked for five minutes at ISO-200 F. Finally, a message 36 is screened on the face of the sign using an opaque screening ink and the sign is again baked for twenty minutes at 150 200 F.
A phosphorescent binder 28 (made up of Advance Process Supply Companys PB412 phosphorescent base and a phosphorescent pigment milled in a 1:1 ratio) is sprayed on the back of the Plexiglas sheet 28 at a 3-5 mil thickness, the phosphorescent coating being translucent. The sign is baked for ten minutes at ISO-200 F.
Resulting from the above-described procedure, a three way safety transparent sign is produced. The half mirrored spheres give a brilliant light return from a vehicles headlights. A light source placed behind the sign filters through the clear spheres giving a bright sign to a pedestrian at night. The third safety feature relates to the phosphorescent layer on the back of the sign; in case of power failure or light source bum-out, the charged phosphorescent layer will continue to illuminate the message which can be observed by a pedestrian. The phosphorescent layer 28 will also be recharged every time a vehicles headlight strikes the sign.
Signs with dififerent messages can have the same dimensions so as to use the same housing 12. The color of the sign can be varied, such as yellow, red, White, etc., depending upon the desired needs. The light source 18, 20 can either be continuous or blinking.
It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and that the invention is not to be considered limited to what is shown in the drawings and described in the specification.
What is claimed is:
1. A three-way safety sign for display along a road wherein said sign will be struck by the light from headlights of oncoming vehicles, said sign comprising:
a generally vertical transparent plate, said plate having transparent-adhesive coating on the front side thereof, a plurality of light reflecting beads carried on said adhesive layer, opaque indicia coated over said beadcontaining adhesive layer so as to provide a desired message, and a phosphorescent coating on the back side of said plate; and
a source of light fixedly disposed behind said plate.
2. A sign in accordance with claim 1 wherein said source of light is disposed within a housing the front face of which comprises said transparent plate.
3. A sign in accordance with claim 1 wherein said plate comprises acrylic plastic.
4. A sign in accordance with claim 1 wherein approximately 50% of said light-reflecting beads are mirror coated on their back surfaces.
References Cited UNITED STATES PATENTS 2,509,707 5/1950 Taylor 134 2,910,792 11/1959 Pfaff. 3,190,178 6/1965 McKenzie 40'1 36 EUGENE R. CAPOZIO, Primary Examiner L. R. OREMLAND, Assistant Examiner US. Cl. X.R. 40134