Reflective roadway marker
United States Patent 1 1 1111 3,877,785  
 Schaefer 1 Apr. 15, 1975 [5 REFLECTIVE ROADWAY MARKER 2,224,088 12/1940 Schroder 404 15 2.330.097 9 1943 W&#39;t 350 107 Inventor: Howard A. Schaefer, Lancaster, u Ohio 2,991,698 7/1961 Leubaz 350/109 [73] Assigneez Anchor Hocking Corporation 3,409,344 11/1968 Balmt et a1. 350/103 Lancaster, Ohio FOREIGN PATENTS OR APPLICATIONS 22 Filed; ()CL 12 1973 438,328 11/1935 United Kingdom 350/109 [21] Appl&#39; 296947 Primary Examiner-Ronald L. Wibert Assistant ExaminerMichael J. Tokar [52] U.S. Cl. 350/104; 350/106; 404/12 n y, Ag or i m nn lly n H z [51] Int. Cl. G02b 5/12 [58] Field of Search 404/9-16; 57 ABSTRACT 35O/97 109 A reflective roadwa marker includes a body member 3 5 6 R f d of internally dished-out construction and with an inte- 1 e erences gral retroreflective optical system in opposite side UNITED STATES PATENTS walls of the body. The body and optical system are 1,903,748 4/1933 Woolums 404/16 made of tempered glass to provide improved impact 1,934,492 1l/l933 Garbarini 350/104 strength thereof and to disintegrate should failure oc- 2,151,279 3/1939 Pascucci 350/106 Gun 2,179,382 11/1939 Persons 350/107 2,180,093 11/1939 Persons 350/106 9 Claims, 14 Drawing Flgures REFLECTIVE ROADWAY MARKER BACKGROUND OF INVENTION Reflective markers have long been used in the prior art. Exemplary of such markers are US. Pat. Nos.  
 2.005.170; 1.973.176; 1.966.678; Des. 215.376; Des. 212.263; Des. 210.329; Des. 209.880; Des. 208.121; Br. Patents; 1.065.622; 537.453; 301.280; and 278.308.  
  In general the prior art has taken the following approaches with respect to reflective markers which are secured to the roadway itself: 1 ceramic markers with glass optics; (2) glass optics embedded in plastic markers or (3) plastic optics in a plastic body. These prior art arrangements have numerous disadvantages. For example ceramic markers are not reflective under wet conditions and have a tendency to break on asphalt. Additionally. optics which are embedded in the markers frequently become covered with dirt or other road debris during use which severely hampers their effectiveness. Moreover. plastic markers are not completely satisfactory since plastic loses its color over a period of time and becomes generally grey whereby it is not readily visible during the day. Additionally. the various markers which are painted have a limited life because of the paint wearing off. The prior art markers utilizing non-integral optics are unsatisfactory since these nonintegral optics have been found to fall off during usage. Further. ceramic optics are unsatisfactory since in usage the glazed ceramics chip and peel. Moreover. where plastic materials are utilized the life of these materials is generally only about six months whereupon the plastic material becomes mechanically broken up. A further disadvantage with certain prior art markers are that those markers having the optics embedded or shielded cannot provide sufficient angular dispersion or retroreflectivity. A still further disadvantage of various prior art is that the plastic material is affected by the ultraviolet light of the sun which is particularly detrimental in the southern states of the United States with respect to the position of the sun.  
  Despite the numerous disadvantages with the prior art approaches which rely upon plastic or ceramic materials for the markers. the prior art has never seriously attempted to make the markers out of glass. While the advantages of glass might suggest the desirability of this material because of its highly developed state of technology and because of the effectiveness of glass optics. other physical propereties of glass have been considered so detrimental that the prior art has continued to resort to plastics and ceramics. The primary disadvantages of glass are of course the low impact strength generally attendant with this material and the consequent road hazzards which would be created upon failure of the material resulting in sharp pieces of glass being placed on or near the roadway.  
 SUMMARY OF THE INVENTION An object of this invention is to provide a roadway marker which overcomes the disadvantages of the prior art.  
  A further object of this invention is to provide such a roadway marker wherein the marker body and its optics are of integral construction and made of glass.  
  In accordance with this invention a roadway marker is provided wherein the body is of internally dished-out construction and includes integral retroreflective optics in opposite side walls. The glass is rendered useful for its purposes as a roadway marker by being tempered which thereby improves its impact strength and causes the glass material to disintegrate should failure occur.  
  In a preferred embodiment of this invention the optical system is exposed for angular dispersion. The external surfaces of the body are preferably of smooth rounded construction without sharp edges to thus facilitatae self-cleaning and traffic flow. Various advantageous optics may be utilized in the marker.  
  Additionally. the concepts of this invention may be applied to fields other than roadway markers and be incorporated. for example. in a thich biconvex lens.  
 THE DRAWINGS FIG. 1 is a top plan view of a roadway marker in accordance with one embodiment of this invention;  
  FIG. 2 is a side view in elevation of the marker shown in FIG. 1;  
  FIG. 3 is a bottom plan view of the marker shown in FIGS. I-2;  
  FIG. 4 is an end elevation view of the marker shown in FIGS. l-3;  
  FIG. 5 is a cross-sectional view taken through FIG. I along the line 55 and showing the marker in use;  
  FIG. 6 is a fragmentary cross-sectional view of a portion of the marker shown in FIGS. l-5 drawn to scale approximately 2% times full size;  
  FIG. 7 is a view similar to FIG. 6 shown an alternative optics system;  
  FIG. 8 is a cross-section view in elevation of a further optic system in accordance with this invention;  
  FIGS. 9-10 and 11-12 are front and side profile views respectively of still further optics systems in accordance with this invention; and  
  FIGS. 13-14 are front and side views of yet another optic system in accordance with this invention as incorporated in a thick boconvex lens.  
 DETAILED DESCRIPTION FIGS. 1-5 illustrate a reflective roadway marker in accordance with this invention is made of an internally dished-out body member 10 which has a peripheral rim l2 and top and side walls l4, l6, 18. A retroreflective optical system 20 is included in opposite side walls of the body. As described hereinafter the body and its optical system are of one piece integral construction made of tempered glass to provide improved impact strength and also whereby the glass will disintegrate should there be failure.  
  As also illustrated in the drawings retroreflective optics 20 are exposed or project from the side walls to provide for angular dispersion. The body is made of generally transparent material which is internally colored. as later described. so that it may be easily seen during the day. At night an approaching car would bathe the body with a beam of light whereby the optics would fully flash and all of the balls included in the optics would glow to delineate the road. The light rays from the approaching car retroreflect from the optics back to the drivers eyes to give a warning signal and thus assurement of the highway lane location. As is apparent from the drawings the external surfaces of the body above the rim are without sharp edges to facilitate traffic as well as dirt and debris flow. In use this type of construction is self-cleaning so that any dirt or debris that might have a tendency to accumulate would be washed off by rain. In the embodiment shown in FIGS. 2-5 the top wall 14 has a crown or is domed shaped to further facilitate traffic and dirt flow. If desired, however, the top wall may be flat. As illustrated particularly in FIGS. 2-4 the lower exposed surface 22 of rim 12 includes stippling 24 to create pockets for better receiving adhesive material so that the marker may be secured to the road.  
  The optical system for the reflective marker may take various forms. In general. however, the internal surface is coated with a suitable reflective material so that the rays of light passing through the outer or condensing lens surface will be collected and reflected back through the lens toward the driver&#39;s eye. The remainder of the interior of the generally transparent body is painted, as with a suitable ceramic paint, to provide the desired coloring to enhance the visibility of the marker. The body is then filled with a suitable potting material 26 which serves a multiple of functions. In this respect the potting material or potting compound shields the color coating to thereby increase the effective life or the color. Additionally, the potting com pound adds strength to the body. Finally, the lower surface of the potting compound may have suitable adhesive applied thereto to maximize the area over which the entire marker may be secured to the road. Moreover. not only does the potting compound bury or shield the color coating but it also shields the reflective coating for the optics. In an alternative form of this invention the potting compound itself may be colored. thus eliminating the need to apply a color coating to the interior surface of the body.  
  In accordance with this invention it is possible to form the body and its integral optics of glass by tempering the glass material. In an exemplary form of this invention the marker is made from any suitable glass material such as soda lime glass. After being made in the desired shape a ceramic color is sprayed on the interior of the body with the optics being shielded so that a reflective material may be also applied thereto. The body is then treated such as by heating to the softening temperature of about 1300F to automatically fire the ceramic color into the glass. Next the uniformly heated body is quenched by air in a suitable manner to simultaneously impart high compression strains on all surfaces by applying the proper veleocity and volume of air to all surfaces at the same time from a suitable nozzle. The foregoing heat treatment results in building tremendous mechanical strength in the body. For example, such a marker would have an impact strength greater than 10,000 psi. Additionally, the tempered glass which results from this heat treatment is such that if there should be failure. the glass body would disintegrate into particles wherein the fracture surfaces are generally rounded with minimal sharp edges so as to minimize any road hazzard which might otherwise be created. It is emphasized that the utilization of such tempered glass as a roadway marker represents a distinct departure from the prior art and a significant teaching of this invention. Such a teaching is not limited to reflective markers, but may also be applied to non-reflective markers such as used for designating walkways.  
  FIG. 6 illustrates a preferred form of optics 20 in accordance with this invention. As indicated therein the optical system is of multiple ball construction and includes a first set of internal and external spherical section surfaces 28, 30 adjacent to and below top wall 14. A second set of internal and external spherical section surfaces 32, 34 are adjacent to and below the first set and a set of internal and external cylindrical sections 36, 38 are adjacent to and below the second set while being above the rim 12. The balls or spherical surfaces are each about one-fourth of a sphere. As illustrated in FIG. 6 the center point 40 of spherical section 28 is generally vertically in line with but displaced from the center point 42 for spherical section 30. Similarly, the center point 44 of spherical section 32 is generally vertically in line with but displaced from the center point 46 of spherical section 34. It is further noted that the cylindrical segment 36 is inclined at a suitable .angle such as 5 /2 with respect to the vertical. while the cylindrical section 38 is inclined at a slightly greater angle of, for example 10 with resect to the vertical. As previously indicated the various surfaces smoothly blend into each other to facilitate traffic and dirt flow. As noted above. FIG. 6 is drawn to scale approximately 2 A. full size. Accordingly, as illustrated in FIG. 6, the body has a height of less than 1 inch.  
  FIG. 7 illustrates an alternative optics system 20A in accordance with this invention. As indicated therein optics system 20A includes a set of internal and external spherical section surfaces 48, 50 adjacent top wall 14 with a lower set of such sections 52, 54. The optics system further includes external cylindrical section 56. In the illustrated embodiment spherical section 52 extends a sufflcient distance so as to blend into the inner, wall of the rim section without there being an internal cylindrical section. The optical system 20A further differs from that shown in FIG. 6 in that in FIG. 7 not only are the center points 58,60 displaced from each other but also the center points are at an angle of, for example. about 7from the vertical whereas the center points in FIG. 6 were generally vertically aligned. Similarly, the center points 62, 64 in the lower set of balls are also displaced and are at the same angle to each other as with center points 58, 60. It is further noted that the cylinidrical section 56 is inclined at this same angle. The optics of FIG. 6 and FIG. 7 have in common, however. that the systems are generally inclined from the rim 12 toward the top wall 14, although the particular type of inclination with respect to the optical components differ. In such arrangements the angular disper sion is maximized which is particularly advantageous since it renders the marker effective not only at far distances but also as the vehicle continues to approach the marker.  
  FIGS. 6 and 7 illustrate particularly advantageous. forms of optical systems wherein the optics are of multiple ball construction. The concepts of this invention may be carried out with other optical systems. Thus FIG. 8 illustrates an arrangement which includes aninternal spherical section 66 and an external section 68 which is of smaller radius than section 66 with both sections having a common center point 70. In this illustrated arrangement lens surface 68 is slightly depressed within the side wall of the marker.  
  FIGS. 9-10 illustrate yet another possible optical arrangement wherein the condensing lens or external ball 72 is a spherical section as is the internal reflective ball 74 with both sections having a common center point 76. In the illustrated arrangement the planar end walls 78 of the marker are inclined at an acute angle of. for example 0-l0 with respect to the vertical.  
  FIGS. 11-12 illustrate yet another arrangement wherein the condensing lens 80 is a spherical section as is internal reflective section 82 with a common center point 84. In this arrangement the planar end walls 86 of the marker are vertical.  
  The concepts of this invention are not limited to reflective markers and may have other applications. One particular advantageous utilization of these concepts is in a thick biconvex lens such as illustrated in FIGS. 13-14. As indicated therein the condensing lens curvature is a spherical section 88, as is the reflecting mirror curvature 90 with both convex spherical sections having a common center point 92. The interconnecting surface 94 is frusto-conical. The relationship between the radius of the reflecting mirror curvature to that of the condensing lens curvature is such that the reflective mirror radius should be at least as large as that of the condensing lens with the preferred range being 121 to 4:1 and a more preferred range being 1.511. It is noted that this ratio arrangement is also applicable to the arrangements illustrated, for example in FIGS. 8-12.  
  Although the main emphasis of this invention has been to form the balls of the optics as segments of spheres and particularly with the rear surfaces being of different radius than the front surface, the concepts of this invention may also be effectuated wherein either of the surfaces such as the rear surface is of aspheric form. Similarly. the rear surface may or may be off-axis with respect to the front surface.  
  As is apparent from the foregoing description the roadway marker of this invention has a number of distinct advantages over the prior art. For example, the mirrored and colored surfaces are permanently bonded to the interior. This protects the surfaces from weathering whereupon the marker will retain its new-like appearance even after road use since the mirrored and colored surfaces are protected from traffic by the thickness of the glass itself. This is a distinct advantage over prior art arrangements where the external surfaces are colored and wherein these prior art markers pick up dirt, get dull and frequently result in the color chipping off and flaking. The marker of this invention can be permanently bonded to any road surface with commercially available epoxy cements without breakage. Moreover, the optical retroreflectors of this invention are designed to take into account various criteria. The optics and the entire article can be mass produced by automated process. The optics are so designed that they will be illuminated by headlights from vehicles and reflect light back into the drivers eyes to give visual perception of the road marking at various distances down the road. The invention markers may in fact replace all painted highway lines now being used including the center lines by utilizing, for example, red coloring for no passing zones and green coloring for passing zones. The inventive optics are also capable of reflecting light back to the drivers eyes even when located off axis of car travel up to minimum of Moreover, the optics also lend themselves to computer programming.  
 What is claimed is:  
  1. A retroreflective roadway marker comprising a body member. said body member having a peripheral rim and having top and side walls, said body member being of concave internally dished-out construction with an internal cavity exposed at its lower surface, at least one side wall being inclined inwardly from said rim to said top wall and disposed for facing oncoming traffic, a retroreflective optical system in said one side wall. said body member and its optical system being integral and made of tempered glass having an impact strength of at least 10.000 psi and which disintegrates into harmless particles upon failure, said optical system being exposed for angular dispersion up to a minimum of 20 deviation off axis of vehicle travel toward said marker, said optical including a smoothly curved spherical segment lens surface projecting outwardly from its side wall and disposed toward the exterior of said body member for receiving rays of light from the headlight of an approaching vehicle, a smoothly curved spherical segment reflective surface associated with said lens surface and disposed toward the interior of said dody for reflecting the light passing through said lens surface. the focal point of said lens surface being disposed with respect to said reflective surface to assure reflection of the light to the eyes of the driver as the vehicle continues to approach the marker, securing means on the lower surface of said rim for mounting said marker directly to the roadway surface without the necessity of partially embedding the marker below the roadway, and entirely all of said optical system being disposed above said securing means whereby the entire optical system is disposed above the roadway.  
  2. A marker as set forth in claim 1 wherein the external surfaces of said body above said rim are of smooth rounded construction without sharp edges to render the marker self-cleaning and to facilitate traffic flow.  
  3. A marker as set forth in claim 1 wherein the optical system includes a first set of internal and external spherical section surfaces adjacent to and below said top wall, a second set of internal and external spherical section surfaces adjacent to and below said first set, and a cylindrical section adjacent said second set.  
  4. A marker as set forth in claim 3 wherein the cylindrical section includes an inclined outer cylindrical section surface and an inclined inner cylindrical section surface which is inclined at a different angle than the outer surface.  
  5. A marker as set forth in claim 1 wherein said top wall is dome shaped, and said body member has a heighth of less than 1 inch.  
  6. A marker as set forth in claim 1 wherein the opti cal system includes at least one set of balls comprising an inner reflective spherical section surface and an outer condensing lens spherical section surface, and said reflective surface having a radius at least as large as the radius of said condensing lens surface.  
  7. A marker as set forth in claim 6 wherein the ratic of the radius of said reflective surface to the radius 0! said condensing lens surface is between 1:1 and 4:1.  
  8. A marker as set forth in claim 1 wherein said opti cal system is incorporated in each of two opposite side walls of said body.  
  9. A marker as set forth in claim 1 wherein the center points of said lens surface and said reflective surfacr are offset from each other.