GB2147038A - Road surface marker - Google Patents

Abstract

A road surface marker comprising a reflector unit (30) mounted in a suitable housing for securing to the road surface, said reflector unit including a reflector element made of synthetic plastics material (40) and surfaced at its substantially flat front face with a light transmitting material which is substantially more abrasion resistant than said synthetic plastics material. <IMAGE>

Description

SPECIFICATION Road surface marker This invention relates to road surface markers and, more particularly, to reflective markers of the type generally referred to as road studs or cats eyes. This markers generally consist of a metal casting disposed in a pocket cut into the road surface, in which is positioned a core of a resilient material such as a white or brightly colored elastomeric or rubber composition, supported entirely or partially within the rectangular or otherwise shaped cavity of the metal casting. The core generally is provided with two glass bead type reflectors which are intended to retro-reflect the headlights of approaching vehicles. The elastomeric or rubber material of which the core is comprised generally is of natural rubber and includes a portion which can wipe the front face of the glass lens as the upper marker body is depressed by the contact of a tire thereon.Lens members of the cube-corner type, if molded of glass, could be used but molded glass cube-corner reflectors do not have the accuracy or reflectivity of plastics cube-corner type reflectors and consequently for many years glass has not been used to make cube-corner type roadway reflectors. Indeed, plastics has supplanted glass for cubecorner reflectors for both automotive and roadway uses since the mid-1 940's.

Because plastics is subjects to abrasion however, its use as a lens element in the conventional rubber cats eye core, where it is subjected to constant wiping action, would have a deleterious effect on the front face and would promptly degrade the reflectivity of the marker to a point where it would no longer be an effective signal. While it has been ascertained that positioning a plastics reflector element at an appropriate angle will effect a balancing combination of wiping and abrasion, such angular construction cannot conveniently be used in the existing cats eye casting because no wiping action could be accomplished either by a tire or by a single wiping element in the core.Plastics cube-corner type reflectors are advantageous over glass beads because they have a higher specific intensity than glass beads, they can be manufactured more economically and, most importantly, they can be consistently molded to provide relatively uniform specific intensity, whereas glass beads vary widely in reflectance.

Viewed from one aspect the present invention provides a reflector unit for a road surface marker, such reflector unit being adapted to be mounted in a suitable housing securable to the road surface, and including a reflector element made of synthetic plastics material and surfaced at its substantially flat front face with a light transmitting material which is substantially more abrasion resistant than said synthetic plastics material.

In a preferred form the invention provides a reflector assembly for use in a metal housing to provide a road surface marker. The metal housing has a generally rectangular cavity with a horizontal base formed therein, front and rear walls adapted to be positioned perpendicular to the direction of traffic when the housing is secured to the roadway surface, and opposed side walls provided with pairs of integral attachment fingers extending into the cavity, said front, rear and side walls having upper edges extending above the associated road surface when the metal housing is fixedly installed thereon. The reflector assembly comprises a resilient elastomeric body adapted to be removably positioned in the associated metal housing.The body includes a generally rectangular hollow base portion and an upper lens housing portion; the hollow base portion has a pair of oppositely disposed side walls, each having apertures therein adapted to receive therein the opposing pairs of fingers of the associated housing side walls when the body is positioned in the associated cavity.

The lens housing portion includes generally parallel front and rear walls to be juxtapositioned with associated front and rear walls of the associated housing and includes opposed inwardly inclined side walls extending upwardly from the base portion side walls and joined to a generally flat upper wall positioned almost parallel to the top edges of the associated housing. At least one of the front or rear walls of the base portion is provided with an inwardly extending wiper blade extending substantially from one side wall to the other side wall. A corresponding end of the front or rear walls of the lens housing portion also is provided with a recess therein adapted to receive an elongate lens member.The lens member has a generally flat front face and is provided on the rear face thereof with a plurality of cube-corner type reflecting ele -ments for reflecting light incident on the front face generally parallel and back to the source thereof. The lens member is formed of a synthetic organic resin and provided with an outer light transmitting protective surface generally coextensive to the reflective area of the lens member, the outer surface being formed of a more abrasion resistant material than the lens member.When the body is disposed in the associated housing, engagement of the lens housing portion by a vehicle tire will cause the lens housing portion to be depressed within the hollow area provided by the base member and into the cavity defined by the associated housing, and upon such movement the lens member and the associated abrasion resistant surface formed thereon will effect a wiping movement relative to the associated wiping blade formed on the base member, and the lens housing portion then will return to the normal position thereof.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a reflector assembly according to the present invention, with an associated metal housing partially in phantom; Figure 2 is a perspective of the traditional housing used for a cats eye marker, with a reflector assembly according to the present invention shown in phantom; Figure 3 is an enlarged partial sectional view of the lens assembly of the reflector assembly, taken along lines 3-3 in Fig. 6A; Figure 4 is a bottom plan view of the reflector assembly; Figure 5 is a sectional view of the reflector assembly taken in the direction of the arrows 5-5 in Fig. 4;; Figure 6A is a sectional view of the reflector assembly taken in the direction of the arrows 6-6 in Fig. 1, and illustrates the assembly in the normal operating position; Figure 6B is a view similar to view Fig. 6A but illustrating the lens housing portion of the reflector assembly in the depressed condition under the action of a vehicle tire.

Referring now to the drawings, and more particularly to Figs. 1 and 2 thereof, reference numeral 10 designates a road marker which has as its major components a metal housing in the form of a casting 20 of the type generally used for the conventional road stud or cats eye marker (which may be of the type similar for example to that shown in U.S.

Patent No. 2,703,038); in which is mounted a reflector assembly comprising a core member 30, preferably formed of Neoprene and which includes a reflective lens member 40 for providing a signal function.

The metal casting has a generally rectangular cavity 21 formed therein with a horizontal base 22. The metal casting 20 has parallel front and rear walls designated generally as 23, intended to be disposed generally perpendicular to the direction of traffic flow when the casting is secured to the roadway surface designated "R" in Fig. 2. The casting 20 also is provided with opposed parallel side walls 24. Each of the side walls is provided with pairs of integral attachment fingers 25 extending into the cavity defined by the bottom, side and front and rear walls. For illustration purposes, a pair of attachment fingers 25 is shown in Fig. 6A.The frong, rear and side walls terminate in upper edges 26 intended to be disposed above the associated roadway surface when the metal casting is fixedly installed therein, and provide an enclosure to provide some protection against snow plow blades and the like.

Referring now to Fig. 4, a reflector assembly according to the present invention, which is intended to be disposed within the otherwise conventional metal casting 20, comprises a resilient elastomeric core 30 adapted to be removably positioned in the associated casting 20. The core 30 includes a generally rectangular hollow base portion 31 and an upper lens housing portion 32. The entire core 30 is injection molded in a conventional and well-known fashion. The hollow base portion 31 has a pair of oppositely disposed side walls 33, each having apertures 34 formed therein at the time of molding the core 30, which apertures 34 are adapted to receive therethrough the opposing pairs of attachment fingers 25 of the associated casting side walls when the core 30 is positioned in the metal casting.

The lens housing portion 32 includes generally parallel front and rear walls 35 intended to be parallel to the associated front and rear walls 23 of casting 20. The lens housing portion 32 also includes opposed inwardly inclined side walls 36, extending inwardly from the base portion side walls 33 and integrally joined to a generally flat upper or top wall 37. The lens housing portion 32 further is provided with a generally rectangu lar notch defining a lens holding "T" shaped pocket 38 on at least one (or both as shown) of the front or rear faces thereof, and also is provided with an internal cavity 39 in the top wall 37, permitting flexing of the lens housing portion during depression under a vehicle tire as illustrated in Fig. 6B.

The lens pocket 38 (Fig. 4) is intended to receive an improved composite lens member 40 (Fig. 3) which provides the retroreflective function of the roadway marker. In the present instance, the lens member 40 consists of a reflector portion which has a generally flat front face and is provided on the reverse face with a plurality of reflector elements 42 thereon of the cube-corner type.

While no specific arrangement of cube-corner elements has been illustrated in the drawings it will be understood that for purposes of this application a cube-corner type reflector (also known as trihedral or triple mirror reflector) consists of three mutually perpendicular faces intended to retroreflect light in a direction generally parallel to the light incident upon the front face of the lens element. The three faces need not be of equal size or equal shape and may include rectangular parallelpipeds, triangles, squares, etc. It is also known in the art that cube-corner type reflectors may be designed so that their optical axes are aligned with the nominal incident ray for optimum reflectivity under certain lighting conditions.

The lens 41 generally is formed of a light transmitting synthetic organic resin such as polymethyl-methacrylate or polycarbonate. Polycarbonate is preferred because of its impact strength. Normally polycarbonate would not be used because of its susceptibility to abra sion compared with polymethyl-methacrylate and its deterioration under ultraviolet light, but the protective outer surface of the present invention serves the double function of protecting against abrasion and of filtering out the effects of ultraviolet light. The lens member 40 is provided with a light transmitting protective outer surface 43 generally coextensive to the reflector area of the lens member 40, the outer surface 43 being formed of a more abrasion resistant material then the lens member. One material satisfactory for this purpose is glass having a thickness of about 6 mils.Such glass may be applied in a fashion such as disclosed in our U.S. Patent No.

4,232,979. The lens 41 further is provided with a series of parallel, rearwardly extending dividing and peripheral walls 44, which are in turn hermetically secured to a rigid backing plastic member 45. The rear member 45 preferably is "T" shaped such that it has a rearwardly extending leg 45A to faciliate mounting in the "T" shaped pocket 38 of the lens housing portion 32. The reflector lens member 40 may be adhered within the lens pocket 38 by use of an appropriate adhesive whereby the lens member is fixedly secured to the elastomeric core 30. Finally, each of the front and rear walls 35 of the core 30 is provided with a slit or cut line 46 therein which extends substantially between the side walls 33 and separates the upper lens housing portion 32 from the base portion 31.The slit is provided in such a fashion so as to leave an inwardly extending lip which forms a wiper blade 47 thereon (Fig 6A). The slit also permits downward movement of the upper lens housing portion 32 past the blade 47 and into the hollow base portion 31.

As illustrated in Figs 6A and 6B, upon placement of the core 30 into the associated metal casting 20, the upper edge 26 of the casting and the top wall 37 will be disposed approximately 3/4" above the road surface.

As a vehicle tire rolls over the upper body portion 32 and top wall 37, it will cause wall 37 to flex and to be depressed into the hollow area provided by the base member 31 and into the cavity defined by the associated casting. Upon such movement, the lens member 40, and particularly abrasion resistant surface 43, will be moved past the wiper blade 47 contained on the lower body portion 31 of core 30. Such movement will affect a debris cleaning and wiping function on the front abrasion resistant surface 43 of the lens member, thereby maintaining the lens member clean and keeping it in an efficient condition.

Also, as noted, by providing the cavity 39 in the top wall 37, there will be permitted substantial flexing of the upper lens housing portion 31 while at the same time providing substantial support area behind the lens member 40 to prevent deleterious stress which could cause cracking or breakage thereof.

Also, it may be appropriate to form the wiper blade 47 so that it is curved inwardly in the center thereof, thereby to assure uniform pressure on the lens member 40.

Traditionally the cats eye marker has used two glass beads each having a diameter of about .43". Under the present system, a single lens member 40 is used; it has a dimension of approximately 3/4" high by 1 - 1 /2" wide andit will provide specific intensity at 0.2 observation angle and 0" entrance angle of approximately five times the specific intensity of the typical cats eye. One would have to use at least five glass bead elements in a similar sized core to obtain the same reflectivity. Using more than two beads is not practical however, for a number of reasons: it would weaken the core element by having the additional lens elements therein; also, there would be incomplete wiping caused by the serrated type wiping surface which would be required. Finally, there is not enough area on the housing to accomodate more than two glass beads in their metal cans.

The elastomeric body 30 is preferably formed of Neoprene having a hardness in the range of 45 to 60 durometer, Shore A. The material will extend the useful life of the core as compared to a core formed of natural rubber; yet it is soft and flexible enough to deform and provide the necessary wiping action. Neoprene also has characteristics of not "breaking down" to leave residue on the reflector.

Claims (11)

1. A reflector assembly for use in an associated metal housing to provide a road surface marker, the associated metal housing having a generally rectangular cavity with a horizontal base formed therein, front and rear walls adapted to be positioned perpendicular to the direction of traffic when the housing is secured to the road surface, and opposed side walls provided with integral attachment fingers extending into the cavity, said front, rear and side walls having upper edges intended to be above the associated road surface when the metal housing is fixedly installed thereon; said reflector assembly comprising a resilient eleastomeric body adapted to be removably positioned in the associated metal housing; said body including a generally rectangular hollow base portion and an upper lens housing portion; said hollow base portion having a pair of oppositely disposed side walls each having apertures therein adapted to receive the opposing pairs of attachment fingers of the associated housing side walls when said body is positioned in the associated cavity; said lens housing portion including generally parallel front and rear walls to be parallel to the associated front and rear walls of the associated housing and including opposed in wardly inclined side walls extending upwardly from said base side walls and joined to a generally flat upper wall; at least one of said front and rear walls of said base portion being provided with an inwardly extending wiper blade extending substantially from one side wall to the other side wall; a corresponding end of said front and rear walls of said lens housing portion being provided with a recess therein adapted to receive an elongate lens member; said lens member having a generally flat front face and being provided on the rear face thereof with a plurality of cube-corner type reflecting elements for reflecting light incident on said front face generally parallel and back to the source thereof; said lens member being formed of a synthetic organic resin and further being provided with an outer light transmitting protective surface generally coextensive to the relfective area of said lens member, said outer surface being formed of a more abrasion resistant material than said lens member, whereby upon placement of said body in the associated housing engagement of said lens housing portion by a vehicel tire will cause said lens housing portion to be depressed within the hollow area provided by the base member and into the cavity defined by the associated housing and upon such movement said lens member and the associated abrasive resistant surface thereon will effect a wiping and debris cleaning movement relative to the associated wiper blade formed on said base member and said lens housing portion will then return to the normal position thereof.

2. A reflector assembly as claimed in Claim 1, wherein said elastomeric body is formed of Neoprene and has a hardness in the range of 45 to 60 durometer, Shore A.

3. A reflector assembly as claimed in claim 1 or 2 wherein said outer protective surface of said lens member is comprised of glass.

4. A reflector assembly as claimed in any of claims 1 to 3 wherein said wiper blade is arranged to be positioned in use approximately at the plane of the associated road surface and adjacent to the front face of said lens member.

5. A reflector assembly as claimed in any preceding claim, wherein said lens member and said wiper blade are configured and arranged to that upon movement of said lens housing portion to the depressed position and return to the said normal position said front face of said lens member moves past said wiper blade and in direct contact therewith whereby said wiper blade effects a debris cleaning and wiping function of said front face.

6. A reflector assembly as claimed in any preceding claim, said lens member is fixedly secured to said lens housing portion by means of a "T" shaped section adhered to the lens member and having a leg of the "T" embedded in a groove provided in the said lens housing portion.

7. A reflector assembly as claimed in any preceding claim, wherein said lens housing portion includes an integral body portion depending from the upper wall thereof and disposed below the lower edge of said lens member thereby to provide substantial protection for said lens member during wiping movement of the lens member past the wiper blade and during flexing of the body member under vehicle contact therewith.

8. A reflector assembly as claimed in any preceding claim, wherein said wiper blade is configured such that the central portion thereof between said side walls is curved inwardly toward said lens member thereby to assure uniform pressure on said lens member during wiping movement thereof past said wiper blade.

9. A reflector assembly as claimed in any preceding claim, wherein said cube-corner type reflecting rear face of said lens member includes a rearwardly extending peripheral wall and a plurality of rearwardly extending dividing walls separating areas of said cubecorner elements into discrete cellular sections, and a rigid backing member secured to said walls thereby to hermetically seal the same.

10. A reflector unit for a road surface marker, such a reflector unit being adapted to be mounted in a suitable housing securable to the road surface, and including a reflector element made of synthetic plastics material and surfaced at its substantially flat front face with a light transmitting material which is substantially more abrasion resistant than said synthetic plastics material.

11. A reflector unit for a road surface marker substantially as hereinbefore described with reference to the accompanying drawings.