CA1084465A - Pavement marker - Google Patents
Pavement markerInfo
- Publication number
- CA1084465A CA1084465A CA277,303A CA277303A CA1084465A CA 1084465 A CA1084465 A CA 1084465A CA 277303 A CA277303 A CA 277303A CA 1084465 A CA1084465 A CA 1084465A
- Authority
- CA
- Canada
- Prior art keywords
- lens member
- marker
- reflex
- base
- reflector
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Road Signs Or Road Markings (AREA)
Abstract
PAVEMENT MARKER
ABSTRACT OF THE DISCLOSURE
A low-profile pavement marker includes a base of an opaque, light-diffusing synthetic resin having at least one support wall positioned in use in the direction of an oncoming vehicle, and having a plurality of inwardly extending recesses defining adjacent pockets therein. A lens member of light-transmitting synthetic resin, rigidly secured to the base, has a peripheral edge portion intersected by a plurality of dividing portions for dividing the lens member into a plurality of areas respectively overlying and coextensive with the pockets formed in the support wall, the dividing portions and the edge portion being sealed to the support wall to provide a plurality of in-dependent and hermetically sealed cells thereon. The lens mem-ber has a plurality of retrodirective cube-corner-type reflector elements extending beyond the dividing portions and the edge portion and into the cells and oriented to render the reflector structure highly visible at night. The base and the support wall and the lens member in the areas corresponding to the dividing portions and the edge portion reflect daylight to render the marker highly visible in daylight. An adhesive impact-absorbing material fixedly secures the pavement marker to the roadway and reduces the impact energy imparted by vehicles to the marker and to the roadway.
A snowplowable version of the pavement marker is dis-closed, as well as two embodiments of abrasion-resistant con-structions. Construction of the base and lens member of rubber-modified methyl methacrylate is also disclosed.
ABSTRACT OF THE DISCLOSURE
A low-profile pavement marker includes a base of an opaque, light-diffusing synthetic resin having at least one support wall positioned in use in the direction of an oncoming vehicle, and having a plurality of inwardly extending recesses defining adjacent pockets therein. A lens member of light-transmitting synthetic resin, rigidly secured to the base, has a peripheral edge portion intersected by a plurality of dividing portions for dividing the lens member into a plurality of areas respectively overlying and coextensive with the pockets formed in the support wall, the dividing portions and the edge portion being sealed to the support wall to provide a plurality of in-dependent and hermetically sealed cells thereon. The lens mem-ber has a plurality of retrodirective cube-corner-type reflector elements extending beyond the dividing portions and the edge portion and into the cells and oriented to render the reflector structure highly visible at night. The base and the support wall and the lens member in the areas corresponding to the dividing portions and the edge portion reflect daylight to render the marker highly visible in daylight. An adhesive impact-absorbing material fixedly secures the pavement marker to the roadway and reduces the impact energy imparted by vehicles to the marker and to the roadway.
A snowplowable version of the pavement marker is dis-closed, as well as two embodiments of abrasion-resistant con-structions. Construction of the base and lens member of rubber-modified methyl methacrylate is also disclosed.
Description
2 BACKGROUND OF THE INVENTION
3 In applicant's prior Canadian Patent No. 763,714, there is
4 disclosed a pavement marker adapted to be placed on highways and in which the pavement marker front face is inclined at a predeter-6 mined angle to the roadway surface so that a self-cleaning effect 7 is provided by virtue of that predetermined angle, whereby that 8 pavement marker achieves initial high optical efficiency and 9 the optical deterioration arising out of contact with tires of oncoming vehicles is substantially reduced by allowing the 11 face to be periodically wiped clean by contact with such 12 vehicles. In addition, there is disclosed in that patent a 13 cube-corner reflex reflective optical system in which the cube 14 axes of the cube-corner reflective elements are inclined so as to be substantially coincidental with the nominal incoming 16 refracted ray. Pavement markers made in accordance with 17 Canadian Patent 763,714 and similar to the structure disclosed 18 therein have been extremely successful in operation, and 19 several millions of them have been installed, primarily in areas where no snowplowing of the roads is required. That 21 earlier pavement marker, while highly effective as a nighttime 22 signal, is substantially ineffective as a daytime marker, be-23 cause of the nature of its construction, and, in particular, 24 the large metallized area of the reflective portion thereof, which metallizing is required because of the epoxy fill. Also, 26 the height of the earlier pavement marker precluded its practi-27 cal use under snowplow conditions.
28 Furthermore, the marker of Canadian Patent 763,714 in-. . - ~ . . , : . .: , . ..
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1 ;,volves a tradeoff between abrasion-resistance and self-cleaning 2 or wiping character;stics whereby given the materials used there 3 are limits to the improvement that can be made in one quality 4 without adversely affecting the other.
Also, where a road is constructed of a particular material, 6 or is newly installed asphalt, the marker of Canadian Patent 7 763,714 has caused deterioration of the road surfaces. Some 8 users have recommended delaying installation of such markers 9 for a year to allow the road to cure. In an attempt to over-come these problems caused by unsatisfactory road surfaces or ll newly installed surfaces, the markers of Canadian Patent 763,714 12 were installed with an impact-absorbing pad. However, the use 13 of the impact-absorbing material still did not completely re-14 solve the problem.
In applicant's prior Canadian Patent No. 966,529 there 16 is disclosed an optical system for use with cube-corner-type 17 reflectors, wherein the reflectivity of the reflector is in-18 creased by enlarging one of the three dihedral angles forming l9 the cube-corner element, thereby improving the visibility of the reflector at a selected wider observation angle.
21 Canadian Application 008,999 discloses a cellular system 22 for reflectors in which, in one embodiment, a cellular reflector 23 member is provided on an underlying metal casting for providing 24 a snowplow-type marking. That reflector design is capable of in-~``
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creased daylight reflectivity. Applicant also is aware of pavement markers used on the roadway and put out by Ray-0-Lite, Inc., of Huntington Beach, California, and identified on the shell thereof as a model "FLD", in which three sub-stantially large cells are provided, the cells being provi-ded by walls which extend beyond the apices of the cube-o~er elements and in which the lens member is affixed to a substantially flat support wall lying thereunder. These prior markers presented an undesirable high profile and other disadvantages.
SUMMARY OF THE INVENTION
Applicant, while utilizing some of the features dis-closed i~ the aforementioned prior art, has provided a novel structure which is capable of providing substantially improved daytime and nighttime visibility in a durable pavement marker having ~everal advantages over those disclosed.
It is an object of the present invention to provide an improved, low-profile pavement marker which i8 substantial-ly more durable and provides greater daytime and nighttime reflectivity than existing forms of pavement markers.
It i8 another object of the present invention to provide a low-profile pavement marker in which the maximum height of the marker above the roadway surface does not exceed about .55 inches, thereby reducing the impact energy imparted to the marker and to the underlying roadway surface.
It i9 a further object of the present invention ~o provide a low-profile pavement marker in which the reflective portions thereof are provided in a plurality of hermetically sealed cells so that in the event of damage or destruction to one of the cells, the pavement marker can still effect-~0~4465 ively function to provide continued sufficient reflectivity.
It is a further object of the invention to pro-vide a low-profile pavement marker which can be installed directly on the roadway and which also is capable of use with a metal casting or other housing, whereby the pavement marker also can be used in areas which are frequently heav-ily snowplowed during the winter months.
It is a further object of the invention to provide a low-profile pavement marker which, because of its substan-tially reduced height relative to existing pavement markers,and in cooperation with an impact-absorbing material on the lower surface thereof, minimizes the impact damage to itself and to the underlying roadway surface as vehicles strike the marker and ride over same.
It i8 a further object of the present invention to provide a low-profile pavement marker having maximum abrasion resistance to vehicles striking the marker, whereby the opti-cal ~ualities of the face of the reflective portion of the marker are substantially less degraded, thereby increasing the durability and effectiveness of the marker over a lonqer time period.
Still another object of this invention is the pro-vision of a low-profile pavement marker having improved self-cleaning or wiping characteristics without adverse effect on abrasion resistance.
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f' 1~)8~465 .
1 According to the present invention there is provided 2 a reflex reflector incorporating a base member including a 3 support surface having a plurality of separate recesses therein 4 and a transparent light-transmitting lens member having a front face and a rear face, said rear face of said lens member having 6 discrete groups of reflex-reflecting elements thereon, said lens 7 member being affixed to said base member with said rear surface 8 of said lens member being in contact with said support surface 9 and each of said groups of reflex-reflecting elements being located in a corresponding one of said recesses to form a 11 plurality of discrete reflex-reflector zones capable of re-12 flecting light impinging upon said front face of said lens 13 member back toward the source thereof.
14 According to a further aspect of the invention there is provided a road marker comprising a reflex reflector, said 16 reflex reflector incorporating a base member including a support 17 surface having a plurality of separate recesses therein and a 18 transparent light-transmitting lens member having a front face ~9 and a rear face, said rear face of said lens member having discrete groups of reflex-reflecting elements thereon, said 21 lens member being affixed to said base member with said rear 22 surface of said lens member being in contact with said support 23 surface and each of said groups of reflex-reflecting elements 24 being located in a corresponding one of said recesses to form a plurality of discrete reflex-reflector zones capable of 26 reflecting light impinging upon said front face of said lens 27 member back toward the source thereof.
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l r--iO84465 BRIEF DESCRIPTION OF THE DRAWINGS
The invention, together with further objects and advantages thereof, can best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:
FIG. 1 is a partially sectioned perspective view of one embodiment of a pavement marker constructed in ac-cordance with the present invention;
FIG. 2 is a top plan view of the pavement marker of FIG. l;
FIG. 3 is an end elevational view of the pavement marker illustrated in FIGS. 1 and 2;
FIG. 4 is an enlarged view of the rear face of a lens member forming part of the pavement marker of the pres-ent invention, taken in a direction perpendicular to therear face thereof;
FIG. 4A is a fragmentary view, on an enlarged ~S)84~6S
scale, of a portion of the rear reflective surface of the lens member within the circle 4A of FIG. 4, but taken in a direction parallel to the cube axis of the elements;
FIG. S iS a top plan view of the base of the pavement marker of the present invention;
FIG. 6 is a side elevational view of the base of FIG. 5, as viewed from the right-hand side thereof;
FIG. 7 is a greatly enlarged cross-sectional view of the base., taken along the line 7-7 in FIG. 5, with the lens member of FIG. 4 shown mounted in place on one ~ide of the base;
FIG. 8 i8 a greatly enlarged cross-sectional view of the lens member taken along the line 8-8 in FIG.
4 and rotated approximately 90 degrees;
FIG. 9 i8 an enlarged fragmentary sectional view of the lens member taken along the line 9-9 of FIG. 4;
FIG. 10 i8 an end elevational view of a second - ' ~ . , . . . . .:
~0~44~i5 embodiment of the pavement marker of the present invention;
FIG. 11 is a top plan view of a third embodiment of the pavement marker of the present invention;
FIG. 12 is an end elevational view of the pave-ment marker of ~IG. 11;
FIG. 13 is a top plan view of a fourth embodimentof the pavement marker of the present invention;
FIG. 14 is an end elevational view of the pave-ment marker of FIG. 13;
la FIG. 15 is an enlarged view of the rear face of a second embodiment of lens ms~r fo~ng a par~ of the pave-ment marker of FIG. 13, taken in a direction perpendicular to the rear face thereof;
FIG. 16 is a top plan view of the base of the pave-ment marker of FIG. 11;
FIG. 17 is a side elevational view of the base of FIG. 16, as viewed from the right-hand 3ide thereof;
FIG. 18 is a fragmentary bottom plan view of the base of FIGS. 16 and 17;
FIG, 19 is a greatly enlarged view in vertical sec-tion taken along the line 19-19 in FIG. 13;
FIG, 20 i8 a greatly enlarged view in vertical sec-tion taken along the line 20-20 in FIG. 15, and rotated ap-proximately 90;
FIG. 21 is an enlarged fragmentary sectional view of the lens member of FIG. 15, taken along the line 21-21 therein;
FIG. 22 i9 a diagrammatic view of a roadway illu8-trating prior art arrangements of pavement markers utilizing different types of pavement markers for daytime and nighttime _g_ ..
, l~B4465 visibility; and FIG. 23 is a view similar to FIG. 22, illustrating an axrangem~nt of pavement markers utilizing ~nly the pavement markers of the present invention for both daytime and ~ighttime visibility.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A pavement marker constructed in accordance with the present invention i8 shown in perspective at 10 in FIG. 1 and includes a body or base 20, of an opaque, light-diffus-ing synthetic resin having mounted thereon two lens membersof light-transmitttng synthetic resin, each generally desig-nated as 30.
The base 30 is substantially solid and is formed as a one-piece member to provide a durable structure capable of withstanding impact forces applied to the pavement marker when it i8 struck by a tire of an oncoming vehicle.
The pavement marker 10 is employed to provide a marking on a generally horizontal roadway surface, the mark-ing being visible from an oncoming vehicle on the roadway to delineate traffic lanes and for edge delineation, as is well recognized in the art. In addition, the pavement marker 10 of the present invention may be utilized with metal base mem-bers of the type illustrated and claimed in applicant's co-pending Canadian Application No. 277,306.
Referring now more particularly to FIGS. 5, 6 and 7, it will be seen that the base 20 has a generally horizon-tal bottom surface 21. In order to prevent sinks or shrink stre~ses in molding, the base 20 may be provided with a plu-rality of molding recesses 21A ~FIGS. 5 and 7). The base further includes a pair of generally vertically disposed .. . .. . .
iO8446~;
end wallæ 22 and 23 (FIG. 2), and a generally horizontal top wall 24 having ,a rectangular channel 24A extending from one end wall 22 to the opposite end wall 23.
There is provided a pair of inclined support walls 25, disposed at opposite sides of the base 20, and positioned such that in use, they will be facing the direction of oncom-ing vehicles. Each of these support walls 25 has a plurality of recesses 26 formed therein, which recesses have substan-tiàlly rectangular openings intersecting the plane of the wall, the portions of eadh support wall 25 between the reoesses 26 de-fining partiti3nscr dividing portions 25A. The recesses or pock-ets 26 and the support wail 25 cooperate ~'ith the'over~ying lens member 30 in a manner hereinafter described.
The base 20 further includes side edges 27 and 28 disposed on the opposite ends of each of the respective end wall~ 22 and 23, the side edges 27 and 28 extending outwardly beyond the support walls 25, and defining a channel between the opposite side edges and the adjacent support wall 25 dis-posed therebetween. The base 20 also includes a tab opening 29 formed in the end walls 22 and 23 adjacent to the respect-ive inclined support walls 25 for purposes of facilitating the alignment of the lens member 30 during attachment thereof to the base 20.
The lens member 30 which provides the reflective structure for reflecting light back toward the source there-of, thereby rendering the pavement marker highly visible at night, is best illustrated in FIGS. 4, 7, 8 and 9. The lens member 30 is formed of a light-transmitting synthetic resin and includes a substantially planar front face 31 and a rear face 32. As illustrated, the lens member 30 is gene-, 1~84~65 rally rectangular and is intended to be positioned in the channel provided by the side edges 27, 28 and the support wall 25.
The rear face 32 of the lens member 30 is provi-ded with a peripheral edge portion 33 which extends aboutthe entire periphery of the lens member 30 (FIG. 4) and includes a portion 33A which is originally in the form of a generally triangular bead ~FIGS. 8 and 9). The rear sur-face 32 further is provided with a plurality of dividing portions 34, the dividing portions 34 intersecting the peri-pher~l edge portion 33 at equally spaced distances there-along, thereby dividing the lens member into a plurality of generally rectangular areas circumscribed by the peripheral edge portion 33 and the dividing portions 34. As illustra-ted, the dividing portions 34 originally may include araised triangular sealing bead 34A, and hereinafter, in the specification, for convenience, the dividing portions 34 may be referred to as "dividing ribs".
The lens member 30 is intended to be positioned over the inclined support wall 25 of the base 2G and rigidly secured thereto, preferably by ultrasonic welding. When properly positi~ned, each of the rectangular areas circum-scribed by the peripheral edge portion 33 and dividing por-tions 34 will coextensively overlie and be in registry with the rectangular-shaped openings of the recesses or pockets 26 formed in the support wall 25, while the dividing portions 34 will overlie the dividing portions 25A of the support wall 25.
When the lens m~mber 30 is ultrasonically welded to the base 20, the sealing beads 33A and 34A become sub-~ ~o~4~6~
stantially flattened as a result of the energy imparted thereto during the ultrasonic welding process, whereby the peripheral edge portion 33 directly abuts the support wall 25, as best illustrated in FIG. 7, and provides a substan-tial welded surface area visible through the transparentlens member 30.
Similarly, the dividing ribs 34 will become sub-stantially flattened as they are sealed to the underlying dividing portions 25A of the support wall 25.
~he lens member 30 also includes an outwardly extend~ng tab 37 adapted to be positioned within the tab opening 29 on the base 20, and serves as a locator to fix the lens member 30 in position prior to welding.
After welding the lens member 30 to the base 20, each of the dividing wall portions 25A of the support wall 25, and the peripheral portion thereof, in cooperation with the dividing ribs 34 and peripheral edge portion 33, pro-vide a plurality of hermetioally sealed cells 35 having a rectangular configuration when viewed in a direction normal to the front face 31.
~ he pavement marXer lO is provided with a retro-directive oube-corner-type reflector system to effect the signal function of reflecting light back to the driver of an oncoming vehicle whose headlights illuminate the pavement marker.
As best seen in FIG. 4, the rear face of the lens member 30, in those rectangular areas circumscribed by the dividing ribs 34 and peripheral edge portion 33, is confi-gured to provide a plurality of cube-corner-type retrodir-ective reflector elements 40.
446$
In the embodiments illustrated herein, the cube-corner elements 40 are intended to be generally rectangular when viewed in a direction along the line of the cube axis, as be~t illustrated in FIG. 4A.
Each of the cube-corner elements 40 includes co-operating faces 41, 42 and 43, respectively, the faces in-tersecting to form first and second and third dihedral angles in a manner well known to those skilled in the art.
In the preferred embodiment illustrated, two of the dihedral angles would be on the order of substantially 90 whereas the third dihedral angle would be formed at an angle signi-ficantly different from the first and second dihedral angles, so that the light reflected by such cube-corner element is caused to be diverged to a greater extent in one direction than in the other. One such structure is set forth in grea-ter detail in applicant's Canadian Patent No. 966,529.
In the illustrated embodiment, the different dihe-dral angle is formed between those faces designated as 41 and 42 in FIG. 4A, whereby the reflectivity of the reflector will be substantially increased at a greater observation angle, as more fully demonstrated hereinafter.
AB seen in FIG. 7, the apices of the cube-corner reflective elements 40 extend beyond the peripheral edge portion 33 and the dividing ribs 34, and into the cell 35, when the lens member 30 is secured to the base 20. Al-though in the embodiment illustrated the cells 35 are sub-stantially large and ~pen, it should of course be under-stood that the pockets 26 may be recessed less deeply than indicated, and, in fact, the apices of the cube corners 40 may contact the underlying surface 26A defining the inte-~)84~65 rior boundary of the recess 26 thereby further to strength-en the lens member 30 and provide additional support there-for as the lens member lS contacted by a tire of an oncom-ing vehicle.
To facilitate installation of the pavement marker on an underlying roadway surface, or on a metal casting in the event the marker 10 is used in snowplow country, an ad-hesive impact-absorbing material or pad 15 is secured to the bottom surface 21 of the base 20. The pad 15 may com-prise an elastomeric polymeric adhesive material such as, for example, butyl rubber. A protective sheet of release paper 16 is applied to the bottom of the pad. In use, the paper 16 is peeled from the pad 15 and the pavement marker 10 pressed onto the roadway surface. In installation it may be desirable to use a suitable primer on the roadway to enhance securement of the pavement marker. Satisfactory butyl tape, T-9463, and primer, P-1130, are products of Protective Treatments, Inc. of Dayton, Ohio.
After the pavement is primed, the marker is posi-tioned on the primed road surface with light pressure, after which greater pressure may be applied by driving slowly over the marker with one tire of a service truck. The use of the adhesive pad 15 greatly facilitates installation of the pavement marker 10 on the roadway surface. More parti-cularly, this arrangement permits rapid installation of the pavement markers from a slowly moving vehicle, thereby ob-viating lane closures and their attendant inconvenience and safety hazards which were necessitated with prior art installation techni~ues.
It is believed that the impact-absorbing material ~ ?446S
15, together with the low profile of the marker 10 achieved by the low height thereof relative to the roadway surface, effects both a reduction and absorption of some of the im-pact energy normally transmitted through to the underlying pavement su~ace.
It is also believed that the low profile allows the pavement marker 10 to be ingested by a tire body 80 that the tire body rolls over the marker 10 and is still partially supported by the roadway surface, rather than causing the full load of the tire to impact upon the marker, which is what i8 thought to happen with existing markers of a higher elevation. Moreover, it is further believed that the low profile, in combination with the impact-absorbing material 15 on the bottom sur~ace 21 of the base 20, renders the in-dividual cell structure formed by the combined lens member30 and base 20 more resistant to impact damage.
An important feature of the present invention in leading to a reduction of the overall height of the marker is ~he provision ~f the recesses 26 in the support wall 25, rather than by providing the cells in a fashion where the walls are carried by the lens member 30 and extend beyond the apices of the aube corners 40. ~his fea~ure of the present invention permits reduction in the overall height of the lens member 30, and particularly the elements 40 thereof, relative to the bottom surace of the base 20.
It will be observed with reference to FIG. 8 that the cube-aorner elements 40 disposed toward the lower end of the lens member 30 extend outwardly to a greater ex-tent from the rear wall 32 of the lens member 30 than do those reflector elements disposed toward the upper end. The ~ ~ .
1~8446S
plane defined by the apices of the elements 40 is parallel to the front face 31, but is inclined at an acute angle ~
to the rear face 32 tFIG. 8). This feature alows a further reduction in overall helght of the marker, without requiring undesirable undercuts in the base 20, which otherwise would have to be provided therein if the cube corners 40 at the upper portion of the lens member extended outwardly as far as the lower elements.
As diqclosed in applicant's Canadian Patent 763,714, there is an optimum balance obtained in maintaining optical effectiveness by limiting abrasion and achieving adequate wiping or cleaning of the front face of the marker upon con-tact by a moving tire. Such optimum balance is achieved when the angle of the front face of the lens member i5 dis-posed at approximately 30 to the horizontal, with a satis-factory result being obtained where such angle is approxi-mately from 15 to 45. In general, abrasion resistance is directly proportional to the front face angle while self-cleaning ability is inversely proportional to the front face angle.
~ owever, the abrasive action on the front face of the marker due to tire contact becomes an even more critical factor than the aforementioned wiping or cleaning action when the pavement marker is used where abrasive ma-terials are purposely placed on the road. Thus, in an areawhere salt or sand is put on the road during the wintertime, the wiping action by such abrasive materials in contact bet-ween the tire and front face of the lens member causes more serious damage to the front face than is the case where those markers are located in other areas of the country where such . , , , ~ .
1~8446~
abras~ve m~terial~ are not on the roadway. In order to mini-mize the loss of reflectivity due to abrasion, and to prolong the reflective qualities of the pavement marker under these conditions, the front surface 31 of the lens member 30 of the present invention is preferably inclined at an angle of 45 relative to the horizontal surface 21 of the base 20. It will be appreciated that the effects of abrasion may be further mi-nimized by increasing the angle of the front face above 45;
however, it is believed that at front face angles above 60, the cleaning and wiping action by tire contact will be inade-guate to maintain optical effectiveness.
It is also known that the front surface reflection loS8 due to the inherent nature of the material of the lens member itself is less at 45 than at 30. As an example, the typical front surface reflection loss of a pavement marker in which the front surface of the lens ic located at 30 to the horizontal would be approximately 24%, whereas the front surface loss with the reflector at 45 to the horizontal would be only 12%. Also, by inclining the front face of the marker at 45, there-~s-a ~maller area e~posed to contact by automob~le tire studs or stones carried in the tire treads, and al o the pressure on the front surface is reduced. Fur-ther, by inclining the front face of the marker at 45, it is possible to further reduce the overall height of the mar-ker because there will be a lesser inclination of the cubeaxis relative to the horizontal than is provided in appli-cant's Canadian Patent 763,714, and it will not be necessary to tilt the cube-corner elements 40 as much.
To further protect the front surface 31 from exces-sive abrasion, and particularly from a grinding action by ~8~4~S
sand or salt being disposed on the roadways, the front sur-face 31 of the lens member 30 may be provided with abrasion-limiting means; in the illustrated embodiment such means comprise a plurality of outwardly extending ridges 45. The operation of the ridges 45 is set forth in the copending C~ian application 277,305. The ridges 45 are disposed directlyover and in alignment with the dividing ribs 34 on the back face 32 of the lens member 30, whereby the ridges 45 do not in-terfere with the operation of the reflex portions 40 on the lens membe~ he ridges 45 may be integrally molded with the lens member 30, or, if desired, they could be made of a more abrasion-resistant material than the lens member and thereafter secured to the lens member 30 by welding or ad-hesive, thereby to provide further protection for the front surface of the marker.
As previously described, the side edges 27 and 28 extend outwardly beyond the inclined support walls 25 of the base 20, and provide a channel between the side edges a~d the support wall 25 within which is disposed the lens member 30. The side edges 27 and 28 provide further structural sup-port and protection for the lens member 30 adjacent those areas in which the ultrasonic welding occurs at the corners of the marker, thereby serving to substantially protect the integrity of the marker at those points. It will also be noted that the side edges 27-28 and the front edges of the protective ridges 45 lie in the same plane, in effect defin-ing a protective barrier for the front face 31 of the marker 10.
The pavement marker 10 also may be provided with a metal cover plate 19 to overlie and protec~ the entire top 1~8446~
wall 24 thereof, the cover plate 19 also extending beyond and overlying the upper edge of the lens member 30, as best seen in FIG. 3. The metal cover plate 19 is intended to be u~ed on those embodiments of the pavement marker 10 which are to be installed in a metal casting and subje~ted~ to possible contact by studded snow tires passing over the top of the marker, the cover plate serving to provide additional protection against such studs.
The cover plate 19 may be adhesively secured to the top wall 24 or, alternatively, a second impact-absorb-~ng pad (not shown) may be fixedly secured therebetween.
As the use of tire studs becomes more widely prohibited, the metal plate and recessed channel may be eliminated.
The rectangularly shaped longitudinally extend-ing channel 24A provided in the cover plate 19 and in the top wall 24 i8 adapted to receive a retaining member in a well-known manner, the retaining member serving to further hold the pavement marker in place on the underlying metal casting, if such retaining member is desired.
The arrangement of the lens member 30 with its peripheral transparent edge portion 33 and dividi~g ribs 34, and the underlying light-diffusing opaque support wall 25, imparts substantial daytime visibility to the pavement marker 10 rendering it of greater utility than prior mar-ker5.
In the illustrated embodiment, the total area oc-cupied by the peripheral edge portion 33 and the dividing ribs 34 is substantially equal to that occupied by the re-trodirective reflector elements 40 in those areas circum-scribed by the edge portion 33 and the dividing ribs 34.
~84465 By using rectangular retrodirective cube-corner elements 40 and rectangular cells 35, maximum use of the area of the lens member 30 is accomplished, as there will be no partial cube-corner elements along the edge of any cell, while at the same time it is possible to substantial-ly completely fill the area circumscribed by the peripheral edge portion 33 and the dividing ribs 34 with retrodirect-ive reflective elements 40.
Further, the use of the rectangular cells 35 and square reflector elements 40 permits the use of vertical side wall surfaces in each recess 26 of the marker, if de-sired, whereby su~stant~ally the full width of the marker 10 is provided with complete reflective elements.
The opaque, light-diffusing base 20 serves to reflect daylight impinging thereon to an observer. At a distance, the unifoxm spacing of the dividing ribs 34 and dividing wall portions 25A causes the pavement marker to appear as a substantially uniform reflective body, with the cells 35 te~ding to disappear to the eye of the ob-server under daylight conditions. Alternatively, undernighttime driving conditions, the uniform size and spacing of the cells 35 causes the pavement marker to appear as a uniform reflective member, the dividing ribs 34, which im-prove daytime visibility, tending to disappear under eve-ning driving conditions.
To achieve these benefits, together with a lowprofile, it is believed that the maximum rectangular pro-jected dimensions of each cell 35 should not exceed about .3 inches high and about .75 inches wide, with the pre-ferred construction providing cells substantially square ~34465 in projected view with a projected height of approximately .3 inches and a projected width of approximately .36 inches.
While the preferred embodiment has eight such rectangular cells therein, it is believed that a minimum of five cells is required in order to obtain the substan-tial daytime reflective qualities achieved by the present marker and to preserve nighttime reflectivity of the mar-ker in the event of damage to one or more of the cells, which would cause it to lose its hermetic seal and thereby ultimately render it optically ineffective.
Despite having at least half of its projected area devoted to wall structure for providing strength and daytime visibilit~, the pavement marker 10 of the present invention also provides substantially improved reflectivity over that of Canadian Patent 763,714. As an ex~ple, the table set forth herebelow indicates representative figures for typi-cal units of the marker of Canadian Patent 763,714 contrasted with the present invention at two different observation angles.
It will be observed that a pavement marker of the type of the present invention ~s almost two and one-half times bright-er at a .2 observation angle, corresponding to a distance of approximately 500 feet, and almost five times brighter at a .4 observation angle, corresponding to a distance of about 250 feet.
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l REPRESENTATIVE BRIGHTNESS
Candlepower per Fo tcandle per_Square Inch of Reflector i Observation Angle 3,332,327 Patent Present Invention .2 1 3 . i 40 _ _ I~ 1.5 8 ;
_ 44~S
The increased brightness of the present inven~ion permits the reduction in height of the marker ~ithout any loss in specific intensity, as indicated in the table below.
¦ SPECIFIC_INTENSITY
~andlepower per Footcandl . .
Ob3ervation Angle 3,332,327 Patent Present Invention .2 ` 6 4o 3 8 Moreover, the specific intensity of the present invention is 3$gnificantly greater at .4 observation angle than that of the marker of Canadian Patent 763,714 for a smaller area, thereby causing the marker of the present in-vention, though of a low profile, to be ~ubstantially brighter in appearance.
In the embodiment illustrated, the height of the ba5e 20 from the bottom horizontal surface 21 to the top wall 24 i8 approximately .43 inches; the pad 15 i8 approxi-mately .06 inches, for a total height above the roadway of approximately .49 inches, as contrasted with the overall height of the pavement marker manufactured in accordance with Canadian Patent 763,714 of approximately .72 inches.
Moreover, an epoxy adhesive normally was utilized to apply the pavement marker of Canadian Patent 763,714 to the pave-ment, or, in those in3tances in which a pad was used, therewould be a further increase in height Gf the prior marker of up to .06 inches. Thus, the present invention represents a reducti4n of about 38~ in overall height.
The front face of the lens member 30 is disposed at an angle of approximately 45 to the horizontal surface .
~ 4465 21, while the support wall 25 is inclined at an angle of approximately 41. The ridges 45 on the front face 31 of the lens member 30 are positioned at angles of approxi-mately 53 relative to the horizontal surface 21 and simi-larly the side edges 27 and 28 forming extensions of the side walls 22 and 23 also are inclined at angles of appro-ximately 53 relative to the underlying æurace 21. It will be apparent from the foregoing that the outer edges of the ridges 45 and the side edges 27 and 28 thereore are substantially coplanar and provide a protective area for the front surface of the lens member.
The base 20 may be made of a thermoplastic resin such as acrylonitrile butadiene styrene ~commonly known as ABS), glass-filled ABS, methyl methacrylate or rubber-modi-fied methyl methacrylate ~commonly known as Plexiglass DR~
or Lexan (T.M.), or may be made of a thermosetting material and be adhesively mounted. The lens may be of methyl meth-acrylate or a rubber-modified methyl methacrylate or a poly-carbonate such as Lexan.
Normally, the lens and base will be chosen to provide the same colors, day and night, with the specific color being determined by the specific function of the marker, e.g., lane delineation vs. median edge delineation.
The embodiment of the pavement marker illustrated in FIG. 10 is primarily intended to be used independently of any metal housing or casting. In that embodiment the top wall 24, rather than being generally horizontal, as in the first embodiment illustrated in FIG. 1, instead has surfaces 47 and 48 which incline upwardly in the same general direction as the support walls 25, the inclined , ~ - . : , , . ':
~ 4465 surfaces 47 and 48 forming a crown above the he~ght of th~ lens member to provide additional reflective body area for reflecting daylight back to an observer. The metal cover plate 19 would of course not be used with this marker which would preferably be used under non-snowplowable conditions. The added crown at the top of the base 20 increases the overall height of the marker by about another .06 inches, whereby the total height of such marker would be approximately .55 inches.
Referring now to FIGS. 11, 12 and 16 through 19 of the drawings, there is illustrated another embodi-ment of the pavement marker of the present invention, generally designated by the numeral 50, and comprising a body or base 60 of an opaque, light-diffusing synthetic resin having mounted thereon two of the lens members 30.
The base 60 is substantially solid and is formed as a one-piece member to provide a durable structure capable of withstanding impact forces applied to the pavement marker 50 when it is struck by a tire of an oncoming ve-hicle. More particularly, the base 60 has a generallyhorizontal bottom surface 61 having a plurality of gene-rally rectangular molding recesses 62 formed therein for the purpose of preventing sinks or shrink stresses during the molding of the base member 60. The molding openings 62 extend well up into the base 60 and cooperate to define therebetween a plurality of substantially vertically ex-tending partitions or walls 63 and a pair of upstanding opposed side walls 64 and 68 interconnected by a top wall 69 which is peaked or gabled to form two halves each in-0 clined at a slight angle to the plane of the bottom sur-: . . .:
-face 61. There is also provided a pair of inclined sup-port walls 65, respectively disposed at opposite sides of the base 60, and positioned such that in use they will be facing the directions of onc~ming vehicles. Each of the support walls 65 has a plurality of recesses 66 formed therein, which recesses have substantially rectangular openings intersecting the plane of the outer surface of the support wall 65, the portions of each of the support walls 65 between the recesses 66 defining septa or divid-ing portions 67.
The top wall 69 of the base 60 has inclined top - surfaces 70 and 71 which respectively extend upwardly from the upper ends of the outer surfaces of the support walls 65 and intersect along a line substantially parallel to the support walls 65 and midway therebetween. Each of the end walls 64 and 68 i8 provided at the upper end thereof with upstanding shoulders 72 and 73 which respectively project upwardly above the top surfaces 70 and 71 of the top wall 69 and outwardly beyond the outer surfaces of the support walls 65, the shoulders 72 cooperating with one of the sup-port walls 65 to define a channel therealong and the shoul-ders 73 cooperating with the other of the support walls 65 to define a channel therealong. Preferably, each of the side walls 64 and 68 i8 also provided with a tab opening 74 therein adjacent to the corresponding inclined support wall 65 for purposes of facilitating the alignment of the lens members 30 during attachment thereof to the base 60.
The lens members 30 were described above in con-nection with the pavement marker 10, and each of the lens members 30 is mounted on the base 60 and cooperates there-iS)~4~6S
~ith in the same manner as was described above with respect to the base 20 of the pavement marker 10. More particular-ly, each of the lens member 30 is positioned over one of the inclined support walls 65 of the base 60 and rigidly gecured thereto, as by ultrasonic welding, with the rectan-gular areas circumscribed by the peripheral edge portion 33 and dividing portions 34 coextensively overlying in registry with the rectangular-shaped openings of the recesses or pock-e~s 66 formed in the support walls 65, while the dividing portions 34 overlie the dividing portions 67 of the support walls 65. When the lens members 30 are ultrasonically welded to the base 60, the sealing beads 33A and 34A become subs~an-tially flattened so that the peri~heral edge portion 33 dir-ectly abuts the support wall 25 and provides a substantial welded surface area visible through the transparent lens mem-bers 30. Similarly, the dividing ribs 34 become substantially flattened as they are sealed to the underlying dividing por-tions 67 of the support walls 65. The tabs 37 are respectively adapted to be positioned within the tab openings 74 of the base 60 and serve to fix the position of the lens members 30 prior to welding. After welding, the lens members 30 cooperate with the associated suppor~ walls 65 to provide a plurality of her-metically sealed cells as described above.
It is an important feature of th~s invention that the dimensions of the molding openings 62 are such that none of the base walls 63, 64, 65, 68 or 69 has a thickness greater than 1/8 inch. ~he purpose of this arrangement is to minimize molding time, since, in general, the molding time is proportional to the thickness of the members being molded. It has been found that a wall thickness of 1/8 .. . . . . . . .
" i~B446S
inch corresponds to a molding time of approximately 3a sec-onds. This reduced molding time conQiderably reduces the cost of the manufacture of the base 60.
The pavement marker 50 may be installed on the S pavement in the same manner as was described above with respect to the pavement marker 10, an adheQive pad 15 of impact-absorbing ma~erial being utilized.
The pavement marker 50 i8 primarily intended to be used indep~ndently of any metal housing or casting, the inalined top ~urfaces 70 and 71 forming a crown above the he~ght of the lens membQrs 30 to provide additional reflect-ive body area for reflecting daylight back to an observer.
The metal cov~r plate 19 would of course not ba used with the pavement marker 50, which would preferably be used under non-snowplowable conditions. In a con~tructional model of the pavement marker 50, the overall height of the marker, including the adhesive pad 15, i8 approximately .62 inches, the outer surfaces of th~support walls 65 being inclined at approximately 41 to the surface of the pavement, 80 that the front face of each of the lens menbers 30 is inclined at an angle of approximately 45 to the horizontal. In use, ths front edges of the ridges 45 of the lens members 30 lie in the ~ame plane as the front edges of the shoulders 72 and 73 of the base 60, in effect defining a protective barrier ~or th~ front faces 31 of the lens mernbers 30 in the pave-m~nt markor S~.
Referrlng now also to FIGS. 13 through 15, 20 and 21, there i~ illustrated another em~odiment of the pavement marker of the present ~nvention, generally de~ignated by the numeral 100, and inaluding the base 60 having mounted thereon i~8446S
two.lens members, each generally designated by the numeral 80.
Each of the lens member 80 is similar in contruction to the lens member 30, with the exception that the lens members 80 are not provided with the outwardly extending protecti~e ridges 45. More particularly, the lens member 80 is formed of a light-transmitting synthetic resin and includes a sub-stantially 1at front face 31 and a rear face 32~ As illus-trated, the lens member 80 is generally rectangular and is intended to be positioned in the channel provided by the shoulders 72 and 73 and the support walls 65. The rear face 82 of the lens member 80 is provided with a peripheral edge portion 83 which extends about the entire periphery of the lens member 80 ~FIG. 15) and includes a portion 88 which is originally in the form of a generally triangular bead (FIGS.
20 and 21~. The rear surface 82 fur~her i8 provided with a plurality of dividing portions 84, the dividing portions 84 intersecting the peripheral edge portion 83 at equally-spaced distances therealong, thereby dividing the lens member 80 in-! to a plurality of generally rectangular areas circumscribed by the peripheral edge portion 83 and the dividing portions 84. As illustrated, the dividing portions 84 originally may include a raised triangular sealing bead 89, and here-inafter, in the specification the dividing portions 84 may be referred to as "dividing ribs".
~he lens member 80 is intended to be positioned over the inclined support wall 65 of the base 60 and rigid-ly secured thereto, preferably by ultrasonic welding~ When properly positioned, each of the rectangular areas circum-scribed by the peripheral edge portion 83 and dividing por-tions 84 will coextensively overlie and be in registry with ~ 8446S
the rectangular-shaped openings of the recesses or pockets 66 formed in the support wall 65 while the dividing por~ions 84 will overlie the dividing portions 67 of the support wall 65.
When the lens member 80 i5 ultrasonically welded to the base 60, the sealing beads 88 and 89 become substan-tially flattened as a result of the energy imparted thereto during the ultrasonic welding process, whereby the peripheral edge portion 83 directly abuts the support wall 65, as best illustrated in FIG. 19, and provides a substantial welded qurface area visible through the transparent lens member ao.
Similarly, the dividing ribs 84 will become substantially flattened as they are sealed to the underlying dividing por-tions 67 of the support wall 65. The lens member 80 also includes an ou~rdly extending tab 87 adapted to be posi-tioned within the tab opening 74 on the base 60, and serves as a locator to fix the lens member 80 in position prior to welding.
After welding the lens member 80 to the base 60, each of the dividing wall portions 67 of the support wall 65, and the peripheral portion thereof, ln cooperation with the dividing ribs 84 and peripheral edge portion 83, provide a plurality of hermetically sealed cells 85, each having a rectangular config~ration when viewed in a direc-tion normal to the front face 81.
The lens member 80 is provided with a retrodir-ective cube-corner-type reflector system to effect the signal function of reflecting light back to the dr~ver of an oncoming vehicle whose headlights illuminate the pave-ment marker. As best seen in FIGS. 15 and 20, the rear ~Ot:~4465 face of the lens member 80, in those rectangular areas circumscribed by the dividing ribs 84 and the peripheral edge portion 83, is configured to provide a plurality of cube-corner-type retrodirective reflector elements 90.
The retrodirective reflector elements 90 are diagrammati-cally illustrated in FIGS. 13 and 15 as a crisscross pat-tern of lines, but it will be appreciated that these re-flector elements may be identical in construction to the reflector elements 40 described above in connection with the lens member 30 in FIGS. 8 and 9.
As seen in FIGS. 19 and 20, the apices of the cube-corner reflector elements 90 extend beyond the peri-pheral edge portion 83 and the dividing ribs 84, and into the cell 85, when the lens member 80 is secured to the base 60. Since the pavement marker 100 is intended prima-rily for use independently of a metal housing or casting in non-snowplowable applications, no protective ridges such as the ridges 45 of the lens members 30 are necessary in the lens members 80. But the abrasion resistance of the lens member 80 may be substantiaily increased by the pro-vision of a layer 95 of protective material such as glass or the like overlying and adhered to the front face 81 of the lens member 80. Preferably, the glass layer 95 has a thickness of approximately .005 inches and is secured by a layer of suitable adhesive material of between about .006 and .012 inch thick to the front face 81 so as substantially to cover all of the portions of the front face 81 which over-lie the retrodirective cube-corner reflector elements gO of the lens member 80. It has been found that the use of this glass layer ~5 has dramatically increased the abrasion re-~a~446s sistance of the lens member 90, as is more fully explained in the aforementioned copending application Serial No. 277,305.
The use of the glass overlay significantly reduces the degrad-ation of the brightness of the lens member 80 as a result of S normal wear in service.
Also, the arrangement of the lens member 80 with its peripheral transparent edge portion 83 and dividing ribs 84, and the underlying light-diffusing opaque support wall 65, imparts substankial daytime visibility to the pavement marker 100, rendering it of greater utility than prior markers.
~he opaque, light-diffusing base 60 serves to reflect daylight impinging thereon to an observer and, at a distance, the uni-form spacing of the dividing ribs 84 and dividing wall portions 67 cau~es the pavement marker 100 to appear as a substantially uniform reflective body, with the cells 85 tending to disappear to the eye of the observer under daylight conditions.
The base 60 and the lens members 80 may respect-ively be constructed of any of the materials set forth above with respect to the base 20 and lens members 30, but preferably the base 60 and lens members 80 are both formed of a rubber-modified methyl methacrylate such as that sold under the trademark "PLEXIGLAS DR".
PLEXIGLAS DR, because it is rubber modified, gives higher impact resistance than unmodified Plexiglas; but re-portedly it i8 a softer material than the unmodified Plexi-glas. Because of this, it was expected that PLEXIGLAS DR
would not prove sufflciently abrasion resistant for use in pavement markers. Surprisingly, pavement markers of the character disclosed herein molded of PLEXIGLAS DR proved to be as abrasion resistant as those of unmodified Plexiglas.
.
Thus, the pavement markers of the present inven-tion have very great daytime as well as nighttime visibili-ty, as well as being substantially cheaper to manufacture than prior pavement maxkers. This affords substantial ad-vantages and economies in application of the pavement mar-kers. More particularly, referring to FIG. 22, there is illustrated a prior art arrangement of pavement markers as a lane marking on a roadway 110. This typical arrangement includes a combination of day~ime and nighttime markers substantially equidistantly spaced apart, and arranged 80 that there are about four daytime markers 116 (such as the so-called "Botts D~ts") or 117 ~such as painted stripes) between every two nighttime markers 115. The nighttime markers 115 may, for example, be of the type of retrodir-ective reflector markers disclosed in the aforementionedCanadian Patent No. 763,714, which markers have a high nighttime visibility over a substantial distance and, therefore, can be widely separated on the pavement. But these prior art nighttime pavement markers 115 have a rel-atively low daytime visibility. Therefore, the Botts Dots 116 or the painted stripes 117 are typically utilized at their normal spacing~ between the nighttime markers 115 to achieve the necessary visibility both in daylight and at night.
But the daytime visibility of the pavement mar-kerR of the present invention is so superior to that o the prior art markers 115 that they can be utilized eect-ively as both daytime and nighttime markers and can, there-fore, be utilized in lieu of the prior type daytime mark-ings at the normal marker spacings on the pavement, as il-1~844~$
lustrated in FIG. 23. This offers several significant advantages. First of all, since only one type of pavement marker is utilized in thisarrangement, only one type of ;
application equipment need be used, thereby reducing the
28 Furthermore, the marker of Canadian Patent 763,714 in-. . - ~ . . , : . .: , . ..
.
' '' ' : :''' ,' ". ' ' '. ' " ' ' ' ~ ' . , .' ' '~ . . ' ..
1~ 46S
1 ;,volves a tradeoff between abrasion-resistance and self-cleaning 2 or wiping character;stics whereby given the materials used there 3 are limits to the improvement that can be made in one quality 4 without adversely affecting the other.
Also, where a road is constructed of a particular material, 6 or is newly installed asphalt, the marker of Canadian Patent 7 763,714 has caused deterioration of the road surfaces. Some 8 users have recommended delaying installation of such markers 9 for a year to allow the road to cure. In an attempt to over-come these problems caused by unsatisfactory road surfaces or ll newly installed surfaces, the markers of Canadian Patent 763,714 12 were installed with an impact-absorbing pad. However, the use 13 of the impact-absorbing material still did not completely re-14 solve the problem.
In applicant's prior Canadian Patent No. 966,529 there 16 is disclosed an optical system for use with cube-corner-type 17 reflectors, wherein the reflectivity of the reflector is in-18 creased by enlarging one of the three dihedral angles forming l9 the cube-corner element, thereby improving the visibility of the reflector at a selected wider observation angle.
21 Canadian Application 008,999 discloses a cellular system 22 for reflectors in which, in one embodiment, a cellular reflector 23 member is provided on an underlying metal casting for providing 24 a snowplow-type marking. That reflector design is capable of in-~``
_ . ~
.
creased daylight reflectivity. Applicant also is aware of pavement markers used on the roadway and put out by Ray-0-Lite, Inc., of Huntington Beach, California, and identified on the shell thereof as a model "FLD", in which three sub-stantially large cells are provided, the cells being provi-ded by walls which extend beyond the apices of the cube-o~er elements and in which the lens member is affixed to a substantially flat support wall lying thereunder. These prior markers presented an undesirable high profile and other disadvantages.
SUMMARY OF THE INVENTION
Applicant, while utilizing some of the features dis-closed i~ the aforementioned prior art, has provided a novel structure which is capable of providing substantially improved daytime and nighttime visibility in a durable pavement marker having ~everal advantages over those disclosed.
It is an object of the present invention to provide an improved, low-profile pavement marker which i8 substantial-ly more durable and provides greater daytime and nighttime reflectivity than existing forms of pavement markers.
It i8 another object of the present invention to provide a low-profile pavement marker in which the maximum height of the marker above the roadway surface does not exceed about .55 inches, thereby reducing the impact energy imparted to the marker and to the underlying roadway surface.
It i9 a further object of the present invention ~o provide a low-profile pavement marker in which the reflective portions thereof are provided in a plurality of hermetically sealed cells so that in the event of damage or destruction to one of the cells, the pavement marker can still effect-~0~4465 ively function to provide continued sufficient reflectivity.
It is a further object of the invention to pro-vide a low-profile pavement marker which can be installed directly on the roadway and which also is capable of use with a metal casting or other housing, whereby the pavement marker also can be used in areas which are frequently heav-ily snowplowed during the winter months.
It is a further object of the invention to provide a low-profile pavement marker which, because of its substan-tially reduced height relative to existing pavement markers,and in cooperation with an impact-absorbing material on the lower surface thereof, minimizes the impact damage to itself and to the underlying roadway surface as vehicles strike the marker and ride over same.
It i8 a further object of the present invention to provide a low-profile pavement marker having maximum abrasion resistance to vehicles striking the marker, whereby the opti-cal ~ualities of the face of the reflective portion of the marker are substantially less degraded, thereby increasing the durability and effectiveness of the marker over a lonqer time period.
Still another object of this invention is the pro-vision of a low-profile pavement marker having improved self-cleaning or wiping characteristics without adverse effect on abrasion resistance.
. , .
f' 1~)8~465 .
1 According to the present invention there is provided 2 a reflex reflector incorporating a base member including a 3 support surface having a plurality of separate recesses therein 4 and a transparent light-transmitting lens member having a front face and a rear face, said rear face of said lens member having 6 discrete groups of reflex-reflecting elements thereon, said lens 7 member being affixed to said base member with said rear surface 8 of said lens member being in contact with said support surface 9 and each of said groups of reflex-reflecting elements being located in a corresponding one of said recesses to form a 11 plurality of discrete reflex-reflector zones capable of re-12 flecting light impinging upon said front face of said lens 13 member back toward the source thereof.
14 According to a further aspect of the invention there is provided a road marker comprising a reflex reflector, said 16 reflex reflector incorporating a base member including a support 17 surface having a plurality of separate recesses therein and a 18 transparent light-transmitting lens member having a front face ~9 and a rear face, said rear face of said lens member having discrete groups of reflex-reflecting elements thereon, said 21 lens member being affixed to said base member with said rear 22 surface of said lens member being in contact with said support 23 surface and each of said groups of reflex-reflecting elements 24 being located in a corresponding one of said recesses to form a plurality of discrete reflex-reflector zones capable of 26 reflecting light impinging upon said front face of said lens 27 member back toward the source thereof.
~ .
: .............. .. .. - .... . . ... . :
- . , . . - .. - . ~ .: ~ . . -: . .
l r--iO84465 BRIEF DESCRIPTION OF THE DRAWINGS
The invention, together with further objects and advantages thereof, can best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:
FIG. 1 is a partially sectioned perspective view of one embodiment of a pavement marker constructed in ac-cordance with the present invention;
FIG. 2 is a top plan view of the pavement marker of FIG. l;
FIG. 3 is an end elevational view of the pavement marker illustrated in FIGS. 1 and 2;
FIG. 4 is an enlarged view of the rear face of a lens member forming part of the pavement marker of the pres-ent invention, taken in a direction perpendicular to therear face thereof;
FIG. 4A is a fragmentary view, on an enlarged ~S)84~6S
scale, of a portion of the rear reflective surface of the lens member within the circle 4A of FIG. 4, but taken in a direction parallel to the cube axis of the elements;
FIG. S iS a top plan view of the base of the pavement marker of the present invention;
FIG. 6 is a side elevational view of the base of FIG. 5, as viewed from the right-hand side thereof;
FIG. 7 is a greatly enlarged cross-sectional view of the base., taken along the line 7-7 in FIG. 5, with the lens member of FIG. 4 shown mounted in place on one ~ide of the base;
FIG. 8 i8 a greatly enlarged cross-sectional view of the lens member taken along the line 8-8 in FIG.
4 and rotated approximately 90 degrees;
FIG. 9 i8 an enlarged fragmentary sectional view of the lens member taken along the line 9-9 of FIG. 4;
FIG. 10 i8 an end elevational view of a second - ' ~ . , . . . . .:
~0~44~i5 embodiment of the pavement marker of the present invention;
FIG. 11 is a top plan view of a third embodiment of the pavement marker of the present invention;
FIG. 12 is an end elevational view of the pave-ment marker of ~IG. 11;
FIG. 13 is a top plan view of a fourth embodimentof the pavement marker of the present invention;
FIG. 14 is an end elevational view of the pave-ment marker of FIG. 13;
la FIG. 15 is an enlarged view of the rear face of a second embodiment of lens ms~r fo~ng a par~ of the pave-ment marker of FIG. 13, taken in a direction perpendicular to the rear face thereof;
FIG. 16 is a top plan view of the base of the pave-ment marker of FIG. 11;
FIG. 17 is a side elevational view of the base of FIG. 16, as viewed from the right-hand 3ide thereof;
FIG. 18 is a fragmentary bottom plan view of the base of FIGS. 16 and 17;
FIG, 19 is a greatly enlarged view in vertical sec-tion taken along the line 19-19 in FIG. 13;
FIG, 20 i8 a greatly enlarged view in vertical sec-tion taken along the line 20-20 in FIG. 15, and rotated ap-proximately 90;
FIG. 21 is an enlarged fragmentary sectional view of the lens member of FIG. 15, taken along the line 21-21 therein;
FIG. 22 i9 a diagrammatic view of a roadway illu8-trating prior art arrangements of pavement markers utilizing different types of pavement markers for daytime and nighttime _g_ ..
, l~B4465 visibility; and FIG. 23 is a view similar to FIG. 22, illustrating an axrangem~nt of pavement markers utilizing ~nly the pavement markers of the present invention for both daytime and ~ighttime visibility.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A pavement marker constructed in accordance with the present invention i8 shown in perspective at 10 in FIG. 1 and includes a body or base 20, of an opaque, light-diffus-ing synthetic resin having mounted thereon two lens membersof light-transmitttng synthetic resin, each generally desig-nated as 30.
The base 30 is substantially solid and is formed as a one-piece member to provide a durable structure capable of withstanding impact forces applied to the pavement marker when it i8 struck by a tire of an oncoming vehicle.
The pavement marker 10 is employed to provide a marking on a generally horizontal roadway surface, the mark-ing being visible from an oncoming vehicle on the roadway to delineate traffic lanes and for edge delineation, as is well recognized in the art. In addition, the pavement marker 10 of the present invention may be utilized with metal base mem-bers of the type illustrated and claimed in applicant's co-pending Canadian Application No. 277,306.
Referring now more particularly to FIGS. 5, 6 and 7, it will be seen that the base 20 has a generally horizon-tal bottom surface 21. In order to prevent sinks or shrink stre~ses in molding, the base 20 may be provided with a plu-rality of molding recesses 21A ~FIGS. 5 and 7). The base further includes a pair of generally vertically disposed .. . .. . .
iO8446~;
end wallæ 22 and 23 (FIG. 2), and a generally horizontal top wall 24 having ,a rectangular channel 24A extending from one end wall 22 to the opposite end wall 23.
There is provided a pair of inclined support walls 25, disposed at opposite sides of the base 20, and positioned such that in use, they will be facing the direction of oncom-ing vehicles. Each of these support walls 25 has a plurality of recesses 26 formed therein, which recesses have substan-tiàlly rectangular openings intersecting the plane of the wall, the portions of eadh support wall 25 between the reoesses 26 de-fining partiti3nscr dividing portions 25A. The recesses or pock-ets 26 and the support wail 25 cooperate ~'ith the'over~ying lens member 30 in a manner hereinafter described.
The base 20 further includes side edges 27 and 28 disposed on the opposite ends of each of the respective end wall~ 22 and 23, the side edges 27 and 28 extending outwardly beyond the support walls 25, and defining a channel between the opposite side edges and the adjacent support wall 25 dis-posed therebetween. The base 20 also includes a tab opening 29 formed in the end walls 22 and 23 adjacent to the respect-ive inclined support walls 25 for purposes of facilitating the alignment of the lens member 30 during attachment thereof to the base 20.
The lens member 30 which provides the reflective structure for reflecting light back toward the source there-of, thereby rendering the pavement marker highly visible at night, is best illustrated in FIGS. 4, 7, 8 and 9. The lens member 30 is formed of a light-transmitting synthetic resin and includes a substantially planar front face 31 and a rear face 32. As illustrated, the lens member 30 is gene-, 1~84~65 rally rectangular and is intended to be positioned in the channel provided by the side edges 27, 28 and the support wall 25.
The rear face 32 of the lens member 30 is provi-ded with a peripheral edge portion 33 which extends aboutthe entire periphery of the lens member 30 (FIG. 4) and includes a portion 33A which is originally in the form of a generally triangular bead ~FIGS. 8 and 9). The rear sur-face 32 further is provided with a plurality of dividing portions 34, the dividing portions 34 intersecting the peri-pher~l edge portion 33 at equally spaced distances there-along, thereby dividing the lens member into a plurality of generally rectangular areas circumscribed by the peripheral edge portion 33 and the dividing portions 34. As illustra-ted, the dividing portions 34 originally may include araised triangular sealing bead 34A, and hereinafter, in the specification, for convenience, the dividing portions 34 may be referred to as "dividing ribs".
The lens member 30 is intended to be positioned over the inclined support wall 25 of the base 2G and rigidly secured thereto, preferably by ultrasonic welding. When properly positi~ned, each of the rectangular areas circum-scribed by the peripheral edge portion 33 and dividing por-tions 34 will coextensively overlie and be in registry with the rectangular-shaped openings of the recesses or pockets 26 formed in the support wall 25, while the dividing portions 34 will overlie the dividing portions 25A of the support wall 25.
When the lens m~mber 30 is ultrasonically welded to the base 20, the sealing beads 33A and 34A become sub-~ ~o~4~6~
stantially flattened as a result of the energy imparted thereto during the ultrasonic welding process, whereby the peripheral edge portion 33 directly abuts the support wall 25, as best illustrated in FIG. 7, and provides a substan-tial welded surface area visible through the transparentlens member 30.
Similarly, the dividing ribs 34 will become sub-stantially flattened as they are sealed to the underlying dividing portions 25A of the support wall 25.
~he lens member 30 also includes an outwardly extend~ng tab 37 adapted to be positioned within the tab opening 29 on the base 20, and serves as a locator to fix the lens member 30 in position prior to welding.
After welding the lens member 30 to the base 20, each of the dividing wall portions 25A of the support wall 25, and the peripheral portion thereof, in cooperation with the dividing ribs 34 and peripheral edge portion 33, pro-vide a plurality of hermetioally sealed cells 35 having a rectangular configuration when viewed in a direction normal to the front face 31.
~ he pavement marXer lO is provided with a retro-directive oube-corner-type reflector system to effect the signal function of reflecting light back to the driver of an oncoming vehicle whose headlights illuminate the pavement marker.
As best seen in FIG. 4, the rear face of the lens member 30, in those rectangular areas circumscribed by the dividing ribs 34 and peripheral edge portion 33, is confi-gured to provide a plurality of cube-corner-type retrodir-ective reflector elements 40.
446$
In the embodiments illustrated herein, the cube-corner elements 40 are intended to be generally rectangular when viewed in a direction along the line of the cube axis, as be~t illustrated in FIG. 4A.
Each of the cube-corner elements 40 includes co-operating faces 41, 42 and 43, respectively, the faces in-tersecting to form first and second and third dihedral angles in a manner well known to those skilled in the art.
In the preferred embodiment illustrated, two of the dihedral angles would be on the order of substantially 90 whereas the third dihedral angle would be formed at an angle signi-ficantly different from the first and second dihedral angles, so that the light reflected by such cube-corner element is caused to be diverged to a greater extent in one direction than in the other. One such structure is set forth in grea-ter detail in applicant's Canadian Patent No. 966,529.
In the illustrated embodiment, the different dihe-dral angle is formed between those faces designated as 41 and 42 in FIG. 4A, whereby the reflectivity of the reflector will be substantially increased at a greater observation angle, as more fully demonstrated hereinafter.
AB seen in FIG. 7, the apices of the cube-corner reflective elements 40 extend beyond the peripheral edge portion 33 and the dividing ribs 34, and into the cell 35, when the lens member 30 is secured to the base 20. Al-though in the embodiment illustrated the cells 35 are sub-stantially large and ~pen, it should of course be under-stood that the pockets 26 may be recessed less deeply than indicated, and, in fact, the apices of the cube corners 40 may contact the underlying surface 26A defining the inte-~)84~65 rior boundary of the recess 26 thereby further to strength-en the lens member 30 and provide additional support there-for as the lens member lS contacted by a tire of an oncom-ing vehicle.
To facilitate installation of the pavement marker on an underlying roadway surface, or on a metal casting in the event the marker 10 is used in snowplow country, an ad-hesive impact-absorbing material or pad 15 is secured to the bottom surface 21 of the base 20. The pad 15 may com-prise an elastomeric polymeric adhesive material such as, for example, butyl rubber. A protective sheet of release paper 16 is applied to the bottom of the pad. In use, the paper 16 is peeled from the pad 15 and the pavement marker 10 pressed onto the roadway surface. In installation it may be desirable to use a suitable primer on the roadway to enhance securement of the pavement marker. Satisfactory butyl tape, T-9463, and primer, P-1130, are products of Protective Treatments, Inc. of Dayton, Ohio.
After the pavement is primed, the marker is posi-tioned on the primed road surface with light pressure, after which greater pressure may be applied by driving slowly over the marker with one tire of a service truck. The use of the adhesive pad 15 greatly facilitates installation of the pavement marker 10 on the roadway surface. More parti-cularly, this arrangement permits rapid installation of the pavement markers from a slowly moving vehicle, thereby ob-viating lane closures and their attendant inconvenience and safety hazards which were necessitated with prior art installation techni~ues.
It is believed that the impact-absorbing material ~ ?446S
15, together with the low profile of the marker 10 achieved by the low height thereof relative to the roadway surface, effects both a reduction and absorption of some of the im-pact energy normally transmitted through to the underlying pavement su~ace.
It is also believed that the low profile allows the pavement marker 10 to be ingested by a tire body 80 that the tire body rolls over the marker 10 and is still partially supported by the roadway surface, rather than causing the full load of the tire to impact upon the marker, which is what i8 thought to happen with existing markers of a higher elevation. Moreover, it is further believed that the low profile, in combination with the impact-absorbing material 15 on the bottom sur~ace 21 of the base 20, renders the in-dividual cell structure formed by the combined lens member30 and base 20 more resistant to impact damage.
An important feature of the present invention in leading to a reduction of the overall height of the marker is ~he provision ~f the recesses 26 in the support wall 25, rather than by providing the cells in a fashion where the walls are carried by the lens member 30 and extend beyond the apices of the aube corners 40. ~his fea~ure of the present invention permits reduction in the overall height of the lens member 30, and particularly the elements 40 thereof, relative to the bottom surace of the base 20.
It will be observed with reference to FIG. 8 that the cube-aorner elements 40 disposed toward the lower end of the lens member 30 extend outwardly to a greater ex-tent from the rear wall 32 of the lens member 30 than do those reflector elements disposed toward the upper end. The ~ ~ .
1~8446S
plane defined by the apices of the elements 40 is parallel to the front face 31, but is inclined at an acute angle ~
to the rear face 32 tFIG. 8). This feature alows a further reduction in overall helght of the marker, without requiring undesirable undercuts in the base 20, which otherwise would have to be provided therein if the cube corners 40 at the upper portion of the lens member extended outwardly as far as the lower elements.
As diqclosed in applicant's Canadian Patent 763,714, there is an optimum balance obtained in maintaining optical effectiveness by limiting abrasion and achieving adequate wiping or cleaning of the front face of the marker upon con-tact by a moving tire. Such optimum balance is achieved when the angle of the front face of the lens member i5 dis-posed at approximately 30 to the horizontal, with a satis-factory result being obtained where such angle is approxi-mately from 15 to 45. In general, abrasion resistance is directly proportional to the front face angle while self-cleaning ability is inversely proportional to the front face angle.
~ owever, the abrasive action on the front face of the marker due to tire contact becomes an even more critical factor than the aforementioned wiping or cleaning action when the pavement marker is used where abrasive ma-terials are purposely placed on the road. Thus, in an areawhere salt or sand is put on the road during the wintertime, the wiping action by such abrasive materials in contact bet-ween the tire and front face of the lens member causes more serious damage to the front face than is the case where those markers are located in other areas of the country where such . , , , ~ .
1~8446~
abras~ve m~terial~ are not on the roadway. In order to mini-mize the loss of reflectivity due to abrasion, and to prolong the reflective qualities of the pavement marker under these conditions, the front surface 31 of the lens member 30 of the present invention is preferably inclined at an angle of 45 relative to the horizontal surface 21 of the base 20. It will be appreciated that the effects of abrasion may be further mi-nimized by increasing the angle of the front face above 45;
however, it is believed that at front face angles above 60, the cleaning and wiping action by tire contact will be inade-guate to maintain optical effectiveness.
It is also known that the front surface reflection loS8 due to the inherent nature of the material of the lens member itself is less at 45 than at 30. As an example, the typical front surface reflection loss of a pavement marker in which the front surface of the lens ic located at 30 to the horizontal would be approximately 24%, whereas the front surface loss with the reflector at 45 to the horizontal would be only 12%. Also, by inclining the front face of the marker at 45, there-~s-a ~maller area e~posed to contact by automob~le tire studs or stones carried in the tire treads, and al o the pressure on the front surface is reduced. Fur-ther, by inclining the front face of the marker at 45, it is possible to further reduce the overall height of the mar-ker because there will be a lesser inclination of the cubeaxis relative to the horizontal than is provided in appli-cant's Canadian Patent 763,714, and it will not be necessary to tilt the cube-corner elements 40 as much.
To further protect the front surface 31 from exces-sive abrasion, and particularly from a grinding action by ~8~4~S
sand or salt being disposed on the roadways, the front sur-face 31 of the lens member 30 may be provided with abrasion-limiting means; in the illustrated embodiment such means comprise a plurality of outwardly extending ridges 45. The operation of the ridges 45 is set forth in the copending C~ian application 277,305. The ridges 45 are disposed directlyover and in alignment with the dividing ribs 34 on the back face 32 of the lens member 30, whereby the ridges 45 do not in-terfere with the operation of the reflex portions 40 on the lens membe~ he ridges 45 may be integrally molded with the lens member 30, or, if desired, they could be made of a more abrasion-resistant material than the lens member and thereafter secured to the lens member 30 by welding or ad-hesive, thereby to provide further protection for the front surface of the marker.
As previously described, the side edges 27 and 28 extend outwardly beyond the inclined support walls 25 of the base 20, and provide a channel between the side edges a~d the support wall 25 within which is disposed the lens member 30. The side edges 27 and 28 provide further structural sup-port and protection for the lens member 30 adjacent those areas in which the ultrasonic welding occurs at the corners of the marker, thereby serving to substantially protect the integrity of the marker at those points. It will also be noted that the side edges 27-28 and the front edges of the protective ridges 45 lie in the same plane, in effect defin-ing a protective barrier for the front face 31 of the marker 10.
The pavement marker 10 also may be provided with a metal cover plate 19 to overlie and protec~ the entire top 1~8446~
wall 24 thereof, the cover plate 19 also extending beyond and overlying the upper edge of the lens member 30, as best seen in FIG. 3. The metal cover plate 19 is intended to be u~ed on those embodiments of the pavement marker 10 which are to be installed in a metal casting and subje~ted~ to possible contact by studded snow tires passing over the top of the marker, the cover plate serving to provide additional protection against such studs.
The cover plate 19 may be adhesively secured to the top wall 24 or, alternatively, a second impact-absorb-~ng pad (not shown) may be fixedly secured therebetween.
As the use of tire studs becomes more widely prohibited, the metal plate and recessed channel may be eliminated.
The rectangularly shaped longitudinally extend-ing channel 24A provided in the cover plate 19 and in the top wall 24 i8 adapted to receive a retaining member in a well-known manner, the retaining member serving to further hold the pavement marker in place on the underlying metal casting, if such retaining member is desired.
The arrangement of the lens member 30 with its peripheral transparent edge portion 33 and dividi~g ribs 34, and the underlying light-diffusing opaque support wall 25, imparts substantial daytime visibility to the pavement marker 10 rendering it of greater utility than prior mar-ker5.
In the illustrated embodiment, the total area oc-cupied by the peripheral edge portion 33 and the dividing ribs 34 is substantially equal to that occupied by the re-trodirective reflector elements 40 in those areas circum-scribed by the edge portion 33 and the dividing ribs 34.
~84465 By using rectangular retrodirective cube-corner elements 40 and rectangular cells 35, maximum use of the area of the lens member 30 is accomplished, as there will be no partial cube-corner elements along the edge of any cell, while at the same time it is possible to substantial-ly completely fill the area circumscribed by the peripheral edge portion 33 and the dividing ribs 34 with retrodirect-ive reflective elements 40.
Further, the use of the rectangular cells 35 and square reflector elements 40 permits the use of vertical side wall surfaces in each recess 26 of the marker, if de-sired, whereby su~stant~ally the full width of the marker 10 is provided with complete reflective elements.
The opaque, light-diffusing base 20 serves to reflect daylight impinging thereon to an observer. At a distance, the unifoxm spacing of the dividing ribs 34 and dividing wall portions 25A causes the pavement marker to appear as a substantially uniform reflective body, with the cells 35 te~ding to disappear to the eye of the ob-server under daylight conditions. Alternatively, undernighttime driving conditions, the uniform size and spacing of the cells 35 causes the pavement marker to appear as a uniform reflective member, the dividing ribs 34, which im-prove daytime visibility, tending to disappear under eve-ning driving conditions.
To achieve these benefits, together with a lowprofile, it is believed that the maximum rectangular pro-jected dimensions of each cell 35 should not exceed about .3 inches high and about .75 inches wide, with the pre-ferred construction providing cells substantially square ~34465 in projected view with a projected height of approximately .3 inches and a projected width of approximately .36 inches.
While the preferred embodiment has eight such rectangular cells therein, it is believed that a minimum of five cells is required in order to obtain the substan-tial daytime reflective qualities achieved by the present marker and to preserve nighttime reflectivity of the mar-ker in the event of damage to one or more of the cells, which would cause it to lose its hermetic seal and thereby ultimately render it optically ineffective.
Despite having at least half of its projected area devoted to wall structure for providing strength and daytime visibilit~, the pavement marker 10 of the present invention also provides substantially improved reflectivity over that of Canadian Patent 763,714. As an ex~ple, the table set forth herebelow indicates representative figures for typi-cal units of the marker of Canadian Patent 763,714 contrasted with the present invention at two different observation angles.
It will be observed that a pavement marker of the type of the present invention ~s almost two and one-half times bright-er at a .2 observation angle, corresponding to a distance of approximately 500 feet, and almost five times brighter at a .4 observation angle, corresponding to a distance of about 250 feet.
.
l REPRESENTATIVE BRIGHTNESS
Candlepower per Fo tcandle per_Square Inch of Reflector i Observation Angle 3,332,327 Patent Present Invention .2 1 3 . i 40 _ _ I~ 1.5 8 ;
_ 44~S
The increased brightness of the present inven~ion permits the reduction in height of the marker ~ithout any loss in specific intensity, as indicated in the table below.
¦ SPECIFIC_INTENSITY
~andlepower per Footcandl . .
Ob3ervation Angle 3,332,327 Patent Present Invention .2 ` 6 4o 3 8 Moreover, the specific intensity of the present invention is 3$gnificantly greater at .4 observation angle than that of the marker of Canadian Patent 763,714 for a smaller area, thereby causing the marker of the present in-vention, though of a low profile, to be ~ubstantially brighter in appearance.
In the embodiment illustrated, the height of the ba5e 20 from the bottom horizontal surface 21 to the top wall 24 i8 approximately .43 inches; the pad 15 i8 approxi-mately .06 inches, for a total height above the roadway of approximately .49 inches, as contrasted with the overall height of the pavement marker manufactured in accordance with Canadian Patent 763,714 of approximately .72 inches.
Moreover, an epoxy adhesive normally was utilized to apply the pavement marker of Canadian Patent 763,714 to the pave-ment, or, in those in3tances in which a pad was used, therewould be a further increase in height Gf the prior marker of up to .06 inches. Thus, the present invention represents a reducti4n of about 38~ in overall height.
The front face of the lens member 30 is disposed at an angle of approximately 45 to the horizontal surface .
~ 4465 21, while the support wall 25 is inclined at an angle of approximately 41. The ridges 45 on the front face 31 of the lens member 30 are positioned at angles of approxi-mately 53 relative to the horizontal surface 21 and simi-larly the side edges 27 and 28 forming extensions of the side walls 22 and 23 also are inclined at angles of appro-ximately 53 relative to the underlying æurace 21. It will be apparent from the foregoing that the outer edges of the ridges 45 and the side edges 27 and 28 thereore are substantially coplanar and provide a protective area for the front surface of the lens member.
The base 20 may be made of a thermoplastic resin such as acrylonitrile butadiene styrene ~commonly known as ABS), glass-filled ABS, methyl methacrylate or rubber-modi-fied methyl methacrylate ~commonly known as Plexiglass DR~
or Lexan (T.M.), or may be made of a thermosetting material and be adhesively mounted. The lens may be of methyl meth-acrylate or a rubber-modified methyl methacrylate or a poly-carbonate such as Lexan.
Normally, the lens and base will be chosen to provide the same colors, day and night, with the specific color being determined by the specific function of the marker, e.g., lane delineation vs. median edge delineation.
The embodiment of the pavement marker illustrated in FIG. 10 is primarily intended to be used independently of any metal housing or casting. In that embodiment the top wall 24, rather than being generally horizontal, as in the first embodiment illustrated in FIG. 1, instead has surfaces 47 and 48 which incline upwardly in the same general direction as the support walls 25, the inclined , ~ - . : , , . ':
~ 4465 surfaces 47 and 48 forming a crown above the he~ght of th~ lens member to provide additional reflective body area for reflecting daylight back to an observer. The metal cover plate 19 would of course not be used with this marker which would preferably be used under non-snowplowable conditions. The added crown at the top of the base 20 increases the overall height of the marker by about another .06 inches, whereby the total height of such marker would be approximately .55 inches.
Referring now to FIGS. 11, 12 and 16 through 19 of the drawings, there is illustrated another embodi-ment of the pavement marker of the present invention, generally designated by the numeral 50, and comprising a body or base 60 of an opaque, light-diffusing synthetic resin having mounted thereon two of the lens members 30.
The base 60 is substantially solid and is formed as a one-piece member to provide a durable structure capable of withstanding impact forces applied to the pavement marker 50 when it is struck by a tire of an oncoming ve-hicle. More particularly, the base 60 has a generallyhorizontal bottom surface 61 having a plurality of gene-rally rectangular molding recesses 62 formed therein for the purpose of preventing sinks or shrink stresses during the molding of the base member 60. The molding openings 62 extend well up into the base 60 and cooperate to define therebetween a plurality of substantially vertically ex-tending partitions or walls 63 and a pair of upstanding opposed side walls 64 and 68 interconnected by a top wall 69 which is peaked or gabled to form two halves each in-0 clined at a slight angle to the plane of the bottom sur-: . . .:
-face 61. There is also provided a pair of inclined sup-port walls 65, respectively disposed at opposite sides of the base 60, and positioned such that in use they will be facing the directions of onc~ming vehicles. Each of the support walls 65 has a plurality of recesses 66 formed therein, which recesses have substantially rectangular openings intersecting the plane of the outer surface of the support wall 65, the portions of each of the support walls 65 between the recesses 66 defining septa or divid-ing portions 67.
The top wall 69 of the base 60 has inclined top - surfaces 70 and 71 which respectively extend upwardly from the upper ends of the outer surfaces of the support walls 65 and intersect along a line substantially parallel to the support walls 65 and midway therebetween. Each of the end walls 64 and 68 i8 provided at the upper end thereof with upstanding shoulders 72 and 73 which respectively project upwardly above the top surfaces 70 and 71 of the top wall 69 and outwardly beyond the outer surfaces of the support walls 65, the shoulders 72 cooperating with one of the sup-port walls 65 to define a channel therealong and the shoul-ders 73 cooperating with the other of the support walls 65 to define a channel therealong. Preferably, each of the side walls 64 and 68 i8 also provided with a tab opening 74 therein adjacent to the corresponding inclined support wall 65 for purposes of facilitating the alignment of the lens members 30 during attachment thereof to the base 60.
The lens members 30 were described above in con-nection with the pavement marker 10, and each of the lens members 30 is mounted on the base 60 and cooperates there-iS)~4~6S
~ith in the same manner as was described above with respect to the base 20 of the pavement marker 10. More particular-ly, each of the lens member 30 is positioned over one of the inclined support walls 65 of the base 60 and rigidly gecured thereto, as by ultrasonic welding, with the rectan-gular areas circumscribed by the peripheral edge portion 33 and dividing portions 34 coextensively overlying in registry with the rectangular-shaped openings of the recesses or pock-e~s 66 formed in the support walls 65, while the dividing portions 34 overlie the dividing portions 67 of the support walls 65. When the lens members 30 are ultrasonically welded to the base 60, the sealing beads 33A and 34A become subs~an-tially flattened so that the peri~heral edge portion 33 dir-ectly abuts the support wall 25 and provides a substantial welded surface area visible through the transparent lens mem-bers 30. Similarly, the dividing ribs 34 become substantially flattened as they are sealed to the underlying dividing por-tions 67 of the support walls 65. The tabs 37 are respectively adapted to be positioned within the tab openings 74 of the base 60 and serve to fix the position of the lens members 30 prior to welding. After welding, the lens members 30 cooperate with the associated suppor~ walls 65 to provide a plurality of her-metically sealed cells as described above.
It is an important feature of th~s invention that the dimensions of the molding openings 62 are such that none of the base walls 63, 64, 65, 68 or 69 has a thickness greater than 1/8 inch. ~he purpose of this arrangement is to minimize molding time, since, in general, the molding time is proportional to the thickness of the members being molded. It has been found that a wall thickness of 1/8 .. . . . . . . .
" i~B446S
inch corresponds to a molding time of approximately 3a sec-onds. This reduced molding time conQiderably reduces the cost of the manufacture of the base 60.
The pavement marker 50 may be installed on the S pavement in the same manner as was described above with respect to the pavement marker 10, an adheQive pad 15 of impact-absorbing ma~erial being utilized.
The pavement marker 50 i8 primarily intended to be used indep~ndently of any metal housing or casting, the inalined top ~urfaces 70 and 71 forming a crown above the he~ght of the lens membQrs 30 to provide additional reflect-ive body area for reflecting daylight back to an observer.
The metal cov~r plate 19 would of course not ba used with the pavement marker 50, which would preferably be used under non-snowplowable conditions. In a con~tructional model of the pavement marker 50, the overall height of the marker, including the adhesive pad 15, i8 approximately .62 inches, the outer surfaces of th~support walls 65 being inclined at approximately 41 to the surface of the pavement, 80 that the front face of each of the lens menbers 30 is inclined at an angle of approximately 45 to the horizontal. In use, ths front edges of the ridges 45 of the lens members 30 lie in the ~ame plane as the front edges of the shoulders 72 and 73 of the base 60, in effect defining a protective barrier ~or th~ front faces 31 of the lens mernbers 30 in the pave-m~nt markor S~.
Referrlng now also to FIGS. 13 through 15, 20 and 21, there i~ illustrated another em~odiment of the pavement marker of the present ~nvention, generally de~ignated by the numeral 100, and inaluding the base 60 having mounted thereon i~8446S
two.lens members, each generally designated by the numeral 80.
Each of the lens member 80 is similar in contruction to the lens member 30, with the exception that the lens members 80 are not provided with the outwardly extending protecti~e ridges 45. More particularly, the lens member 80 is formed of a light-transmitting synthetic resin and includes a sub-stantially 1at front face 31 and a rear face 32~ As illus-trated, the lens member 80 is generally rectangular and is intended to be positioned in the channel provided by the shoulders 72 and 73 and the support walls 65. The rear face 82 of the lens member 80 is provided with a peripheral edge portion 83 which extends about the entire periphery of the lens member 80 ~FIG. 15) and includes a portion 88 which is originally in the form of a generally triangular bead (FIGS.
20 and 21~. The rear surface 82 fur~her i8 provided with a plurality of dividing portions 84, the dividing portions 84 intersecting the peripheral edge portion 83 at equally-spaced distances therealong, thereby dividing the lens member 80 in-! to a plurality of generally rectangular areas circumscribed by the peripheral edge portion 83 and the dividing portions 84. As illustrated, the dividing portions 84 originally may include a raised triangular sealing bead 89, and here-inafter, in the specification the dividing portions 84 may be referred to as "dividing ribs".
~he lens member 80 is intended to be positioned over the inclined support wall 65 of the base 60 and rigid-ly secured thereto, preferably by ultrasonic welding~ When properly positioned, each of the rectangular areas circum-scribed by the peripheral edge portion 83 and dividing por-tions 84 will coextensively overlie and be in registry with ~ 8446S
the rectangular-shaped openings of the recesses or pockets 66 formed in the support wall 65 while the dividing por~ions 84 will overlie the dividing portions 67 of the support wall 65.
When the lens member 80 i5 ultrasonically welded to the base 60, the sealing beads 88 and 89 become substan-tially flattened as a result of the energy imparted thereto during the ultrasonic welding process, whereby the peripheral edge portion 83 directly abuts the support wall 65, as best illustrated in FIG. 19, and provides a substantial welded qurface area visible through the transparent lens member ao.
Similarly, the dividing ribs 84 will become substantially flattened as they are sealed to the underlying dividing por-tions 67 of the support wall 65. The lens member 80 also includes an ou~rdly extending tab 87 adapted to be posi-tioned within the tab opening 74 on the base 60, and serves as a locator to fix the lens member 80 in position prior to welding.
After welding the lens member 80 to the base 60, each of the dividing wall portions 67 of the support wall 65, and the peripheral portion thereof, ln cooperation with the dividing ribs 84 and peripheral edge portion 83, provide a plurality of hermetically sealed cells 85, each having a rectangular config~ration when viewed in a direc-tion normal to the front face 81.
The lens member 80 is provided with a retrodir-ective cube-corner-type reflector system to effect the signal function of reflecting light back to the dr~ver of an oncoming vehicle whose headlights illuminate the pave-ment marker. As best seen in FIGS. 15 and 20, the rear ~Ot:~4465 face of the lens member 80, in those rectangular areas circumscribed by the dividing ribs 84 and the peripheral edge portion 83, is configured to provide a plurality of cube-corner-type retrodirective reflector elements 90.
The retrodirective reflector elements 90 are diagrammati-cally illustrated in FIGS. 13 and 15 as a crisscross pat-tern of lines, but it will be appreciated that these re-flector elements may be identical in construction to the reflector elements 40 described above in connection with the lens member 30 in FIGS. 8 and 9.
As seen in FIGS. 19 and 20, the apices of the cube-corner reflector elements 90 extend beyond the peri-pheral edge portion 83 and the dividing ribs 84, and into the cell 85, when the lens member 80 is secured to the base 60. Since the pavement marker 100 is intended prima-rily for use independently of a metal housing or casting in non-snowplowable applications, no protective ridges such as the ridges 45 of the lens members 30 are necessary in the lens members 80. But the abrasion resistance of the lens member 80 may be substantiaily increased by the pro-vision of a layer 95 of protective material such as glass or the like overlying and adhered to the front face 81 of the lens member 80. Preferably, the glass layer 95 has a thickness of approximately .005 inches and is secured by a layer of suitable adhesive material of between about .006 and .012 inch thick to the front face 81 so as substantially to cover all of the portions of the front face 81 which over-lie the retrodirective cube-corner reflector elements gO of the lens member 80. It has been found that the use of this glass layer ~5 has dramatically increased the abrasion re-~a~446s sistance of the lens member 90, as is more fully explained in the aforementioned copending application Serial No. 277,305.
The use of the glass overlay significantly reduces the degrad-ation of the brightness of the lens member 80 as a result of S normal wear in service.
Also, the arrangement of the lens member 80 with its peripheral transparent edge portion 83 and dividing ribs 84, and the underlying light-diffusing opaque support wall 65, imparts substankial daytime visibility to the pavement marker 100, rendering it of greater utility than prior markers.
~he opaque, light-diffusing base 60 serves to reflect daylight impinging thereon to an observer and, at a distance, the uni-form spacing of the dividing ribs 84 and dividing wall portions 67 cau~es the pavement marker 100 to appear as a substantially uniform reflective body, with the cells 85 tending to disappear to the eye of the observer under daylight conditions.
The base 60 and the lens members 80 may respect-ively be constructed of any of the materials set forth above with respect to the base 20 and lens members 30, but preferably the base 60 and lens members 80 are both formed of a rubber-modified methyl methacrylate such as that sold under the trademark "PLEXIGLAS DR".
PLEXIGLAS DR, because it is rubber modified, gives higher impact resistance than unmodified Plexiglas; but re-portedly it i8 a softer material than the unmodified Plexi-glas. Because of this, it was expected that PLEXIGLAS DR
would not prove sufflciently abrasion resistant for use in pavement markers. Surprisingly, pavement markers of the character disclosed herein molded of PLEXIGLAS DR proved to be as abrasion resistant as those of unmodified Plexiglas.
.
Thus, the pavement markers of the present inven-tion have very great daytime as well as nighttime visibili-ty, as well as being substantially cheaper to manufacture than prior pavement maxkers. This affords substantial ad-vantages and economies in application of the pavement mar-kers. More particularly, referring to FIG. 22, there is illustrated a prior art arrangement of pavement markers as a lane marking on a roadway 110. This typical arrangement includes a combination of day~ime and nighttime markers substantially equidistantly spaced apart, and arranged 80 that there are about four daytime markers 116 (such as the so-called "Botts D~ts") or 117 ~such as painted stripes) between every two nighttime markers 115. The nighttime markers 115 may, for example, be of the type of retrodir-ective reflector markers disclosed in the aforementionedCanadian Patent No. 763,714, which markers have a high nighttime visibility over a substantial distance and, therefore, can be widely separated on the pavement. But these prior art nighttime pavement markers 115 have a rel-atively low daytime visibility. Therefore, the Botts Dots 116 or the painted stripes 117 are typically utilized at their normal spacing~ between the nighttime markers 115 to achieve the necessary visibility both in daylight and at night.
But the daytime visibility of the pavement mar-kerR of the present invention is so superior to that o the prior art markers 115 that they can be utilized eect-ively as both daytime and nighttime markers and can, there-fore, be utilized in lieu of the prior type daytime mark-ings at the normal marker spacings on the pavement, as il-1~844~$
lustrated in FIG. 23. This offers several significant advantages. First of all, since only one type of pavement marker is utilized in thisarrangement, only one type of ;
application equipment need be used, thereby reducing the
5 time and expense of installation. Moreover, fewer total markers for the same distance are needed--four instead of five or eight instead of nine--depending upon state requirements. There are additional safety benefits, be-cause the system of pavement markers of the present in-10 vention requires no lane closures and requires less fre-quent installation than the prior art arrangement illus-trated in FIG. 22. Furthermore, the pavement markers of f the present invention have been found to have better day- ;
light visibility in the rain than the painted lines 117 15 of the prior art systems. Finally, the system has added safety benefits over present installations because the same pattern of reflected signals appears to the motorist under day and night driving conditions.
The above detailed description is provided by 20 way of example only. Various details of design and con-struction may be modified without departing from the true spirit and scope of the invention as defined in the appen-ded claims.
light visibility in the rain than the painted lines 117 15 of the prior art systems. Finally, the system has added safety benefits over present installations because the same pattern of reflected signals appears to the motorist under day and night driving conditions.
The above detailed description is provided by 20 way of example only. Various details of design and con-struction may be modified without departing from the true spirit and scope of the invention as defined in the appen-ded claims.
Claims (9)
1. A reflex reflector incorporating a base member including a support surface having a plurality of separate recesses therein and a transparent light-transmitting lens member having a front face and a rear face, said rear face of said lens member having discrete groups of reflex-reflecting elements thereon, said lens member being affixed to said base member with said rear surface of said lens member being in contact with said support surface and each of said groups of reflex-reflecting elements being located in a corresponding one of said recesses to form a plurality of discrete reflex-reflector zones capable of reflect-ing light impinging upon said front face of said lens member back toward the source thereof.
2. A reflector according to claim 1, wherein said reflex-reflecting elements are of the cube-corner type.
3. A reflector according to claim 2, wherein each of said discrete groups of cube-corner elements substantially completely fills one of said recesses.
4. A reflector according to claim 1, wherein said base member is formed of an opaque, light-diffusing synthetic resin and wherein the areas of said base member covered by said transparent lens member not occupied by said reflex-reflecting elements reflect daylight impinging upon the front face of said lens member.
5. A reflector according to claim 1, wherein said lens member is heremetically sealed to said support surface around each recess, whereby each of said groups of said reflex-reflecting elements is located in a hermetically sealed cell.
6. A reflector according to claim 1, wherein at least one of said base member and said lens member is formed of a rubber-modified methyl methacrylate material.
7. A road marker comprising a reflex reflector, said reflex reflector incorporating a base member including a support surface having a plurality of separate recesses therein and a transparent light-transmitting lens member having a front face and a rear face, said rear face of said lens member having discrete groups of reflex-reflecting elements thereon, said lens member being affixed to said base member with said rear surface of said lens member being in contact with said support surface and each of said groups of reflex-reflecting elements being located in a corresponding one of said recesses to form a plurality of discrete reflex-reflector zones capable of reflecting light impinging upon said front face of said lens member back toward the source thereof.
8. A road marker according to claim 7, wherein said base member has a bottom surface and said front face of said lens member is generally planar and is so oriented as to make an acute angle of between 15° and 60° with said bottom surface.
9. A road marker according to claim 8, wherein an adhesive impact-absorbing material is secured to said bottom surface for fixedly securing said road marker to an underlying support surface.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US68185976A | 1976-04-30 | 1976-04-30 | |
| US681,859 | 1976-04-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1084465A true CA1084465A (en) | 1980-08-26 |
Family
ID=24737144
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,303A Expired CA1084465A (en) | 1976-04-30 | 1977-04-29 | Pavement marker |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1084465A (en) |
-
1977
- 1977-04-29 CA CA277,303A patent/CA1084465A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |