Illumination – With static structure – Pavement
Reexamination Certificate
2001-05-29
2004-09-14
Sember, Thomas M. (Department: 2875)
Illumination
With static structure
Pavement
C404S009000, C404S012000
Reexamination Certificate
active
06789915
ABSTRACT:
The invention relates to a road-marking system comprising:
at least a first and a second road-marking unit each having an emission surface, the first unit comprising a first light source and the second unit comprising a second light source.
Such a road-marking system is known from WO-00/20691 (PHN 17533). The road-marking system is used in traffic-control systems for marking traffic routes for vehicles, such as roads for cars and other road users, and runways for aircraft. One of the methods used by traffic planners in their attempts to reduce traffic jams is a so-called “tidal flow system”. In such a dynamic system, the direction of the traffic of multi-lane roads is changed in one or more lanes in accordance with the direction of the main flow of traffic. In an alternative embodiment, the number of lanes available to traffic moving in a specific direction is increased or reduced in dependence on the amount of traffic. A problem with these methods lies in the indication of the direction of the desired flow of traffic for a specific lane in a flexible manner, or in the actual changing of the arrangement of the traffic route in a flexible manner. Known means for indicating the desirable direction of the flow of traffic include signaling lights beside or above the traffic route.
Said road-marking systems cannot only be used as dynamic road-marking systems; they can also be given static applications. Static applications of road-marking systems include marking parts of traffic routes (for example straight parts or bends) so as to give guidance to the direction of the traffic under certain weather conditions, for example during fog, rain, black ice, etc., and/or under certain light conditions, such as daylight, twilight, a low position of the sun, night, etc.
Road-marking systems may be provided beside and/or above the traffic route, for example on a crash barrier alongside the traffic route. Road-marking systems may also be provided in a road surface of the traffic route by making recesses therein, in which recesses the known systems are to be inserted and retained. The known road-marking systems have the disadvantage that the method of making said recesses is cumbersome and difficult and leads to relatively large decrease in the mechanical strength of the road at the locations of the recesses.
It is an object of the invention to provide a road marking system of the type described in the opening paragraph in which this disadvantage is counteracted.
According to the invention, this object is achieved in that each unit has a shape adapted to a saw-cut recess for accommodating the unit. Such a recess made in a (solid) body, for example a road, in which the unit is to be accommodated, is simple and easily obtainable by a movement perpendicular to a surface of said body by a saw. The movement may also be skew with respect to said surface, resulting in a skew recess in which the unit is positioned at an acute angle to said surface. Such a position of the unit enables a reduction of the risk of impact damage and tilting of the unit with respect to said surface due to forces exerted by vehicles. Preferably, the recess for accommodating the unit has a cylindrical bottom part in the shape of a circular segment, in which case the saw, for example, is a circular saw. The recess thus obtained in the body, for example in a road made of asphalt or concrete or ZOAB, i.e. “Zeer Open Asfalt Beton” in English “open-pore bituminous concrete”, has smooth walls which a relatively great mechanical strength. Contrary to the method of making the recess used for the known unit with the aid of a milling cutter, an extra number of voids in these walls is avoided because particles are cut in the method of making the recess for the unit of the system according to the invention instead of being thrown out. Since the unit and the recess are adapted to each other, the unit has a narrow fit in the recess. A unit accommodated in the recess thus bears for a substantial portion on the walls of the recess and is kept positioned thereby. The adapted shape of the unit achieves that the emission surface of the unit projects only to a small extent, for example by 3-4 mm, above a road surface of the road provided with the recess.
In the description of the current invention, a “light source” is defined as a subunit which emits (visible) light, the origin of said light not necessarily being situated at the location of the light source. For example, light emitted by the light source may also be generated at a distant location and be transmitted, for example, by means of light waveguides, such as optical fibers, from a so-called light generator to the “light source”. The term “light source” generally does not refer to light generated by reflection of light, in particular light emitted by a vehicle which is reflected at the location of the “light source”. Furthermore, in this description, light beams which show a “uniform overlap” are to be taken to mean light beams which cannot be distinguished by the human eye under the above-mentioned conditions.
Light issues from the first and the second light source at an angle &agr; of 0.1-25° with the road surface. The light has a beam width angle of about 45° enabling it to be seen by a viewer at an angle &agr; of at least 45° with the road surface. It is achieved by the measure in accordance with the invention that a road user, for example a motorist or a truck driver who, from his vehicle, looks ahead at the traffic on the road and the markings in the road surface, observes from a distance equal to or above 40 m that the light beams originating from the first light source in the first road-marking unit and from the second light source in the second road-marking unit show a uniform overlap. Light originating from the first and the second light source at an angle &agr; of 0.1-8° with the road surface is perceived as an imaginary “white” line under said conditions. The light has a beam angle of about 45° enabling it to be seen by a viewer under an angle of 45° with the road surface. This is the case particularly if the light originates from a plurality of such light sources, for example a suitably chosen (two-dimensional) arrangement of light sources. A particularly suitable arrangement of light sources is a one-dimensional array of four light sources per unit. Said four light sources, which extend transversely to the direction of view of the road user, are so closely spaced that the human eye cannot distinguish these four light sources at a distance equal to or greater than 40 m. Said units situated in the extension of the observation field of the road user are provided, in accordance with the inventive measure, in such a manner that, given the viewing angle of the observer, light beams originating from the light sources of said units show a uniform overlap at a distance equal to or above 40 m. An observer situated at a distance greater than or equal to 40 m from the entire arrangement of a number of units with four light beams originating from each of said light sources, the angle of view of the observer ranging between 0.1 and 8°, will perceive said used said arrangement of light beams as an imaginary line in the road surface. The present invention may be used particularly effectively if the distance a between the road user and the first light source is in a range of: 40 m≦a≦100 m.
Preferably, a distance d between the first and the second unit lies in a range of between 10 and 25 cm. In this manner, a good display of the imaginary line is obtained by means of a limited number of units. If the distance d is smaller than 10 cm, a large number of units are necessary to achieve the desired effect. For distances above 25 cm, the coherence of the units is such that they are no longer perceived as forming a coherent object (imaginary line) by the road user. Particularly suitable is a distance d in the range between 15 and 20 cm.
The road-marking system of the invention is built up from independent units, which may, however, be electrically connected. The independent units do not form
Konings Leonardus Urbanus Emile
Raaijmakers Antonius Henricus Maria
Van Bochove Gerrit Gijsbertus
Van Der Poel Lucas Leo Desiree
Bartlett Ernestine C.
Choi Jacob Y.
Koninklijke Philips Electronics , N.V.
Sember Thomas M.
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