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(11) | EP 0 299 386 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Prefabricated continuous road marking tape having optical and electromagnetic function |
| (57) A prefabricated continuous road marking tape is described, which includes retroreflecting
optical components, light emitting diodes (LEDs), solar cells, storage batteries,
and reflectors and transmitters of electromagnetic waves. There are given examples of the use of the reflectors in order to control the speed of a vehicle which travels at the side of the tape, and examples of the use of erasable programmable read only memories (EPROMs) where messages are recorded, with the purpose of giving informations about the conditions of the road, the presence of ice or of traffic jams, said messages being transmitted by a radio-transmitter. |
[0001] The continuous horizontal road-marking tape technology is reaching by the present application a further important improvement. Applicant, starting almost twenty years ago, has developed layered road-marking tapes, and later on the use of electric energy and of electromagnetic energy in the technique of the road-marking has been developed.
[0002] In this last specific field following patents may be cited:
No. 641.585 in Switzerland
No. 491.399 in Spain
No. 80-10745 in France
No. 539,631 in Australia
No. 233,797 in Argentina
No. 883,208 in Belgium
No. 1,149,491 in Canada
No. 1,050,769 in the UK
No. 80 03002 in Brazil
No. 80 03558-7 in Sweden
[0003] As a matter of fact, the denomination "Road marking tape" is today very vague, because the informations supplied by the tape include not only optical irradiations, but also electromagnetic irradiations, that one has to suitably transform.
[0004] As we are referring to horizontal road-marking tapes, of course the road-marking effect is the more important function and, consequently, the tape has to include retroreflective elements, light emitting diodes (LEDs), solar cells, storage batteries, and the tape has to be in position to exploit only that solar energy which is incident on the tape.
[0005] On the other hand, we have not yet reached a high level safety if we dont exploit the contribution of electromagnetic energy, transmitted by the low layers of the tape.
[0006] The following are specific examples where the contribution of the electromagnetic energy is nearly vital:
1) Dangerous locations: One cannot be always aware of a dangerous location in the road which requires a
reduction in vehicle speed. In such case, the warning impulse has to come from the
tape, e.g. from a gigaherz reflector dipped in a layer of adhesive, and positioned
upon the low layers of the tape.
Said warning impulse originates the activation of a comparator placed on the vehicle
and, consequently, the activation of an optical or an acoustical indicator within
the vehicle.
2) Presence of ice: This hazard is very important, since the presence of ice cannot be seen. A negative temperature control (NTC) acti vates an EPROM (erasable program read only memory) chip and, consequently, a megaherz transmitter, which is positioned, together with its antenna, upon the low layers of the tape. A message for reduction of speed is then emitted.
3) Traffic jam: This hazard is becoming more and more frequent today, with drivers sometimes loosing their tempers. In this case, as it will be explained in detail later on, the drivers intervene as the vehicle presses an emergency microswitch placed under the tape. The EPROM, the megaherz transmitter and its antenna are consequently activated, but at the same time a one-directional light emitting tape is activated for discharging the jam.
[0007] From the above examples it appears consequently obvious that both types of irradiations are useful and necessary, i.e., optical and electromagnetic irradiation.
[0008] Before describing the electromagnetic irradiation, let us detail the structure of the tape which has assured the best results.
DESCRIPTION OF THE DRAWINGS
[0009]
Fig. 1 is an exploded, fragmentary schematic view showing in side elevation and top plan the several layers of a tape constructed according to the present invention.
Fig. 2 is a fragmentary top plan of a third tape layer 6 which includes various groups of equidistant metallic stripes 26 adhering to the tape.
Fig. 3 is a fragmentary top plan of tape shielding layer 10.
Fig. 4 is a schematic, showing a suggested gigaherz transmitter and receiver.
Fig. 5 is a schematic of a mode utilizing a negative temperature control (NTC) device 46 for warning the vehicle driver as to the presence of ice on the roadway.
Fig. 6 is a fragmentary top plan showing the employement of parallel signalling tapes 56,62 for signalling a traffic jam and activating directional signals so as to direct vehicles away from the traffic jam.
[0010] Reference is made to fig. 1, with the remark that not all the layers shown have to be necessarily present in the tape. A cross-section and a plane view of every layer are shown.
[0011] The upper layer 2 is a wear resistant film made of polyurethane resin, which is since more years securing the best results. Upper layer 2 is pigmented in order to ensure the best visibility by day; retroreflecting components 14 are applied upon it, and at 16 there is represented one of the transparent protrusions, in which there are placed light emitting diodes (LEDs), solar cells, storage batteries and the like.
[0012] The following intermediate layer 4 consists of a non-woven fabric, strongly impregnated with a polyurethane prepolymer, which provides the mechanical properties of the tape.
[0013] The third layer 6 includes antennas and reflectors 18, which are dipped in adhesive, schematically shown in fig. 1, and which will be described in detail later on.
[0014] The fourth layer 8 consists of the circuits connecting the electric and the electromagnetic components, which circuits are concretized by conductive stripes 20, dipped in adhesive.
[0015] The fifth layer 10 is the EMI (electromagnetic interference) shielding layer, which has the function of protecting the electromagnetic elements from disturbing interferences coming from the ground. Layer 10 consists of a dispersion of conductive particles, or of a metallization, schematically shown at 22. Good results have been obtained by using high percentage nickel dispersions in acrilic prepolymer, like the nickel dispersions manufactured by the firm Metalgalvano Sozzi of Rovello Porro (Italy) or the acrilic coating 3M110 manufactured by Minnesota Mining & Manufacturing Co.
[0016] Since the aforedescribed tape has a certain cost, even if not very high, we need to have the possibility of removing the tape to another locality. To this purpose, the sixth layer 12 is consisting of a strong, extensible webb, strongly impregnated by an adhesive, which has a good adhesion to the road surface, but at the same time allows removal of the tape without damaging it, said layer being illustrated in plane view by 24.
[0017] Returning to the functions of the tape, gigaherz reflector 6, shown in Figs. 1 and 2, which reflects back electromagnetic energy irradiated by the vehicle, and is located on the low layers of the tape, is fundamental for the control of the speed of the vehicle. Gigaherz reflector 6 is concretized by multiple conductive stripes 26 dipped in adhesive, illustrated in Fig. 2, which stripes are positioned at an angular direction - usually 15° - related to the direction of vehicle traffic. This angular feature assures good reception of the reflected waves at the side of the tape, within a sufficiently wide lateral lane.
[0018] As shown in fig. 2, reflector 6 consists of several groups of equidistant metallic stripes 26, adhering to the tape, for example metal foils of 1 mm width, every group being marked by a different distance between the stripes: e.g, in fig. 2 there are shown two groups, 28 and 30, wherein the metal foils have a different spaced apart distance.
[0019] Gigaherz reflector 6 shows a diffuse reflection behaviour in elevation, and since the position of the vehicle on the road may vary within a certain space of several meters perpendicularly to the direction of the traffic, the reflection maxima should be as close as possible within the reflection diagram.
[0020] Good results have been obtained by choosing, for a space of 0-4 meters, four groups of stripes, with a first group having a spaced apart distance of 2 cm between each stripe, of 1,8 cm spaced apart in a second group, of 1,6 cm spaced apart in a third group, and of 1,4 cm spaced apart in a fourth group. More than five stripes 26 have been used in every group, with the length of each stripe 26 being at least 50 cm, but usually much more.
[0021] In fig. 3 there is shown the shielding layer 10, concretized as described, and which shielding is somewhat wider than the group of the reflectors, in order to obtain the best possible shielding effect.
[0022] In fig. 4 there are schematically shown the techiques for transmission and reception. These occur at a frequency in the field of the gigaherz, advantegeously, for example, at 24 GHz.
[0023] Transmitter 32 on the vehicle consists of a frequency stability oscillator, which is connected by means of a coupling 34 to a horn antenna 33, which has an angle of 45 with respect of the road surface, and irradiates towards the reflector 36, which here is only schematically shown.
[0024] The energy returning from reflector 36 is received by another horn antenna 35, also placed on the vehicle, and is conducted to mixer 38, from which a frequency fD comes out, which is the difference between the frequency emitted by antenna 33 and the one received by antenna 35. In fact, as the reflector 36 is swept at a certain speed, the transmission and reception frequencies will not be the same, because of the Doppler effect.
[0025] The signal, from mixer 38 is conducted to a high-pass filter and 80 dB amplifier 40, then to low-pass filter 42, and finally to a comparator and pulse former 44.
[0027] The first method is based on the impulses originating from the metal stripes 26, upon sweeping of the transmitted waves on the tape, the waves frequency, and only refers to vehicl- speed. The impulses build an impulse train, such that the threshold of the comparator 44 is overpassed and an indicator is activated. The second method is more sure. Comparator 44 of fig. 4 includes a generator of a tuning note, fitted for a selected speed, which provides impulses of a certain form and frequency. When the refleczed waves and the impulses provided for a selected speed are overlapping, an indicator on the vehicle is activated. This described technology is very well known.
[0028] The control of vehicle speed in dangerous locations is very important, and one can predict a kind of a "black box" for these dangerous locations in order to compel the vehicles drivers to reduce speed.
[0029] As mentioned in accordance with an embodiment of the invention, the composite road marking tape which is the object of the present invention includes a small radiotransmitter 52 (fig. 5) operating at a frequency in the megahertz field, and which irradiates messages recorded in EPROM. Said transmitter 52, which has a very low consumption of energy, for example 8 mW, is fed by small storage batteries which in their turn are fed by solar cells placed on the tape, as it was specified concerning the transparent protrusions 16 of fig. 1.
[0030] The messages recorded in EPROM and transmitted under the action of suitable controls, may be of different kind, and two of them, of particular importance, are here described.
[0031] In fig. 5 a mode is shown which warns the vehicle driver as to the presence of ice. It utilizes a Negative Temperature Control - NTC 46, consisting of sensor 48 and of calibration device 50; the EPROM 51 consists of an integrator 47, memory 49, and amplifier 53; the transmitter 52 has a dipole-antenna 54.
[0033] Another very important hazard is the traffic jam. In fig. 6 there is shown how a traffic jam may be signaled, and how indicators may be activated in order to discharge the traffic jam.
[0034] There are illustrated two signaling tapes 56, 62, placed in parallel, and connected by means of an electric cable (not illustrated).
[0035] Tape 56 is a conventional marking tape, and tape 62 is an emergency tape. On tape 56 there are shown the transparent protrusions 60, in which LEDs, solar cells, storage batteries are placed, as within those transparent protrusions 16 of fig. 1. There are provided also, at predetermined locations, compressible portions 61, in which a microswitch is placed. Concerning such compressible tape, see applicant's European Patent No. 0100524 and US Patent No. 4,685,824.
[0036] In case of a traffic jam, a vehicle driver who takes the initiative, or a traffic policeman, activates the microswitch by placing his car on the compressible portion 61. This activates an alarm system like the one which has been aforedescribed for signalling the presence of ice. On the one hand, a message "traffic jam" is transmitted, on the other hand the tape 62 is activated; on said tape 62 there are provided transversal pulsing lights 66, of red color, and longitudinally aligned pulsing lights 64, of green color. Lights 64 guide the traffic towards a direction which is opposite to the normal direction, towards an exit. The pulsing of the lights 64 may be very rapid.
[0037] The traffic in the opposite direction may take place on the overtaking lane or on the mergency lane, as possible in the particular situation.
[0038] At the same time, a further entry of vehicles in the concerned portion of the highway must be prevented, and to this purpose at the beginning of said traffic jam portion a red light (not illustrated) will be lighted. Furthermore, a couple or more couples of sensors are placed at the beginning of the concerned traffic jam portion, so that if a car enters in the forbidden direction, notwithstanding the red traffic light, its plate will be identified by a camera.
[0039] Tje circuits which are required in order to concretize what described above pertain to a known technique.
a) an upper face layer having protrusions including an electrical circuit having
operably interconnected:
I. retroreflective components
II. solar cells
III. storage batteries
IV. light emitting diodes (LEDs), and
V. transmitting units exploiting only the solar energy incident on the tape itself,
the roadmarking function of the tape being based upon the optical irradiations originating
from the upper face layer of the tape; and
b) at least one lower layer, including electromagnetic irradiation means in the form of reflectors, together with an EMI shielding from road bottom perturbations.
I. a microswitch placed within a compressible portion of said tape, said microswitch being activated upon compression by a vehicle positioned on said compressible portion;
II. an EPROM connected to said microswitch so as to transmit a message concerning a traffic jam; and
III. a series of directional lights activated by said microswitch, so as to divert vehicular traffic during a traffic jam.
a) a wear resistant upper face and
b) an impregnated non-woven layer, and said lower face further including:
I. a gigaherz reflector supported at a distance from a megaherz antenna activated
by a megaherz transmitter positioned on the tape;
II. a circuit layer with conductive net stripes dipped in adhesive;
III. an EMI shielding layer with extensible textile web, so as to allow removal of
said tape from the road surface.