GB2314107A

GB2314107A - Road visibility system

Info

Publication number: GB2314107A
Application number: GB9612221A
Authority: GB
Inventors: Steven Vince Carroll
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-06-12
Filing date: 1996-06-12
Publication date: 1997-12-17
Also published as: GB9612221D0

Abstract

A road visibility system 10 comprises a plurality of units 12 and communication means 14, 54, which may be optical or electrical, operative between the units 12 such that light shone on one unit 12 causes light to be emitted from at least one further unit 12. Also disclosed is a road visibility unit comprising first means for converting the energy of sunlight into a storable form, second means for converting the stored energy into light, and control means activated by sunlight to control the second means.

Description

A VISIBILITY SYSTEM The invention relates to a visibility system.

An example of a visibility system is a system of cat's eyes on a road. A known cat's eye comprises a pair of glass bullets having reflective rear surfaces which are mounted in a large metal casting. The glass bullets are mounted in a separate sub-assembly which is resiliently mounted in the casting for up and down movement. A wiper is mounted on the casting so that when the bullets are moved downwards by a vehicle driving over the cat's eye, their front faces are wiped clean by the wiper.

The cat's eyes are laid in the middle of the road with the casting being sunk into the road surface and sealed in place with bitumen. The glass bullets with their reflective surfaces reflect incident light from a car's headlights. The car driver will thus see reflections from the cat's eyes which are within the pool of light from his headlights. When a car is driving with dipped beam, for example, because another car is coming in the opposite direction, the pool of light from his headlights will be relatively small and also will be biased toward the side of the road away from the cat's eyes so that it will be difficult to see how the road direction changes ahead. In particular, the stopping distance of a car at 60mph, the current legal U.K. speed limit on "A" roads, is much greater than the length of the pool of light from dipped beam headlights. Also, once the road has turned by a certain amount, the cat's eyes will be at the wrong orientation to reflect light back to a driver and so only the initial part of any turn in the road can be seen, and that may be seen too late to slow down.

According to the invention, there is provided a visibility system comprising a plurality of units and communication means operative between the units such that light shone on one unit causes light to be emitted from at least one further unit.

In this way, the units can be used in place of the known cat's eyes on a road and units which are outside the pool of light from a car's headlights will still emit light towards the driver so that he can see the direction that the road turns. This additional information significantly increases the safety of driving in particular where there are sharp corners or in the circumstances of a fast road with frequent traffic in the opposite direction such that driving with dipped beam is necessary.

In a preferred embodiment, the communication means includes means to conduct light from one unit to another. The light conducting means may take any suitable form and may comprise at least one optic fibre. The or each optic fibre may exhibit substantially total internal reflection or may be arranged to emit a significant proportion of light along its length. Each unit may include means to direct light into the light conducting means and the directing means may include a lens and/or a prism.

Each unit may include means to output light from the light conducting means and the output means may comprise a lens and/or a prism.

In an alternative embodiment the communication means may include a photosensitive cell in each unit. The communication means may include an LED in each unit.

The communication means may further include a wire linking the units to carry an electric signal. Thus, in this case light incident on the photoelectric cell creates an electrical signal which is transmitted down the wire to the next unit to light an LED which can be seen by a driver. The LED's are preferably connected in series.

Each unit may include a reflector which may take any suitable form.

The communication means may take any suitable form and may include infra-red or other transmitted wave communication devices between the units. Preferably however the communication means includes a line between each of the units. The line is preferably encased in a casing and the casing may be sufficiently strong to be driven over by a road vehicle.

Each unit may be of any suitable outer shape and preferably is substantially cylindrical in outer shape. In this way, the unit can be fitted in the road by boring a cylindrical hole to receive the unit.

Each unit may include a casing from which the remainder of the unit can be removed. The casing is preferably cup shaped. In this way, if the road needs to be re-surfaced, the main part of the unit can be removed from the casing for re-use and the units need not be dug up.

According to another aspect of the invention there is provided a road visibility unit comprising first means for converting the energy of sunlight into a storable form for storage in a store, second means for converting the stored energy from the store into light, and control means activated by sunlight to control the second means.

The store may be a battery and the first means may be a photosensitive diode. The second means may be an LED.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1 shows a car on a road including the system of the first embodiment of the invention; Fig. 2 is a side elevation in partial crosssection of a unit of the first embodiment in a road; Fig. 3 is a front elevation in partial crosssection of the unit of Fig. 2; Fig. 4 is a top plan view of the unit of Fig. 2; Fig. 5 is a diagrammatical view of the lens system of the first embodiment; Fig. 6 is a simplified view of one part of Fig.

5; Fig. 7 is a simplified view of another part of Fig. 5; Fig. 8 is a side elevation in cross-section of a unit of the second embodiment in a road; Fig. 9 is a front elevation in cross-section of a unit of Fig. 8; and Fig. 10 is a perspective view of part of a unit of a third embodiment.

The system 10 of the first embodiment comprises a plurality of units 12 linked by optic fibres 14 which exhibit substantially total internal reflection for efficient transmission of light. The units 12 are mounted in the road in the same position as the known and are linked by the optic fibres 14. Each unit 12 is substantially cylindrical and comprises a ribbed, cup shaped casing 16 which encases the main part 18 of the unit 12. The casing 16 includes a plurality of axially spaced radially extending flexible ribs 20.

While the outer surface of the casing 16 is generally cylindrical, the inner surface is frusto-conical and includes axially extending screw threaded bores 22 to receive bolts 24. The main part 18 of each unit 12 includes a complementary part to fit into the frustoconical interior of the casing 16 and includes a generally part spherical cap 28. The main part 18 includes plain bores 30 which extend from the upper surface of the cap 28 and are aligned with the screw threaded bores 22 to receive the shank and head of the bolts 24 to secure the main part 18 of the unit 12 to the casing 16.

A plastic pipe 32 extends between each two adjacent units 12 of the series and encases the optic fibres 14. The plastic pipe 32 is laid in a trench so as to be under the road surface and meets each unit 12 at about half of its height. The optic fibres 14 within the plastic pipe 32 enter the unit 12 through an aperture 34 in the side of the casing 16 and a further aperture in the side of the casing 18. The optic fibres 14 rise to the cap 28 of the unit 12 and are directed at lenses 36,38. The lenses 36,38 are mounted in the centre of the cap 28 and the cap includes two sector shaped cut outs 40 one to each side of the lenses 36,38 and subtending an angle of about 60 . The side walls 42 of the cut outs are reflective. The wall 46 in which the lenses 36,38 are set is also reflective. There are four optic fibre paths on each side of the lenses 36,38. The lenses 36,38 are arranged one above the other. The lower lens 36 is a convex lens, and the upper lens 38 is a concave lens. On each side of the convex lens 36, an optic fibre path commences. Each optic fibre path is arranged to conduct light from the convex lens 36 to the concave lens 38 of the succeeding unit 12 in the series to be emitted from that unit 12. A semireflecting surface 44 is provided at the end of the optic fibre path at the concave lens 38 such that a proportion of the light arriving at the concave lens 38 is emitted through the lens 38 while a proportion of the light is reflected into a further optic fibre path to be carried to a further concave lens 38 in the next unit 12 to be emitted there. Thus, on each side of each convex lens there is a single optic fibre path and on each side of each concave lens 38 there are three optic fibre paths as shown in Fig. 5. Each optic fibre path may be served by one or a bundle of optic fibres. The individual connections are shown in Figs. 6 and 7 in which Fig. 6 shows the optic fibre path from a convex lens 36 to a concave lens 38 to show the collection of light at one unit 12 and the emission of light from the next unit 12, while Fig. 7 shows the optic fibre path between two concave lenses 38 to show how light delivered to a concave lens 38 is partly emitted and partly reflected into an optic fibre path connecting to the next concave lens 38.

Each unit 12 may comprise a single concave lens 38 and a single convex lens 36, as shown in Fig. 5, or alternatively each unit 12 may include two of each type of lens 36,38, one facing in each direction. In the arrangement shown in Fig. 5, part of the light delivered through optic fibres 14 to one side of a concave lens 38 will be directed at optic fibres on the opposite side of the lens 38 and so the light emission will not be as high although the cost of the unit will be reduced.

As shown in Fig. 1, in use, a car 47 driving along the road 48 will cast a pool of light 49 from its headlights. The units 12a, b, c within the pool 49 will reflect light from the lens walls 46. The lenses 36 of the units 12a, b, c within the pool of light 49 will direct light through the optic fibres 14 to units 12d, e outside the pool of light 49 which will be emitted through the concave lenses 38 of those units 12d, e to guide the driver of the car 47 who otherwise would not be able to see the extent of the approaching bend in the road 48.

The concave lenses 38 may be coated with a coloured gel so that the light emitted is coloured, e.g. red, green or blue, in the same manner as certain cat's eyes currently, for example at motorway junctions.

In the second embodiment, the convex lenses 36 of units 12 are replaced by photosensitive diodes 50 and the concave lenses 38 are replaced by LED's 52. The optic fibres 14 are replaced by electrically conducting wires 54. Each unit 12 includes two LED's 52, one facing in each direction, and two photosensitive diodes 50, one facing in each direction. The LED's 52 facing in one direction are connected in series and the photosensitive diodes 50 facing in that same direction are connected to the wire linking the LED's 52. In this way, when light is shone onto the photosensitive diodes 50 facing in one direction, the LED's 52 in the neighbouring unit 12 will be lit. The LED's 52 outside the pool of light incident on the units 12 will be lit with steadily diminishing intensity corresponding to the diminishing electrical signal.

In a further embodiment, a wiper blade may be resiliently mounted for upwards'and downwards movement in front of the central part of the unit 12 on which the lenses 36,38 or photosensitive diode 50 and LED 52 are mounted so as to wipe clean those components when the unit 12 is driven over by a vehicle. Equally, the central part 56 of the unit 12 may be resiliently movable with respect to a fixed wiper blade, but the first arrangement is preferred to avoid possible fatigue damage to the connecting wires 54 or optic fibres 14.

In order to lay the system into a road, a tine is drawn along the centre of the road to create a trench.

The casing 32 containing the optic fibres 14 or wires 54 is laid into the trench and covered over with bitumen or other appropriate material and at intervals, a cylindrical bore is cut and a unit 12 is pushed into the bore with the flexible ribs 20 holding the unit 12 in place. The unit 12 may further be sealed in place using bitumen or other suitable material. If it is desired to re-surface the road, the bolts 30 can be undone and the main part 18 of the unit 12 can then be lifted out pulling the wires 54 or optic fibres 14 with it for re-use. The casing 16 and tubes 32, which are firmly fixed into the road, can be left in place and covered over.

In an alternative embodiment, the casing 32 may be substantially flat and may be laid on the surface of the road being adhered in position with the bitumen or the like. The casing must of course in this case be sufficiently strong to be driven over by a vehicle.

In a further embodiment which is similar to the first embodiment units 12 are linked by optic fibres 14 which exhibit partial internal reflection. Such fibres 14 are also called side glow" fibres. The fibres 14 are aligned side by side. In this case the lenses 36,38 are replaced by a prism 60 which has its lower horizontal force 62 on top of the fibres 14.

In use light from a car headlight is shone onto a sloping face 64 of the prism 60. The light is refracted through the lower face 62 of the prism 60 into the fibres 14 and thus along the fibres to the next unit 12. As light is emitted in all directions from the fibres 14, some of the light will be refracted by the next prism back towards the driver, which some of the light will be emitted redundantly in the opposite direction.

In order to reduce losses the optic fibres 14 have a reflective coating, except on the surface which is under the prism 60, to reflect light back into the fibres 14.

This arrangement is considerably simpler and less expensive than the first embodiment although the losses in light transmission are greater.

In a further embodiment a Fresnel lens may be provided between the prism 60 and the optic fibres 14.

In another embodiment which is similar to the second embodiment, the photosensitive diodes 50 face upwardly and are connected to a battery, in the unit 12 which is also connected to the LED 52. There is no connection between the units 12. In daylight the photosensitive diode 50 will charge the battery. When there is no signal from the photosensitive diode 50 the battery will be switched to power the LED 52 so that at night the battery will light the LED 52. The LED 52 will thus be lit permanently at night.

In a variation on the second embodiment a single chip transponder may be used between the units 12 to introduce a delay in transmission of the signal from one unit to the next. This increases efficiency as more power is available to each unit and also will create a flashing effect which is more effective in attracting the eye.

Claims

1. A visibility system comprising a plurality of units and communication means operative between the units such that light shone on one unit causes light to be emitted from at least one further unit.

2. A visibility system as claimed in claim 1, wherein the communication means includes means to conduct light from one unit to another.

3. A visibility system as claimed in claim 2, wherein the light conducting means comprises at least one optic fibre.

4. A visibility system as claimed in claim 3, wherein the or each optic fibre is arranged to emit a significant proportion of light along its length.

5. A visibility system as claimed in claims 2, 3 or 4, wherein each unit includes means to direct light into the light conducting means.

6. A visibility system as claimed in claim 5, wherein the light directing means includes a lens and/or a prism.

7. A visibility system as claimed in any of claims 2 to 6, wherein each unit includes means to output light from the light conducting means.

8. A visibility system as claimed in claim 7, wherein the output means comprises a lens and/or a prism.

9. A visibility system as claimed in claim 1, wherein the communication means includes a photosensitive cell in each unit.

10. A visibility system as claimed in claim 1 or 9, wherein the communication means includes an LED in each unit.

11. A visibility system as claimed in claims 9 or 10, wherein the communication means further includes a wire linking the units to carry an electric signal.

12. A visibility system as claimed in claim 11 when dependent on claim 10, wherein the LED's are connected in series.

13. A visibility system as claimed in any preceding claim wherein each unit includes a reflector.

14. A visibility system as claimed in any preceding claim, wherein the communication means includes a line between each of the units.

15. A visibility system as claimed in claim 14, wherein the line is encased in a casing.

16. A visibility system as claimed in claim 15, wherein the casing is sufficiently strong to be driven over by a road vehicle.

17. A visibility system as claimed in any preceding claim, wherein each unit is substantially cylindrical in outer shape.

18. A visibility system as claimed in any preceding claim, wherein each unit includes a casing from which the remainder of the unit can be removed.

19. A visibility system as claimed in claim 18, wherein the casing is cup shaped.

20. A visibility system substantially as described herein with reference to Figs. 1 to 7, 8 and 9 or Fig.

10 of the accompanying drawing.

21. A road visibility unit comprising first means for converting the energy of sunlight into a storable form for storage in a store, second means for converting the stored energy from the store into light, and control means activated by sunlight to control the second means.

22. A road visibility unit as claimed in claim 21, wherein the store is a battery.

23. A road visibility unit as claimed in claim 21 or claim 22, wherein the first means is a photosensitive diode.

24. A road visibility unit as claimed in claim 21, 22 or 23, wherein the second means is an LED.

25. A road visibility unit substantially as described herein with reference to Figs. 1 to 7, 8 and 9 or Fig.

10 of the accompanying drawings.