WO2005056926A1

WO2005056926A1 - A road information display device, a road surveillance system comprising such device and a compact electrical power generator therefore

Info

Publication number: WO2005056926A1
Application number: PCT/DK2004/000865
Authority: WO
Inventors: Lars Christensen
Original assignee: Pl Brake
Priority date: 2003-12-15
Filing date: 2004-12-15
Publication date: 2005-06-23

Abstract

The invention concerns to a road information display device comprising a display area comprising a plurality of light emitting elements for the display of a multitude of signs; and a compact electrical power generator connected to said display area; wherein the compact electrical power generator comprises a combination of a wind turbine generator and a solar cell generator provided on said display device. Also, it concerns a road surveillance system, comprising at least one road information display device according to the invention, comprising an external communication connection. The compact electrical power generator is suitable for supplying electricity for a road information display device and a road surveillance system according to the invention, comprising a combination of a wind turbine generator and a solar cell generator. Accordingly, a road information display device, a road surveillance system and a compact electrical power generator is provided, which provides a durable, safe, and sufficient autonomous electrical supply for the functions of such a device and system.

Description

A ROAD INFORMATION DISPLAY DEVICE, A ROAD SURVEILLANCE SYSTEM COMPRISING SUCH DEVICE AND A COMPACT ELECTRICAL POWER GENERATOR THEREFORE

The present invention relates to a road information display device comprising a display area comprising a plurality of light emitting elements for the display of a multitude of signs, and a compact electrical power generator.

Further, the present invention relates to a road surveillance system, comprising at least one road information display device according to the invention, comprising an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof.

In addition, the present invention relates to a compact electrical power generator suitable for powering said road information display device.

Many types of road information display devices are available, i.e. fixed or removable road signposts or traffic lights presenting information like local speed limits, prohibitory or mandatory signs, and red, green and yellow signs. Conventional road signs are often provided on a reflector background, which requires a minimum of maintenance. However, in recent years, the use of light emitting elements in road signs in the form of LED's has increased due to their present low cost and high efficiency. Accordingly, a problem to be solved is the electrical power supply for such road signs. Solutions to this problem has been suggested by several road sign suppliers by the provision of e.g. batteries and battery charging means, such as solar cell chargers, of which examples may be found in FR 2 748 040, UK-A- 2,397,706, and US 6,053,658. Other, less practical alternatives are transportable generators, when only a few road signs are to be supplied, such as at a road work or accident site, or net supplied road signs in urban areas or in other areas, where the net supply is close at hand, such net supplied road signs remaining high in installation and maintenance costs.

Several problems are associated with such prior art road signs having each their own power supply. Firstly, the battery accumulator needed for the service provided is relatively large depending upon display service for the sign and light intensity needed, and must be placed in the vicinity or even upon the road sign, which may result in a rather heavy road sign. As several road safety authorities impose strict requirements upon road signs due to road safety during impact, such as maximum weight, position of centre of mass, and provision of a breakage point when a pole is provided, these requirements are hard to meet for the prior art road signs.

Patent application DE 40 02 337 describes a fixed warning device for alerting cars going the wrong way, such as "ghost-riders", which device comprises a solar cell and battery accumulator provided upon a post having warning lights and further comprises a car direction detector, which is provided away from the warning device. Said warning device is limited in it versatility, because the warning lights and the direction detector must be placed fixedly in relation to each other, i.e. are intended for permanent placement.

Further, traffic and road conditions surveillance systems are available, e.g. as described in the patent US 6,243,644, which disclose a device for mounting on an existing stop sign, which device is able to monitor movement, alert pedestrians and drivers to the sign, and to store and report traffic movements to a remote monitoring station with a telephone transceiver. However, the disclosed device is not suited for any other application than as a motion detector for alerting drivers to a stop sign.

The aforementioned electrically autonomous road information displays and road surveillance system all suffer from one inherent problem. This problem is the low solar power output from the solar panels provided, which is evident in geographical areas, in which solar light is scarce, e.g. in Denmark, where the weather and seasons reduces the solar light quantity. Solar cells and rechargeable batteries are sufficient for most low current applications in countries with a medium to high solar light input. But when the known road information displays and road surveillance system are subjected to moisture, overcast skies, wind, extreme temperature fluctuations, and to a high risk of impacts from vehicles, combined with the fact that the available space for the required solar panels is limited, the existing road information displays and road surveillance system are not suitable in these geographical areas.

Accordingly, the object of the present invention is how to provide an electrically autonomous road information display device and road surveillance system, which evades the above mentioned problems and provides a durable, safe, and sufficient autonomous electrical supply for the functions of such a device and system.

This object is achieved by a road information display device comprising a display area comprising a plurality of light emitting elements for the display of a multitude of signs; and a compact electrical power generator connected to said display area; characterized in that the compact electrical power generator comprises a combination of a wind turbine generator and a solar cell generator.

The object is also achieved by a road surveillance system, comprising at least one road information display device according to the invention, comprising an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof.

The inventive concept underlying the present invention is the provision of a compact electrical power generator suitable for supplying electricity for a road information display device and a road surveillance system according to the invention, said compact electrical power generator comprising a combination of a wind turbine generator and a solar cell generator; in which said solar cell generator is disposed on the exterior surface of said wind turbine generator and has a surface provided with solar cells, which is rotatably mounted for enabling maximum exposure of said solar cells to the available solar radiation, and in which said wind turbine generator is comprising a substantially vertically rotatable shaft provided with at least two radial arms, which distal ends are provided with each their wing element extending with one surface substantially perpendicular to the respective arm, the joint between the distal end of each arm and corresponding wing element being flexible in the rotation plane.

Accordingly, a road information display device, a road surveillance system and a compact electrical power generator is provided, which provides a durable, safe, and sufficient autonomous electrical supply for the functions of such a device and system.

The invention will in the following be described in detail with reference to the accompanying schematic drawings, in which:

Fig. 1 and 2 are front and side views of a road information display device according to a first embodiment of the invention; figs. 3A, 3B, 3C are elevated perspective exploded views of the road information display device of fig. 1 and 2; fig. 4 is side view of the wind turbine generator in a device according to the first embodiment; fig. 5 is a perspective view from the bottom of the wind turbine generator in fig. 4; figs. 6A, 6B, 6C, 6D are front, side, and elevated perspective views, respectively, of a sender unit in a road surveillance system according to the present invention; fig. 7 is an elevated perspective view of a road information display device according to a second embodiment of the invention; fig. 8 is a parts list for a road information display device according to the invention; and fig. 9 is a perspective view of a road surveillance system according to the present invention.

In fig. 1 and 2 are shown a front and side view, respectively, of a road information display device according to a preferred first embodiment of the invention, in which said device generally comprises a display area 10, a compact electrical power generator 20, a pole 30 and a battery housing 40, which is adapted for a subsurface arrangement, said battery housing accommodating a battery accumulator (not shown).

The display area 10 comprises a background plate 14 provided with a plurality of LED's or light emitting diodes as light emitting elements 12 for display on the front side of the road information display device 1, i.e. the side facing towards an approaching vehicle. In an advantageous embodiment of the present invention, the background plate 14 is further provided with a plurality of light emitting elements 12 for display on the back side of the road information display device 1, i.e. the side facing towards a ghost driver or a car in the reverse gear. In fig. 1, only the emitting light elements are shown, forming the numbers "90". Obviously, several of the light emitting elements 12 are not shown as they are not emitting light in figure 1. The main part of the background plate is preferably provided with said plurality of light emitting elements, which are individually activatable, in order to enable the road information display device to show different signs, e.g. red, yellow, green light, prohibitory or mandatory traffic signs such as stop, or do not enter. Said display area 10 is protected against environmental influences by a transparent screen element 102, which preferably is provided with venting holes and an inclining surface for the prevention of formation of condensation, by providing a chimney effect, which keeps the transparent screen element substantially mist-free. The background plate 14 texture may be selected from the group consisting of transparent, reflecting, i.e. reflector surface, coloured e.g. grey, black or metal colour and combinations thereof.

Due to power consumption considerations, the individually activated LED's may advantageously be supplied with a double net frequency, i.e. in the order of 100-120 Hz in order to provide a non-flickering sign, in combination with a automatic delay process, such that the time period for a light emitting series is increased from e.g. a series once each 6 seconds to a series once each 30 seconds.

Examples of such light emitting signs series are: Blue round flashes continually flashing at a frequency of 4 Hz for indicating an accident area, a yellow arrow downwardly pointing to the right or left at a frequency of 2 Hz or once every 1 second to indicate drive around to the right or left of the sign, red stop sign, continuously flashing at a frequency of 2 Hz or once each second, yellow speed limit indication, e.g. 90 km or mph, continuously flashing at a frequency of 2 Hz or once each second. These signs may advantageously be used when alerting drivers of road conditions ahead, such as traffic lines, accidents, fog, ice, smoke, ghost drivers, and the like.

For the provision of sufficient electrical power at least for supplying said light emitting elements 12 the road information display device 1 further comprises a battery housing 40 accommodating a battery accumulator, said battery housing 40 being adapted for subsurface placement, and a compact electrical power generator 20, where both will be described below, for providing the electrical power to charge said battery accumulator via the preferably hollow pole 30 accommodating the electrical power connections (not shown) there between, said pole 30 being supported by said battery housing 40. Said battery accumulator may be a fuel cell. The road information display device 1 may additionally comprise a connection to the electrical supply net for providing supplemental electrical power, if required. In order to provide for enhanced road safety and to live up to authority requirements, the pole 30 preferably is provided with a breakage point 32 at a predetermined distance from ground level, said distance being laid down in road safety regulations, which breakage point distance for example in Denmark being at least 7 cm above ground level. Also imposed by road safety regulations may be a provision of the total weight of the road information display device 1 being low or reduced by using light weight materials, i.e. aluminium, poly carbonate, plastic composite materials or combinations thereof or other light weight and strong materials for the constituting parts, i.e. the display area 10, the compact electrical power generator 20, and the pole 30. Further, the provision of the battery accumulator under ground is an advantage, because, during impact with a vehicle, this removes a relatively large part of the total mass being encountered by the vehicle from the road sign or display device. Thus, no road safety regulations impose limitations upon the maximum weight of the battery accumulator, which increases the power potentially available from said accumulator.

Further, the compact electrical power generator 20 is provided in the top part of the road information display device in order to move the centre of mass up along the pole, reducing impact risk to a vehicle and passengers therein, i.e. the display device may be more heavy in the top part. Another advantage provided by such a position of the compact electrical power generator 20 is the improved positioning in relation to maximum solar input and wind action.

Said battery housing and battery accumulator are preferably provided with a locking arrangement 70, which locks the battery accumulator in place inside the battery housing for preventing theft of the battery accumulator. Further, a provision may be made for removing the total display device in one handling step by forming the locking arrangement 70 is such a way, e.g. like a cover or lid, that when unlocking the locking arrangement, the assembly comprising the compact electrical power generator 20, the display area 10, the pole 30, and the battery accumulator is easy to lift away from the battery housing 40 remaining in the ground, by suitable lifting devices. The battery accumulator is preferably provided in a self contained, environmental impact protecting battery accumulator unit 420, substantially to protect against humidity and to ease removal of said unit 420, when the battery accumulator needs to be replaced. The battery housing is provided with extendable wings (not shown), which during mounting of the battery housing for attachment to the ground are able to protrude into the surrounding ground. This provides for a securing of the display device and the securing of the relatively heavy battery accumulator below ground level, providing further impact safety for a colliding vehicle. Preferably, said battery housing 40 or said battery accumulator unit 420 is provided with isolation material, protecting the battery accumulator from sudden and high temperature fluctuations.

The compact electrical power generator 20 comprises a combination of a wind turbine generator 22 and a solar cell generator 24, as shown in fig. 1 and 2. The solar cells 242 of the solar cell generator 24 are preferably disposed on the exterior surface of said wind turbine generator 22 for providing maximum solar input exposure. The solar cells and the wind turbine are independently rotatable around a vertical axis, preferably a common vertical axis.

As shown in fig. 3, 4, and 5, said wind turbine generator 22 comprises a substantially vertically rotatable shaft 228 provided with at least two radial arms 2262, which distal ends are provided with each their wing element 226 extending with one surface substantially perpendicular to the respective arm 2262, the joint between the distal end of each arm and corresponding wing element being flexible in the rotation plane. The profile of the wing elements 226 may preferably be substantially a profile termed "neutral", i.e. the NACA 0012 standard, where reference is made to "Theory of Wing Sections", I. H. Abbott, A. E. Von Doenhoff, Dover Publications Inc. p. 463, and may be provided with rounded edges for preventing injuries if fingers are entered into the path of the rotating wing elements. By joining the wing elements 226 on front side of or on the back side of their neutral point and by controlling them flexibly, e.g. by a leaf spring or rubber element at the joint, an advantage is achieved by allowing the wind to turn the wind turbine generator by overcoming the start impulse, i.e. the wind elements 226 are moving just slightly due to the flexible joint to provide the rotational impulse needed for a start of the wind turbine generator. Rigidly fixed wings would not turn the wind turbine. Preferably, the wing elements are provided with flyweights for regulation of the power output at high wind speeds to provide a stall function, when a predetermined maximum wind turbine rotation speed is achieved in order to mechanically protect the integrity of the wind turbine, because the wind elements 226 are turned by a maximum wind speed to such a degree in their flexible joints, that they practically deflect the wind power exerted upon them. The flyweights, spring or rubber element and neutral point is adapted for an optimal performance. The wind turbine has a power capacity in it self to be able to supply the main part of the electricity needed during the dark winter in the northern hemisphere (and southern as well). The rotor and generator 26 for the wind turbine are mounted upon the pole and the transmission there between is a non-lubricated toothed wheel gear. The rotatable shaft 228 is provided with an attachment ring 28 and is preferably a hollow extension of the pole 30 for accommodating the electrical line to the battery accumulator, and for providing an advantageous effect of providing further chimney effect and cooling for the electricity line and the solar cell generator. The supporting surface for the solar cells 242 is mounted rotatably upon the pole, and may be provided with a bottom plate for closure. Preferably, said rotating movement may be provided by a step motor (not shown), accommodated under the supporting surface of the solar cells 242.

The lower boundary of the solar cell generator 24 preferably rests upon the upper boundary of the wind turbine generator 22, where said boundaries may be integrally formed, where this provides an added advantage of the wing elements 226 of the wind turbine generator 22 is cooling the solar cell generator 24 during rotation of said wind turbine generator by the force exerted by wind upon the wing elements 226, said effect being enhanced by the "chimney effect" of such a combination construction. Alternatively, the upper boundary of the wind turbine may be provided as a plate with a axially upwards extending conical shape for enabling the rotatory movement of the solar cell supporting surface and/or a vibrating action for the wind turbine Further the solar cells 242 may be mounted on a thin and resilient plastic plate constituting the solar cell support, said plate being provided with cooling ribs (not shown) for an enhanced cooling of the solar cells 242 during maximum solar input periods. The support for the solar cell panel, which is providing the top cover for the display device 1 , is also providing an impact dampening buffer block when hit by a vehicle, said support being easily collapsible. Generally, the solar cells provided upon said support are sufficient to provide the main part of the electricity needed for supplying the LED's upon the display area during at least the summer in the northern part of Europe, i.e. Denmark. The dimensions of said compact electrical power generator 20 depends upon the power output needed, the availability and cost of the components, and the size of the supporting structure, i.e. a pole or surface of the display device 1. Working first embodiments have been produced resulting in sufficient electricity power having a total dimension in the range of 50-80 cm in height and 50-100 cm in diameter. Other sizes are conceivable, depending on size of display area, i.e. electrical power output required, for example in a conceivable third embodiment, in which the display area is mountable to a vehicle, and the compact electrical power generator is placeable upon the vehicle, e.g. as a hood for the roof of the vehicle, where the dimensions of the compact electrical power generator may be 50-100 cm in height and 20-200 cm in diameter. Obviously, alternatively, several compact electrical power generators according to the present invention may be provided instead or additionally.

The road information display device 1 further comprises processor means (not shown) and storage means (not shown) for processing and storing, respectively, different types of data for the control of the solar cell generator positioning, and for the monitoring of the road and environment conditions in the vicinity of the display device, and the condition of the display device it self. These data may arrive from different optional sensors 50 disposed upon said display device 1, comprising environmental sensor means selected from the group consisting of temperature sensor for the detection of the external temperature, humidity sensor for the detection of the external air humidity, light sensor for the detection of the external light intensity, and combinations thereof, and/or comprising traffic information detector means selected from the group consisting of camera, radar sensor, laser sensor, infrared sensor, and combinations thereof, and/or preset data from a calendar data medium and a timer.

Further, the processor means may be a DSP processor or a microcontroller, which is able to control and monitor the battery level, evaluate and process error and vandalism signals from said display device, operate a step motor for rotating said solar cell generator 24 around the vertical axis, said step motor being controlled by said processor means based upon data from said calendar data medium and timer. The storage may be of such a size as to accommodate camera still or moving pictures, or such pictures compressed, and these being entered in a log database. The processor means and the storage may advantageously be provided in the accumulator housing for a protection against the environment.

The processor and storage means may be provided with predetermined picture recognition or image processing software, which based on the camera input from one or more camera means such as CCD-chips is able to determined road conditions by selecting information data sets or code sets in said storage describing the road and display device conditions as sensed by said display device, such as the forming of vehicle queues, temperature values, angle of solar cell support, fog, smoke, and conditions advantageously detected by a radar such as snow avalanches and rock slides and velocities of cars approaching or driving away from the display device, etc. The road information display device 1 further comprises an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof. The use of blue tooth technology may be provided. Thus, the data being acquired by the display device 1 may be communicated to remotely provided units, such as another road information device or a computer or server being in connection with the Internet or a SMS-server. The display device 1 may use standard external and internal protocols for said communication.

Fig. 7 is an elevated perspective view of a road information display device according to a second embodiment of the invention in which the display device 1 comprises a display area 10 comprising a plurality of activated light emitting elements 12, provided on a tripod, and a compact electrical power generator comprising the above described wind turbine 22 and solar cell 24 generators. In order for the tripod to be independent and removable, the battery housing 40 containing the battery accumulator may be provided upon the tripod construction and not be adapted for a ground disposal.

In fig. 8 is shown a parts list for a road information display device according to the invention as described above for an overview of the parts included. A processor

Fig. 9 is showing a schematic perspective view of a road surveillance system comprising at least one road information display device, shown as four such display devices 1, 1 ', 1 ", 1'" according to the invention, comprising an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof. The road surveillance system further comprises at least one sender/receiver unit 2, shown in fig. 6A, 6B, 6C, 6D comprising: an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof; a solar cell generator 24 for the supply of electricity to said sender/receiver unit 2; in which solar cells are disposed on the exterior surface of said sender unit on a supporting surface, which supporting surface is rotatable by a step motor around a vertical axis, said step motor being controlled by a processor means based upon data from a calendar data medium and a timer; a battery housing being arranged for a subsurface placement and accommodating a battery accumulator; said battery housing and battery accumulator being provided with a lock for locking said battery accumulator to said battery housing. The communication is advantageously performed wireless and the communicated data is in code, each code describing a specific road or weather condition, and each picture being communicated being compressed. The server unit comprises traffic information data, subscriber data and a communication line in order for said traffic information data to be communicated to a subscriber identified by said subscriber data via said communication line. This data may be sent in the form of a SMS-message to road users via their mobile phone being a subscriber, or via an e- mail to their computer system or the like messages.

The road surveillance system comprises one sender/receiver unit 2, the master unit, and several road information display devices 1, the slave units, and one server unit 3, substantially for presenting and storing time interval data sequences from said master and slave units. The server unit 3 may be placed near or at a road safety authority for the provision of real time data and images from the number of display devices provided in said road surveillance system. The data provided to the server unit 3 advantageously comprises the precise coordinates i.e. GPS-coordinates of the road condition or traffic incident being presented by the number of display devices 1, 1',

1 ", 1 '". Advantageously, the data provided from a display unit 1 to said server unit

3 may comprise maintenance data or vandalism data, optionally conditioned by the road safety authority, being directly accessible to the relevant repair shop for immediate repair action. Error or repair messages from the display unit, and check signals to be communicated between units and display devices, may be communicated periodically for example each five seconds. Obviously, the individual units/devices of the road surveillance system must be placed with a distance in between each other and positions in relation to each other to enable an efficient and reliable communication there between. Good working results have resulted from a spacing of approximately 1000 meter, depending on sending power of the transmitter.

A compact electrical power generator comprises a combination of a wind turbine generator and a solar cell generator; in which said solar cell generator is disposed on the exterior surface of said wind turbine generator and has a surface provided with solar cells, and in which said wind turbine generator is comprising a substantially vertically rotatable shaft provided with at least two radial arms, which distal ends are provided with each their wing element extending with one surface substantially perpendicular to the respective arm, the joint between the distal end of each arm and corresponding wing element being flexible in the rotation plane. The compact electrical power generator further comprises a battery housing accommodating a battery accumulator. Said battery housing may be arranged for a subsurface placement. Further, said battery housing and battery accumulator are provided with a locking arrangement. Accordingly, a compact electrical power generator is provided, which is able to supply electrical power in a reduced solar light environment, such as the northern hemisphere.

Other embodiments may be conceived with the scope of the present invention, such as the server unit may be integrated with the sender/transmitter unit, the electrical power for the server and/or sender/receiver unit may be supplied from a compact electrical power generator according to the invention, disposed upon or near such unit, the main storage facility for the log containing data, pictures etc. may be located in the serve unit or in the sender/receiver unit.

Claims

1. A road information display device comprising a display area comprising a plurality of light emitting elements for the display of a multitude of signs; and a compact electrical power generator connected to said display area; characterized in that the compact electrical power generator comprises a combination of a wind turbine generator and a solar cell generator.

2. A device according to claim 1, in which said wind turbine generator comprises a substantially vertically rotatable shaft provided with at least two radial arms, which distal ends are provided with each their wing element extending with one surface substantially perpendicular to the respective arm, the joint between the distal end of each arm and corresponding wing element being flexible in the rotation plane.

3. A device according to claim 1 or 2, in which solar cells of the solar cell generator is disposed on an exterior surface of said wind turbine generator and is rotatably mounted for enabling maximum exposure of said solar cells to the available solar radiation.

4. A device according to any of the claims 1 to 3, further comprising at least one pole supporting said display area and said compact electrical power generator.

5. A device according to claim 4, said at least one pole being provided with a breakage point at a predetermined distance from ground level.

6. A device according to any of the preceding claims, further comprising a battery housing accommodating a battery accumulator connected between said compact electrical power generator and said display area.

7. A device according to claim 6, said battery housing abutting said pole.

8. A device according to claim 6 or 7, said battery housing being arranged for a subsurface placement

9. A device according to any of the claims 6 to 8, said battery accumulator being a fuel cell.

10. A device according to any the claims 6 to 9, said battery housing and battery accumulator being provided with a locking arrangement for locking the battery housing and the battery accumulator to each other.

11. A device according to claim 6 to 10, in which the battery housing is provided with extendable wings, which during mounting of the battery housing for attachment to the ground are able to protrude into the surrounding ground for a securing thereto.

12. A device according to any the preceding claims, further comprising traffic information detector means selected from the group consisting of camera, radar sensor, laser sensor, infrared sensor, and combinations thereof.

13. A device according to any the preceding claims, further comprising environmental sensor means selected from the group consisting of temperature sensor, humidity sensor, light sensor, and combinations thereof.

14. A device according to any the preceding claims, further comprising a calendar data medium and a timer.

15. A device according to any of the claims 7 to 9, further comprising a processor means and storage for processing and storing, respectively, data from said sensor and/or detector means and/or said calendar data medium.

16. A device according to any the preceding claims, said light emitting elements being LED's.

17. A device according to any of the claims 14 to 16, in which said solar cell generator is disposed on the upper boundary of said wind turbine generator and is provided with a step motor for rotating said solar cell generator around a vertical axis, said step motor being controlled by said processor means based upon data from said calendar data medium.

18. A device according to any the preceding claims, further comprising a remote communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof.

19. A device according to any the preceding claims, further comprising a connection to the electrical supply net.

20. A device according to any the preceding claims, the total weight of said road information display device being reduced by using a light weight material for the constituting parts, said material being selected from the group consisting of polycarbonate, plastic composite material, aluminium, and combinations thereof.

21. A device according to any the preceding claims, in which the display area comprises a background plate which texture is selected from the group consisting of transparent, reflecting, coloured, and combinations thereof.

22. A road surveillance system, comprising at least one road information display device according to any of the claims 1 to 21, comprising an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof.

23. A system according to claim 22, further comprising at least one sender/receiver unit comprising an external communication connection selected from the group consisting of Internet connection, modem connection, telephone connection, wireless radio connection, wireless phone connection and a combination thereof; a solar cell generator for the supply of electricity to said sender/receiver unit; in which solar cells are disposed on the exterior surface of said sender unit on a supporting surface, which is rotatably mounted for enabling maximum exposure of said solar cells to the available solar radiation; a battery housing being arranged for a subsurface placement and accommodating a battery accumulator.

24. A system according to claim 22 or 23, further comprising at least at least one data receiving server unit adapted for communication and storage of data obtained by said at least one road information display device.

25. A system according to any of the claims 22 to 24, said at least one server unit comprising traffic information data, subscriber data and a communication line in order for said traffic information data to be communicated to a subscriber identified by said subscriber data via said communication line.

26. A compact electrical power generator for supplying electricity to a road information display device according to claims 1 to 21 or a road surveillance system according to claims 22 to 25, comprising a combination of a wind turbine generator and a solar cell generator; in which said solar cell generator is disposed on the exterior surface of said wind turbine generator and has a surface provided with solar cells, which is rotatably mounted for enabling maximum exposure of said solar cells to the available solar radiation, and in which said wind turbine generator is comprising a substantially vertically rotatable shaft provided with at least two radial arms, which distal ends are provided with each their wing element extending with one surface substantially perpendicular to the respective arm, the joint between the distal end of each arm and corresponding wing element being flexible in the rotation plane.

27. A compact electrical power generator according to claim 26, further comprising a battery housing accommodating a battery accumulator.

28. A compact electrical power generator according to claim 27, said battery housing being arranged for a subsurface placement.

29. A compact electrical power generator according to any of the claims 26 to 28, said battery housing and battery accumulator being provided with a locking arrangement.