Patent Application
20110261564
This invention relates to a lighting device for lighting a tunnel tube with a traffic direction, comprising a number of individual approximately point-like light sources which are fixed against a tunnel tube wall, distributed along a line extending in the longitudinal direction of the tunnel tube and each adapted to generate a light beam, the main direction of which comprises a component extending opposite to the traffic direction of the tunnel tube. The tunnel wall tube is also understood to include the tunnel wall ceiling.
Such tunnel lighting devices are known, usually with symmetrical radiation. They comprising light sources placed at a mutual distance of about 10 to 15 metres.
Such prior art lighting devices do however have the drawback that the array of light sources is discontinuous, which results in a highly location-dependent variation in the lighting level in the tunnel. Drivers perceive this as unpleasant variation of the discerned lighting level in time, also referred to as flickering.
The invention has for its object to provide a lighting device in which this drawback is obviated.
This object is achieved with such a lighting device, wherein the distance between the light sources in the longitudinal direction of the tunnel is less than 5 m. The row of light points is hereby seen as a continuous band of light, this being perceived as much less irritating.
It is noted here that the lighting levels in the interior of tunnels are low relative to the entrance lighting, the level of which is usually related to that of the light level prevailing outside, so that it is usually possible to suffice with low-power light sources. In view of the price of electrical energy, it is important that high-efficiency light sources are applied. Use is commonly made of gas-discharge lamps, which are restricted to minimum powers, and thereby to a minimum light output, in achieving a desired efficiency. The distance between the light sources is determined by this minimum light output per light source together with the desired increase would therefore result in a reduced efficiency or an increase in the lighting level, neither of which is desirable from the viewpoint of energy consumption. Contrary to this consideration, the present invention proposes to reduce this distance.
It is noted here that it is known from the prior art to apply light sources which are placed closer together, i.e., elongate light sources in the form of tubular lamps extending in the longitudinal direction of the tunnel. These light sources have the drawback, however, that no or hardly any lighting control takes place in the longitudinal direction of the tunnel, so that the above state advantages are not therefore achieved.
The distance can be reduced still further, i.e., to distances less than 0.5 m, by applying light source with light outputs, which are more than a factor often smaller than those of usual gas-discharge lamps. This has the result that the variations in the light intensity discerned by drivers are greatly decreased.
The distance between the light sources is more preferably less than 0.05 m. Not only is the variation in light intensity hereby reduced still further, a guiding effect is moreover obtained. This is because drivers subconsciously tend to follow the illuminated band, which they can thus see, this enhancing road safety.
It is recommended that the light sources are each provided with at least one LED. This is because LEDs have a long lifespan, which a greater part of the generated light can be used efficiently than is the case in gas-discharge lamps, since LEDs do not emit omnidirectional light. It is also expected that the efficiency of LEDs manufactured in the near further will increase.
According to a preferred embodiment, the light sources are adapted to generate a light beam, the main direction of which comprises a main component extending opposite to the traffic direction. The visible contrast for drivers of vehicles traveling in the tunnel is hereby greatly increased relative to the contrast of usual, symmetrical prior art lighting devices for the interior of the tunnel, wherein the main direction of the light exiting the light sources extends parallel to the transverse plane of the tunnel. A surface of a possible obstacle in the tunnel facing the driver is after all hardly illuminated, so that it contrasts sharply with the tunnel walls and the road surface that are illuminated. As a result of the fact that semi-diffuse scattering surfaces reflect the light more in the direction away from the light source than toward the light source, the lighting level of the tunnel walls and the road surface visible to the driver is also greater. As a result of the two above stated effects, the lighting level in the tunnel can be reduced, this resulting in lower energy costs.
Such a light distribution can be obtained when the LEDs are placed with a component of their main beam direction opposite to the traffic direction. Only few demands need then be made of the optical means for converting the light generated by the LED to the exiting light, such as reflectors and lenses.
It is, however, also possible for the light sources to be provided with an optical element with an axial direction which extends with a component opposite to the traffic direction.
For some situations, it can be attractive for the light sources to be adapted to generate a light beam, the main direction of which comprises a component extending in the traffic direction, this representing the most useful solution for such a lighting device.
For such situations, the LEDs can be place with a component of their main beam direction in the traffic direction, although it is also possible for the light sources to be provided with an optical element with an axial direction which extends with a component in the traffic direction.
It is equally possible to apply a symmetrical light distribution. All these light distributions can be achieved by appropriate placing of LEDs of the relevant optical means, such as lenses or reflectors or a combination thereof. In a symmetrical light distribution, it is otherwise possible to adapt the light sources to alternately generate a main light beam with a directional component opposite to the direction of traffic and in the direction of traffic. The direction of traffic in tunnel tubes can change a result of the closure of parallel tunnel tubes or when the tunnel tube is used alternately in both directions. A symmetrical distribution can of course be used in such situations, although it is also possible for the light sources to be adapted to change the main direction of the light beam.
It is noted here that the light sources are received in fittings, preferably fittings extending in the longitudinal direction of the tunnel tube. A plurality of light sources will generally be arranged in such a fitting. In order to obtain a continuous band, it is recommended that the fittings are placed connecting to each other. Although it is not recommended, it is possible to envisage the fittings being placed at a mutual distance, for instance with an intermediate space equal to half the length of a fitting or the length of a fitting. This achieves only some of the advantages of the invention. It is also possible to envisage some of the fittings being switched off at night, for instance alternatively, whereby a similar effect is achieved. It is, however, more attractive to achieve a lower light level by dimming the light sources. Although in most cases the light sources are placed arrange in a single line against the ceiling of the tunnel tube, it is not precluded for the light sources to be arranged in more than a single line against the tunnel tube ceiling.
Yet another preferred embodiment provides the measure that the light sources are placed in fittings, and that fittings which are placed closer than a predetermined distance to the entrance of the tunnel tube are provided with a light source adapted to generate a light level which gradually changes from that in the vicinity of the tunnel entrance to that in the interior of the tunnel. This embodiment is suitable for use in tunnels in the vicinity of the tunnel entrances. There is, after all, a sudden transition here of light levels from that of daylight to that of the tunnel lighting. In order to allow this transition to take place gradually, the light level is reduced in each fitting as the distance from the tunnel entrance increases. This per se known measure can be combined with the measures according to the invention. The invention is further elucidated in the accompanying drawings.
Tunnel tube 1 is of course provided with sidewalls, which are not shown in the drawing. The sidewalls usually transpose into ceiling 3 by means of a curved part. The tunnel tube is adapted to guide the traffic in a traffic direction indicated by an arrow 4.
A number of light fittings 5 are fixed against the ceiling. In the present case, these are fittings placed parallel to the axis of the tunnel tube 1, although it will also be apparent that the fittings can be place in other configurations. Fittings 5 also connect to each other, although it is likewise possible for fittings 5 to be placed at regular intermediate distances.
Light sources 6 provided with LEDs are preferably placed in fittings 5. Other, approximately point-like light sources 6 can be placed instead of light sources 6 provdied with LEDs. Each of the light sources 6 is adapted to emit light with a distribution comprising a predominant component in the direction opposite to the traffic direction in tunnel tube 1. This is represented in
The desired light distribution is obtained when, as is usually the case, the main beam of a LED corresponds with its axis. The fitting is closed on its underside by a cover 13 manufactured from transparent material.
It will be apparent to the skilled person that ballasts for LEDs will be present in the housing, and preferably also means for interconnecting the successively connected fittings.
In the above elucidated embodiment, the desired light distribution is obtained by appropriate placing of the LEDs, although the effect can likewise be obtained by other means, such as by applying a reflector, a lens or a combination thereof.
Finally,
It will be apparent that the measures shown in the above discussed embodiments can be combined with each other.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002205 | Nov 2008 | NL | national |
| 2002408 | Jan 2009 | NL | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/NL2009/050681 | 11/12/2009 | WO | 00 | 6/21/2011 |
