GB2531784A - Improvement in or relating to outdoor lighting - Google Patents

Abstract

An outdoor luminaire 1 such as a street light comprises a plurality of LED light sources 2 which, when all of the light sources are fully illuminated, produce a first pattern or distribution of light emitted from the luminaire. Control means varies the intensity of light (by extinguishing and/or dimming) emitted by a selected individual light source and/or selected subset of light sources of the plurality of light sources, thereby achieving a different, second pattern or distribution of light emitted from the luminaire.

Description

Improvement in or Relating to Outdoor Lighting

Field of the Invention

This invention relates to luminaires for outdoor lighting, and a lighting system comprising the luminaires.

Background of the Invention

A traditional street lighting luminaire uses one or more lamps to illuminate the street and its immediate surroundings. Conventionally the light source is a high intensity discharge (HID) lamp. The distribution of light is achieved by the use of reflectors, refractors and/or diffusers mounted in the luminaire. This distribution is fixed by the luminaire: it cannot be modified to suit the immediate environment, nor can it be changed in response to different requirements during the night. The result is light being cast where it's not needed which wastes energy and causes light pollution.

The output of the light from the luminaire can be crudely controlled -i.e. turned 'on' or 'off' -but the distribution or pattern of the light emitted from the luminaire is essentially fixed.

Street lights may be controlled (i.e. switched on or oft) under the influence of a photocell, in response to the level of ambient light, the photocell conveniently being located on the street light which is under its control.

Greater degrees of control can be achieved by use of a "centralised management system" (CMS). Using a CMS, a central controller can switch on or off individual luminaires in a lighting system, or impose a degree of dimming on selected individual luminaires. Typically the central controller communicates with the luminaires by wireless transmission, each luminaire being provided with a wireless receiver or transceiver, known as a CMS node. However, even sophisticated CMS control cannot substantially alter the distribution or pattern of light emitted from the luminaires, merely the intensity of their output.

An LED luminaire creates its lighting distribution by the combination of the output of an array of LEDs. The light output can be roughly controlled by dimming, but again the lighting distribution remains the same.

The present invention provides a luminaire in which the distribution can be changed by turning off, on, or dimming selected light sources. By turning on, dimming or extinguishing selected light sources the distribution can be changed to suit the luminaire's environment and/or change the distribution at certain times of the night. This saves energy and reduces light pollution. This switching can controlled locally by either a photocell or remotely by a CMS system. The CMS controller can additionally override settings for unexpected conditions e.g. high traffic flow, adverse weather conditions etc. or be used to set the distribution of the luminaire remotely.

Summary of the Invention

In a first aspect the invention provides an outdoor lighting luminaire, the luminaire comprising a plurality of light sources which, when all of the light sources are fully illuminated, produce a first pattern or distribution of light emitted from the luminaire; and control means for varying the intensity of light emitted by a selected individual light source and/or selected subset of light sources of the plurality of light sources, thereby achieving a different, second pattern or distribution of light emitted from the luminaire.

For present purposes, "varying the intensity" encompasses extinguishing a light source or selected subset of light sources in the array and/or dimming said light source or selected subset of light sources.

The outdoor lighting luminaire is preferably a luminaire for a street light (which term encompasses lights for illuminating any sort of carriageway for motorised vehicles, such as motorways, dual carriage ways, residential street etc.), but any other sort of outdoor lighting could potentially benefit from the invention, which may thus also apply to lighting for sports grounds, parks or other recreational spaces, car parks or public places in general.

The plurality of light sources most preferably comprises a plurality of LEDs, housed in a main body of the luminaire.

Preferably the plurality of LEDs is provided as a plurality of LED arrays, each array being controllable independently of the other arrays of LEDs provided in the luminaire.

Advantageously each array will comprise two or more LEDs having a main axis which is at a common angle to the luminaire main body. Other arrays may have LEDs with a main axis at a common angle which is different to the other arrays (in this context, the 'different' common angles might be, for example, +45° and -45° to the vertical). The arrays of LEDs may be arranged substantially symmetrically in the luminaire main body (i.e. having at least one axis of symmetry and/or rotational symmetry of order 2 or higher), or may be arranged asymmetrically.

If desired, one or more of the LEDs may be adapted and configured to emit light in a substantially directional manner. Generally this is achieved by the positioning of the LED or LEDs on the body of the luminaire but, if desired or necessary optical baffle arrangements may be employed to restrict the angles through which light is emitted by an individual LED or LED array, and/or directionality of light output may be increased by e.g. a lens, reflector or the like.

Conveniently, but not necessarily, an array of LEDs will comprise three or more LEDs at substantially constant spacing. Equally it is preferable, but not essential, that an array of LEDs will comprise a linear array i.e. three or more LEDs arranged in a substantially straight line. Preferably, but not essentially, the linear array will comprise LEDs positioned at substantially constant spacing or pitch.

The control means may vary the intensity of light output from the light sources. This includes switching the light sources fully on or fully off, and more especially includes being able to dim the light sources to an output level intermediate between those two extremes. Where there is a single intermediate illumination level, this will preferably be about 50%, but it is envisaged that the control means may be able to cause a plurality of intermediate illumination outputs. These may be variable outputs between 1 and 99%, or may be a number of selected, predetermined outputs (e.g. 33% and 66%; or 25, 50 and 75%). Thus, for example, the control means may cause one or more arrays of light sources (such as LEDs) in the luminaire to be fully illuminated and one or more arrays of light sources to be fully deactivated and/or one or more arrays of light sources to be dimmed, operating at an output of between 1 and 99%, preferably 25-75%. It will be apparent to those skilled in the art that a particular luminaire in accordance with the invention may have third, fourth or even fifth or sixth patterns or distributions of light, depending on the number of light arrays and/or their patterns of illumination.

The control means will typically comprise an LED driver and a CMS node (e.g. a wireless receiver or transceiver; internet connection or the like) or, less preferably, a photocell.

In a second aspect, the invention provides an outdoor lighting system, the system comprising: at least one luminaire in accordance with the first aspect of the invention; and a remote central management system (CMS) which operates via the control means located on the outdoor light.

Typically the lighting system will comprise a plurality of luminaires. The CMS will conveniently send control instructions to the luminaires via wireless signals, generally received by a CMS node located on the outdoor light. Preferably the CMS will be able to control individual luminaires individually, so as to provide the optimum degree of fine control over the pattern or distribution of light generated by the lighting system. For example, the CMS could be used to alter the light distribution for an individual luminaire depending on its location, e.g. on a narrow street, or at a crossroads, or on a bend in a road. Further modification could be allowed for in residential area e.g. in case of "light trespass" where householders or building occupants require the light distribution to be altered.

A particular "custom" light distribution for a luminaire, if controlled by a CMS, will allow that distribution to be stored remotely such that, if a luminaire is damaged, it can be replaced and the replacement luminaire can adopt the customised light distribution of the previous luminaire.

The present invention is associated with a number of advantages. Energy is saved as only the required amount of light is directed where it is needed. The luminaire can be customised for its immediate environment by selecting which LEDs should be activated.

Different distributions of light are required at different times of the night. This can be catered for by changing the distribution at pre-selected times during the night. This will save further energy and reduce light pollution.

Ongoing research into circadian rhythms and sleep suggests that light intrusion in bedrooms (particularly of shorter 'blue' wavelengths) may be detrimental to health (see, for example, http//www.darksky.org/light-pollution-topics/ill-health; http//www.psychologytoday. com/blog/sleep-newzzz/201309/blocking-blue-lighthelps-sleep; and http//ww-w. heal th. haryard edu/n ewsl etters/Harvard_heal th_l etter/20 1 2/may/blue-light-has-a-dark-side/). Therefore both dimming and dipping (lowering the angle of the light distribution at later times of the night) may also provide health benefits.

Luminaires on motorways and main roads can be programmed with different distributions in response to traffic flow at various times of the night. Large energy savings can be made by use of these different distributions late at night when the traffic flow has decreased.

At least three types of light distribution could be pre-programmed in luminaires in accordance with the invention: "Unidirectional" could be used for motorways and dual-carriageways; "High Beam" could be used for motorways, dual-carriageways and traffic routes; whilst "Residential" could be used for residential areas and side roads. These three modes or distributions are described in the Examples below. Further customisation could be achieved through software control.

Switching of the distributions and their setting times can either be controlled by a photo-electric cell mounted on the luminaire itself or by a Centralised Management System (CMS). CMS systems offer further flexibility as the distributions can be remotely controlled and directly altered in response crowd control conditions, extreme weather, unexpectedly heavy traffic flow or accidents.

In some embodiments, the lighting system may cause alternate luminaires to be completely extinguished. In some embodiments the lighting system may cause one or more LED arrays in a luminaire to be dimmed, and one or more LED arrays in the same luminaire to be completely extinguished.

The features of the invention will now be further described by way of illustrative embodiment and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an embodiment of an LED luminaire intended to illuminate motorway or dual/carriageways; Figure 2 is a cross section through the LED luminaire embodiment of Figure 1 (Section A-A) illustrating how the various rows of LEDs are mounted at different angles.

Figure 3 is a perspective view of the underside of the same LED luminaire in Figure 1; Figure 4 is a cross section through the LED luminaire of Figure 3 (Section BB) and shows how different selected rows of LEDs can be dimmed to provide a "Unidirectional" distribution; Figure 5 is a schematic representation of a stretch of road with "Unidirectional" distribution from each LED luminaire; Figure 6 shows a cross section through an embodiment of an LED luminaire adapted and configured to provide a "High Beam" distribution; Figure 7 is a schematic representation of a stretch of road with "High Beam" distribution from each illuminated LED luminaire; Figures 8(A) and (B) show an embodiment of an LED luminaire intended for residential installations; Figure 9 shows a cross section through part of the LED luminaire of Figure 8 (Section A-A) and how the various rows of LEDs are mounted at different angles; Figure 10 is a schematic representation of part of a residential street with early evening "Residential" distribution from the LED luminaire embodiment of Figures 8(A) and (B); and Figure 11 shows the same representation as Figure 10 but with late evening dipped "Residential" distribution from an LED luminaire.

EXAMPLES

Example 1

A proposed LED luminaire in accordance with the invention for motorway and dual carriageways is illustrated in Figure 1. The main body (1) carries a plurality of LED arrays (2) and a heat sink. This is connected to the main driver housing (3) by means of two or more connecting arms (6) to further dissipate heat. The driver housing contains an LED driver and a universal spigot which allows either bracket or pole top mounting. The illustration shows the pole top mounting option with the top section of the pole (4) shown. A CMS node (5) or photocell is connected to the top of the driver housing.

Figure 2 shows the section A-A through the LED body (1) illustrated in Figure 1. This shows how the LEDs (2) are mounted across this arched section. The LEDs mounted towards the edge of the main body contribute to the main beams of the distribution whilst the LEDs mounted in the centre of the main body contribute to the vertical distribution directly beneath the luminaire. The direction of the flux from each row of LEDs is indicated by the dotted lines (7).

The light distribution is substantially confined to just laterally across the road so that just the hard shoulder, main carriageways and central reservation are lit. Under normal conditions, when traffic flow is high, all the LEDs are fully lit, creating a bright patch on the road surface around the base of the pole of the lantern. All the LEDs may be dimmed uniformly under LED driver control when the traffic flow lessens in the later hours of the night.

Figure 3 shows the underside of the LED luminaire. When in use under normal conditions when traffic flow is high, all the LEDs are fully lit.

Light emitted from a street light in a direction away from a driver (i.e. in the same direction in which the vehicle is heading) is unlikely to be reflected back towards the driver unless it is incident upon the rear of another vehicle. Accordingly, at times when the traffic density is very low, light emitted from street lights in the same direction as the flow of traffic (i.e. away from the oncoming traffic) is normally wasted, as it is unlikely to be seen by a driver, and the present invention provides a method of reducing this waste, by using a "unidirectional" lighting mode.

When switched to "Unidirectional Lighting", the LEDs facing the oncoming traffic are still fully lit but those facing away from the oncoming traffic are dimmed or extinguished completely. The vehicle driver will generally be unaware of this change as the light in his carriageway is provided by the LEDs in rows (12), (13), (14), (15) and (16). The LEDs in rows (8), (9), (10) and (11) are dimmed or turned off completely. By switching off or dimming the LEDs facing away from the oncoming traffic in this way, up to 50% of energy can be saved. Further savings can be realised if the remaining LEDs are also dimmed. "Unidirectional Lighting" should only be used when the traffic flow has decreased and spacing has increased between vehicles. In times of heavy traffic, the LEDs in rows (8), (9), (10) and (11) contribute to the vertical illumination of the cars in front, and therefore should be turned on.

In times of contra-flows, accidents or heavy traffic flow then the "Unidirectional Lighting" should not be used and the luminaire should be switched back to its normal distribution via the CMS system. Note that this control would not be available using a standard photocell so their use is not recommended when finer control is required.

Figure 4 shows the section B-B through the LED body (1) illustrated in Figure 3. This shows how the LEDs facing away from the oncoming traffic are dimmed to lower levels (50% down to 0%).

Figure 5 illustrates schematically a stretch of motorway or dual carriageway illuminated by luminaires in accordance with the invention. A car (17) is travelling from left-to-right along the carriageway (18). Three luminaires (1) mounted on poles (4) are shown along the road. The distribution has been switched to "Unidirectional Lighting" with the light distribution facing the oncoming traffic being retained at 100% (7) and the light distribution away from the oncoming traffic dimmed to between 50% and 0%.

Example 2

An LED luminaire in accordance with the invention for two-way traffic and arterial routes has a similar form to that shown in Figure 1. Figure 6 shows the section A-A through the LED body (1). This luminaire has three sets of LEDs arranged in rows. The rows (19) of LEDs contribute to the illumination beneath the luminaire and of the immediate environment. The rows (20) of LEDs contribute to the two main beams, one in either direction along the road, to increase the illumination of the road surface for two way traffic.

Under normal conditions of high traffic flow, the LED rows (21) are turned off and the other rows (19 and 20) are turned on to 100% power. This produces the standard, medium-angle, cut-off beam used in conventional road lighting schemes.

In the early hours of the morning, when traffic flow is less, the luminaire can be switched to "High Beam Lighting" either by instructions relayed via the CMS node controller or automatically by the photo-electric cell. Under these circumstances, the LED rows (19) beneath the lantern are optionally dimmed, the LEDs of the medium-angle beam rows (20) are dimmed or turned off and those of the high-angle beam (21) are turned on. In this manner, the angle of the main beam can be increased.

The effect of increasing the angle of the main beam is shown in Figure 7 which is a schematic representation longitudinally along a traffic-route/arterial road. Cars (17) can travel in either direction, either left to right or right to left, along the carriageway (18). Four luminaires (1) mounted on poles (4) are shown along the road. Normally, under medium-angle beam conditions, the distribution is the same as that shown in Figure 5 but with 100% illumination levels for both beams. Under the "High Beam Lighting" system, the angle of the main beam is increased so that the illumination range of the lantern is increased. Alternate luminaires (22) can then be dimmed, or turned off entirely, thus saving energy.

When traffic is light, and the mean spacing between cars increased, then the vertical illumination of the car in front of the driver becomes less important, and more of the road surface can be seen. In these cases, increasing the angle of the beam will illuminate more of the exposed road surface, and reveal more distant objects in negative contrast.

In times of heavy traffic, adverse weather conditions or accident, the luminaires, if controlled by CMS nodes, can be instructed to switch back to their normal lighting configuration.

Example 3

A proposed luminaire for residential lighting e.g. side streets, large areas, squares, car parks etc. is shown in Figures 8. Two views are shown: Figure 8(A) is a side elevation and Figure 8(B) a plan elevation from below. A toroidal-shaped body (1) carries multiple arrays of LEDs (2) at increasingly high angles of curvature. The LED driver housing (3) controls the lighting of the LEDs for the various distributions. This is, in turn, controlled by either a conventional photocell or CMS node (5). The LED driver housing (3) also contains a universal spigot which allows either bracket or pole top (4) mounting. The toroidal-shaped luminaire body (1) is attached to the LED driver housing (3) by means of two or more arms (6) to further dissipate heat and keep it away from the driver.

If all LEDs are lit evenly then the luminaire provides a symmetrical distribution in plan, suitable for area lighting.

By programming the driver, either via the photocell or remotely by the CMS controller, then individual or grouped LEDs may be turned off or dimmed, thereby modifying the distribution of light emitted by the luminaire. Main beams can be formed up and down the roadway. More than two main beams can be formed in cases 1l of positioning at T-junctions or cross-roads. Bends in the road may also be catered for by altering the LEDs which are lit therefore angling the light distribution to suit the environment. If this is achieved by CMS control, the light distribution may be programmed once for this node (the unique CMS controller for this luminaire), and then the luminaire will then switch to this light distribution. If the luminaire is damaged and needs replacement, the new luminaire will simply respond to the existing, customised light levels if the same CNIS node is used -there would be no need for reprogramming.

Figure 9 shows a cross-section through the main part of the toroidal body (1). This shows how some LEDs are mounted at high angles (23), medium angles (24) and at low angles (25) from the vertical. The LEDs mounted at low angles contribute to the illumination below the luminaire and are always illuminated; they can be dimmed in the early hours of the morning when traffic and pedestrian flow is less.

Light emitted from other parts of the LED could be used to illuminate pavements, front gardens and the fronts of houses. In the evening, the light distribution should be programmed such that the light cuts off at the first-floor level of the house, so that house numbers are illuminated, and paths to doorways are illuminated, but bedrooms are not. The luminaires' shape again allows customisation; if gardens are long then the LEDs at higher angles on the ring (23) of the LED array are lit. For short gardens, or no gardens at all, then the LEDs at low angles of the ring (24) of the LED array are lit.

Figure 10 shows an ideal early evening distribution. The view shows a schematic cross-section across the road (26). The luminaire and column is shown at (1) with houses (27), fences (28) and pavements (29). The light distribution in this plane is shown with dotted lines. The light distribution should cut-off at the first floors of the houses. Note that light would also be directed up and down the road in the conventional manner (but with the correct LEDs programmed to be lit to suit the local environment as detailed above.) Figure 11 shows a dimmed, dropped early-hours distribution. At this time, the traffic flow will be light with negligible numbers of cyclists or pedestrians. Rather than just dim the standard illumination, the light from the luminaire is both dimmed and dropped. This angular drop is achieved with reference to Figure 9. For high beam illumination as shown in Figure 10, the LED rings of (23) and (22) are illuminated. When the beam is dropped the LED ring of (23) is turned off, the LED ring of (24) is dimmed and the LED ring of (25) is illuminated. The resulting distribution will be that of Figure 11, where only the road, pavements and front fences are illuminated. The main beams along the roadway will either remain the same or be dimmed. In this manner energy is saved, light pollution is reduced and the front windows of houses are left dark so that householders can sleep well.

Claims (1)

1. Claims An outdoor lighting luminaire, the luminaire comprising a plurality of light sources which, when all of the light sources are fully illuminated, produce a first pattern or distribution of light emitted from the luminaire; and control means for varying the intensity of light emitted by a selected individual light source and/or selected subset of light sources of the plurality of light sources, thereby achieving a different, second pattern or distribution of light emitted from the luminaire.

   A luminaire according to claim 1, comprising a plurality of LEDs housed in a main body of the luminaire.

   A luminaire according to claim 2, wherein the LEDs are provided as a plurality of LED arrays, each array being controllable independently of the other arrays of LEDs provided in the luminaire.

   A luminaire according to claim 3, where the LEDs in one particular array emit light in the same general direction.

   A luminaire according to claim 3 or 4, wherein the directionality of the light from an array is enhanced by the use of an optical baffle, lens, reflector or the like.

   A luminaire according to any one of claims 3-5, wherein the arrays of LEDs are arranged substantially symmetrically in the main body of the luminaire.

   A luminaire according to any one of claims 3-6, wherein the luminaire comprises at least one linear array of three or more LEDs.

   A luminaire according to any one of claims 3-7, wherein there is substantially constant pitch between three or more LEDs within an array.

   A luminaire according to any one of the preceding claims, wherein the control means comprises a centralised management system (CMS) node, which receives commands from a remote central controller.

   10. A luminaire according to any one of the preceding claims wherein the control means comprises an LED driver.

   11. An outdoor lighting system comprising at least one luminaire in accordance with any one of the preceding claims, and a centralised management system which remotely controls the operation of the luminaire.

   12. A luminaire substantially as hereinbefore described and with reference to the accompanying drawings.

   13. An outdoor lighting system as hereinbefore described and with reference to the accompanying drawings.Amendments to the claims have been filed as follows Claims An outdoor lighting luminaire, the luminaire comprising a plurality of LED arrays which, when all of the arrays are fully illuminated, produce a first pattern or distribution of light emitted from the luminaire; and control means for varying the intensity of light emitted by a selected individual LED array or selected subset of LED arrays from the plurality of LED arrays, thereby achieving a different, second pattern or distribution of light emitted from the luminaire.A luminaire according to claim 1, wherein each array is controllable independently of the other arrays of LEDs provided in the luminaire.3. A luminaire according to claim 2, where the LEDs in one particular array emit light in the same general direction.O A luminaire according to claim 2 or 3, wherein the directionality of the light from an array is enhanced by the use of an optical baffle, lens or reflector.OA luminaire according to any one of claims 2-4, wherein the arrays of LEDs are arranged substantially symmetrically in the main body of the luminaire.A luminaire according to any one of claims 2-5, wherein the luminaire comprises at least one linear array of three or more LEDs.A luminaire according to any one of claims 2-6, wherein there is substantially constant pitch between three or more LEDs within an array.A luminaire according to any one of the preceding claims, wherein the control means comprises a centralised management system (CMS) node, which receives commands from a remote central controller.A luminaire according to any one of the preceding claims, wherein the control means comprises an LED driver.10. An outdoor lighting system comprising at least one luminaire in accordance with any one of the preceding claims, and a centralised management system which remotely controls the operation of the luminaire.11. A luminaire substantially as hereinbefore described and with reference to the accompanying drawings.12. An outdoor lighting system as hereinbefore described and with reference to the accompanying drawings.CO OO