According to an example aspect of the present invention, there is provided a novel illuminator 100 having a light source (10) and optics (20). The light source (10) and optics have light emitting and light path modifying components (11, 12, 21, 22, 23), which form two different combinations. The components of the first combination cooperate so as to output a first output light pattern (A) having a width in a plane and the components of the second combination cooperate such to output a second output light pattern (B) having a width in said plane. The width of the second output light pattern (B) is narrower than that of the first output light pattern (A), whereby the total output light pattern (A+B) of the illuminator (100) is a sum of the output light patterns (A, B) produced by the combinations of components (11, 12, 21, 22). The illuminator may be a flight obstacle illuminator or a navigational aid.

FIELD

The present invention relates to illuminated markers, specifically fixed illuminators for indicating the presence of a flight obstacle or for aiding navigation. In particular, the present invention relates to forming a particular lighting pattern of such an illuminator. More specifically, the present invention relates to an illuminator according to the preamble portion of claim1.

BACKGROUND

Illuminated markers of various sorts are fixed to the environment to inform approaching vessels of obstacles that might pose a risk of a collision with the vessel or for indicating the appropriate route. In sea navigation, such markers are called navigational aids, which may take the form of lighthouses, buoys, fog signals, day beacons etc. In aviation, tall buildings, bridges and the like are provided with flight obstacle illuminators for warning an approaching aircraft of the presence of an obstacle. EP 2541134 A2, for example, discloses a flight obstacle illuminator with a plurality of light emitting components arranged inside a respective plurality of lenses.

There is regulation concerning the specification of illuminated markers. The output of flight obstacle illuminators, for example, is regulated by standards drawn up by local and international aviation bodies such as the International Civil Aviation Organization (ICAO). Volume 1 (Aerodrome Design and Operations) of Annex 14 to the Convention on International Civil Aviation by the ICAO, for example, contains strict minimum requirements for the output light pattern of flight obstacle illuminators. The regulations vary around the World. Common to all such regulations is that the desired light pattern should be directed to all horizontal directions around the illuminator at quite a narrow beam spread in the respective vertical planes. In other words, the light pattern should peak at a zero line, which is the horizontal radial direction from a leveled flight obstacle illuminator.

There are, however, also recommendations for maximum output light pattern. Many of the modern standards pose desired maximum values for the intensity of light directed to different vertical deviations from the zero line. When examining the light intensity of the light pattern in the vertical plane, the desired light pattern should have a relatively narrow peak section surrounded by decreased intensity sections at both sides of the peak, which decreased intensity sections are further surrounded by trailing low intensity sections further apart from the zero line. The decreased intensity sections between the peak and trailing low intensity sections create so called shoulders to the light pattern. Indeed, the required minimum and recommended maximum values define quite a narrow tolerance for the desired shape of the output light pattern.

It is therefore an object to provide an illuminator suitable for use as a flight obstacle illuminator or navigational aid having a controlled output light pattern that will not only achieve an adequate minimum output light pattern but also not exceed recommended maximum values for a given vertical deviation from the zero line.

SUMMARY

The aim is achieved with a novel illuminator having a light source and optics. The light source and optics have light emitting and light path modifying components, which form two different combinations. The components of the first combination cooperate so as to output a first output light pattern having a width in a plane and the components of the second combination cooperate such to output a second output light pattern having a width in said plane. The width of the second output light pattern is narrower than that of the first output light pattern, whereby the total output light pattern of the illuminator is a sum of the output light patterns produced by the combinations of components. The first combination of components includes a first light emitting component of the light source and a light path modifying component of the optics. The second combination of components includes a second light emitting component of the light source and a light path modifying component of the optics. The first light emitting component has a first optical size and the second light emitting component has a second optical size, which is smaller than the first optical size.

The invention is defined by the features of claim1. Some specific embodiments are defined in the dependent claims.

Considerable benefits are gained with aid of the novel illuminator. Not only can the minimum output light intensity requirements be met but it is also possible to comply with the maximum output intensity recommendations at different elevations from the so called zero line. While catering for safe aviation and/or shipping, the ability to limit the intensity of the light pattern outside the required angle range significantly reduces the amount of “light pollution” emitted to the environment, namely to settled areas around tall buildings, bridges, wind farms, etc.

BRIEF DESCRIPTION OF EXEMPLARY EMBODIMENTS

In a broad sense, the proposed exemplary solution provides an output light pattern particularly suitable for an illuminator for warning of a flight obstacle or for aiding navigation. The total output light pattern A+B is the sum of two light patterns A, B produced with two different combinations of components11,20;12,20. The proposed exemplary illuminator100includes a light source10with at least one light emitting component11,12and optics20with at least one light path modifying component21,22,23, which is positioned on the light path of the at least one light emitting component11,12. There are in any case enough components11,12,21,22,23in the light source10and optics20to form two different combinations of components that produce two different output light patterns A, B that have different widths in a plane.

One example of a suitable illuminator100is shown inFIG. 1, where the illuminator100includes a single lens20as optics and two light emitting components11,12as the light source10. The embodiments described with reference to the drawings relate specifically to a flight obstacle illuminator. The same principles apply, however, also to navigational aids. The two kinds of illuminated markers should therefore be considered as interchangeable throughout of this description. Also it should be understood that the components of the device can or are to be constructed as a single unit as opposed to being provided to separate illuminators.

In the illustrated embodiment, the first light emitting component11has a larger optical size than the second light emitting component12. In this context, the term optical size refers to the size of the projection of an object as measured at the input surface of the light path modifying component of the optics. Another way of considering the optical size would be the size of an object as it appears to the light path modifying component. The optical size may be altered by varying the area of the light emitting surface of the light emitting component or by adding a dome to the light emitting component or both. The introduction of a dome to a light emitting surface will spread the emitted light beams so as to appear on a larger area on the input surface of the light path modifying component as compared to that of a domeless light emitting component. The first light emitting component11may therefore be a larger LED chip and the second light emitting component12a smaller LED chip as shown inFIG. 1in an exaggerated fashion. The second light emitting component12may be for example 20 percent smaller than the first light emitting component11so as to create two light output patterns that are different enough. Alternatively or additionally, the first light emitting component is provided with a dome whereas the second light emitting component is domeless (not shown). With modern LED technology, the LED chips with and without domes may be integrated into a single or onto the same surface mounted device (SMD in short) placed under the light path modifying component. Here it should be noted that the possible dome on an LED chip is not considered as the lens or other light path modifying component. Instead, the components forming the cooperating combinations of components are distanced from each other by a space, whereby the light beams emitted by the light emitting component pass through the medium occupying said space. Accordingly, the potential dome on the light emitting component should be considered as an integrated piece of the light emitting component. In case two LED chips of different size are placed under a spot light lens, the widths of the output light patterns vary according to the size of the chips, which affects not only the vertical but also the horizontal beam spread.

The first light emitting component11emits light to the lens20such that they form a first cooperating combination of components, which produces an output light pattern A shown inFIG. 2. The lens20may be, for example, a Fresnel lens. The curves shown inFIG. 2illustrate the spread of the intensity of light in both output light patterns A, B across the vertical plane that extends radially from the vertical center line of the flight obstacle illuminator. In other words, the diagram shows the light intensity as the function of deviation from the radial direction extending from the flight obstacle illuminator. In yet other words,FIG. 2shows the so called vertical beam (spread) of the illuminator. As can be seen fromFIG. 2, the first output light pattern A of the first combination of components11,20is quite wide. By contrast, the second output pattern B produced by the second combination of components, namely the optically smaller light emitting component12and lens20, is considerably narrower than the first output light pattern A. This is because the light originates from a more point-form source of light. On the other hand, the second output light pattern B has higher peak intensity than the first output light pattern A. The width of the output light pattern A, B is measured at half intensity, i.e. the so called full width at half maximum, FWHM. The components of the flight obstacle illuminator are arranged such that the output light patterns A, B are matched to some extent. In the illustrated example, the output light patterns A, B are mutually centered. It is, however, possible to offset the center lines of the output light patterns so as to create a total output light pattern, which is asymmetric in respect to the horizontal (not shown). Depending from the application of the illuminator, it may be preferable to offset the peak values of the output light pattern by even several degrees so as to adapt the total output light pattern to suit a particular demand.

FIG. 3shows the total output light pattern A+B, which is the sum of the output light patterns A, B of the first and second combination of components,11,20;12,20. InFIG. 3, the zero line represents the horizontal, i.e. the radial direction to all horizontal directions from and around the coverage angle of the illuminator. Here it should be noted that the illuminator may be constructed of several panels or sub-assemblies, for example, which have narrow coverage angles and when assembled, form a wider coverage angle up to 360 degrees. Ascending deviations from the zero line in the vertical plane in degrees are expressed with positive integers and descending with negative integers. As may be seen fromFIG. 3, the total output light pattern A+B peaks at the zero line, i.e. the radial horizontal direction extending from the vertical center line of the flight obstacle illuminator. When observing the total output light pattern A+B to either direction perpendicular to the zero line in the vertical plane, one may observe a considerable decrease in light intensity. At approximately 3 degrees from the center line, the light intensity asymptotically approaches zero. Also noticeable fromFIG. 3is a slight shoulder at approximately 1 and 1 degrees from the center line, which is the net result of crossing between the summed wider first output light pattern A and the narrower second output light pattern B. The produced shoulder is particularly advantageous because the total output light pattern A+B thus manages to comply not only with the required minimum intensity requirements sketched with the dashed line Iminbut also the recommended maximum intensity requirements sketched with the dashed line Imax. Thus the total output light pattern can be modified from the conventional output light pattern of known illuminators.

The embodiment ofFIG. 1could be varied by introducing a second similar lens to the illuminator so that the first light emitting component would emit light to the first lens and the second light emitting component would emit light to the second lens. The summed output light patterns could still produce a pattern illustrated inFIG. 3.

An alternative flight obstacle illuminator100is depicted inFIG. 4, where two similar light emitting components11and two cooperating but mutually different lenses21,22form two different combinations for producing a total output light pattern A, B, such as shown inFIG. 3. The light emitting components11of the light source10have similar optical sizes. However, the light path modifying properties of the first and second lens21,22are different. The first lens21may have a smaller radius in the overall output surface than the second lens22thus leading to a wider output light pattern A than the second lens22, which produces a narrower output light pattern B (FIG. 2). As a rule of thumb it may be calculated that for reducing the beam spread of the lens in half, the size of the lens would need to be quadrupled without modifying the optical size of the light source. For example in a double lens arrangement, where the first (wide) light output pattern has a width of three degrees and the same light source is used for the second (narrow) light output pattern having a width of 1.5 degrees, the second lens would need to be dimensioned to a size four times the size of the first lens. Alternatively or additionally, the first and second lenses may have different focal points. More specifically, the lenses21,22may be Fresnel lenses. Also, it is possible to vary the distance of the light emitting component from the lens21,22for modifying the output light pattern.

The embodiments above could be varied by replacing a lens or lenses of similar or different light path modifying properties with a reflector or reflectors.FIG. 5shows a modification of the embodiment shown inFIG. 1, where the lens has been replaced with a concave reflector23. The flight obstacle illuminator100according to the embodiment shown inFIG. 5includes a light source10with a first light emitting component11and a second light emitting component12. The optical size of the first light emitting component11is larger than that of the second light emitting component12. The difference between optical sizes may be achieved with the above-described options of adding a dome to or increasing the size of the light emitting surface of the LED chip of the first light emitting component11. The light emitting components11,12emit light to the reflector23, the concave reflective surface of which is configured to collect the emitted light beams and to guide the output light patterns as the first and second output light pattern A, B shown inFIG. 2, respectively.

A similar reflector replacement could be performed to the embodiment shown inFIG. 4, where the lenses of different size would be replaced with reflectors of different size.

REFERENCE SIGNS LIST10light source11first light emitting component, such as an LED12second light emitting component, such as an LED20optics21first lens22second lens23reflectorAoutput light pattern of the first combination of componentsBoutput light pattern of the second combination of componentsA + Bcombined output light pattern of the first and secondcombination of componentsIminminimum requirement for light intensity as a function ofdeviation from the zero lineImaxrecommended maximum for light intensity as a function ofdeviation from the zero line

CITATION LIST

Patent Literature

Non Patent Literature

International Civil Aviation Organization: Annex 14 to Volume 1 (Aerodrome Design and Operations) of the Convention on International Civil Aviation, 6thEdition, July 2013, ISBN 978-92-9249-281-6