EP0201581B1

EP0201581B1 - A marker beacon

Info

Publication number: EP0201581B1
Application number: EP85905906A
Authority: EP
Inventors: Lars Anders Bergkvist
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-11-06
Filing date: 1985-11-05
Publication date: 1989-10-04
Also published as: FI862841A; FI88010C; SE8405562L; DE3573414D1; WO1986002899A1; JPS62500713A; FI862841A0; JPH0774029B2; SE455407B; EP0201581A1; SE8405562D0; FI88010B

Abstract

A marker beacon comprising one or more planar surfaces and intended to be seen by those at sea which is characterized by the combination in which the surfaces (2, 3, 4) are provided with a fluorescent paint which transmits light in the visible waveband when irradiated with ultraviolet light, and in which a lighting arrangement (7, 8) is provided for illuminating the surfaces (2, 3, 4) with light containing a high proportion of ultraviolet light.

Description

The present invention relates to a marker beacon, and more particularly to an illuminated marker beacon.
There are many kinds of beacons.
A marker beacon is a type of beacon which in recent years has been standadized in Sweden to the form of pyramidal box having a height of about 1.5 meters. Certain beacons, such as pyramidal marker beacons, are illuminated at night, so as to be more readily seen by those at sea.
In Sweden newly erected marker beacons are painted with a so-called daylight luminous paint, i.e. a paint which transmits light of visible wavelength when irradiated with ultraviolet light. Thus, the ultraviolet light present in the sunlight falling on the beacon will cause the beacon to fluoresce, so that it can be readily seen in daylight. Red is the most commonly used daylight luminous paint employed in this respect.
In order to make the marker beacon visible at night, it is illuminated with the aid of a lighting arrangement or lamp unit, such as a halogen lamp, which shines with a relatively white light.
A beacon which is illuminated in this way, however, can only be seen from a distance of about 1.5 nautical miles. When drawing away from such a beacon at night, the naked eye sees progressively more and more white in the light emanating from the beacon, and consequently progressively less red light. At a distance of about 1.5 nautical miles, the beacon is seen as a white lamp, resembling approximately a stationary street lamp or some other source of white light.
One of the reasons forthisisth at the light cast by the lamp unit onto the surroundings in the vicinity of the beacon illuminates an area which is far greater than the surface area of the beacon itself, while the solid angle included by the beacon, measured from the eye is extremely small at a distance of 1.5 nautical miles. Consequently, at distances such as these, the light which illuminates the surroundings dominates over the light reflected by the beacon.
This means that in practice it is not possible with the naked eye to distinguish an illuminated marker beacon from a street lamp, an outdoor lamp attached to a house or like building, or a corresponding light source. Consequently, in order to be able to identify a marker beacon with the naked eye at greater distances it is necessary to know the bearing of the beacon concerned.
This is a most unsatisfactory condition, since the concept of a beacon is conversely that it should be possible to identify first the beacon and then to establish one's own position, inter alia by taking a bearing on the beacon.
It is practically impossible to discern an illuminated marker beacon at distances greater than 1.5 nautical miles in fairways which include many buildings and where other stationary lighting is to be found.
These problems are solved by means of the present invention.
In DE-A-17 66 816 a screen is shown which is intended to be illuminated by ultraviolet light. The screen contains fluorescent particles. However, there is no suggestion in DE 17 66 816 of how to improve the visibility at long distances.
Accordingly, the present invention relates to a marker beacon for sea navigation purposes, which incorporates one or more planar surfaces making an angle to the horizontal plane and which planar surfaces are intended to be seen by those at sea, characterized by the combination in which said surfaces are coated with a fluorescent paint, in a manner known per se, which paint transmits light of visible wavelength when irradiated with ultraviolet light, in which a lighting arrangement is provided for irradiating said surfaces with light containing a high proportion of ultraviolet light, in which the light source of the lighting arrangement, optionally in combination with a cover glass, is arranged so as to transmit substantially no light within the visible light spectrum.
An exemplifying embodiment of a marker beacon according to the invention will now be described in more detail with reference to the accompanying drawing, in which
Figure 1 shows a marker beacon 1 as seen from one side, i.e. as seen by those on the seaward side of the beacon. Figure 2 shows the beacon 1 from above.
According to one preferred embodimentthere is used a marker beacon 1 of substantially pyramidal configuration and having a square cross-sectional shape in the horizontal plane, as shown in Figure 2. The beacon suitably comprises three sheet- metal side panels 2, 3, 4. Each of the panels has the shape of an equilateral triangle, with a side length of 1.8 meters. This construction is used in those cases when the side 5 to which no panel is fitted faces inland. Naturally, the beacon may be fitted with two or four side panels.
The outer surfaces of respective panels 2, 3, 4 are coated with a paint which fluoresces when irradiated with ultraviolet light and reflects light having a wavelength which lies within the visible spectrum, i.e. a so-called daylight luminous paint. The paint used is preferably one which when irradiated with ultraviolet light, transmits light within the red region of the spectrum.
The illustrated beacon incorporates a lighting arrangement 6, 7, 8 for the transmission of ultraviolet light. The lighting includes, for example, two lamp units 7, 8, each of which comprises a light source in the form of a mercury lamp. The lighting arrangement is preferably constructed to transmit light in the wavelength band of 360-370 nanometers.
According to one preferred embodiment, the lighting arrangement is so constructed that the light source, optionally in combination with the cover glass of the lamp units, transmits no light within the visible spectrum. This means that no part of the surroundings will be illuminated in a manner discernible to the eye.
The lamp units are suitably carried by a frame 6 and are so mounted that the light passing through respective light apertures illuminates all the side panels 2, 3, 4 of the beacon. In this regard, an advantage is gained when the lamp units are constructed so that substantially all light transmitted falls within the sectors indicated in broken lines in Figure 1, since ultraviolet light which falls outside the beacon serves no useful purpose.
A marker beacon constructed in accordance with the invention is a remarkable improvement on beacons illuminated with white light, especially during the dark hours.
Practical tests have shown that when a marker beacon constructed in accordance with the invention and having the aforesaid dimensions is illuminated by two lamp units each of 125 W and transmitting ultraviolet light, there is seen solely an intensive red light, even at distances of up to about 5 nautical miles.
Since the surroundings are not illuminated in a manner to be visible to the eye, the beacon is seen only as an intensive red light. In addition to being visible over distances which are four times greater than those possible when using visible light, the beacon can be readily distinguished from other fixed land lighting.
A marker beacon according to the invention thus constitutes a remarkable improvement for those at sea.
In the aforegoing the marker beacon has been described by way of an example as having a pyramidal form, although it will be understood that beacons of other configurations and other types also fall within the scope of the invention.
The present invention is therefore not restricted to the aforedescribed embodiments, and modifications thereto can be carried out within the scope of the following Claims.

Claims

1. A marker beacon for sea navigation purposes, which incorporates one or more planar surfaces making an angle to the horizontal plane and which planar surfaces are intended to be seen by those at sea, characterized by the combination in which said surfaces (2, 3, 4) are coated with a fluorescent paint, in a manner known per se, which paint transmits light of visible wavelength when irradiated with ultraviolet light, in which a lighting arrangement (7,8) is provided for irradiating said surfaces (2, 3, 4) with light containing a high proportion of ultraviolet light, and in which the light source of the lighting arrangement (7, 8), optionally in combination with a cover glass, is arranged so as to transmit substantially no light within the visible light spectrum.

2. A marker beacon according to Claim 1, characterized in that said surfaces (2, 3, 4) are provided in a known manner with a paint which when irradiated with ultraviolet light transmits a visible wavelength within the red area; and in that the lighting arrangement (7, 8) is arranged to transmit light of a wavelength of about 360-370 nanometers.

3. A marker beacon according to Claim 1 or 2, characterized in that the beacon (1) has a pyramidal configuration and a square cross section in the horizontal plane.