EP2143990A1

EP2143990A1 - A light guiding element, a light assembly and a method for manufacturing said light guiding element

Info

Publication number: EP2143990A1
Application number: EP08159984A
Authority: EP
Inventors: Mattias Hallberg; Ola Håkansson
Original assignee: Safegate International AB
Current assignee: ADB Safegate Sweden AB
Priority date: 2008-07-09
Filing date: 2008-07-09
Publication date: 2010-01-13

Abstract

A light guiding element is presented. The light guiding element is made of a first material and comprises an input surface and an output surface. In order to protect the light guiding element the output surface is provided with a coating of a second material. The output surface is in direct contact with the coating, and the second material has a degree of hardness that is higher than a degree of hardness of the first material. Further, a light assembly comprising the light guiding element is presented, as well as a method for manufacturing a light guiding element.

Description

Technical Field

The invention relates to a light guiding element, a light assembly and a method for manufacturing said light guiding element.

Background

For several years different types of lamps have been used for guiding airplanes. For example, one type of lamp has been used for indicating the borders of a landing runway and another type of lamp has been used for guiding the airplanes at a docking station.
In order to keep a high level of safety, it is important that the lamps are reliable in operation, or in other words, that the number of interruptions is kept at a low level. One way of keeping the number of interruptions at a low level is to include a light source with a long life.
Today it is common to use a halogen lamp as light source. However, the life of halogen lamps is quite short and therefore the lamps and the halogen lamps must be replaced with new ones quite frequently. Because of this, more and more lamps are provided with light emitting diodes (LED) which have a longer life than halogen lamps.
Another problem associated with lamps at airfields is that the lamps are subject to heavy mechanical wear. For instance, airplanes may drive over the lamps and snowploughs clearing the runway may drive over the lamps.
One solution, as described in WO 03/027397 , may be to provide the lamp with a housing protecting the inner parts of the lamp. A problem with this solution is that it does not solve the problem of the lamp being subject to mechanical wear induced by sand and other small particles.
Consequently, there is still a problem with the life of lamps.

Summary

In view of the above, an objective of the invention is to solve or at least reduce the problems discussed above.
An object of the invention is to reduce the maintenance of light assemblies.
Generally, the above objectives are achieved by the attached independent patent claims.
The general concept is to improve light assemblies having a light source with a long life by having a light guiding element with an output surface withstanding mechanical stress and wear at the same time as the optical quality is maintained.
According to a first aspect, the present invention is realized by a light guiding element of a first material comprising an input surface and an output surface, said output surface being provided with a coating of a second material. The output surface is in direct contact with the coating, and the second material has a degree of hardness that is higher than a degree of hardness of the first material.
The second material having a higher degree of hardness that is higher than a degree of hardness of the first material is advantageous in that the second material protects the first material from mechanical wear and stress. The output surface being in direct contact with the coating is advantageous in that light guided through the output surface is only affected by the output surface and the coating, that is there is no materiel between the output surface and the coating that could induce further refraction. An advantage with the light guiding element and the coating being of different materials is that a more inexpensive material can be used for the light guiding element than for the coating.
The light guiding element may be a prism comprising a reflection surface. This is advantageous in that the light is guided in a desired direction.
An area of the output surface may be smaller than an area of the input surface. This is advantageous in that the area that is subject to stress and wear is smaller.
The second material may have a degree of hardness that is equivalent to at least a degree of hardness of silicon dioxide. This is advantageous in that silicon dioxide is hard and hence provides a very good protection against stress and wear.
A thickness of the coating may at most be 10 µm. The coating being thin is advantageous in that the direction of the light output through the coating is only slightly affected by the coating.
The coating may be applied to the output surface by atomic interaction. An advantage with atomic interaction is that the coating is attached to the output surface without the need of glue, hence avoiding undesired refraction of the light.
The atomic interaction may be achieved by deposition. Deposition is advantageous in that the coating is applied to the output surface in a cost efficient way.
The deposition may be physical vapour deposition. This is advantageous in that the coating may be made very thin.
The physical vapour deposition may be sputter deposition. This is advantageous in that it provides a large degree of control of the application of the coating to the output surface.
The second material may comprise at least one from the group of silicon dioxide and sapphire. Both silicon dioxide and sapphire have high degrees of hardness which implies that they provide a good protection against mechanical wear and stress.
The first material may be at least one from the group of glass and plastic. Glass is advantageous in that it is a hard material. Plastic is advantageous in that it is easy to mould and in that it is inexpensive.
According to a second aspect, the present invention is realized by a light assembly comprising at least one light guiding element according to the first aspect, and at least one light source.
An advantage of the light assembly is that it requires less maintenance. The light leaving the light assembly is less affected by the coating, compared to glued layers of the prior art. Furthermore, the light assembly has a long life. An advantage with the light assembly having a prism comprising a reflection surface is that the at least one light source may be arranged horizontally which simplifies the installation and which reduces the height of the light assembly.
A first subset of the light guiding elements may be arranged to direct light in a first direction, and a second subset of the light guiding elements may be arranged to direct light in a second direction. This is advantageous in that the same light assembly may be used to emit light in two directions.
The at least one light source may be a light emitting diode. This is advantageous in that light emitting diodes have a long life.
The light assembly may further comprise a housing having a first part and a second part, wherein the first part may be arranged to reside above a hardened surface for vehicular traffic and the second part may be arranged to reside under the hardened surface for vehicular traffic. This arrangement is advantageous in that the second part is protected from the vehicular traffic.
The first part may be provided with an aperture for the output surface of the at least one light guiding element, and the first part may be provided with a recess in connection to the aperture, the recess being adapted to coincide with a light beam output through the output surface. This is advantageous in that the recess prevents vehicles from making direct contact with the output surface and hence reduces the risk for damages to the output surfaces.
The light assembly may be an airfield inset light. This is advantageous in that the light assembly can be used as inset lighting in for example airfields and tunnels. The light assembly being inset reduces the wear on the light assembly. Furthermore, the light assembly does not break when vehicles drive over it.
The light assembly may be an airfield elevated light. This is advantageous in that the light assembly can be used in for example airfields and does not have to be embedded but is easy to mount.
According to a third aspect, the present invention is realized by a method for manufacturing a light guiding element of a first material comprising an input surface and an output surface. The method comprising: coating the output surface with a coating of a second material. The output surface is in direct contact with the coating, and the second material has a degree of hardness that is higher than a degree of hardness of the first material.
The method for manufacturing is advantageous in that it is capacity and cost efficient.
It is to be noted that the third aspect of the invention can be embodied with any combination of features corresponding to any of the features of the first aspect of the invention.
Other objectives, features and advantages of the present invention will appear from the following detailed disclosure, from the attached claims as well as from the drawings.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Brief Description of the Drawings

Other features and advantages of the present invention will become apparent from the following detailed description of a presently preferred embodiment, with reference to the accompanying drawings, in which

Fig 1 is an exploded side view of an embodiment of a light assembly according to a second aspect of the invention.
Fig 2 is a side view of an embodiment of a light guiding element according to a first aspect of the invention.
Fig 3 is a side top view of another embodiment of a light guiding element according to a first aspect of the invention.
Fig 4a-f are top views of different embodiments of the light assembly according to the second aspect of the invention.
Fig 5 is a top view of an airfield inset light.
Fig 6 is a side view of an airfield elevated light.

Detailed Description of an Embodiment

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
Fig 1 is an exploded side view of an embodiment of a light assembly 100 according to the present invention. The light assembly comprises at least one light guiding element 110, 112 and at least one light source 120. A first subset of the light guiding elements 110 is arranged to direct light in a first direction and a second subset of the light guiding elements 112 is arranged to direct light in a second direction.
The light sources 120 are light emitting diodes. It is however obvious to a person skilled in the art that other light sources having a long life can be used instead. The light sources 120 may for example be microwave lamps or halogen lamps.
The light assembly 100 may further comprise a housing having a first part 132 and a second part 134. The first part 132 can be arranged to reside above a hardened surface for vehicular traffic, such as a taxiway for airplanes. In one embodiment a top part of the first part 132 can be arranged to reside in the same plane as the hardened surface for vehicular traffic. In another embodiment a bottom part of the first part 132 can be arranged to reside in the same plane as a the hardened surface for vehicular traffic.
The second part 134 can be arranged to reside under the hardened surface for vehicular traffic.
The first part 132 can be provided with at least one aperture 136. The at least one aperture 136 can be associated with an output surface 114 of the light guiding element 114. The first part 132 can further be provided with a recess 138 in connection to the at least one aperture 136, said at least one recess 138 being adapted to coincide with a light beam output through the output surface 114.
The light assembly 100 further comprises at least one light guiding element gasket 122 arranged to receive the at least one light guiding element 110. The light guiding element gasket 122 may be made of plastic.
The light assembly 100 may further comprise a collimator (not shown) for aligning the light.
Fig 2 is a side view of an embodiment of a light guiding element 110, 112 according to the present invention. The light guiding element 110, 112 can be of a first material and comprises an input surface 114 and an output surface 116. The output surface 116 can be provided with a coating of a second material. The output surface 116 can be in direct contact with the coating and the second material may have a degree of hardness that is higher than a degree of hardness of the first material.
In fig 2, the light guiding element 110 is realised as a prism comprising a reflection surface 118.
The second material has a degree of hardness equivalent to at least a degree of hardness of silicon dioxide. It is realised that different hard materials can be used for the coating that are suitable for protecting the light guiding element 110 such as for example silicon dioxide, sapphire. The silicon dioxide may be crystalline.
The area of the output surface 116 can be smaller than the area of the input surface 114.
A thickness of the coating is at most 10 µm. The thinner the coating is, the smaller is the influence of the coating on the optical quality of light passing through the coating. However, the coating has to be of some thickness in order to protect the light guiding element 110 from wear and stress. A coating having a thickness of 10 µm provides a good protection at the same time as it affects the optical quality to a very small extent.
The coating can be applied to the output surface 116 by atomic interaction. More specifically, the atomic interaction can be achieved by deposition. Deposition may be the settling of particles (atoms or molecules) or sediment from a solution, suspension and mixture or vapor onto a pre-existing surface. Deposition generally results in growth of new phase.
The deposition can be physical vapour deposition. It is however realised that different deposition techniques known to a person skilled in the art can be used. Physical vapour deposition is a technology where material is evaporated and condensed to form a thin film coating over an object (substrate). In general, coatings consist of metals or ceramics, usually, nitrides, carbides, and oxides. Using this technology, the thickness of the coating can be varied.
The physical vapour deposition is sputter deposition. Sputter deposition comprises ejecting material from a target and then depositing the ejected material on a substrate.
The first material may for example be glass or plastic. If the first material is glass, it may for example be B270 or BK7. B270 is advantageous in that it provides a better permeability. BK7 is advantageous in that it has a higher degree of hardness.
Fig 3 is a side top view of an embodiment of a light guiding element 110, 112 according to the present invention. The light guiding element 110, 112 is realised as a curved prism comprising a reflection surface 118. The reflection surface 118 comprises plates 120 which are arranged to deflect the the light when the light is reflected on the reflection surface 118.
Fig 4a-f are top views of different embodiments of the light assembly 100. The arrows represent the light emitted from the light assemblies 100. Fig 4a-c display different embodiments of bi-directional light assemblies 100. In bi-directional light assemblies, light is emitted in two directions. Fig 4a displays a light assembly 100 providing a narrow light path. Fig 4b displays a light assembly 100 providing a wide light path. Fig 4c displays a light assembly 100 comprising a light guiding element according to fig 3. The light assembly 100 of fig 4c deflects the light.
Fig 4d-f display different embodiments of unidirectional light assemblies 100. In unidirectional light assemblies, light is emitted in one direction. Fig 4d displays a light assembly 100 providing a narrow light path. Fig 4e displays a light assembly 100 providing a wide light path. Fig 4f displays a light assembly 100 comprising a light guiding element according to fig 3. The light assembly 100 of fig 4f deflects the light.
The light assembly 100 has many different fields of use. It may for example be used on airfields as runway lightning, or taxiway lightning. The light assembly 100 may further be used as lightning in tunnels. The light assembly 100 may also be used as road lightning.
The light assembly 100 may be realised as for example inset lights or elevated lights. Fig 5 is a top view of an airfield inset light. Fig 6 is a side view of an airfield elevated light.
In the following, a method for manufacturing a light guiding element of a first material comprising an input surface and an output surface will be described. The method comprises coating said output surface with a coating of a second material, the output surface is in direct contact with the coating, and the second material has a degree of hardness that is higher than a degree of hardness of the first material.
The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

Claims

A light guiding element of a first material comprising an input surface and an output surface, said output surface being provided with a coating of a second material, characterised in that,
the output surface is in direct contact with the coating, and
the second material has a degree of hardness that is higher than a degree of hardness of the first material.
The light guiding element according to claim 1, wherein the light guiding element is a prism comprising a reflection surface.
The light guiding element according to any of claims 1-2, wherein an area of the output surface is smaller than an area of the input surface.
The light guiding element according to any of claims 1-3, wherein the second material has a degree of hardness equivalent to at least a degree of hardness of silicon dioxide.
The light guiding element according to any of claims 1-4, wherein a thickness of the coating is at most 10 µm.
The light guiding element according to any of claims 1-5, wherein said coating is applied to the output surface by atomic interaction.
The light guiding element according to claim 6, wherein said atomic interaction is achieved by deposition.
The light guiding element according to claim 7, wherein said deposition is physical vapour deposition.
The light guiding element according to claim 8, wherein said physical vapour deposition is sputter deposition.
The light guiding element according to any of claims 1-9, wherein the second material comprises at least one from the group of silicon dioxide and sapphire.
The light guiding element according to any of claims 1-10, wherein the first material is at least one from the group of glass and plastic.
A light assembly comprising at least one light guiding element according to any of claims 1-11, and at least one light source.
The light assembly according to claim 12, wherein a first subset of said light guiding elements is arranged to direct light in a first direction, and a second subset of said light guiding elements is arranged to direct light in a second direction.
The light assembly according to any of claims 12-13, wherein the at least one light source is a light emitting diode.
The light assembly according to any of claims 12-14, further comprising a housing having a first part and a second part,
wherein the first part is arranged to reside above a hardened surface for vehicular traffic and the second part is arranged to reside under the hardened surface for vehicular traffic.
The light assembly according to claim 15, wherein the first part is provided with an aperture for the output surface of the at least one light guiding element, and
wherein the first part is provided with a recess in connection to the aperture, said recess being adapted to coincide with a light beam output through the output surface.
The light assembly according to any of claims 12-16, wherein the light assembly is an airfield inset light.
The light assembly according to any of claims 12-17, wherein the light assembly is an airfield elevated light.
A method for manufacturing a light guiding element of a first material comprising an input surface and an output surface, the method comprising:
coating said output surface with a coating of a second material, characterised in that,
the output surface is in direct contact with the coating, and
the second material has a degree of hardness that is higher than a degree of hardness of the first material.