TITLE LIGHTING DEVICE DESCRIPTION Technical field The present invention relates to a lighting device comprising a series of optical fibre cables and a light source, which lightning device is in particular intended for persons being weak- sighted, and in particular for trying out lighting to weak-sighted persons The object of the present invention is to obtain a lighting device by means of which correct lighting strength and lighting-colour temperature can be obtained, in particular to weak- sighted persons.

A further object is to obtain a lighting device for trying out lighting strength and lighting colour temperature for weak-sighted to facilitate their reading and writing.

Background of the invention For persons encountering vision problems the need for good light ergonomics is great at close-up work such as reading and writing. The light of the armature should have the correct light strength, light colour and spreading angle, and should be selected after the individual needs of the weak-sighted, whereby correct optics should be used, as well. In order to find the right conditions for near sight vision a testing is required, which is carried out together with nursing personal at a vision centre.

In the testing rooms there are thereby today several armatures mounted, sometimes more than 5 pieces, which have different light properties which are tested against the patient at reading and writing examinations. These, e. g., five different armatures are, however, most often commercial armatures having each their individual design and properties and the testing will thus more or less become a test of finding an armature which is as close to optimum as possible, not to find the optimal situation.

Thus there is a demand for another solution of the problem wherein the different light properties can be controlled in a more simple way to replace presently available armatures and to thereby obtain optimal results.

There is also a need for finding an armature which exhibits optimal conditions to the individual and which can be used at the daily reading and writing.

Description of the present invention It has now surprisingly turned out possible to be able to solve this problem by means of the present invention which is characterized in that it further comprises at least one colour temperature filtre placed between the light source and the optical fibre cables, that it comprises at least one light providing unit comprising at least one centrally directed optical fibre cable unit and at least four, from the centrally directed unit, diverging optical fibre cable units.

Further characteristics are evident from the accompanying claims.

By means of the present invention a lighting device is obtained which is functional, flexible with regard to testing out the lighting requirements of a weak-sighted person. Further, a device is obtained that is very flexible and suitable for personal at a vision centre for such testing out.

Further a lighting device is obtained which can be used by the weak-sighted person in his/her daily work and which fulfils the requirements as a vision test established, are needed to provide for an optimal vision.

Thereby the lighting device shows the advantage, as well, that it can be used without any unpleasant feeling by an extreme nearsighted person as the non-heat emissive, light providing unit can be placed close to the body/face.

The present invention will now be described more in detail in the following with reference to a preferred embodiment of the present invention shown in the accompanying drawing, however, without being restricted thereto. In the drawing FIG. 1 shows a cross-sectional view of a light source according to the present invention ; FIG. 2 shows schematically a light providing unit according to the present invention; FIG. 3 shows a cross-sectional view of an optical fibre cable of the present invention; FIG. 4 shows a light providing unit according to the present invention seen from the side; and FIG. 5 shows an armature containing a lighting device according to the present invention.

1 denotes a cylindrical house containing a light source 2, which can be a low voltage halogen lamp which obtains its current from a transformer (not shown) which is controlled by a dimmer. In those cases the light source will emit to much heating energy a fan (not shown) can be placed behind the light source to ventilate the cylindrical house 1. In front of the light source 2 there is a colour temperature filter 3 arranged. The filter is variable as it

can rotate in different filters into the way of the light stream given by the light source 2.

Thereby the colour temperature can be varied from 2700°K to 5000°K, either continuously or in steps of 300 to 400°K or more. In front of the colour temperature filter 3 there is a terminal 4 of a bundle 5 of optical fibre cables. The bundle 5 comprises a centrally placed cable (Fig. 3) and a number of cables 7 evenly arranged around this. These can be everything from four up to ten or more. The diameter of the central cable 6 is larger than the diameter of the surrounding cables 7, suitably in the relation 3-2 : 1. The more smaller cables 7 which are used, the smaller their diameters can be to give an optimal light picture. The bundle 5 is led through an armature 8, whereby the central cable 6, after the armature is provided with a flexo-winding 13 to be able to control the direction and placement of the cable in the room. Thereby, the smaller cables 7 placed around the central cable 6 outside the flexo-winding and are collected in a rubber housing 9. The cables go up to a light providing unit 10, into which the different cables 6,7 are attached. The centrally placed cable 6 is thereby placed centrally and directed perpendicular from this unit 10. The evenly distributed, surrounding cables 7 are placed, still evenly distributed around the central cable 6, but directed diverging from this using an angle of 1-20o. Thereby it is achieved a very evenly distributed light cascade. A diffusing means 11 can be placed in front of the light providing unit 10 to further even out the light.

On the armature there are control units 12 arranged to control on one hand the colour temperature 3, on the other hand to control the dimmer to provide the right amount of light.

Thereby the dimmer can control the light strength from 0 to 2000 lux, preferably continuously or in steps of 100 lux.

By means of the present invention the correct lighting strength and correct colour temperature of the light of a weak-sighted can easily be determined. Further, the lighting device can be readily used by extremely nearsighted, weak-sighted persons as the light providing unit can be placed close to the temple or in front of the forehead of the weak- sighted. As no heat is emitted the light emitting unit will not cause any trouble in the form of heating up of skin and tissue. When right values have been determined for a weak-sighted a fixed armature can be readily produced which then will contain a fixed colour temperature filter and suitable a fixed light strength. Optionally, a dimmer may be present in such a fix armature when it, sometimes, may be desirable, due to other in-falling light to be able to control the light strength.