The present invention relates to an arrangement in connection with further processing of fibers, ribbon or filaments, the arrangement comprising a coating unit for spreading a coating on fiber, ribbon or filament being proc¬ essed, at least one UV illuminator positioned after the coating unit for curing the coating material on the fiber, ribbon or filament, and means for applying inert gas to the quartz tube of the UV illuminator whereby the fiber, ribbon or filament being processed is arranged to pass through the coating unit and the UV illuminator quartz tube.

Such solutions are presently rather common in connection with processing of optical fibers, in particular, whereby the solutions are employed e.g. in connection with dyeing of fibers. It is, of course, obvious that the pur- pose of coating may also be something else than creating colour differences. The purpose of coating may be e.g. recoating of optical fiber. What is essential is that the coating material is such that UV radiation is employed for its curing. As examples of solutions previously used, those in the Finnish Pat¬ ent publication 90381 and the U.S. Patent publication 5 294 260 may be men- tioned.

The previously known solutions share the drawback that between the coating unit and the UV illuminator, the fiber or similar has been unpro¬ tected. This means that dust and air adhere to the coating, which slows down the UV curing process. Consequently, the end result, i.e. the quality of the coating and the product, has not always been the best possible.

It is the object of the present invention to create an arrangement by means of which the drawbacks of the previous solutions may be eliminated. This object is achieved by means of the arrangement according to the present invention, characterized in that an openable protective housing is arranged between the coating unit and the UV illuminator, said housing being arranged to constitute a passage sealed from the environment for the fiber, ribbon or filament being processed.

Above all, the invention provides the advantage that the drawbacks caused by dust and air may be eliminated most efficiently. In addition, the in- vention provides the advantage that, compared to the prior art technique, threading of the fiber, ribbon or filament becomes easier. Further, in connec-

tion with manufacturing ribbon, the entering angle of the fibers may be re¬ duced.

In the following, the invention will be described in closer detail by means of the examples illustrated in the accompanying drawings, in which Figure 1 shows the principle of a first embodiment of the invention at the initial stage,

Figure 2 shows the principle of the embodiment in Figure 1 at the coating stage,

Figure 3 shows the principle of a second embodiment of the inven- tion at the coating stage, and

Figure 4 shows the principle of the protective housing according to a third embodiment of the invention.

Figures 1 and 2 show the principle of the first embodiment of the in¬ vention. Figure 1 illustrates the initial stage, i.e. the stage at which fiber, such as optical fiber, is threaded through the apparatus. Figure 2 shows the appa¬ ratus according to Figure 1 at the coating stage. Reference number 1 denotes the coating unit, and reference number 2 denotes the fiber to be coated. Ref¬ erence number 3 refers in general to an UV illuminator. Reference number 4 denotes the lamp of the UV illuminator 3, and reference number 5 the quartz tube of the UV illuminator. Reference number 6 refers to the means for apply¬ ing inert gas to the quartz tube 5, and reference mark 7 to the means for ap¬ plying coating material to the coating unit 1. Reference mark 8 refers to suc¬ tion means 8 for sucking the inert gas from the quartz tube 5.

As coating agent, any suitable material may be used, for example coating material, dyeing material etc. that are cured with UV radiation. As ex¬ amples, epoxy acrylate, silicone acrylate etc. may be mentioned. The fiber to be coated may, instead of optical fiber, also be ribbon that consists of several fibers, another combined structure, or textile fiber such as aramid fiber.

The matters disclosed above, and drawing fiber through the coating apparatus represent conventional technique for a person skilled in the art, and therefore these matters will not be described here in greater detail. In this context, it is in general terms noted that fiber 2 to be provided with a coating is drawn through the coating unit 1 to which the coating material is also applied with the means 7. Next, fiber 2 provided with a coating is applied to the quartz tube 5 of the UV illuminator 3, whereby UV radiation emitted by a lamp 4 cures the coating as desired. With the aid of means 6, inert gas, such as nitrogen, is

applied to the quartz tube 5. The purpose of the inert gas is to protect the coating prior to the curing and also to enable the curing. After the curing of the coating, the fiber exits the quartz tube 5. By the sucking means 8, the inert gas may be sucked for later use. The inert gas may also be let out freely to the en- vironment.

The essential point of the invention is that an openable protective housing 9 has been arranged between the coating unit 1 and the UV illumina¬ tor 3. The openable protective housing 9 is arranged to constitute a passage sealed from the environment for the fiber 2 being processed. The structure described above provides a sealed space, isolated from the environment, extending from the coating unit 1 to the UV illuminator 3, whereby the air, dust or other impurities of the environment cannot affect an uncured coating.

In the embodiments of Figures 1 and 2, the openable protective housing is made of a fixed protective tube 10 and a coating unit 1 which is dis- placeable relative to the protective tube 10 in the movement direction of fiber 2. The movability of the coating unit 1 may be implemented in many ways. The coating unit 1 may e.g. be arranged to be suspended from guide rails 11 ar¬ ranged parallel to the movement direction of fiber 2 so that the coating unit 1 may be moved on the guide rails 11 as shown by Figures 1 and 2. The idea is that by raising the coating unit 1 to a vertical position, illustrated by Figure 1 , fiber may be threaded with a simple procedure through the coating unit. By lowering the coating unit to its lower position, illustrated by Figure 2, the pro¬ tective housing 9 seals the space between the coating unit 1 and the UV illu- minator 3 from the environment, whereby the aforementioned drawbacks will be eliminated. The sealing is achieved with suitable seals.

Figure 3 illustrates the second embodiment of the invention. In this embodiment, the openable protective housing 29 is made of tubular means 21 operating on the telescopic principle. In this embodiment, the coating unit 1 is fixed, and the protective housing may be opened by pushing in the tubular means 21 operating on the telescopic principle, as illustrated by the arrow in Figure 3. The protective housing 29 may be closed by drawing the tubular means 21 back to its extended position, whereby it seals the space between the coating unit 1 and the UV illuminator 3 from the environment. Figure 4 illustrates the third embodiment of the invention. Figure 4 only shows an openable protective housing 39 which in this embodiment is

represented by openable tubular part 31. The tubular part 31 consist of two halves which are connected to each another with pivot means 32 in the longi¬ tudinal direction of the tubular part. The halves of the tubular part 31 may also be arranged as detachable parts. The halves may be coupled to each other detachably e.g. by means of suitable quick-release tabs. The halves need not be of equal size, either; it is fully conceivable that the tubular part 31 is made of two unequal halves.

As to the operation of the embodiment of Figure 4, it could be noted that the protective housing 39 in question may be placed e.g. in the place of the protective housing 29 of the embodiment illustrated by Figure 3. The seal¬ ing may be accomplished by means of suitable seals.

The exemplary embodiments above are not intended to restrict the invention in any way, but the invention may be modified freely within the scope of the claims. Therefore, it is clear that the arrangement of the invention, or details thereof, need not fully correspond to those in the figures, but other kinds of solutions are possible. Although the emphasis in the above examples has been on optical fibers, it is obvious that the invention is not restricted to be used in connection with optical fibers only. As noted in the above, the inven¬ tion may also be employed in connection with e.g. ribbons or textile fibers.