FIELD OF THE INVENTION

[0001] The present invention relates to a method of On-Line Multi-fiber colouring, particularly with LED ink during loose tube production and curing with UV LED light.

BACKGROUND OF THE INVENTION

[0002] Optical fiber cables are surrounded by a type of protective tube called jacket.
These jackets are color coded, mainly because it makes it very simple to tell the difference between the cables. Therefore, it’s important to identify the right cables, because each serves a different purpose. Connecting the wrong cable can lead to malfunction. So, to identify the right optical fiber cables it is important to colouring the fiber cables.

[0003] Further, UV light is used in the manufacture of optical fibers. The UV cured optical fiber coating prevents crack propagation and also protect and strengthen the optical fibers. UV curing inks are applied to color code and mark the optical fibers and they cured within seconds with UV radiation. The curing protects the fibers against decomposition caused by cable gels, particularly in the case of multiple-fiber cable production. The UV radiation cured fibers are resistant to abrasion and scratching at high production speeds.

[0004] UV curing is used whenever there is a need for curing and drying of inks, adhesives
and coatings. UV curing requires that the coated glass fiber be exposed to high intensity UV radiation. Curing time can be reduced by exposing the coating to higher intensity UV radiation. Reducing curing time is particularly desirable to permit an increase in fiber drawing line speeds and thus optical-fiber production rates.

[0005] Generally, mercury lamps (e.g., high pressure mercury lamps or mercury xenon lamps) and UV lamps are used to generate the UV radiation needed for UV curing. One downside of using mercury lamps is that mercury lamps require a significant amount of power to generate sufficiently intense UV radiation. For example, UV lamps used to cure a single coated fiber requires a collective power consumption of around 50 kilowatts.

[0006] Another shortcoming of mercury lamps or UV lamps is that much of the energy used for powering mercury lamps is emitted not as UV radiation, but rather as heat. Therefore, mercury lamps must be cooled (e.g., using a heat exchanger) to prevent overheating. In addition, the undesirable heat generated by the mercury lamps may slow the rate at which the optical fiber coatings cure.

[0007] The offline colouring method uses colouring of single fiber in colouring machines and then uses coloured fibers of 12 different shades to make loose tube. In a loose tube design, a coated fiber is contained in a long tube, with inner diameter much larger than the fiber diameter. The fiber is installed in a loose helix inside the tube, so it can move freely with respect to the tube walls. This design protects the fiber from the stresses applied to the cable in installation or service, including effects of changing temperature. Further, imported metallic reflectors are used to reflect the light during curing process. Due to offline colouring of single fiber, use of UV lamps and metallic reflectors, the colouring process consumes too high power.

[0008] Further, the conventional offline method requires blowers for cooling the process because of high power consumption of UV bulbs. The said process also requires more manpower and increases the spare part cost due to limited life of UV bulbs and imported metallic reflectors.

[0009] Therefore, a solution is required that provides an intelligent and interactive method to colour multiple optical fiber cables. The present invention is one such solution and provides a method to significantly improve the curing efficiency by on-line multi-fiber colouring with LED ink during loose tube production and curing process with UV LED light. Further, the present invention uses UV LED apparatus that, as compared with a conventional mercury-lamp device or UV Lamp device, not only consumes less power and generates less unwanted heat, but also is capable of curing glass-fiber coatings with improved curing efficiency.

OBJECT OF THE INVENTION

[00010] The primary object of the present invention is to provide a method for On-Line Multi-fiber colouring with LED ink during loose tube production and curing process with UV LED light.

[00011] Another object of the present invention is to eliminate the requirement of imported high cost metallic reflectors and improve the curing efficiency by LED light reflection by using the special silver coating on quartz tubes.

[00012] Another object of the present invention is to reduce the power consumption and maximize the utilization of UV radiations by using narrow beam of LED and increasing reflecting surface area.

[00013] Yet another object of the present invention is to significantly improve the curing efficiency by controlling and utilizing the UV radiations (wavelength) to initiate the polymerization reaction.

[00014] Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, illustrations and examples to disclose the aspects of the present invention.

SUMMARY OF THE INVENTION

[00015] The present invention relates to a method for On-Line Multi-fiber colouring with LED ink during loose tube production and curing process with UV LED light. In the present invention, during the curing process of an optical cables power consumption is reduced and UV radiations are utilized to its maximum. The present invention uses narrow beam of LED and increased reflecting surface area to achieve the high curing efficiency by curing the multiple fibers (upto 12) accurately.

BRIEF DESCRIPTION OF DRAWING

[00016] The present invention will be better understood after reading the following detailed description of the presently preferred aspects with reference to the appended drawing:

Figure 1 illustrates the conventional metallic reflectors;

Figure 2 illustrates the conventional UV lamp system;

Figure 3 illustrates multi fiber (upto 12) colouring device;

Figure 4 illustrates UV LEDs with reflective coating on quartz tube;

Figure 5 illustrate quartz tube with and without silver coating;

Figure 6 illustrates LED lamp design used in the curing process;

Figure 7 illustrates the conventional (prior-art) single fiber offline colouring process; and

Figure 8 illustrates method of loose tube production during multifiber online colouring process.

DETAILED DESCRIPTION

[00017] The present disclosure pertains to colouring and curing multiple optical fiber. In
the following description, for purposes of explanation, numerous examples and specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be evident, however, to one skilled in the art that the present disclosure as expressed in the claims may include some or all of the features in these examples alone or in combination with other features described below, and may further include modifications and equivalents of the features and concepts described herein.

[00018] The following description describes various features and functions of the
disclosed method with reference to the accompanying figures. In the figures, similar symbols identify similar components, unless context dictates otherwise. The illustrative aspects described herein are not meant to be limiting. It may be readily understood that certain aspects of the disclosed method can be arranged and combined in a wide variety of different configurations, all of which are contemplated.

[00019] The present invention discloses method of online multi-fiber colouring with LED ink during loose tube production and curing process with UV LED light. It is very difficult to colour multiple optical fibers online during the production of loose tubes. The present invention provides a method of colouring multiple fibers online during the production of loose tubes.

[00020] The present invention discloses online multiple optical fiber colouring method using the device as shown in Fig. 3. The multiple fibers (upto 12) are connected in the said device wherein the device contains 12 different type of LED ink to colour the fibers. In the existing (old) processes, the steps of clouring and curing and loose tube formation process are done step by step after completion of each step for each fiber. In the present invention, multiple fibers are coloured, cured and taken up for loose tube process simultaneously, thereby reducing the time taken to colour the fibers.

[00021] Further, in loose tube production process (as shown in Fig. 8), a number of fibers are passed through during extrusion process and jelly is filled inside it. Due to this, the fibers are protected with the shell of the extruded material like PBT or Nylon and the jelly prevents water from entering tube for safeguard of Optical fibers. In the present invention, simultaneously 12 natural fibers are coloured in 12 different colours and are then cured through very low energy consuming UV LEDs before extruded to form loose tube. In the existing (old) process, when cured with UV bulbs, multi-angle power is required thereby effecting curing of fiber from all sides. Therefore, many UV bulbs are required for curing thereby increasing the power consumption.

[00022] The present invention eliminates the wastage of energy, reduces manpower cost and maintenance cost. In normal colouring operations, as disclosed in conventional Figs 1 and 2, optical fiber passes through the quartz tube and then wide beam of UV light from UV bulb enters the quartz tube and it reaches the optical fiber. The UV light comes out from the quartz tube and it is reflected back from the metallic reflector. Then, again UV light from the UV bulb enters the quartz tube and the whole above mentioned process is repeated until the colouring process is done or completed. The said process is called offline single fiber colouring process.

[00023] The present invention, as disclosed in Fig 4, where 70% of quartz tube is coated with silver mirror to make the area suitable for reflection of narrow beam from UV LED source. In other words, silver coated quartz tube is used instead of metallic reflectors to cure the multiple optical fiber cables. The present invention uses UV LED instead of UV bulbs to cure the multiple optical fiber cables.

[00024] In the present invention, during the colouring process optical fibers pass through the transparent quartz tube. The light from UV LED pass through the transparent area of the quartz tube, reaches the optical fiber and is then reflected back from silver mirror coating on quartz tube to again reach the fiber. This reflection process eliminates the absorption loss of light passing through the quartz tube during reflection.

[00025] In order to ensure that all the 12 fibers are cured equally, three arrays of UV LEDs are arranged at 120 degrees apart. Moreover, the power of each UV LED array is about 1.2 kw. Therefore, with the said arrangement the curing of 12 fibers is achieved at a speed of 600 mpm.

[00026] Further, the process of present invention saves upto 75% power using UV LED instead of UV bulb. During the curing process, most of power generated by UV bulbs wasted as a heat. As a result, cooling blowers are required to cool the bulbs. Whereas, in the present invention most of the energy is saved by using right combination of UV ink and UV LED source.

[00027] The above description illustrates various embodiments of the present disclosure
along with examples of how aspects of the particular embodiments may be implemented. The above examples should not be deemed to be the only embodiments, and are presented to illustrate the flexibility and advantages of the particular embodiments as defined by the following claims. Based on the above disclosure and the following claims, other arrangements, embodiments, implementations and equivalents may be employed without departing from the scope of the present disclosure as defined by the claims.

WE CLAIM:
1.A method of On-Line Multi-fiber colouring, the method comprising:
colouring the multi fibers online using LED ink during loose tube production process;
simultaneously curing the optical fibers by passing the optical fibers through the silver coated quartz tube;
passing the light from UV LED to transparent area of quartz tube;
allowing the light to reach the optical fiber; and
reflecting the light back from quartz tube to optical fiber; and
repeating the method until completion of colouring.

2. The method as claimed in claim 1, wherein the three arrays of UV LEDs are arranged at 120 degrees apart to ensure the curing rate of all 12 fibers.

3. The method as claimed in claim 1, wherein the quartz tube is coated with silver mirror
for better reflection.

4. The method as claimed in claim 1, wherein the colouring process is done with LED ink during the loose tube production.

5. The method as claimed in claim 1, wherein the curing process narrow beam of LED is used to reduce the power consumption and maximize the utilization of UV radiations.