JP2000203870A - Method for winding fiber element having mutually different longitudinal portions - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and automatically distinguish longitudinal portions mutually different in characteristics, at a very low probability of error, while releasing optical fiber from a reel. SOLUTION: This method for winding, around a support, a fiber element 2 having at least two longitudinal portions Pi mutually different in characteristics through a step for feeding the element 2 to the support 16, includes a step for relating the corresponding value of a winding pitch pi different from that relating to an adjacent portion to each of longitudinal portions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for winding a fiber portion having different longitudinal portions. In particular, the present invention
A method for winding an optical fiber having different major axis portions onto a reel at the end of the process of drawing the fiber.

For the purposes of the present invention, a "fiber element" (fi
A bre element is understood to mean an optical fiber provided with a surface coating and other coatings as appropriate.

[0003]

BACKGROUND OF THE INVENTION As is known in the art, optical fibers are pre-formed preforms.
ms), made in a special drawing tower. In practice, a preform is fed to a furnace along a vertical direction and casts a molten material (molten).
g) is obtained. Next, the molten material is drawn and cooled to obtain an optical fiber having desired properties. These properties are parameters of the drawing process, namely
Furnace temperature, fiber drawing speed and all other parameters that define the process conditions (described in more detail below)
Is set appropriately. At the end of the drawing process, the optical fiber has been wound onto a storage reel and released therefrom for later use to perform a test or to rewind on another reel. Is done.

[0004] Generally, the drawing process is performed under the same process conditions throughout its duration, ie,
Performed without any change in process parameters. In such a case, the fiber is drawn from a single preform to be substantially uniform and uniform along its entire length. At the end of the manufacturing process, the fiber is wound in a cylindrical spiral at a constant pitch on a storage reel without interruption. For the purposes of the present invention, "winding pitch" (winding pitch)
Pitch) is understood to mean the distance between the same generatrix of the cylinder on which the helix rests and the two successive intersections of the helix. Spiral winding with a constant pitch is usually achieved by moving the reel axially and in an alternating movement at a constant speed, or by moving a member that feeds the fiber to the reel. Is obtained.

With known types of draw towers, recent advances in technology have resulted in optical fibers having a length of hundreds of kilometers from a single preform. In the future, innovations will result in longer fibers from one preform. Given the high yields already obtained in the drawing process today, long-axis sections with different chemical / physical properties, such as cores and / or claddings,
ng) It may be necessary or desirable to form fibers composed of long axis portions with different diameters, internal tensions, etc. from one preform. These physical variations can be obtained by changing process parameters that determine one or more properties during the fiber drawing process.

For example, it is meaningful to form a fiber having two or more long axis portions whose basic properties are substantially the same, but differ in one or more of the optical, geometric or mechanical properties. It is. The first example is from M. Ohashi et a
l., "Dispersion-Modified Single Mode Fiber by VAD
Method ", NTT, Japan, The Transaction of the IEICE,
Vol. E73, No. 4, April 1990. In this paper, a low dispersion (dispersio) from about 1.5-1.6 μm to micro-bending is considered.
In order to examine the sensitivity of a single mode optical fiber with n), a single preform having a length of several kilometers and having a zero chromatic dispersion wavelength (zero-chrom
Fiber sections that differ from each other only in terms of atic-dispersion were used.

Another example is the mode dispersion (mo
dal dispersion) ("PolarizationMode Dispersion" or
PMD) related to the study of phenomena. As is known, this phenomenon is caused by the photoelastic effect (photoelast
ic effect), which depends on the structural properties associated with the tension that the fiber experiences during the drawing process. For this type of study, it would therefore be beneficial to be able to use fiber sections with the same physical / chemical properties but different internal tensions.

US Pat. No. 5,400,422 proposes a technique for forming a sequence of Bragg gratings of different pitches in an optical fiber during the actual fiber drawing process. The grating is formed by exposing the fiber to a pulse of ultraviolet radiation using optical techniques of the interference type. The gratings are formed at a predetermined distance from each other along the fiber. Thus, in this case, by varying the operating conditions of the process during the drawing process, fiber sections having different properties are formed.

[0009] In other cases, it may be necessary to cause local variations in the properties of the drawn fiber, ie, to vary only a small portion of the fiber. This type of situation is described in U.S. Pat.No. 4,163,370, where by increasing the diameter of certain short sections of fiber,
It improves the performance of the fiber for modal dispersion.

The Applicant has realized that it is not very useful to wind on reels at a constant pitch without interruption when it is necessary to form fibers of different longitudinal parts. . This is because the different parts of the wound fiber cannot then be distinguished from one another. One way to solve this problem is to allow a given fiber section to be completely wound and the fiber to be cut at the end of the section, replacing the reel on which the section is wound with an empty reel. Sometimes it is always interrupting the winding process and thus the drawing process. At this point, the winding process (and the drawing process) can begin again, and the next fiber section will be wound on a new reel. However, disadvantages arise if the drawing process must be interrupted each time. This includes lost time, wasted molten material from the preform,
Then, for example, the possibility of a change in the drawing condition caused by a temporary change in the characteristic parameter of the process is included.

Also, if the fiber must be wound completely on the same reel, instead of cutting the fiber at the end of each wound portion, a marker is placed at a predetermined point in each portion. It is possible to attach. This operation can be performed without interrupting the drawing process as described in US Pat. No. 5,400,422 already cited. However, the use of markers to distinguish different fiber sections is less reliable. Because at normal fiber release speeds, some of these markers may be inadvertently overlooked. Further, this technique generally requires that the operator responsible for identifying the marker be present during the release of the fiber.

Applicants have determined that in the case of a fiber composed of mutually different major axis portions, the fiber is wound by associating a corresponding winding pitch different from the winding pitch of the portion adjacent to each portion. If taken, it has been found that identifying these parts later while releasing the fiber can be done quickly, automatically, and with a very low probability of error. The applicant proposes, in particular, a winding method which can be carried out without interruption and thus avoids the disadvantages mentioned above.

Applicants have also proposed that the winding pitch be modulated using a periodic function in order to minimize the probability of error in identifying various fiber sections during fiber release. I found something favorable. This variation in winding pitch is preferably performed by modulating the axial translation speed of the reel during winding, using the same rules. Identifying the different fiber sections during subsequent release from the reel if the fiber is wound in this manner is accomplished in accordance with the present invention by detecting variations in the winding pitch.

According to a first aspect, the invention relates to a method of winding a fiber element on a support, said fiber element comprising at least two longitudinal parts having different properties, said fiber element comprising: To the support, comprising associating each of the portions with a corresponding value of a winding parameter that is different from a value associated with an adjacent portion.

In particular, the step of associating a corresponding value of a winding parameter with each of the parts includes associating a corresponding winding pitch with each of the parts.

In particular, said step of associating a corresponding winding pitch with each of said portions comprises associating a corresponding function for modulation of said winding pitch with each of said portions.

Preferably, the step of associating a corresponding function for modulation of the winding pitch with each of the portions comprises the step of associating a corresponding modulation frequency of the winding pitch with each of the portions. , The modulation frequency defines the main frequency of the corresponding periodic modulation function.

In particular, the step of associating a corresponding winding pitch with each of the portions is performed simultaneously with the step of supplying the fiber element to the support, the step of applying the support in a predetermined direction to the winding pitch. Translating at a speed that is correlated to

The step of providing the fiber element to the support includes the step of directing the fiber element toward the support using a supply member;
The step of associating a corresponding winding pitch with each of the portions includes the step of translating the supply member in a predetermined direction at a speed correlated to the winding pitch, performed concurrently with the directing step.

Preferably, the step of supplying the fiber element to the support is related to a start time and an end time, and comprises measuring a time between the start time and the end time, Associated with each of the parts is a corresponding time interval between the start time and the end time.

Preferably, the fiber element is an optical fiber, and the step of supplying the fiber element to the support is performed simultaneously with the step of manufacturing the optical fiber, and the step of manufacturing includes the step of connecting the optical fiber. Including the step of drawing from the reform.

The manufacturing steps include preliminary steps of setting process parameters and obtaining predetermined characteristics of the fiber element, each of the portions being associated with a corresponding set of values of the parameters. .

Further, preferably, the manufacturing step includes:
Measuring the process variables performed during the drawing step and, if one of the variables exceeds a predetermined threshold, signaling a corresponding warning condition indicating the presence of a defective fiber section. Associating a corresponding value of the winding parameter with each of the portions includes associating a corresponding value of the winding parameter with the defective fiber portion.

According to another aspect, the present invention relates to a method for distinguishing between different longitudinal parts of a fiber element wound on a support according to the method described above, wherein each of said parts has a corresponding winding pitch. Relatedly, the method comprises the steps of releasing the fiber element from the support, and detecting a change in the winding pitch between the releasing steps.

In particular, the step of detecting a change in the winding pitch comprises the step of repeatedly measuring a parameter correlated with the winding pitch to obtain a continuous value of the parameter during the releasing step. And detecting a change in the value of the parameter,
including.

Preferably, said method of distinguishing between different major axis portions comprises the step of comparing each of said obtained values of said parameter with a set of stored values, wherein each of said stored values is Comprises a step associated with one of said parts, and identifying a major axis part associated with said obtained value based on said comparison.

Preferably, the step of detecting a change in the value of the parameter includes the step of storing the obtained value; the step of comparing a continuous value of the parameter with the stored value; Interrupting the release step if the continuous value differs from the stored value during the performing step.

Preferably, the step of measuring the parameter comprises detecting a distance between an actual point at which a predetermined area is intersected by the fiber element and a predetermined intersection of the area.

[0029] In another case, the step of measuring the parameter includes detecting an angle between a direction in which the fiber element is released from the support and a predetermined direction.

According to another feature, the invention relates to an apparatus for winding a fiber element on a support, said fiber element comprising at least two longitudinal sections having different properties, the apparatus comprising: A supply device that supplies the support to the support, a moving device that moves one of the support and the supply member at a predetermined translation speed along a predetermined axis to obtain a predetermined winding pitch,
A unit for controlling the moving device, wherein the unit controls the translation speed and associates a corresponding winding pitch different from a winding pitch associated with a portion adjacent to each of the portions. It is characterized by having a designed unit.

Preferably, at least one of said winding pitches is modulated using a periodic function. Preferably,
The fiber element is an optical fiber.

According to another aspect, the invention is an apparatus for distinguishing between different longitudinal sections of a fiber element wound on a support, each of said sections being associated with a corresponding winding pitch. Related to the device. The apparatus includes a device for releasing the fiber element from the support, a sensor device designed to repeatedly measure a parameter correlated with the winding pitch and generate a signal indicative of the parameter; A processing unit designed to receive a signal and detect a variation in the parameter based on the signal.

In particular, said processing unit comprises a comparing sub-unit for comparing continuous values of said parameters, a notifying sub-unit for notifying the presence of a new part if said continuous values are different from each other; It has.

Preferably, said sensor device is an optical device having a sensitive area and a reference point on said sensitive area, said sensitive area being intersected by said fiber element and said reference point. It is designed to detect the distance between

[0035] The sensor device is a device designed to detect an angle between a direction in which the fiber element is released from the support and a predetermined direction. According to another feature, the invention is a method of manufacturing a fiber element, comprising the steps of: drawing the fiber element from a preform; and forming two long-axis portions having different properties of the fiber element. A method comprising: The method is characterized in that the method comprises the steps of winding the two long axis portions on a support and associating a corresponding winding pitch with each of the two long axis portions.

According to a last aspect, the invention relates to an assembly for producing a fiber element with a production device designed to produce a fiber element having at least two longitudinal parts having mutually different properties. . The assembly further comprises a winding device designed to receive the fiber element from the manufacturing device, wind the fiber element on a support, and associate a corresponding winding pitch with each of the portions. It is characterized by.

In particular, the winding device comprises: a supply member for supplying the fiber element to the support in a predetermined supply direction; and one of the support and the supply member in a predetermined direction. An axis moving device for moving each of the parts at an axial speed correlated with the winding pitch associated with said parts.

[0038] Preferably, the winding device includes a control unit connected to the shaft moving device and controlling the shaft speed. Preferably, the manufacturing apparatus comprises a plurality of sensor devices connected to the control unit, each being designed to detect a corresponding process variable.

Preferably, said assembly comprises a discriminating device for discriminating between different longitudinal portions of said fiber element wound on said support, said discriminating device comprising:
A release device designed to release the fiber element from the support; and a detector device for detecting a change in the winding pitch during release of the fiber element.

In particular, the detector device receives the signal and a sensor device designed to generate a signal that is correlated with the winding pitch and obtains from the signal a value indicative of the winding pitch. And a processing unit designed in such a manner.

In particular, said sensor device is an optical sensor designed to be intersected by said fiber element. Preferably, said fiber element is an optical fiber and said manufacturing device is a draw tower.

[0042]

1 shows the drawing of an optical fiber from a preform 3 prepared in advance.
1 shows a drawing tower 1 designed to perform the following.
The drawing tower 1 is composed of a plurality of parts substantially aligned in a vertical drawing direction (herein the term "tower" is used). Choosing the vertical direction to perform the main steps of the drawing process is
This is due to the need to use gravity to obtain a casting of molten material from the preform 3 where the fiber 2 can be drawn.

In detail, the tower 1 comprises a device 4 for supporting and supplying the preform 3, a furnace 5 for performing a controlled melting of the preform 3, and a drawing device 6 for drawing the fiber 2 from the preform 3. , And a device 7 for winding the fiber.

The furnace 5 can be of any type designed to produce a controlled melting of the preform. Examples of furnaces that can be used in tower 1 are described in US Pat. No. 4,969,94.
No. 1 and 5,114,338. Furnace 5 is provided with a temperature sensor (not shown) designed to generate a signal indicating the temperature inside the furnace. The furnace temperature is
For example, changing the tension of the fiber 2
Is a process parameter that can be varied during the drawing process to vary the characteristics of

Preferably, at the outlet of the furnace 5 there is a first diameter sensor 8, for example an optical sensor of the interference type, which generates a signal indicating the diameter of the fiber 2 without any coating. Designed to be. Preferably, the first diameter sensor 8 also performs the function of a surface defect detector, detecting defects in the glass of the fiber 2, such as bubbles and inclusions. The first diameter sensor 8 is, for example, available from CERSA of France (Park Expobat 53,
LIS-G type sensors manufactured by Plan de Campagne, F13825, Cabries, Cedex) may be used. Sensors of this type include, in particular, a first signal proportional to the difference between the detected diameter value and a predefined (predetermined) diameter value, a second signal indicating the presence of any surface defects, Is designed to cause

The cooling device 9 is located below the furnace 5 and the diameter sensor 8, but may for example be of the type having a cooling cavity designed to allow a flow of cooling gas to pass through. This cooling device is arranged coaxially with respect to the drawing direction, so that the fiber 2 leaving the furnace 5 can pass through. Device 9 can be of the type described, for example, in U.S. Patent No. 5,314,515 or 4,514,205. The cooling device 9 is provided with a temperature sensor (not shown) designed to indicate the temperature in the cooling cavity. Since the speed at which the optical fiber is drawn is usually relatively high, the cooling device 9 can rapidly cool the fiber 2 to a temperature suitable for the subsequent processing steps, in particular the surface coating described below. There must be. The temperature of the cooling cavity is a process parameter that can be varied appropriately, for example by varying the flow of the cooling gas, to modify the properties of the fiber 2.

First and second coating device 1
0, 11 are located in the vertical drawing direction below the cooling device 9 and, when the fiber 2 passes through, a first protective coating thereon and a second protective coating superimposed on the first protective coating. Laminated with protective coating (depo
sit). Each coating device 10, 11 is in particular a respective application unit 10a, 11a designed to provide a predetermined amount of resin on the fiber and a UV lamp for curing the resin and providing a suitable coating, for example. -It is composed of respective curing units 10b and 11b such as an oven. The amount of resin given to each application unit 10a, 11a
b, temperature at 11b is a parameter that can be varied during the drawing process to produce fiber sections with different coatings. Coating devices 10, 11 are described, for example, in US Pat.
Although it may be of the type described in US Pat. No. 366,527, it may comprise a different number than indicated, depending on the number of protective coatings to be formed on the fiber 2.

First and second coating device 1
The outlets 0, 11 may be provided with second and third diameter sensors 12, 13 of the type described, for example, in US Pat. No. 4,280,827. These are each designed to generate a signal indicative of the diameter of the fiber after the first and second protective coatings have been applied, respectively. These signals may be, for example, proportional to the difference between the measured diameter value and the predetermined diameter value.

Preferably, the tower 1 comprises a third diameter sensor 1
3 further includes a coating defect detector 18 that detects the presence of defects such as bubbles, necks or ramps in the surface coating and generates a signal indicating the presence of any surface defects. The detector 18 can be, for example, a type 360 flow detector (FlawDetector) manufactured by BETA LASERMIKE, Technology Boulevard 8001, Dayton 45424, USA.

The drawing device 6 is located below the coating devices 10, 11 and is preferably of the simple or double pulley type. In this particular case, the drawing device 6 consists of a single motor-driven pulley 14 designed to draw the fiber 2 in a vertical drawing direction. The drawing device 6 is equipped with an angular velocity sensor designed to generate a signal indicative of the angular velocity of the pulley 14 during its operation. The rotational speed of the pulley 14, and thus the drawing speed of the fiber 2 during the drawing process, is a process parameter that can be varied during the drawing process to form fiber sections having different properties. For example, the drawing speed of the fiber 2 can be varied by itself or with the temperature inside the furnace 5 to vary the internal tension in the fiber 2 and / or the diameter of the fiber 2. This drawing speed is
It is preferably faster than 5 m / s, more preferably 10 m / s
It is even more preferred that it be faster.

If it is required to detect the tension of the fiber 2 during the drawing process, the tower 1 is preferably located between the furnace 5 and the drawing device 6 to indicate the tension of the fiber 2. It may be possible to provide a tension monitoring device (not shown) designed to generate a signal. The monitoring device may be, for example, of the type described in US Pat. No. 5,316,562.

In the event that an undesired variation in the diameter of the fiber 2 occurs during the drawing process, the signal of the diameter sensors 8, 12 and 13 is used to automatically vary the drawing speed of the fiber 2 and again to a predetermined value. A diameter value can be obtained. Indeed, if the diameter decreases below a predetermined threshold, the drawing speed will decrease by an amount proportional to the decrease in diameter, while if the diameter increases to a value above the predetermined threshold, the drawing speed will decrease. Rises by an amount proportional to the increase in diameter. An example of the use of a diameter sensor signal with a surface defect sensor is described in U.S. Pat.
967, 5,449,393 and 5,073,179. However, the number and arrangement of the diameter sensors and surface defect sensors may differ from those shown therein.

Preferably, the tower 1 comprises a device 15 for adjusting the tension of the fiber 2, the device comprising:
It is located between the drawing device 6 and the winding device 7 and is designed to balance any fluctuations in the tension of the fiber 2. The device 15 preferably comprises a first and a second installed in an idle state and a fixed position.
1 and a third freely movable pulley 15c shown in FIG. 1 under the action of its own weight and the tension of the fiber 2. In practice, the pulley 15c maintains this tension constant by raising it when the tension in the fiber 2 is undesirably high and lowering it when the tension in the fiber 2 is undesirably low. The pulley 15c can be provided with an axial position sensor designed to indicate the vertical position of the pulley 15c and thus generate a signal indicating the tension of the fiber 2. A similar device that adjusts the fiber tension,
It could be located upstream of the drawing device 6, as described in US Pat. No. 4,163,370.

The take-up device 7 has a reel 16 and a member 17 for supporting and moving the reel 16.
The reel 16 has an axis 16 a and defines a cylindrical support surface for the fiber 2. The member 17 is a reel 16
And is designed to move the reel 16 in a controlled manner both about the axis 16a and in a direction along the axis 16a.

The drawing device 7 further comprises a device 19 for supporting the fiber, this device comprising:
It is designed to feed the fiber 2 to the reel 16 in a direction substantially perpendicular to the axis 16a. In the particular embodiment shown in FIG.
And a pulley 19a which is designed to receive the fiber 2 from the tension adjusting device 15 and supply the fiber 2 to the reel 16. There may be another pulley 20 for guiding the fiber 2 from the tension adjusting device 15 towards the pulley 19a. Any other pulley (or another type of guidance element) can be used as needed. The drawing device 7 further includes a linear velocity sensor and an angular velocity sensor (not shown) such as an encoder, for example.
The translation speed of the reel 16 in the direction along the axis 16a and the axis 16
It is designed to generate a signal indicating the rotation speed of the reel 16 around a.

The draw tower 1 further comprises a processing and control unit 21 electrically connected to a plurality of sensors and detectors present along the tower 1 and to all parts of the tower 1, and The operation can be controlled externally. Unit 21 is designed to control various steps of the drawing process based on preset process parameter values and signals generated by a plurality of sensors and detectors located along tower 1. ing. The exchange of information between the unit 21 and the various parts of the tower 1 to which the unit 21 is connected is via an electronic interface (only three of 22, 23, 24 are shown for simplicity). Occurs. This interface converts the digital signals generated by the unit 21 into analog signals (eg, voltages) suitable for the operation of the individual parts, and interprets the analog signals received from the plurality of sensors and detectors by the unit 21. Can be converted to digital signals designed to The unit 21 also compares the values of the parameters measured by the sensors and detectors arranged along the tower 1 with predetermined threshold values, and if one of these threshold values is exceeded, It is designed to generate a warning code _Aj indicating the j-th warning condition.

The three electronic interfaces shown in FIG. 1 are designed to enable information exchange between the unit 21 and the drawing device 6 and the winding device 7. More specifically, the first interface 22 allows the unit 21 to send a control signal to the drawing device 6.
To control the angular velocity of the pulley 14 and to receive information from the angular velocity sensor associated with the drawing device 6. The second control interface 23 allows the unit 21 to both send control signals to the member 17 to control the rotational speed of the reel 16 and to receive signals from angular velocity sensors associated with the winding device 7. Become. By means of the third control interface 24, the unit 21 sends a control signal to the member 17 to control the translation speed of the reel 16 along the axis 16 a and receives a signal from a linear speed sensor associated with the winding device 7. And both will be possible.

During the process of winding the fiber 2, the translational movement of the reel 16 allows the fiber 2 to be wound spirally. Further, the spiral winding of the fiber 2 can be performed by fixing the reel 16 in the axial direction and translating the pulley 19a in a direction 19b parallel to the axis of the reel 16. This translation is performed by a moving member 19c (shown schematically only by dashed lines) controlled by unit 21, and the axial position of pulley 19a is detected by an axial position sensor (not shown). In both the case where the pulley 19a is fixed and the reel 16 is movable and the case where the pulley 19a is movable and the reel 16 is fixed, the direction in which the fiber 2 is supplied to the reel 16 depends on the length of the reel 16. It is moved parallel to itself within spatial intervals having equal amplitude. Next, the fiber 2 is controlled in a controlled manner by the reel 16.
The method of winding up will be described with reference to the flowchart of FIG.

After the fiber has been completely drawn and wound, the fiber must be released from the reel 16 to be used. In FIG. 2, reference numeral 30
Shows a device that allows the release of the fiber 2 from the reel 16, the identification of different parts of the fiber 2 and the individual rewinding of these parts onto the corresponding reel 31.

The device 30 includes a member 25 for supporting and moving the reel 16, a member (not shown) for supporting and moving the reel 31 in the angular direction, and a processing and control unit 26.
And an optical sensor 33 and preferably a fiber tension adjusting device 3 of the same type as, for example, the device 15 of FIG.
4 is provided. If needed, device 30
May also include a device of the type described in U.S. Pat. No. 4,138,069 for automatically changing reels 31, for example.

The first member 25 is designed to move the reel 16 in a controlled manner both around its axis and in a direction along its axis, for example, when it is already wound up. It can be composed of the member 17 used. The unit 26 is designed to operate the moving member 25 by electronic interfaces 27 and 28 (corresponding to the interfaces 22 and 23 in FIG. 1), and includes, for example, the unit 21 used for winding. When the unit 26 is different from the unit 21,
It is contemplated to have access to all information stored in unit 21 before or during the drawing and winding process.

The optical sensor 33 is a parallel light type, a matrix type (constituted by a CCD optical camera) or a fiber 2
And any other type of position detector suitable for detecting a position in the sensitive area of the body having the same dimension as the transverse dimension of the body in at least one direction.

The optical sensor 33 is located on the opposite side of the reel 16,
It is positioned so that its sensitive area is crossed by fiber 2 during release of fiber 2. Optical sensor 3
3 is electrically connected to the processing unit 21 and, during the release of the fiber 2, the actual point at which the sensitive area is crossed by the fiber 2 and a predetermined intersection, for example the center point of the sensitive area. It is designed to transmit a signal S indicating the distance between them to the unit 26.

The processing unit 26 is designed to use the information contained in the signal S to adjust the translation measure of the reel 16. In fact, at all times, the translation measure varies by an amount proportional to the absolute value and sign of the signal S, so that the fiber 2 passes through the sensitive area of the optical sensor 33 at a given intersection. Become.

At each point in time, the distance between the actual intersection and the given intersection depends on the spatial law associated with the winding pitch of the part under consideration.
The signal S and, consequently, the translation speed of the reel 16 are therefore modulated according to a time law which correlates with the space law governing the winding pitch.

FIG. 3 shows, schematically and partially,
A possible variation on the release device 30 is shown. The device of FIG. 3 is indicated by reference numeral 30 ′, wherein the light sensor 33 pivots on a pulley 37.
(This may be, for example, the first pulley of the tension adjustment device 34) and differs from the device 30 in that it is replaced by an angular position sensor 38 (eg, an encoder). The pulley 37 is located in front of the reel 16 and is designed to receive the fiber 2 during release and to pivot about an axis perpendicular to the plane of the drawing.
An angular position sensor 38 is located between the pulley 37 and the reel 16 and measures the angle at which the fiber 2 reaches the pulley 37, measured in a direction perpendicular to the axis 16a (shown by broken lines). It is designed to detect α. During release, the reel 16 is kept stationary in the axial direction, whereby the angle α correlates at each time point with the winding pitch of the part under consideration. Thus, in a manner similar to the previous case, the sensor 38 is designed to generate a signal S ' _e and its time progression
Correlates with the spatial sequence of the winding pitch.

Depending on the tower 1 shown in FIG. 1 and the release device of FIG. 2 (or, alternatively, the device 30 ′ of FIG. 3), different longitudinal parts
An automated method of manufacturing and winding fibers with orientation and identifying these parts during subsequent release of the fiber is possible.

During the drawing process, fiber sections having different properties may be consciously or unconsciously altered by changing one or more parameters (eg, temperature inside furnace 5). It is formed due to undesired variations in the parameters themselves, or due to the presence of defects in the fiber 2 during drawing. For example, the fiber 2 may be uniform and uniform throughout its length except for one or more short sections where defects or desired modifications are present. Typical examples are those described in U.S. Pat.No. 4,163,370 already cited,
There, shorter fiber sections of larger diameter are formed to improve the performance of the fiber with respect to modal dispersion. In other examples of practical interest as described in the introductory part of the present invention, the fiber may be composed of a plurality of adjacent parts that are different from each other. To illustrate the method according to the invention, the long axis portion of N with different properties _{P 1, P 2, ...,} P N ( provided that, N
Consider a general example of a fiber 2 composed of 2 or more.

According to the invention, during the winding process
The winding pitch distinguishes this part from the adjacent part
To each different fiber section in order to
You. In this way, the subsequent process of releasing fiber 2
During the process, each different part is
Can be identified based on the switch. In fact,
According to Ming, each winding pitch p₁, P_Two,…,
p_NIs the N parts P₁, P _Two, ..., P_NRelated to these
Pitch is related to the part where different winding pitches are adjacent.
They are selected to be linked. Winding pitch p₁,
p_Two, ..., p_NIs selected according to a predetermined space law.
More specifically, the generic part P_iWinding pitch p
_iIs the abscissa measured along axis 16a of reel 16.
x and therefore the function p_iExpressed by (x)
can do. The minimum value for the winding pitch is
It is established by the diameter of the wound fiber 2. roll
If the value of the scraping pitch is too high,
Excessive waste of space should be avoided.
Therefore, it is necessary to define a suitable range of the winding pitch value.
And it is possible. For example, if the diameter is about 0.25mm
Suitable winding pitch range for some fibers
Is 0.3 mm (selected with reference to working tolerances)
3 mm.

In the simplest case, the winding pitch
p₁, P_Two, ..., p_NCan have certain values that differ from each other
You. For example, fiber 2 has four different sections P₁, P_Two,
P_Three, P_FourIf the winding pitch is composed of
It can have the following values: That is, p ₁= 0.3mm, p_Two=
1.2mm, p_Three= 2.1 mm, p_Four= 3 mm. I
However, measurement of a constant winding pitch
Due to fluctuations during the release step or during the release of fiber 2
May be affected by unpredictable factors. Fa
Iva 2 is composed of a plurality of different parts,
Pitch values selected at appropriate intervals are close to each other
If there is a different during the release process of fiber 2
It may be difficult to identify the part.

Presumably, the winding pitch is modulated according to a periodic type of spatial function in order to be able to recognize different fiber sections with a high degree of accuracy independently of the number of sections present. Modulation of the take-up pitch is a spatial function of the reel 1 along the axis 16a during take-up,
6 obtained by modulating according to a time function corresponding to a translation speed of 6. Alternatively, if the reel 16 is fixed in the axial direction and the pulley 19a is movable in the direction 19b, the modulation is made to the translation speed of the pulley 19a along the axis 19b. A general periodic time function s (t) having a period T has a fundamental frequency f ₀ = 1 / T, and can be expressed using Fourier series expansion as follows.

[0072]

(Equation 1)

Here, k can take the whole value,
S (kf ₀ ) is as follows.

[0074]

(Equation 2)

Preferably, the function selected to modulate the winding pitch consists of a small number of harmonics (ie, a sine component having a frequency that is an integer multiple of the fundamental frequency), The frequency f ₀ can be easily extracted. More specifically, this periodic function is a sine function and can therefore be characterized by a single frequency.

The fundamental frequency of the selected specific periodic function and one
Matching modulation frequency f_modTherefore, the winding pitch and
Related. To distinguish different fiber sections
Is a constant function, a sine function or a period with multiple harmonics
Winding using different types of functions selected from the functions
It is also possible to modulate the stripping pitch. For example,
The first part is wound up at a constant pitch, and the second part is triangular
Winding at a pitch modulated by the function of the mold, the third part
Such as winding at a pitch modulated using a sine function
can do. On the other hand, for example, Bragg gratings
A certain number of parts, such as when they are formed along
The fiber is substantially
If it is uniform and uniform, use a constant take-up pitch.
Assign to fiber and modulate using, for example, a periodic function
By winding along parts that have different properties
It is preferable to change the pitch. Figure 4 is purely an example
As shown, a winding formed in accordance with the techniques of the present invention.
Is formed, and the first layer of the winding is a constant winding.
First fiber section P for which the take-up pitch is relevant₁About
I am linked. On the other hand, the second layer uses a periodic function
The second fiber section P to which the modulated pitch is related
_TwoHas to do with.

To obtain modulation of the winding pitch according to a predetermined periodic function, the unit 21 modulates the member 17 (or the member that moves the pulley 19a if it is movable) according to a desired law. Control signal must be sent. This signal must have a different sign each time the wound fiber 2 finishes a layer on the reel 16.

In the most general case, the translation speed v _i (t) applied to the reel 16 (or the pulley 19a) on which the part P _i is wound is the sum of a fixed term and a modulated term. That is,

[0079]

V _i (t) = v ₀ (1 + F _i (t)) where F _i (t) is a specific function selected to modulate the winding pitch of the portion P _i. is there. Function F
_i (t) may be a constant function or a more complex function, as previously mentioned, preferably a periodic function s (t) as defined above.

In the simplest case of the sinusoidal modulation function F _i (t), the translation speed v _i (t) given to the reel 16
Is the result of the sum of the constant term and the sinusoidal term.

[0081]

V _i (t) = v ₀ (1 + Asen2πf _i t) where f _i is the value of the modulation frequency selected to wind up the portion P _i .

The winding pitch p is consequently modulated according to a similar time law.

[0083]

P _i (t) = p ₀ (1 + Bsen2πf _i t) where p ₀ = v ₀ · T _o .

If the rotation speed of the reel 16 is constant, this time law is converted into a uniform space law, and the time t replaces the horizontal axis x measured along the axis of the reel 16. In the case of more complex periodic functions, these time and space times include a series of harmonics.

FIG. 5 shows purely by way of example the first and second
Winding pitch p relating to the respective portions P ₁ and P ₂
The time series of ₁ (t) and p ₂ (t) are shown. Pitch p
₁ (t) and p ₂ (t) is the fundamental frequency f ₁ = 1 / T ₁ and f ₂ = 1 / T ₂ and the triangular function s ₁ with a corresponding to the period T ₁ and T ₂ (t) , S ₂ (t). Possible frequency values are, for example, f ₁ = 20 Hz and f ₂ = 8H
z. In the example shown, the winding pitch is
It oscillates between the same minimum value p _min equal to 0.3 mm and the same maximum value p _max equal to 3 mm.

If necessary, the oscillation amplitude of the winding pitch value associated with one part may be different from the oscillation amplitude of the winding pitch value of the remaining part. The modulation technique of the winding pitch using the periodic function has an effect that is not meaningless as compared with a case where the winding pitch is selected using a constant value. Indeed, if the oscillation of the winding pitch value is sufficiently wide that the effects of mechanical vibrations commonly occurring during both winding and release can be reduced to negligible levels, the measurement of the winding pitch (According to the technology described below) will leave little uncertainty.

The method according to the invention is described below with reference to FIGS.
This will be described in detail with reference to the flowchart of FIG. This method uses N
Longitudinal portions P _1, P ₂ for consecutive, ..., a fiber 2 having a P _N, at least fiber draw 2 as having one detectable characteristic different from the portion where the respective portions adjacent This is done with reference to the process.

Preliminary steps of the method (block 1)
At 00), the process parameters are input to the unit 21. In particular, for each major axis portion P _i to be formed, a group G ₁ of process parameter values.
Are input, and these values are selected so as to obtain desired characteristics of the fiber 2. For each part P _i to be formed, the space law associated with the winding pitch of this part is also input. In the following, only the preferred case where this space law corresponds to a periodic function distinguished by the fundamental modulation frequency f _mod will be considered. Modulation frequency f of the winding pitch, different from that associated with the adjacent part
The value of _mod is therefore associated with each different portions P _i.

Length and assumption assumed for different parts
Part P based on the winding speed₁, P_Two,…,
P_NTime interval T for processing and winding₁, T_Two, ..., T_N
Is also determined. General spacing T_iIs the part
P_iTime t_iDefined by
It is. Unit 21 must be at the time of
There is an internal clock for measuring these times.
You. Also, the time interval T ₁, T_Two, ..., T_NPredefine
Not the part P₁, P_Two, ..., P_NTo form
It is also possible to define the long axis part of the intended preform 3
It is possible. In this case, the part P_iOne of the end of processing
General time point t_iIs detected during the drawing process and the light
Fiber part P_iIs drawn from there
At the end of the program part.

The parameter setting step further comprises a unit 21 for each possible process.
Then, inputting a warning condition that can be detected based on signals from sensors and detectors arranged along the tower 1 is considered. This is the respective value f _Ai of the frequency f _mod for the modulation of the translation speed of the reel 16 different from that used to distinguish the parts P ₁ , P ₂ ,..., P _N. In practice, each value f of the modulation frequency f _mod
Ai is assigned to each warning code A _i. The duration of the modulation at frequency f _Ai may coincide with the duration of the warning condition, or if the warning time of the warning condition is particularly short (such as in the case of surface defect detection),
It can be equal to the predetermined duration T _Ai .

Once the parameters have been entered,
The unit 21 sends corresponding control signals to the various parts of the tower 1 to which it is connected to start the drawing process. In particular, unit 21 biases the various parts, based on the process parameters of the group G _1, to establish the operating conditions envisioned for drawing a first portion P ₁ (block 110). At the same time, unit 21 activates its clock and assigns the value 1 to a variable i that indicates the fiber section currently being processed.

Predetermined angular velocity ω_{a, 1}And translation speed v₁And
Rule 16. Translation speed v ₁Is as follows
You.

[0093]

V ₁ (t) = v ₀ (1 + Asen2πf ₁ t) Assuming that the rotation period T _{0 of the} pulley 16 is constant, the winding pitch at which the first portion P ₁ is wound is as follows. become.

[0094]

P ₁ (t) = p ₀ (1 + Bsen2πf ₁ t) During the drawing process of the fiber 2, the unit 21
Continually receives signals from sensors and detectors and checks for the presence of a process alert (block 120).

If no process alert exists (option N of block 120), unit 21 determines that t <t
_i (where i is equal to 1 for the first part P ₁ ). That is, the part P
_It is checked whether the processing and winding of _i must continue (block 130). If t <t _i (option Y in block 130), ie, if the processing of the part under consideration has not yet been completed, processing and winding of this part continue without modification. . On the other hand, when the processing and winding of the assumed part are completed (N in block 130), the unit 21
Checks whether t <t _N, that is, whether the drawing process of fiber 2 must continue or the end point has been reached (block 14).
0). If the processing end time t _N has not yet been reached (option Y in block 140), the unit 21
Increases the value of the variable i by one unit, assigns the value f _{i + 1} to the modulation frequency f _mod , and selects the process parameter G _{i + 1} associated with the contiguous part P _{i + 1} (block 15).
0). The process conditions are eventually modified and the part P
_The condition assumed for the processing of _{i + 1} is obtained. At the same time, the unit 21
3 and reel 16 modulated using frequency fi _{+ 1}
Signal for modulation of the translation speed. If the reel 16 is axially fixed and the pulley 19a is movable in the axial direction, this modulation frequency is used to modulate the translation speed of the pulley 19a. In each of these two cases, the frequency f _{i + 1} is associated with the winding pitch of the new fiber section P _{i + 1} .

If during the drawing process unit 21 receives a signal identifying the j-th alert condition from the sensors and detectors (option Y of block 120), unit 21 generates a corresponding alert code Aj. , Assign the modulation frequency f _mod the value f _Aj associated with this warning code (block 170). A control signal modulated using the frequency f _Aj is sent to the next moving member 17 and the winding pitch is modulated according to this frequency. This condition is maintained until the warning signal stops or otherwise after the period _Taj when the warning signal was received. Thereafter, the pre-existing conditions relating to the portion P _i are returned (option N of block 120).

When the winding process is detected to have reached the time point t _N indicating the end of the process (option N in block 140), in other words, the last part P _N of the fiber is processed and wound. And (block 16
0), end.

At the end of the drawing process, fiber 2
Is completely wound on the reel 16. Fiber portions _{P 1, P 2, ...,} P N forms a winding layer of a given number, each of the layers are wound in the winding pitch, which is modulated with the corresponding frequency .

The process of releasing the fiber 2 from the reel 16 is performed with the help of the device of FIG. 2 or the device of FIG. This process is described below with reference to the flowchart of FIG.

The fiber releasing process is to provide the reel 16 and the reel 31 with a predetermined rotational speed selected such that the releasing speed of the fiber 2 from the reel 16 is equal to the winding speed of the fiber 2 on the reel 31. Is started by Rotation speed ω _S of reel 16 during release
May be different from the speed ω _a during winding.
In general, as the constant K, written as ω _S = Kω _a. The speed ω _S is reached after a short initial transient.

During the process of release from the reel 16, the fiber 2 passes through the sensitive area of the light sensor 33, and subsequently generates a signal S (block 210). It will be appreciated that the same is true for the other case of the sensor 38, and what is believed to occur subsequently with respect to the signal S is applicable to the signal S '. Signal S
Is modulated according to a time law similar to the spatial law in which the assumed winding pitch of the fiber portion is modulated, as described above. In particular, the frequency f _S of the signal S is modulated, the frequency f _mod for the modulation of the winding pitch of the fiber portion which is assumed by the equation f _S = Kf _mod
Is linked to.

The first released portion corresponds to the last wound portion, ie, the portion _PN or the portion wound in the warning condition. Unit 26 receives the signal S, extracts the frequency value f _mod , and releases it by comparison between the extracted value and a group of frequency values preset before the drawing process and (f _i and f _Aj ). Perform the identification of the part which was done. The value of the detected modulation frequency f _mod is assigned to a variable f and stored (block 23).
0).

In the case of the device 30 of FIG. 2, upon receiving the signal S, the unit 26 adjusts the translation speed of the reel 16 based on the absolute value and sign of the signal S. In particular, the translation speed is adjusted to move the actual intersection of the sensitive area as close as possible to the predetermined intersection, thus reducing the value of S to a minimum. In this way, the translational speed of the reel 16 is modulated with a frequency f _S. A very short time period elapses between the start of the release process and the steps involved in generating the signal S and adjusting the translation speed of the reel 16 described above, whereby the frequency f Modulation with _S actually results from the start of the release process after a short initial transient. The steps involved in adjusting the translation speed of the reel 16 are not present in the case of the release device 30 'of FIG.

Following the steps of this first sequence (blocks 200 to 220) aimed at identifying the first released part and assigning the first value to the variable f , the sequence described below A cycle of steps for determining the objective part continues.

During the release of the fiber 2, the unit 26
Indicates whether the release of fiber 2 has been completed (block 2
30) is checked, for example, using a signal from a device (not shown) that detects the presence of fiber on the reel 16. If the release process has not yet been completed, ie if reel 16 still contains fibers to release (option N of block 230), the process continues and the processing unit again sets the frequency f _mod The error signal S is processed for extraction (block 240).
The value of frequency f _mod is compared to a value associated with variable f using a comparison subunit (not shown) of unit 26 (block 250). If the value of the frequency f _mod matches the value of f (option Y in block 250), this means that a new portion of the fiber does not yet exist, and thus the cycle of steps described above repeats without variation. Means that it could be done.

On the other hand, if the value of f _mod is different from the value associated with f (output N of block 250), this means that the release of fiber parts having different characteristics has begun. In this case, fiber release process is aborted (block 260), unit 26, f _mod
Is compared to the stored frequency value,
Proceed to identifying a characteristic of the new fiber section or a warning condition associated with this frequency (block 270). Unit 26 can then, by its own announcement sub-unit (not shown, eg, display sub-unit), provide the operator with an indication as to the fact that the leading part has been completely released and associated with the new fiber part. (E.g., information about the characteristics of this part or, if this part was wound under warning conditions, information about the warning conditions that occurred during winding, or consideration during winding). Information about any type of defect detected on the part where it is detected. At this point, the operator can intervene to cut the fiber 2 and replace the reel 31 containing the just released part with an empty reel (block 290). Next, the release process is started again (block 300) and the steps described above (block 230-
250, 260-300 if necessary) is repeated until it is detected that the fiber has been completely released. If release is detected, the process ends (block 310).

[Brief description of the drawings]

FIG. 1 relates to a tower for drawing optical fibers formed according to the present invention.

FIG. 2 illustrates an apparatus for releasing a fiber from a reel in accordance with the method of the present invention.

FIG. 3 shows variations on the apparatus shown in FIG. However, some parts have been removed for clarity.

FIG. 4 shows, in schematic and simplified form, a reel on which an optical fiber is wound according to the method of the invention.

FIG. 5 shows a graph of two periodic functions used to modulate the winding pitch of a fiber in accordance with the method of the present invention.

FIG. 6 shows a flowchart relating to some steps of the method according to the invention.

FIG. 7 is a flowchart relating to another step of the method according to the invention.

 ──────────────────────────────────────────────────の Continued on the front page (71) Applicant 591011856 Pirelli Cavies System e. p. A

Claims (25)

[Claims] 1. A method of manufacturing a fiber element (2), comprising the steps of drawing the fiber element from a preform (3), and two long-axis portions (P _i ) having different properties of the fiber element. Forming a support (1)
6) winding up and associating a corresponding winding pitch (p _i ) with each of the two long axis portions. 2. At least two materials having mutually different properties
Manufacturing apparatus (2-5, 8-15) designed to manufacture a fiber element (2) having two long-axis portions (P _i )
An assembly for manufacturing a fiber element comprising receiving the fiber element from the manufacturing equipment and winding the fiber element on a support (16), and setting a corresponding winding pitch (p _i ) to each of the portions Take-up device (7, 21, 2) designed to be associated with
An assembly further comprising (2, 23). 3. The assembly according to claim 2, wherein the winding device (7) comprises: a supply member (19a) for supplying the fiber element (2) to the support (16) in a predetermined supply direction; An axial speed which correlates one of the support (16) and the supply member (19a) in a predetermined direction (16a, 19b) and for each of said parts the winding pitch associated with said part; And an axis moving device (17, 19c) for moving in (1). 4. The assembly according to claim 2, further comprising a distinguishing device for distinguishing between different longitudinal portions of the fiber element (2) wound on the support. A release device (25, 31, 3) designed to release said fiber element (2) from said support (16).
4) and a detector device (26, 33, 2) for detecting fluctuations in the winding pitch while releasing the fiber element (2).
6, 38) and an assembly comprising: 5. The assembly of claim 4, wherein the detector device comprises: a signal (S, S ′) that correlates with the winding pitch based on a point in a sensing area intersected by the fiber element.
Sensor device (33,
38), a processing unit (2) designed to receive the signal and to obtain from the signal a value indicative of the winding pitch.
6) An assembly comprising: 6. The assembly according to claim 2, wherein the fiber element (2) is an optical fiber and the production device (1) is a draw tower. assembly. 7. Support (16) for a fiber element (2)
A method of winding up, wherein the fiber element comprises at least two longitudinal portions (P _i ) having different properties, the method comprising feeding the fiber element to the support. For each of
Associating a corresponding value of a winding parameter (p _i ) that is different from a value associated with an adjacent portion. 8. The method of claim 7, wherein the step of associating a corresponding value of a take-up parameter (p _i ) with each of the portions comprises setting a corresponding take-up pitch (p _i ) of each of the portions. Associated with the method. 9. The method of claim 8, wherein the step of associating a corresponding winding pitch with each of the portions comprises: determining a corresponding function (s _i (t)) for modulation of the winding pitch. Associating with each of said parts. 10. The method according to claim 9, wherein the step of associating a corresponding function for modulation of the winding pitch with each of the portions comprises: adjusting a corresponding modulation frequency (f _i , f _{A, i} ) to each of said portions, said modulation frequency defining a dominant frequency of a corresponding periodic modulation function. 11. The method according to claim 7, wherein the corresponding winding pitch (p
_i ) associating each of said portions with said winding of said support in a predetermined direction (16a) at a speed correlated with said winding pitch, performed simultaneously with said step of providing said fiber element to said support. A method comprising the step of translating. 12. The method according to claim 7, wherein the step of supplying the fiber element to the support comprises the step of supplying the fiber element to the support using a supply member (19a). Directing the feed member in a predetermined direction (19b), wherein the step of associating a corresponding take-up pitch (p _i ) with each of the portions is performed simultaneously with the directing step. Translating at a speed that is correlated with the winding pitch. 13. The method according to claim 7, wherein the fiber element (2) is an optical fiber and the step of supplying the fiber element to the support comprises the step of: The method is performed simultaneously with the step of manufacturing, wherein the manufacturing step includes the step of drawing the optical fiber from a preform. 14. The method of claim 13, wherein the manufacturing step measures a process variable performed during the drawing step and, if one of the variables exceeds a predetermined threshold, identifies a defect. comprising the step of notifying a corresponding warning condition indicating the presence of a fiber portion with said step of associating with each of said portions corresponding values of the winding parameters (p _i), the winding parameter (p _i) Associating a corresponding value of the fiber portion with the defect. 15. A method for distinguishing between different longitudinal parts of a fiber element wound on a support according to the method of any of claims 7 to 14, wherein each of said parts Releasing a fiber element from the support, and detecting a change in the winding pitch during the releasing step, wherein a corresponding winding pitch is associated. A method characterized by the following. 16. The method of claim 15, wherein the step of detecting a change in the winding pitch comprises: adjusting the winding pitch and the winding pitch to obtain a continuous value of the parameter during the releasing step. A method comprising: iteratively measuring a correlated parameter; and detecting a change in the value of the parameter. 17. The method of claim 16, wherein each of the obtained values of the parameter is compared to a set of stored values, wherein each of the stored values is the sub-portion. And a step of identifying a major axis portion associated with the obtained value based on the comparison. 18. The method of claim 16 or claim 17, wherein the step of measuring the parameter comprises:
Detecting a distance between an actual point at which a predetermined region is intersected by said fiber element and a predetermined intersection of said region. 19. The method of claim 16 or claim 17, wherein the step of measuring the parameter comprises:
Detecting the angle between a direction in which the fiber element is released from the support and a predetermined direction. 20. A device for winding a fiber element (2) onto a support, said fiber element comprising at least two longitudinal parts (P _i ) having different properties, said fiber element being supported on said support. A moving member (17, 19c) for moving one of the support and the supplying member at a predetermined translation speed along a predetermined axis to obtain a predetermined winding pitch; A unit (21) for controlling said moving device (17, 19c), wherein said unit controls said translation speed and is different from a winding pitch associated with an adjacent part. An apparatus comprising a unit designed to associate a pitch (p _i ) with each of said parts. 21. The apparatus of claim 20, wherein at least one of the winding pitches is modulated using a periodic function. 22. Apparatus according to claim 20, wherein the fiber element (2) is an optical fiber. 23. A device for distinguishing between different longitudinal sections of a fiber element (2) wound on a support (16), each of said sections being associated with a corresponding winding pitch (p _i ). A device (25, 31, 34) for releasing said fiber element (2) from said support (16), and a signal for repeatedly measuring and indicating said parameter correlating with said winding pitch. Sensor devices (33, 38) designed to generate (S, S ')
And a processing unit (2) designed to receive the signal and detect a variation in the parameter based on the signal.
6) A device comprising: 24. The apparatus according to claim 23, wherein the sensor device (33) is an optical device having a sensitive area and a reference point on the sensitive area, wherein the sensitive area is the fiber element. The apparatus is designed to detect a distance between a point intersected by the reference point and the reference point. 25. The apparatus according to claim 23, wherein the sensor device (38) is designed to detect an angle between a direction in which the fiber element is released from the support and a predetermined direction. An apparatus characterized in that: