JPS6182128A - Measuring method of drawing tension of optical fiber - Google Patents

Abstract

PURPOSE:To calculate tension with high precision without contacting an optical fiber by measuring the oscillation frequency between constraint end of the optical fiber in an optical fiber working process and performing arithmetic according to a specific equation. CONSTITUTION:A base material M is worked into an optical fiber wire by having its lower end part heated and fused in an electric furnace 11. An external diameter measuring machine 2 is used in this wire drawing process between the electric furnace 11 and a primary coat die 12 to measure the diameter of the optical fiber F. The measuring machine 2 measures the diameter of the optical fiber F by a photosensor part 21 and a measuring machine body 22 and it is recorded on a recorder 25. A frequency analyzer 23, on the other hand, calculates the oscillation frequency (f) between constraint ends of the optical fiber F from the output of the main body 22. The frequency (f) is input ted to a computing element 24 and the tension S of the fiber F is calculated from the equation I on the basis of the constraint end distance l, weight (r) per unit length, oscillation degree (n), and weight acceleration (g) of the optical fiber F which are already inputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the tension of an optical fiber during drawing without contacting the optical fiber.

[Prior art]

The strength of an optical fiber is closely related to the tension at the time of drawing it; normally, as the tension increases, the transmission loss decreases but the strength decreases, and conversely, when the tension increases, the strength increases but the transmission loss decreases. There is a declining relationship. Therefore, appropriate tension control is required during the drawing process of optical fiber.
This requires accurate measurement of the tension in the optical fiber before precoating.

However, since bringing a measuring instrument into contact with the optical fiber itself causes a loss of strength of the optical fiber, measurement in a non-contact state is required. However, in the past, a non-contact measurement method had not been established, so lines were drawn from the busbar.
The tension of the precoated optical fiber was measured using a contact tension meter.

[Problem that the invention seeks to solve]

However, in such conventional methods, the primary coat die, buffer code die, etc. each apply external forces to the optical fiber, so corrections for these are necessary, measurement accuracy is not sufficient, and tension control does not depend on experience. There were many parts where I didn't get anything.

[Means to solve the problem]

The present invention has been made in view of the above circumstances, and its purpose is to focus on the fact that the vibration between the bound ends of an optical fiber during drawing can be simulated as the vibration of the thread to which tension is applied. An object of the present invention is to provide a method for measuring the drawing tension of an optical fiber, which allows the tension to be easily measured using the vibration method.

The method for measuring the drawing tension of an optical fiber according to the present invention non-contactly measures the vibration frequency f between the restrained ends of the optical fiber during the process of heating and melting a base material and drawing it into an optical fiber. The method is characterized in that the tension 5-t of the optical fiber is measured according to the following formula based on the predetermined distance l between the restrained ends of the optical fiber and the weight γ per unit length of the optical fiber.

g n where g: gravitational acceleration rL: order of vibration [Example] The implementation state of the present invention will be specifically described below based on the drawings.

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, in which 1 is an optical fiber drawing machine, 2 is an outer diameter measuring device that also serves as a tension measurement, M is an optical fiber base material for drawing, and F is a drawing machine. Optical fiber is shown. The optical fiber drawing machine 8M-1 is composed of an electric furnace 11, a primary coat die 12, a buffer coat die 13, and a capstan I4 arranged in this order upwardly and downwardly. The lower end of the base material M is heated and melted at a high temperature in an electric furnace 11, and drawn into a linear shape of a required diameter, that is, an optical fiber.In the process of passing through a primary coat die 12, a primary coat made of synthetic resin is formed. In addition, in the process of passing through the buff 1 coat die 13, the buff 1 made of 7j I2 resin is
The coats are formed in layers around the optical fibers F, and are wound up on a reel or the like (not shown) through the capstan 14.

In the above-described drawing process, the diameter of the optical fiber F and the tension applied to the optical fiber F are measured using the outer diameter measuring device 2 between the electric furnace 11 and the primary coat die 12. The outer diameter measuring machine 2 includes a sensor part 21, a measuring machine main body 22, a frequency analyzer 23, a computing unit 24, a recorder 25, etc. (for example, the sensor part 21 and the measuring machine main body 22 are M551A manufactured by Anritsu Electric Co., Ltd.). The sensor part 21 is arranged to face the movement area of the optical fiber F between the electric furnace 11 and the primary coat die 12.

Figure 2 is a schematic diagram of a part of the sensor, and laser generation! 21
The tuning fork 2 vibrates the laser beam B emitted from a (He-Ne gas laser) by the mirror M1 electromagnet 21b.
It is reflected by mirror M2 attached to 1c.

A part of the reflected light passes through the half mirror HM and is projected onto the optical fiber F in such a manner that it crosses the optical fiber F, and the light reflected by the half mirror HM mutually passes through the half mirror H.
The light incident on M2 and reflected here is captured by the light receiver 21g and used to generate a sine wave signal synchronized with the vibration of the tuning fork 21c. A tuning fork drive signal is output to 21b.

On the other hand, on the opposite side of the optical fiber F to the laser beam projection side, the light from the optical fiber F and its surroundings is input to the half mirror HM3, and the light transmitted through this is sent to the light receiver 21.
d, the reflected light is captured by light receivers 21e and 21f, and output to the measuring instrument main body 22, respectively.

Fig. 3 (a) is an explanatory diagram showing the relationship between the optical fiber F and a sine wave B' that simulates the vibration axis trace of the laser beam projected onto it, and Fig. 3 (b) is an explanatory diagram showing the relationship between the optical fiber F and the sine wave B' that simulates the vibration axis trace of the laser beam projected onto it. Signal 2
Waveform diagram of valued signal, Fig. 3 (c).

(D) shows a waveform diagram of a binary signal captured by the light receivers 21e and 214. Now, when the laser beam B is projected onto the optical fiber F, one edge of the optical fiber F in the diametrical direction (the upper edge in the same paper) is a(, a2, .
a3..., and the other side edge (lower edge on the same paper) and lotus,
, b2. b3, and when viewed from the opposite side of the optical fiber F, a1~b1° b2~a2. Between a3 and b3, the laser beam B is blocked by the optical fiber F and becomes dark, and in other parts it becomes bright.

Therefore, when the light reception signal of the light receiver 21d is binarized, it is shown in Fig. 3 (
B) As shown in (al, falling at b2.d3, bl, a2
．． It becomes a pulse signal that rises at bl.

The measuring instrument main body 22 uses this signal as a sampling command pulse, and at each falling and rising edge, al + a2 + al '' of the detected sine wave B' of the light receiver 21g.
, bl + b2 + bl "' each electrode VI,
Sample V2 and calculate the difference V2-Ml.

The voltage difference V 2 V 1 obtained in this way is naturally small when the diameter of the optical fiber F is small, and becomes large when the diameter is large, and has a proportional relationship with the diameter. The diameter of the optical fiber F is calculated based on the relationship, and recorded on the recorder 25.

On the other hand, as shown in FIG. 2, the light receivers 21e and 2H are disposed at different positions with respect to the optical axis.
The received light signals from these are shown in Figure 3 (c).

As shown in (d), a phase shift ΔT corresponding to the positional shift of the light receivers 21e and 21f occurs, but this phase shift ΔT changes depending on the position of one side edge of the optical fiber F or the degree of axis shift. . Therefore, the change in ΔT over time corresponds to the change in the vibration frequency of the optical fiber F.
The vibration frequency r can be found. Frequency analyzer 2
3 is a light receiver 21e.

This vibration frequency f is calculated from the 21f output.

The calculated vibration frequency f of the optical fiber F is input to the calculator 24, and is calculated based on the length between the restrained ends of the optical fiber, the weight per unit length of the optical fiber, the vibration order, the gravitational acceleration, etc. that have been input in advance. The tension of the optical fiber F is calculated according to the following equation, and a necessary tension control signal is output.

g n However, g: Gravitational acceleration ((J/sec2) It: Length between the restrained ends of the optical fiber C11) γ: Weight per unit length of the optical fiber (kg/c+n) n: Order of vibration (1, 2, 3...) f: Vibration frequency of optical fiber The length l between the restrained ends of the optical fiber is the distance from the lower end of the base material M to the primary coat die 12, and this length z, g The order n is determined from the specifications of the drawing machine. Note that the weight γ per unit length of the optical fiber is calculated based on the diameter obtained with an optical fiber outer needle measuring device.

〔effect〕

As mentioned above, in the method of the present invention, the tension of an optical fiber can be determined without contacting the optical fiber, so it does not affect the quality of the optical fiber, and it also does not affect the tension. The present invention has excellent effects, such as improved tension measurement accuracy and improved tension control accuracy because the tension is not applied.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the implementation state of the method of the present invention, Fig. 2 is a schematic diagram of the outer diameter measuring machine, and Figs. 3 (a) to (d) are waveform diagrams of signals processed by the outer diameter measuring machine main body. It is. 1... Wire drawing machine 2... Outer diameter measuring machine 11... Electric furnace 12... Die 13... Die 14... Capstan 21... Sensor part 22... Measuring machine Main body 23...Frequency analyzer 24...Performance 1 device 25...
・Recorder B...Laser beam B'...Sine wave patent Applicant Dainichi Nippon Cable Co., Ltd. Agent Patent attorney Noboru Kono 21g Note 2 Drawing procedure amendment (method) % formula % 2. Invention Name: Optical fiber drawing tension measurement method 3, relationship with the case of the person making the amendment Patent applicant location: 8, Higashimukojima Nishinocho, Amagasaki City, Hyogo Prefecture Name (3)
26) Dainichi Nippon Electric Cable Co., Ltd. Representative Yukio Aoyama 4, Agent Address ■543 Kono Patent Office, 207 Nisshin Building, 1-14-22 Shitennoji, Tennoji-ku, Osaka (Telephone: 06-
779-3088) January 9, 1985 (Shipping date 60
．． 1.29) 6. In column 7 of “Brief explanation of drawings” of the specification to be amended, “Fig. 3 (a)
~(d) is corrected to read "Outside diameter measuring machine main body J" as ``Figure 3 is the outside diameter measuring machine main body.''that's all

Claims (1)

[Claims] 1. In the process of heating and melting the base material and drawing it into an optical fiber, the vibration frequency f between the restrained ends of the optical fiber is measured in a non-contact manner, and the predetermined optical fiber is A method for measuring the drawing tension of an optical fiber, characterized in that the tension S of the optical fiber is measured according to the following formula based on the distance l between the restrained ends and the weight r per unit length of the optical fiber. S=r/g[(2fl)/n]^2 where g: gravitational acceleration n: order of vibration