JPH05273416A - Method for controlling tension for winding of optical fiber - Google Patents

Abstract

PURPOSE:To eliminate an increase in the loss of under-wound bobbin by making the lateral pressure applied to the optical fiber of the under-wound bobbin less than the lateral pressure which causes the optical fiber to generate the loss increase. CONSTITUTION:Winding tension is decreased from T1 to T2 as a bobbin take-up radius Ri increases so that when the winding ends, the lateral pressure applied to the optical fiber of the under wound bobbin is less than the value Pc of the lateral pressure which causes the optical fiber to generate the loss increase. Namely, contact pressure (lateral pressure) P applied between the optical fiber of a 1st layer and a bobbin is the sum of its lateral pressure P1 (only between the optical fiber of the 1st layer and the bobbin) and the whole lateral pressure of the optical fiber wound even in several layers. Therefore, when the number (n) of winding layers and the take-up tension T1 in the beginning of winding are determined, the value P is calculated, the take-up tension Tn at the end of the winding with which the value does not exceed the Pc is found, and the tension is varied stepwise from T1 to Tn, so that no increase in the loss of the under-winding of the optical fiber is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension control method when an optical fiber is wound on a bobbin. By using this method, an increase in loss in the lower bobbin winding, which occurs at the time of high tension winding, is increased. Eliminate.

[0002]

2. Description of the Related Art FIG. 2 schematically shows an example of winding an optical fiber 10. Reference numeral 20 is a sending bobbin, 30 is a winding bobbin, and 40 is a winding tension control device. The conventional winding of the optical fiber 10 is performed with a relatively high tension in order to prevent the collapse of the winding. Further, the tension is maintained at a constant value by the control device 40 from the beginning of winding to the end of winding.

[0003]

When the above-described winding is performed, the lateral pressure on the optical fiber at the beginning of winding (bottom winding of the bobbin) increases as the winding diameter increases. When this lateral pressure becomes larger than a certain value Pc (determined for each optical fiber), loss increases in the bobbin underwinding. Figure 3 shows the OTDR of the fiber with increased loss due to underwinding.
A chart is shown. If there is no increase in loss, the area around the start of winding falls straight like a chain line, but it actually has a drooping shape.

[0004]

As shown in FIG. 1 (a), as the bobbin winding radius Ri increases, the winding tension is reduced from T ₁ to T _2, and when the bobbin is completely wound, the bobbin is wound. The lateral pressure applied to the under-wound optical fiber is set to be smaller than the lateral pressure value Pc that causes the loss increase in the optical fiber.

Although the lateral pressure applied to the optical fiber is generated by the winding tension, when a multi-layer (for example, 150 layers) optical fiber is wound, the tension of the optical fiber of the upper layer sequentially affects the optical fiber of the lower layer and the lowermost layer (bobbin). The lateral pressure exerted on the optical fiber of the first layer) is maximized. That is, the contact pressure (lateral pressure) applied between the optical fiber of the first layer and the bobbin.
P is itself (only between the first layer optical fiber and the bobbin)
Is the total of the lateral pressure p ₁ of the optical fiber and the total lateral pressure of the optical fiber wound on it. This lateral pressure P is obtained as follows.

FIG. 4 shows a thin bobbin 30 having a radius a and a diameter d.
2 shows a state in which the optical fiber 10 is closely attached and only one layer is wound.

[Equation 1]

The area of the shaded portion in FIG. 1 (b) indicates this P. When the value of P exceeds the lateral pressure value Pc that causes an increase in loss, an increase in lower winding loss occurs.

From the above, when the number of winding layers n and the winding tension T _{1 at the} start of winding are determined as shown in FIG.
The value of P is calculated by the above formula, the winding tension Tn at the end of winding is calculated so that the value does not exceed Pc, and if it is reduced linearly or stepwise from T ₁ to T _n ,
There is no loss increase in the lower winding of the optical fiber.

[0009]

[Example] When rewinding, on a bobbin with a body diameter of 300 mm,
When winding 150 layers of 250 μm diameter optical fiber, the tension is 80 g.
To 40g. The lateral pressure applied to the lower winding fiber was suppressed to 115 g / mm ² , and no increase in loss was observed. No abnormalities were found in the winding state. On the other hand, when the tension was fixed at 80 g until the end of winding, the lateral pressure applied to the lower wound fiber was 152 g / mm ² , and loss increase was observed.

[0010]

Advantageous Effects of the Invention It is possible to eliminate the increase in loss in the bobbin under-winding which occurs at the time of high tension winding.

[Brief description of drawings]

FIG. 1 is an explanatory view of the present invention, (a) is a diagram showing a state in which the winding tension is reduced as the winding radius is increased,
FIG. 7B is a diagram showing the area of the total lateral pressure P applied between the first layer optical fiber and the bobbin when the optical fiber is wound by n layers.

FIG. 2 is an explanatory view schematically showing a winding state of an optical fiber.

FIG. 3 is an OTDR diagram showing that loss has increased at the winding start portion of the optical fiber.

FIG. 4 is an explanatory diagram for obtaining a lateral pressure of a first layer.

FIG. 5 is an explanatory diagram for obtaining a lateral pressure of the i-th layer.

[Explanation of symbols]

 10 optical fiber 20 sending bobbin 30 winding bobbin 40 winding tension control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Takahashi 1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Electric Wire Co., Ltd. Sakura Factory

Claims (1)

[Claims] 1. When winding an optical fiber around a bobbin, the winding tension is reduced with an increase in the winding radius of the bobbin, and when the winding is finished, the lateral pressure applied to the optical fiber under the bobbin is the optical pressure. A tension control method for winding an optical fiber, which is set to be smaller than a lateral pressure value that causes an increase in loss in the fiber.