JPS6254208A - Optical cable - Google Patents

Abstract

PURPOSE:To protect the optical fiber from the side pressure even when the optical cable is bent and the optical fiber is pushed to the surface groove bottom part of the spacer by the bending distortion by providing the soft layer by the buffering elastic body at the bottom part of the surface groove of the spacer beforehand. CONSTITUTION:On the bottom part of a surface groove 4 of a spacer 1, a soft layer 6 composed of the elastic body with the thickness (t) and the Young's modulus E0 is provided beforehand. Bending is given to the optical cable, a side pressure P is impressed to the optical fiber, and then, only by the depth shown in the formula, the optical fiber core wire is buried into the soft layer 6 of the elastic body and the occurring side pressure can be eased. As for the soft layer 6 of the elastic body, it is preferable the thickness (t) of the soft layer of the elastic body is made thick and the material with a low Young's modulus is used.

Description

[Detailed Description of the Invention] [Summary of the Invention] By providing a soft layer of an elastic material at the bottom of the surface groove of the spacer that accommodates the optical fiber or optical fiber assembly,
Even when the optical cable is bent and the optical fiber is pressed against the bottom of the surface groove of the spacer due to bending strain, the optical fiber is protected from lateral pressure and stable transmission loss characteristics can be obtained.

[Industrial application field]

The present invention relates to a spacer-type optical cable in which an optical fiber or an optical fiber assembly is housed in a surface groove of a central wire-shaped body, and in particular, a structure of a spacer-type optical cable that relieves lateral pressure generated on an optical fiber or an optical fiber assembly when the optical cable is installed in a curved manner. It is related to.

[Conventional technology]

141! This is a cutting-edge construction of the spacer-type optical cable since lf. 1 is a central linear body (hereinafter referred to as a spacer), 2 is an optical fiber, 3 is a cable sheath, 4 is a surface groove provided continuously in the longitudinal direction on the surface of the substrate 1, and 5 is a tensile strength member.

An optical fiber 2 is housed in the surface +1114 of the spacer 10 provided with a surface groove 4, and a cable sheath 5 is applied to the outer peripheral surface of the spacer 1 to cover the entire surface.

The structure of this wooden spanner type optical cable is an excellent structure in which the optical fiber 2 is isolated from external forces applied from outside the cable, so that it is difficult to cause an increase in microbend loss.

[Problem that the invention seeks to solve]

For example, when a spacer-type optical cable with a conventional structure is bent by a radius R as shown in FIG.
It will be pressed against the bottom of the surface groove 4. At this time, the lateral pressure P applied to the optical fiber 2' is given by the following equation.

P=-Σ]i81mu1(1) R''i where r: Distance between the centers of the optical fiber and the optical cable in the cross section of the optical cable. Young's modulus of the optical fiber core material Ai: Cross-sectional area of the optical fiber core material 1: A subscript that distinguishes the constituent material of the optical fiber.

From the above equation (1), it can be seen that even in the spacer-type optical cable having the structure shown in FIG. It is understood that lateral pressure is applied to the fiber & is unavoidable. Therefore, with the structure of the conventional spacer type optical cable, there is a problem that when the optical cable is bent, there is a risk that transmission loss will increase due to micro-bending of the optical fiber.

[Means for solving problems]

In order to solve the conventional problems, the present invention is characterized in that a soft layer made of a cushioning elastic material is provided in advance at the bottom of the surface groove of the spacer.

[Effect]

According to the present invention, even when the optical cable is bent and pressed against the bottom of the surface groove of the spacer due to the bending strain generated in the optical fiber, the soft layer made of the elastic material at the bottom of the surface groove reduces the lateral pressure applied to the optical fiber. It can be relaxed. This will be explained below with reference to the drawings.

〔Example〕

FIG. 1 shows a cross-sectional structure of an embodiment of the spacer type optical cable of the present invention. The same reference numerals as in Figure 114 indicate the same parts. At the bottom of surface #4 of space f1, a thickness t1 of Young's modulus 1. A soft layer 6 made of an elastic body is provided. By using the structure of the present invention, when the optical cable shown in FIG. 5 is bent and the lateral pressure P shown by equation (1) is applied to the optical fiber, the optical fiber will be The optical fiber core is embedded in the soft layer 6 of the elastic body to a depth supported by the radius of the IPA core, thereby making it possible to relieve the generated lateral pressure. As is clear from equation (2), the soft layer 6 of the elastic body is preferably made of a material with a large thickness t and a low Young's modulus E. For example, silicone rubber is preferable. be.

Although the embodiment of the present invention shown in FIG. 1 is an example of one spacer, the present invention is not limited to this embodiment. Optical cables and optical fibers housed in the surface grooves of spacers as shown in Fig.
It may also be an optical fiber assembly unit as shown in the figure. It is also possible to fill the surface grooves with a waterproof resin such as Jieli.

〔Effect of the invention〕

As described above, according to the present invention, by providing a soft layer of elastic material at the bottom of the surface groove of the spacer, even when a spacer-type optical cable is bent and installed, the optical fiber is protected from lateral pressure, and the transmission Stable loss characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 shows the cross-sectional structure of a spacer-type optical cable of the present invention, Fig. 2 and Fig. 6 show examples of optical fibers applied to the present invention, respectively, and Fig. 4 shows the cross-sectional structure of a conventional spacer-type cable.
The figure shows the spacer type cable in a bent state. 1... Spacer 2.2'... Optical fiber 3... Cable sheath 4... Surface groove 5... Tensile strength member 6... Soft layer Patent applicant Sumitomo Electric Industries, Ltd. (1 night stay) teenager
Figure 1 Cross-sectional structure of the spacer-type optical cable of the present invention

Claims (1)

[Claims] A cable sheath is provided on the outer circumferential surface of the centerline body, in which an optical fiber or an optical fiber assembly is accommodated in a surface groove continuously provided in the longitudinal direction on the surface of the centerline body. An optical cable characterized in that a soft layer of an elastic body is provided at the bottom of the surface groove.