JP3407966B2 - Slot type optical cable - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot type optical cable used for optical communication and the like. 2. Description of the Related Art As shown in FIG. 4, a conventional slot type optical cable has a tension line A disposed at the center and a plurality of receiving grooves B formed at an outer periphery at arbitrary intervals in the circumferential direction and in the axial direction. A plurality of optical fiber tapes D are accommodated in a housing groove B of a helically formed plastic slot spacer C, and a plurality of optical fiber tapes D are accommodated therein. Is coated. The slot spacer C is formed by extruding a thermoplastic resin such as high-density polyethylene around a tension line A using a steel wire, FRP, or the like. For example, five spirals are provided in the direction. As shown in FIG. 5, the optical fiber tape D is formed, for example, by integrating eight optical fiber cores F with an ultraviolet curing resin G and integrating them. In recent years, there has been a demand for multi-core and high-density optical cables in preparation for future demand for optical communication. Correspondingly, the number of optical fiber cores F of the optical fiber tape D used for the slot type optical cable is increasing. For this reason, the width of the optical fiber tape D is increased, the width of the accommodation groove B for accommodating the optical fiber tape D is increased, and the diameter of the slot spacer C is increased, so that the slot type optical cable is enlarged (increased in diameter). Tend to. However, on the other hand, miniaturization (smaller diameter) of the slot type optical cable is also required. [0006] In order to reduce the diameter of the slot type optical cable, it is necessary to minimize the outer diameter of the slot spacer C. In this case, the optical fiber tape D
When the outer diameter of the slot spacer C is reduced while keeping the dimensions (the width w and the depth h in FIG. 6) of the accommodation groove B for accommodating the The width of the root portion I supporting the rim portion H (the interval between the adjacent receiving grooves C: t in FIG. 6) must be reduced. At present, the width t of the root portion I of the slot spacer C can be reduced to about 0.7 mm in terms of molding. However, as the width t decreases, the rim portion H of the slot spacer C becomes unstable, When an external force such as lateral pressure is applied to the optical fiber cable, the rim portion H falls down and the receiving groove B
However, there is a problem that the optical fiber tape D stored in the optical fiber tape is liable to cause a loss or an injury. [0007] An object of the present invention is to set the stability of the rim portion of the slot spacer against an external force by setting the elastic modulus of the material of the slot spacer and the interval between adjacent receiving grooves of the slot spacer so as to satisfy a certain relationship. Secure,
An object of the present invention is to provide a multi-core, high-density, small-diameter slot type optical cable having good lateral pressure characteristics. As shown in FIG. 1, a slot type optical cable according to the present invention is provided on an outer periphery of a plastic slot spacer 1 at arbitrary intervals in the circumferential direction and along the axial direction. In an optical cable in which a plurality of housing grooves 2 are spirally formed and a plurality of optical fiber ribbons 3 are stacked and housed in the housing grooves 2, the bending elastic modulus of the plastic material constituting the slot spacer 1 is defined. Ef and rim between adjacent accommodation grooves 2 on the outer periphery of the same slot spacer 1
The width t of the root portion 6 of the portion 4 satisfies the following condition, and the width t of the root portion 6 is 0.9 mm or more and 1.1 mm or less. Ef · t> 100 kg / mm In the slot type optical cable of the present invention, the flexural modulus Ef of the plastic material forming the slot spacer 1
Between the adjacent accommodation grooves 2 on the outer periphery of the slot spacer 1
Width t of the base portion 6 of the rim portion 4 is Ef · t> 100 kg
/ Mm, the strength of the rim portion 4 of the slot spacer 1 is not deteriorated even if the outer diameter of the slot spacer 1 is reduced while the dimensions of the accommodation groove 2 are fixed and the cable The rim portion 4 is less likely to fall even when stress such as lateral pressure is applied to the rim portion 4. An embodiment of the slot type optical cable according to the present invention will be described in detail with reference to FIGS. In FIG. 1, 1
Slot spacer 2 receiving groove which is formed in the axial direction spirally and at arbitrary intervals in the circumferential direction on the outer periphery of the slot spacer 1, the optical fiber tapes accommodated in the accommodating groove 2 3, 5 An anti-tension line 4 provided at the center of the slot spacer 1 is a rim provided between the adjacent accommodation grooves 2. These basic structures are the same as those of the slot type optical cable shown in FIG. 4. However, in the present invention, the plastic material (flexural modulus Ef) of the slot spacer 1 and the slot The interval t between adjacent accommodation grooves 2 on the outer periphery has a relationship of Ef · t> 100 kg / mm. As shown in FIG. 2, the optical fiber tape 3 shown in FIG. 1 has a large number of single mode fiber cores (SM cores).
6 are arranged in a line in a row of 16 cores and are collectively covered with an ultraviolet-curable resin 7, and are formed in a tape shape having dimensions of about 3 mm in width and about 0.25 mm in thickness. The receiving groove 2 of the slot spacer 1 has a width of 3.5.
mm and a depth of about 3.6 mm, and the distance t between adjacent accommodation grooves 2 is reduced to 0.9 mm, so that the diameter of the slot spacer 1 is reduced to 14.0 mm. Here, by using high-density polyethylene having a flexural modulus of elasticity of 120 kg / mm ² or more as the material of the slot spacer 1, it is possible to prevent a decrease in the lateral pressure resistance characteristic due to the reduction in the diameter of the slot spacer 1. . That is, the strength of the slot spacer 1 with respect to the force in the shear direction (circumferential direction) for tilting the rim portion 4 is determined by the distance between the adjacent receiving grooves 2 (the width of the root portion 6 of the rim portion 4) t. Of the material of the slot spacer 1 and the bending elastic modulus Ef
Since it is proportional to the magnitude of t, the flexural modulus Ef may be increased according to the decrease in the width t. As shown in Table 1, slot spacers made of five types (A to E) of high-density polyethylene having different spacings t between adjacent accommodation grooves 2 and different flexural moduli Ef were manufactured as samples. The bottom column of Table 1 shows the measured values of the load when the rim portion 4 falls down by applying a shearing force to the rim portion 4 under the same conditions for each sample having a length of 10 mm. Is the bending elastic modulus Ef of the material of the slot spacer 1,
It is substantially proportional to the product Ef · t of the interval t between the adjacent accommodation grooves 2. Further, these slot spacers 1
FIG. 3 shows the relationship between the lateral pressure load when a lateral pressure is applied to a 0 mm flat plate and the amount of deformation of the slot spacer 1. Sample A ~
In the case of E, when the load is 100 kg / 100 mm or less, the load and the amount of deformation are almost proportional to the elastic modulus of the material of the slot spacer 1, but the samples A, B, and C each
With the boundaries of 0, 120, 160kg / 100mm,
The amount of deformation increases sharply compared to E. This is because the rim portion 4 of the slot spacer 1 starts to fall when the lateral pressure load exceeds a certain value. Due to the fall of the rim 4, the optical fiber tape 3 housed in the housing groove 2 of the slot spacer 1 receives an external force and causes a problem such as an increase in loss. For the slot spacer 1 in which the interval t between the adjacent receiving grooves 2 is reduced to less than 1 mm, the minimum required for a general optical fiber cable is 200 to 300 k.
In order to prevent the loss from increasing in the optical fiber tape 3 even when a lateral pressure load of about g / 100 mm is applied, the product of the bending elastic modulus Ef of the material of the slot spacer 1 and the interval t between the adjacent accommodation grooves 2 is required. Must be 100 kg / mm or more. [Table 1] The slot type optical cable according to the present invention satisfies certain lateral pressure resistance characteristics and can achieve multicore, high density, and small diameter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing an embodiment of a slot type optical cable according to the present invention. FIG. 2 is a front view of an optical fiber tape used in the slot type optical cable of the present invention. FIG. 3 is an explanatory diagram showing lateral pressure applied and deformation of the slot type optical cable of the present invention. FIG. 4 is a front view showing an example of a conventional slotted optical cable. FIG. 5 is a front view of an optical fiber tape used for a conventional slot type optical cable. FIG. 6 is an explanatory view of a slot spacer of a conventional slot type optical cable. [Description of Signs] 1 slot spacer 2 accommodation groove 3 optical fiber ribbon 4 base portion of rim t width of base portion of rim

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiro Otake 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Shigeru Tomita 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Japan (56) References JP-A-5-261844 (JP, A) JP-A-61-179407 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6 / 44

Claims (1)

(57) [Claims] [Claim 1] Plastic slot spacer (1)
A plurality of housing grooves (2) are formed spirally at arbitrary intervals in the circumferential direction and along the axial direction on the outer periphery of the optical fiber tape core wire (3) in the housing groove (2). In an optical cable having a plurality of stacked and accommodated therein, a bending elastic modulus Ef of a plastic material constituting the slot spacer (1) and a rim portion (4 ) between adjacent accommodation grooves (2) on the outer periphery of the slot spacer (1). ) Satisfies the following condition, and the width t of the root portion (6) is
A slot type optical cable having a length of 0.9 mm or more and 1.1 mm or less. Ef · t> 100kg / mm