JPH0917246A - Coaxial cable and its manufacture - Google Patents

Abstract

PURPOSE: To effectively reinforce an outer conductor, and prevent slippage in position between the outer conductor and a sheath while the flexibility of the whole of a cable in the bending direction is being sufficiently secured. CONSTITUTION: An outer conductor 3 is formed out of knitting formed by a plurality of metallic tapes 3b. A synthetic resin layer is coated to the outer side surface of at least a part of the metallic tapes 3b in advance, and a part of the synthetic resin layer which is in contact with the sheath 4, is fusion bonded to the sheath 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to television reception and CATV.
The present invention relates to a coaxial cable used for pulling in a house, etc.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional coaxial cable. This cable has an inner conductor 1 as a center, and an insulator 2, an outer conductor 3, and a synthetic resin sheath 4 arranged coaxially around the inner conductor 1 from the inside. It is composed of a braided conductor wire 3a (usually annealed copper single wire).

As this external conductor, in addition to the one shown in FIG. 3, an aluminum laminate tape 5 (a tape obtained by laminating a synthetic resin layer on the surface of an aluminum tape) 5 as shown in FIG. 4 is vertically provided around the insulator 2. Things
As disclosed in Japanese Utility Model Laid-Open No. 2-47728, one in which a metal tape is braided in place of the conductor wire is known.

[0004]

In the cable shown in FIG. 3 and the cable shown in the above publication, the bending strength of the outer conductor is relatively low, and when the cable is bent, the outer conductor and the sheath are There is a risk of axial displacement between them.

On the other hand, the aluminum laminate tape 5 as shown in FIG. 4 has high strength itself, and the synthetic resin layer and the sheath 4 arranged on the surface of the tape 5 are exposed to heat generated during sheath formation. Sufficient reinforcement is achieved by being fused and integrated. However, such an outer conductor formed by vertically attaching the aluminum laminate tape 5 has a very high bending rigidity as compared with the outer conductor formed by braiding as shown in FIG. Since the entire surface is fused with the sheath 4, the flexibility of the entire cable in the bending direction is extremely low. Therefore, the wiring work of the cable is not easy, and
Forcibly bending the cable may cause a wire breakage.

In Japanese Utility Model Laid-Open No. 56-143732, in the coaxial cable having the structure shown in FIG. 3, plastic threads are mixed with a part of the wires forming the outer conductor 3 to prevent heat generated during sheath formation. Japanese Patent Application Laid-Open No. 2000-242242 discloses that the plastic thread is fused to the inner peripheral surface of the sheath. However, in this structure, the inner peripheral surface of the sheath and the plastic thread that are fused to each other are almost in line contact and the contact area is small. Therefore, there is a disadvantage that fusion reliability and stability are low.

In view of the above circumstances, the present invention provides a coaxial cable and a coaxial cable capable of reliably reinforcing the outer conductor and preventing displacement between the outer conductor and the sheath while maintaining high flexibility in the bending direction. It is intended to provide a manufacturing method.

[0008]

As a means for solving the above-mentioned problems, the present invention has a coaxial structure in which an insulator, an outer conductor, and a synthetic resin sheath are sequentially arranged from the inner side around the inner conductor. In the cable, the outer conductor is formed by braiding a plurality of metal tapes, and a synthetic resin layer is provided on the outer surface of at least a part of the metal tapes. The contacting portion is fused to the inner surface of the sheath (Claim 1).

In this cable, the synthetic resin layer may be provided on the outer surface of only some of the metal tapes (Claim 2), or the outer surface of some of the metal tapes may be provided with a second resin. One synthetic resin layer may be provided, and a second synthetic resin layer having a lower fusion bondability to the inner surface of the sheath than the first synthetic resin layer may be provided on the outer surface of the other metal tape. Good (Claim 3).

Further, the present invention is a manufacturing method for manufacturing the above coaxial cable, wherein a synthetic resin layer is provided on at least one surface of at least a part of the metal tape, and then the synthetic resin layer covers the outside. Form an outer conductor outside the inner conductor and the insulator by braiding all metal tape in a state of facing,
A sheath is molded on the outer side of the outer conductor, and a portion of the synthetic resin layer that comes into contact with the inner surface of the sheath is fused to the inner surface of the sheath by heat during molding (claim 4).

[0011]

According to the coaxial cable of the present invention, since the synthetic resin layer on the outer surface of at least a part of the metal tape forming the outer conductor is fused with the sheath, the outer conductor is formed at this portion. By being integrated with the sheath, the bending strength of the outer conductor is effectively increased, and the positional displacement between the outer conductor and the sheath is prevented. Moreover, since the entire outer conductor is composed of a braided metal tape, the bending rigidity is low, and at least the surface of the outer surface of the metal tape which is remote from the inner surface of the sheath is not fused to the inner surface of the sheath. Since it is free from the sheath, the flexibility in the bending direction of the entire cable is maintained high.

Further, in this cable, as described in claim 4, a synthetic resin layer is provided on at least one surface of at least a portion of the metal tape, and then the synthetic resin layer faces all the outside in a state in which the synthetic resin layer faces outward. The tape is braided to form an outer conductor on the outer side of the inner conductor and the insulator, a sheath is formed on the outer side of the outer conductor, and the inner surface of the sheath and the synthetic resin layer are fused by the heat during the forming. Therefore, it can be easily manufactured.

In the above cable, the synthetic resin layer may be provided on the outer surface of all the metal tapes. However, as described in claims 2 and 3, only a part of the metal tapes is covered with the synthetic resin layer. A synthetic resin layer is provided on the side surface, a first synthetic resin layer is provided on the outer surface of a part of the metal tape, and an inner surface of the sheath is provided on the outer surface of another metal tape rather than the first synthetic resin layer. You may arrange | position the 2nd synthetic resin layer with low fusion-bonding property with respect to a side surface. In the former case, the ratio of the tape on which the synthetic resin layer is arranged and the tape on which the synthetic resin layer is not arranged is set. In the latter case, the tape on which the first synthetic resin layer is arranged and the second synthetic resin layer are arranged. By setting the ratio with the tape, it is possible to freely adjust the balance between the degree of reinforcement of the outer conductor and the flexibility of the entire cable. Specifically, the more the ratio of the tape on which the synthetic resin layer is arranged in the coaxial cable according to claim 2 is increased, and the first is the coaxial cable according to claim 3.
The higher the ratio of the tape on which the synthetic resin layer is arranged, the lower the flexibility of the entire cable, but the higher the degree of reinforcement of the outer conductor. Conversely, the synthetic resin layer is not arranged on the coaxial cable according to claim 2. The higher the ratio of the tape, and the higher the ratio of the tape on which the second synthetic resin layer is arranged in the coaxial cable according to claim 3, the lower the degree of reinforcement of the outer conductor, but the higher the flexibility of the entire cable. Become.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The coaxial cable shown here has an inner conductor 1 in the center, and an insulator 2, an outer conductor 3 ', and a sheath 4 are coaxially arranged in that order from the inside around the inner conductor 1.

The outer conductor 3'is formed by braiding a plurality of flat metal tapes 3b around the insulator 2. As the material of the metal tape 3b, a material having high conductivity is preferable, and copper, aluminum or the like is preferable.

Further, as a feature of this coaxial cable,
The outer surface (upper side surface in FIG. 2) of each metal tape 3b is coated with a synthetic resin layer 3c, and the contact portion between this synthetic resin layer 3c and the inner surface of the sheath 4 is fused. The material of the synthetic resin layer 3c is preferably a thermoplastic resin such as polyethylene or polyvinyl chloride, and more preferably the same material as the sheath 4.

In order to manufacture this coaxial cable, a synthetic resin layer 3c is coated on one surface of each metal tape 3b in advance (it is not particularly necessary, but both surfaces may be coated), and the synthetic resin layer 3c is the outside. The inner conductor 1 and the insulator 2 are formed by braiding the metal tapes 3b so that they face (upper side in FIG. 2).
After forming the outer conductor 3'on the outside of the
The sheath 4 may be extruded and molded with a synthetic resin that is heated and melted on the outside of the synthetic resin layer 3 by the heat generated during the molding.
A portion of c that contacts the inner surface of the sheath 4 can be automatically fused to the inner surface of the sheath.

According to such a coaxial cable, since the synthetic resin layer 3c coated on the outer surface of the metal tape 3b and the inner surface of the sheath 4 are fused together, the two are integrated.
The bending strength of the entire outer conductor 3'can be effectively increased, and the positional displacement between the outer conductor 3'and the sheath 4 can be reliably prevented. Further, the contact between the synthetic resin layer 3c and the sheath 4 fused together is a perfect surface contact,
It is possible to secure a fusion area larger than that of the conventional one in which the plastic yarn and the sheath 4 are fused, and the reliability and stability of the fusion can be increased by that amount.

Further, since the outer conductor 3'is formed by braiding the metal tape 3b, the bending rigidity of the outer conductor 3'itself as compared with the case where the aluminum laminate tape 5 is vertically attached as shown in FIG. And the portion of the synthetic resin layer 3c coated on the metal tape 3b that is distant from the sheath 4 (the portion that digs into the lower stage and is in contact with the lower surface of the upper metal tape 3b in FIG. 2) is
Since the sheath 4 is not fused and is in a free state, the flexibility of the entire cable in the bending direction can be kept sufficiently high.

In this embodiment, the synthetic resin layer 3c is coated on the outer surface of the all-metal tape 3b, but the synthetic resin layer 3c is coated only on the outer surface of a part of the metal tape 3b, and the rest is left. The metal tape 3b may be braided as it is without coating the synthetic resin layer 3c. In this case, the balance between the degree of reinforcement of the outer conductor and the flexibility of the entire cable can be freely adjusted by setting the ratio of the metal tape 3b on which the synthetic resin layer 3c is arranged and the metal tape 3b on which the synthetic resin layer 3c is not arranged. Specifically, the synthetic resin layer 3
As the ratio of the metal tape 3b on which the c is arranged is increased, the flexibility of the entire cable is reduced, but the degree of reinforcement of the outer conductor can be increased, and conversely, the metal tape 3b on which the synthetic resin layer is not arranged is provided.
The higher the ratio, the lower the degree of reinforcement of the outer conductor, but the flexibility of the entire cable can be increased.

However, in this case, the total thickness of the tape varies between the metal tape 3b having the synthetic resin layer 3c and the metal tape 3b not having the synthetic resin layer 3c by the thickness of the synthetic resin layer 3c. When it is desired to make the thickness of all tapes uniform, a part of the metal tape 3b is made of a synthetic resin having a high fusion property with the sheath 4 (for example, a synthetic resin of the same material as the sheath 4). And a second synthetic resin layer made of a synthetic resin having a low fusion property with the sheath 4 (for example, a synthetic resin different in material from the sheath 4) may be provided on the other metal tape 3b. Also in this case, the balance between the degree of reinforcement of the outer conductor and the flexibility of the entire cable is set by setting the ratio between the metal tape 3b having the first synthetic resin layer and the metal tape 3c having the second synthetic resin layer. Can be adjusted freely.

[0022]

As described above, according to the present invention, the outer conductor is formed by braiding a plurality of metal tapes, and the synthetic resin layer is provided on the outer surface of at least a part of the metal tapes.
Since the synthetic resin layer and the inner surface of the sheath are mutually fused, the synthetic resin layer and the sheath can be reliably and stably fused, and the bending strength of the outer conductor can be secured by this fusion. Can be effectively increased, and positional deviation between the outer conductor and the sheath can be reliably prevented. Moreover, the flexural rigidity of the outer conductor itself is lowered, and a part of the synthetic resin layer is separated from the sheath to be in a free state, whereby the flexibility of the entire cable in the bending direction can be maintained high.

According to a fourth aspect of the present invention, the synthetic resin layer is provided on at least one surface of at least a part of the metal tape, and then the synthetic resin layer is oriented toward the outer side. The tape is braided to form an outer conductor on the outer side of the inner conductor and the insulator, a sheath is formed on the outer side of the outer conductor, and the inner surface of the sheath and the synthetic resin layer are fused by the heat during the forming. Thus, it can be easily manufactured.

Further, in the coaxial cable according to the present invention, the ratio of the tape on which the synthetic resin layer is arranged and the tape on which the synthetic resin layer is not arranged, the tape on which the first synthetic resin layer is arranged and the first synthetic resin layer are arranged. Second, which has lower fusion bondability to the sheath than
By setting the ratio with the tape that arranges the synthetic resin layer of
This has the effect of freely adjusting the balance between the degree of reinforcement of the outer conductor and the flexibility of the entire cable. In particular, the coaxial cable according to claim 3 has an advantage that the thickness of all tapes can be made uniform while enabling the balance adjustment.

[Brief description of the drawings]

FIG. 1 is a perspective view of a coaxial cable according to an embodiment of the present invention.

FIG. 2 is a sectional side view of the coaxial cable.

FIG. 3 is a perspective view showing an example of a conventional coaxial cable.

FIG. 4 is a perspective view showing an example of a conventional coaxial cable.

[Explanation of symbols]

 1 Inner Conductor 2 Insulator 3'Outer Conductor 3b Metal Tape 3c Synthetic Resin Layer 4 Sheath

Claims (4)

[Claims] 1. A coaxial cable having an inner conductor as a center, an insulator, an outer conductor, and a synthetic resin sheath arranged around the inner conductor in order from the inside. The outer conductor is formed by braiding a plurality of metal tapes. With configuring
A coaxial cable, wherein a synthetic resin layer is provided on the outer surface of at least a part of the metal tape, and a portion of the synthetic resin layer that contacts the inner surface of the sheath is fused to the inner surface of the sheath. 2. The coaxial cable according to claim 1,
A coaxial cable in which a synthetic resin layer is provided on the outer surface of only some of the metal tapes. 3. The coaxial cable according to claim 1, wherein
Place the first synthetic resin layer on the outer surface of some metal tapes,
A coaxial cable, wherein a second synthetic resin layer having a lower fusion bonding property to the inner surface of the sheath than the first synthetic resin layer is arranged on the outer surface of another metal tape. 4. A manufacturing method for manufacturing the coaxial cable according to claim 1, wherein a synthetic resin layer is provided on at least one surface of at least a part of the metal tape, With the synthetic resin layer facing outward, all metal tape is braided to form an outer conductor on the outer side of the inner conductor and the insulator, and a sheath is formed on the outer side of the outer conductor so that the heat generated during the forming process A method for manufacturing a coaxial cable, characterized in that a portion of the synthetic resin layer that contacts the inner surface of the sheath is fused to the inner surface of the sheath.