JP2004220798A - Shielded cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent shielded cable capable of improving a communication characteristic and productivity without degrading shielding performance. <P>SOLUTION: This shielded cable 21 has: a center conductor 12; an internal insulator 13 formed around the center conductor 12; a tape surrounding body 15 having a layer structure composed by laminating a plastic layer 14b on an aluminum foil layer 14, and composed by longitudinally winding a tape 14 having a lateral width longer than the circumferential length of the outside periphery of the insulator 13 around the insulator 13 by setting the foil layer 14a inside so as to superimpose one edge part 14B on the other edge part 14B; and an outside insulating cover 16 formed around the surrounding body 15. In the superimposed part of the tape 14 constituting the surrounding body 15, the plastic layer 14b positioned at the edge part 14A positioned on the lower side is removed to bring the upper part and the lower part of the foil layer 14a in the superimposed part into contact with each other. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a shielded cable, and more specifically, has an inner insulator provided around a center conductor, a layered structure in which a plastic layer is laminated on a metal foil layer, and has a lateral width longer than the circumference of the outer periphery of the inner insulator. A shield comprising: a tape envelope formed by vertically wrapping a tape having the tape around the inner insulator with the metal foil layer inside; and an outer insulating coating provided around the tape envelope. Regarding cable improvement.
[0002]
[Prior art]
A shielded cable (also referred to as a metal cable having a shield) requires good communication characteristics and shielding to avoid signal leakage and noise contamination in a communication line, and the cable is extremely high in a multiplex digital network. Grade communication characteristics and shielding properties are required. In particular, the quality of communication characteristics and shielding properties of the coaxial drop-in cable are extremely important. Further, in the case of a coaxial cable used for leading-in to a terminal, a structure that can be freely bent is required, and the outer conductor needs to be highly flexible and to maintain a shielding property.
[0003]
In order to ensure high shielding properties and communication characteristics, it is preferable to use an aluminum pipe as a shielding body or an outer conductor, but there is a disadvantage that the flexibility is lacking.
Therefore, in a shielded cable used in a conventional information communication field, a tape-shaped shield in which a plastic layer is laminated on an aluminum foil layer is used to provide electrostatic shielding (see, for example, Patent Document 1).
[0004]
For example, the conventional shielded cable 1 shown in FIG. 2 has a layer structure in which a central conductor 2, an internal insulator 3 provided around the central conductor 2, and a plastic layer 4b laminated on an aluminum foil layer 4a. A tape formed by wrapping a tape 4 having a lateral width longer than the peripheral length of the outer periphery of the inner insulator 3 around the inner insulator 3 with the aluminum foil layer (metal foil layer) 4a inside. It has an enclosure 5 and an outer insulating coating 6 provided around the tape enclosure 5.
[0005]
In the shielded cable 1, first, as shown in FIG. 2A, the aluminum foil layer 4a in the surplus edge portions 7A and 7B on both sides of the tape 4 which are tightly surrounded and surrounded on the entire circumference of the inner insulator 3 are mutually connected. Are attached to each other to form a fin-shaped surplus portion 8.
Next, as shown in FIG. 2B, the fin-shaped surplus portion 8 is folded in two, and then the plastic layer 4b of the fin-shaped surplus portion 8 is applied to the plastic portion of the surrounding portion already in close contact with the internal insulator 3. The overlap portion 9 is formed by folding over the layer 4b, and the end faces 7a, 7b of the surplus edge portions 7A, 7B on both sides in the longitudinal direction of the tape enclosure 5 are sealed in the plastic layer 4b.
[0006]
An outer insulating coating 6 is provided around the tape surrounding body 5 by extrusion. The plastic layer 4b is melted by the heat at the time of the extrusion and fused to the outer insulating coating 6.
Therefore, the fin-shaped surplus portion 8 can maintain the continuity of the aluminum foil layer 4a and prevent a reduction in the shielding effect. In addition, even when the shielded cable 1 is bent or twisted, peeling can be reliably prevented, and loss of the shielding effect can be reliably avoided.
[0007]
[Patent Document 1]
Japanese Patent No. 3088998 [0008]
[Problems to be solved by the invention]
However, in the conventional shielded cable 1 shown in FIG. 2, since the thickness of the overlapped portion of the overlap portion 9 is increased, the internal insulator 3 and the external insulating coating 6 may be greatly deformed. However, there is a possibility that communication characteristics such as return loss are adversely affected.
Further, in the manufacturing process of the shielded cable 1, a folding step of folding the fin-shaped surplus portion 8 is added, so that there is a problem that productivity is reduced.
[0009]
Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a good shielded cable capable of improving communication characteristics and productivity without lowering shielding performance.
[0010]
[Means for Solving the Problems]
An object of the present invention is to provide a center conductor, an inner insulator provided around the center conductor, and a layered structure in which a plastic layer is laminated on a metal foil layer, and a lateral width longer than a circumferential length of an outer periphery of the inner insulator. A tape envelope constituted by vertically wrapping a tape having a peripheral edge around the inner insulator so that one edge portion overlaps the other edge portion with the metal foil layer inside. A shielded cable having an outer insulating coating provided around the tape enclosure,
By removing the plastic layer of the other edge portion located on the lower side in the overlapping portion of the tape constituting the tape enclosure, the metal foil layers in the overlapping portion are configured to contact each other. This is achieved by a shielded cable.
[0011]
According to the shielded cable having the above configuration, since the metal foil layers are brought into contact with each other at the overlapped portions of the tapes constituting the tape enclosure, it is possible to reliably prevent high-frequency noise from being mixed in from the overlapped portions. .
Further, the metal foil layers are brought into contact with each other by removing the plastic layer at the other edge portion located on the lower side in the overlapping portion. Therefore, the thickness of the overlapped portion can be reduced by removing the plastic layer one more, and there is no possibility that the inner insulator or the outer insulating coating is greatly deformed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIG. 1, the shielded cable 11 of the present embodiment includes a center conductor 12, an inner insulator 13 provided around the center conductor 12, an aluminum foil layer (metal foil layer) 14a, and a plastic layer 14b. A tape 14 having a layer structure obtained by laminating a tape and having a lateral width longer than the circumference of the outer periphery of the inner insulator 13 is provided at one edge portion of the inner insulator 13 with the aluminum foil layer 14a inside. This is a coaxial cable having a tape envelope 15 formed by wrapping in a longitudinal direction so that 14B overlaps the other edge portion 14A, and an outer insulating coating 16 provided around the tape envelope 15. .
[0013]
The tape 14 is a tape-shaped shield formed by laminating a plastic layer 14b on an aluminum foil layer 14a, and one edge portion 14B of which the length is longer than the circumferential length of the outer periphery of the inner insulator 13 is applied to the inner insulator. It is longitudinally wrapped so as to overlap the other edge portion 14 </ b> A that directly contacts the body 13.
[0014]
Further, the other edge portion 14A located on the lower side in the overlapping portion of the tape 14 constituting the tape enclosing body 15 has the plastic layer 14b extending along the longitudinal direction (H) in the drawing along the longitudinal direction. The aluminum foil layers 14a in the overlapped portion are configured to be in contact with each other.
[0015]
That is, in the shielded cable 11, for example, the tape 14 in which the plastic layer 14b of the other end portion 14A is not formed in advance in the longitudinal direction by a predetermined width (for example, about 5 to 10 mm) is prepared, and the internal insulation is formed. After the tape 14 is vertically wound around the body 13 so that the one edge portion 14B overlaps the other edge portion 14A with the aluminum foil layer 14a inside, the tape envelope 15 An outer insulating coating 16 is provided around the periphery by extrusion, and the plastic layer 14b is melted by heat generated during the extrusion, and is fused to the outer insulating coating 16.
[0016]
Then, the other edge portion 14A in which the plastic layer 14b is removed by a predetermined width in advance and the aluminum foil layer 14a alone is formed is disposed on the side of the inner insulator 13 at the time of superposition. In addition, continuity between the aluminum foil layers 14a in the overlapped portion in the edge portion 14B is ensured.
[0017]
Therefore, according to the shielded cable 11 of the present embodiment, since the aluminum foil layers 14a are in contact with each other at the overlapping portion of the tape 14 constituting the tape enclosure 15, mixing of high-frequency noise from this overlapping portion is prevented. It can be prevented reliably.
[0018]
Further, in the overlapped portion, the aluminum foil layer 14a of the edge portion 14A and the aluminum foil layer 14a of the edge portion 14B are brought into contact with each other by removing the plastic layer 14b of the other edge portion 14A located on the lower side. Therefore, the thickness of the overlapped portion can be reduced by the removal of the plastic layer 14b, and there is no possibility that the inner insulator 13 and the outer insulating coating 16 are greatly deformed.
Therefore, the shielded cable 11 has improved communication characteristics such as return loss, and also does not require an additional folding step as in the conventional shielded cable 1 manufacturing process shown in FIG.
[0019]
Incidentally, the configuration of the center conductor, the inner insulator, the metal foil layer, the plastic layer, the tape, the tape envelope, the outer insulating coating, and the like in the shielded cable of the present invention are not limited to the configuration of the above-described embodiment, It goes without saying that various forms can be adopted based on the spirit of the present invention.
For example, although an aluminum foil layer is used in the above embodiment, another metal foil layer such as a copper foil layer may be used. Further, in the above-described embodiment, an example in which the shielded cable of the present invention is applied to a coaxial cable has been described, but application to a cable having a similar shielding structure, such as a CCP cable, is also possible.
[0020]
【The invention's effect】
As described above, according to the shielded cable of the present invention, since the metal foil layers are brought into contact with each other at the overlapping portion of the tape constituting the tape enclosure, it is ensured that high-frequency noise is mixed from the overlapping portion. Can be prevented.
Further, the metal foil layers are brought into contact with each other by removing the plastic layer at the other edge portion located on the lower side in the overlapping portion. Therefore, the thickness of the overlapped portion can be reduced by removing the plastic layer one more, and there is no possibility that the inner insulator or the outer insulating coating is greatly deformed.
Therefore, it is possible to provide a good shielded cable that can improve communication characteristics and productivity without lowering the shielding performance.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a configuration of a shielded cable according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a configuration of a conventional shielded cable, in which (a) shows a state in which a fin-shaped surplus portion is formed at a surplus end edge portion and a tape is wrapped in the longitudinal direction, and (b) Indicates an external conductor in the form of a tape in which a fin-shaped surplus portion is folded in two and an overlap portion is formed.
[Explanation of symbols]
11 shielded cable 12 center conductor 13 inner insulator 14 tape 14a aluminum foil layer (metal foil layer)
14b Plastic layer 14A Other edge portion 14B One edge portion 15 Tape enclosure 16 External insulating coating

Claims (1)

A tape having a center conductor, an inner insulator provided around the center conductor, and a layer structure in which a plastic layer is laminated on a metal foil layer and having a width greater than the circumference of the outer periphery of the inner insulator. A tape envelope formed by wrapping around the inner insulator in the longitudinal direction so that one edge portion is overlapped with the other edge portion with the metal foil layer being inside; A shielded cable having an outer insulating coating provided around,
By removing the plastic layer of the other edge portion located on the lower side in the overlapping portion of the tape constituting the tape enclosure, the metal foil layers in the overlapping portion are configured to contact each other. A shielded cable.

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