JPH0132645Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a shielded cable used for transmission within devices such as electronic devices or between devices.

[Conventional technology]

A shielded cable consists of multiple insulated wires and drain wires assembled or arranged in parallel, with copper wire braided, horizontally wound or metal foil wound, or vertically attached on the outside.
Furthermore, a structure in which a protective layer is formed on the outside thereof is common.

[Problem that the invention seeks to solve]

Among the conventionally structured shielded cables mentioned above, those with copper wire braided or metal foil vertically attached have excellent shielding effects and are widely used, but they have the disadvantage of poor cable flexibility, bendability, or workability. be.
Especially recently, it is often used as a curl cable, and when it is repeatedly expanded and contracted in a curled shape,
The stability of the shielding effect over time and the curling property (ease of expansion and contraction of the curled part) tend to be impaired, and there is no material that has both good properties. In addition, in relation to electromagnetic induction countermeasures for electronic equipment, there is a strong tendency for cables to have high frequency shielding properties, and there has been a demand for the development of shielded cables that have all of these required properties.

[Means for solving problems]

In view of the above-mentioned background, an object of the present invention is to provide a shielded cable which has excellent high frequency characteristics and curling properties, and whose shielding characteristics change less over time during use of the cable.

FIG. 1 is a cross-sectional view showing an example of the structure of the cable of the present invention, in which a plurality of strands 3, which are insulated wires with an insulation coating 2 applied on a conductor 1, are assembled together with a drain wire 4.
A laminate film 7 consisting of a metal foil 5 and a plastic film 6 and a laminate film 10 consisting of a metal foil 8 and a plastic film 9 are stacked vertically on the outside so that the metal foil surfaces 5 and 8 are on the inside for further protection. A layer 11 is formed. By folding the side end 12 of one of the two laminated films 7 and 10 outward, both metal foil surfaces 5 and 8 are aligned in the longitudinal direction as shown in the enlarged cross-sectional view of FIG. They are in contact with each other along their entire length.

3 and 4 are cross-sectional views showing other examples of the structure of the cable of the present invention. In FIG. 3, a plurality of wires 3 are arranged in parallel together with a drain wire 4, and two laminate films are placed on the outside thereof. 7 and 10 on metal foil side 5, 8
The laminate film 7 or 10 is placed vertically so that it is on the inside, and both ends 12 of one of the laminate films 7 or 10 are folded back to the outside. Two laminated films 7 and 10 are wound on the outside so that the metal foil surfaces 5 and 8 are on the inside, and one of the laminated films 7
Or, the side end 12 of 10 is folded back to the outside,
Both metal foil surfaces 5 and 8 are in contact with each other over the entire length in the longitudinal direction, and the reference numerals in both figures are the same as those used in FIG. 1.

In manufacturing the shielded cable of the present invention, two laminate films are placed vertically on the outside of a plurality of wires with drain wires arranged together or in parallel, with the side end of one film folded back. death,
Alternatively, a laminate film whose side ends have been folded back in advance and a normal laminate film are rolled in a stacked state, and a protective layer is further formed.

[Effect]

In this invention, since the side edge of one of the two laminated films is folded back, the metal foils of both films are in contact with each other and have the same potential, and furthermore, the contact between the metal foil surface and the drain wire is It is secured over the entire length of the cable in the longitudinal direction.

[Effect of idea]

As a result, the shielded cable of the present invention can effectively exhibit a shielding effect, and a shielding characteristic of 50 dB/m or more can be obtained in a frequency band up to 1000 MHz.

In the present invention, the material of the metal foils of the two laminated films is not particularly limited, but for example, if copper is used for the lower layer and aluminum is used for the upper layer, the excellent conductivity of the copper in the lower layer and the drain wire caused by it may be used. The good contact resistance of the cable and the deformation resistance of the upper layer of aluminum complement each other, and especially when used as a curl cable, due to the additive effect of the two layers of metal foil, the deterioration of shielding properties due to repeated expansion and contraction is extremely small. Shows stable shielding characteristics over time.

〔Example〕

PVC on a conductor made of 7 twisted annealed copper wires of 0.127mmφ
The inner layer is placed on a 6-core cable with an outer diameter of 2.7 mm, which is made up of 6 insulated wires coated with a mixture extruded to a thickness of 0.260 mm, and a drain wire made of 7 twisted annealed copper wires of 0.127 mmφ. Copper 10μ polyester film
A 12μ composite film, an aluminum 10μ polyester film and a 12μ composite film are formed as the outer layer, and the side edges of the inner layer composite film are folded back and attached vertically, and an insulating sheath made of a PVC mixture is placed on top of this with an outer diameter of 4.9mm. A shielded cable according to the present invention was obtained. This shielded cable is formed into a curl shape with a curl diameter of 20 mm and a curl length of 20 mm.
When we manufactured a 200mm curled cable and measured its shielding effect, it showed 57dB at 500MHz. This curled cable was stretched and contracted 10,000 times, and the measured shielding effect showed no decrease compared to before stretching and showed the same value.

As a comparative example, similar measurements were performed on a curled cable manufactured under the same conditions as in the example except that the side ends of the inner layer composite film were not folded back. The shielding effect decreased to 38dB.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the structure of the cable of the present invention, and FIG. 2 is an enlarged view of the main parts thereof. 3 and 4 are sectional views showing other examples of the structure of the cable of the present invention. 3... Insulated wire, 4... Drain wire, 7, 10...
...Laminate film, 12...Side edge.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of insulated wires are assembled or arranged in parallel together with a drain wire, and two laminate films made of metal foil and plastic film are layered on the outside so that the metal foil surface is on the inside. In the shielded cable which is wound or longitudinally attached, the side end of one of the two laminate films is folded back so that the metal foil surfaces of the two laminate films are in contact with each other over the entire length in the longitudinal direction. shielded cable. (2) The shielded cable according to claim (1), which is made of two laminated films, in which copper is used for the metal foil of the lower film, and aluminum is used for the metal foil of the upper film.