JP5793378B2 - Shielded cable - Google Patents

Description

  The present invention relates to a shielded cable, and more particularly to a shielded cable suitable for high-speed transmission.

  In general, shielded cables are used for high-speed transmission. In particular, a shielded cable for high-speed transmission used in a vehicle is required to have flexibility from the viewpoint of wiring in the vehicle.

  For example, a structure in which conductive wires having characteristics of bending durability and shield characteristics are wound in two layers so as to intersect spirally is disclosed (for example, see Patent Document 1). Specifically, as shown in FIG. 5A, the cable 101 includes an insulated wire 110 and a horizontally wound layer 120 formed by spirally winding a conductive wire around the outer periphery of the insulated wire 110. The reversal horizontal winding layer 140 formed by spirally winding a conductive wire in a direction intersecting the winding direction of the horizontal winding layer 120, and the horizontal winding layer 120 and the reverse horizontal winding layer 140 A buffer layer 130 provided therebetween, and a sheath 150 provided on the outer periphery of the inverted horizontal winding layer 140 are provided. The winding angle θ1 of the strands forming the horizontal winding layer 120 and the winding angle θ2 of the strands forming the inverted horizontal winding layer 140 are acute angles, and the absolute difference between the winding angle θ1 and the winding angle θ2 is absolute. The value is 20 ° or less.

  As another technique, there is a technique proposed to reduce the cable outer diameter, improve flexibility and bendability, and improve the attenuation (see, for example, Patent Document 2). In this technique, as shown in FIG. 5B, a two-core parallel cable 201 includes two insulated wires 207 arranged in parallel and an insulated wire 207 in which the outer periphery of the central conductor 203 is covered with an insulating layer 205. A metal tape body 213 composed of a single horizontal winding shield 211 in which a wire 209 is horizontally wound around the outer periphery of the wire and a polyester tape having copper deposited on the surface in a spiral shape around the outer periphery of the single horizontal winding shield 211. And a jacket 215 made of a fluororesin or a polyester tape covering the outer periphery of the metal tape body 213.

JP 2010-225571 A JP 2009-164039 A

  By the way, in the shielded cable used for vehicles, flexibility is required as described above, but at the same time, the demand for low cost is very severe. And in the manufacturing cost of the shielded cable of the braid | blade of a general metal strand, especially the process of the braid | blade (knitting ancestor) which comprises and bundles a strand occupies big specific gravity. The techniques described in Patent Documents 1 and 2 have the same problem. In addition, there is a technique of wrapping and shielding a metal stay, but another technique has been demanded due to the problem of a decrease in the flexibility of the cable and the accompanying breakage of the metal foil. Further, in the case of a braided shielded cable, it is necessary to pay attention to the processing of the wire pieces generated at the time of terminal processing, and measures are still required from the viewpoint of man-hours.

  The object of the present invention is made in view of such a situation, and is to provide a technique for solving the above-described problems.

The shielded cable cable according to the present invention includes a shield layer in which a conductor is patterned on a film-like dielectric layer provided on the outer periphery of the cable, and the shield layer has a structure in which the conductors are stacked face to face.
The shield layer may be formed by patterning the conductor on a flexible substrate.
In addition, a slit may be formed in the shield layer .
The conductor pattern may be formed in a spiral shape so that the conductors intersect each other when the conductors are stacked face to face.

  According to the present invention, it is possible to provide a shielded cable that can be manufactured at low cost while ensuring flexibility.

It is a figure which shows the external appearance of the shielded cable based on embodiment. It is sectional drawing of the shielded cable based on embodiment. It is a figure which shows the 1st FPC shield based on embodiment. It is a figure which shows the FPC shield based on the modification of embodiment. It is a figure which shows the shielded cable based on a prior art.

  Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings. The main characteristic configuration of the present embodiment is that FPC (Flexible Printed Circuits) in which a conventional braid is patterned and provided with slits is used as a shield. Hereinafter, this shield part will be mainly described.

  FIG. 1 is a view showing an appearance and a cross section of a shielded cable 10 according to the present embodiment. FIG. 1B shows a part of the internal structure of FIG. 1A (conductor patterns 54 and 64) by a wavy line. FIG. 2 shows details of the cross-sectional shape of the shielded cable 10. FIG. 2B is an enlarged view of the area A1 in FIG. 2A, and FIG. 2C is an enlarged view of the area A2 in FIG.

  As shown in the figure, the shielded cable 10 of this embodiment includes a twisted pair cable 15 composed of first and second cables 20 and 30 and a multilayer FPC shield 40 that covers the outer periphery of the twisted pair cable 15.

  The first cable 20 is composed of a central conductor (conductor wire) 22 and a dielectric 24 covering it. The second cable 30 has the same configuration. The conductor 22 is made of one or more metal wires such as a copper alloy. The dielectric 24 is formed of an insulating resin material, such as polyethylene (crosslinked foamed PE) or a fluororesin.

  In the illustrated shielded cable 10, a twisted cable (twisted together) of a first cable 20 having a conductor 22 outer diameter of 0.38 mm and a dielectric 24 having an outer diameter of 1.0 mm and a second cable 30 having the same structure. A structure in which a double-layer multilayer FPC shield 40 is wound around an outer diameter of 2.05 mm) is illustrated.

  FIG. 3 shows the multilayer FPC shield 40 before coating. 3A is a plan view, and FIG. 3B is an XX cross-sectional view of FIG. 3A. Hereinafter, a description will be given with reference to FIGS.

  The multi-layer FPC shield 40 is an alternative to the conventional shield structure formed by braiding metal strands. Here, the multi-layer FPC shield 40 has a plurality of layers, more specifically, two layers of first and second FPC shields 50 and 60. It consists of

  In the present embodiment, FPC boards having the same pattern are used for the first and second FPC shields 50 and 60 before being coated. Specifically, as shown in FIG. 4, a conductor pattern 54 corresponding to the braid is patterned on the surface of the dielectric layer 52. The dielectric layer 52 is, for example, 0.1 mm thick Teflon (registered trademark). The formation of the conductor pattern 54 can be realized by the same process as the patterning process of a general FPC circuit.

  The conductor pattern 54 has a conductor thickness of 25 μm and is formed at intervals of 45 degrees. The conductor width is ± 11.25 degrees, and the pitch in the wound state is 10 mm, which is 2.5 turns. Further, in the first FPC shield 50, a slit 56 is provided between the braided conductor patterns 54 to ensure flexibility in the wound state. If flexibility is ensured, the slit 56 is unnecessary. The second FPC shield 60 is also provided with a dielectric layer 62, a conductor pattern 64, and a slit 66 similar to the first FPC shield 50.

  Then, the first FPC shield 50 and the second FPC shield 60 are laminated with the conductor patterns 54 and 64 facing each other to form a multilayer FPC shield 40 before coating. In a state where the multilayer FPC shield 40 is covered with the twisted pair cable 15, the dielectric layer 52 of the first FPC shield 50, the conductor pattern 54, and the conductor of the second FPC shield 60 are sequentially arranged from the center side (twisted pair cable 15 side). The pattern 54 and the dielectric layer 52 are laminated.

  As described above, according to the present embodiment, the shield cable 10 is formed using the multi-layer FPC shield 40 (first and second FPC shields 50 and 60), so that the seal is replaced by the knitting of the metal strand. Can do. As a result, the braiding process can be omitted, the manufacturing cost can be reduced, and the flexibility of the shielded cable 10 can be ensured. Further, the thickness of the multilayer FPC shield 40 can be significantly reduced as compared with the case of braiding a metal strand, and the degree of freedom in design is improved. For example, the diameter of the conductor 22 such as the first cable 20 can be increased. Further, when used as a cable for digital transmission, it may be sufficient to selectively secure shield performance for a predetermined frequency band, and it becomes easy to design an optimum pattern for that band. In addition, it becomes easy to deal with design changes and the like.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to each of those components and combinations thereof, and such modifications are also within the scope of the present invention. For example, in the above-described embodiment, the double-layer FPC shield 40 is used, but a single-layer FPC shield may be used. That is, even in the configuration of only the second FPC shield 60 without the first FPC shield 50, the design values of the conductor pattern 64 and the like may be changed so that the desired performance can be realized. The design can be easily changed. Further, a plurality of multilayer FPC shields 40 may be provided.

  Further, the shape of the conductor pattern 54 is not limited to the above shape. For example, like the modified FPC shield 50a shown in FIG. 4, it may be formed of a circular conductor pattern 54a. Further, the first FPC shield 50 conductor pattern 54 and the conductor pattern 64 of the second FPC shield 60 may have different shapes. For example, one may be the conductor pattern 54 shown in FIG. 3, and the other may be the conductor pattern 54a shown in FIG. That is, the pattern (shape) may be designed so as to obtain desired shield characteristics and impedance characteristics.

10 shielded cable 15 twisted pair cable 20 first cable 30 second cable 40 multilayer FPC shield 50 first FPC shield 50a FPC shield 52, 62 dielectric layers 54, 54a, 64 conductor pattern 56, 66 slit 60 second FPC shield

Claims (4)

Cable and
A shield layer formed by patterning a conductor on a film-like dielectric layer provided on the outer periphery of the cable;
Equipped with a,
The shield layer has a structure in which the conductors are laminated face to face .   The shield cable according to claim 1, wherein the shield layer is formed by patterning the conductor on a flexible substrate.   The shield cable according to claim 1, wherein a slit is formed in the shield layer. 4. The conductor pattern according to claim 1, wherein the conductor pattern is formed in a spiral shape so that the conductors intersect each other when the conductors are stacked face to face. Shielded cable as described in Crab.

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