JP2002208321A - Shield cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield cable that can sufficiently cope with the latest electronic and electric apparatuses that are newly mounted on the vehicles such as automobile. SOLUTION: The shield cable 10 includes a plurality of insulating covered signal wire 11 and a drain wire 12, and covers the surroundings of these with a shield layer 13 and an insulating sheath 14 in order. The outer diameter of the signal wire is 1.3 mm, the cross section area of the lead wire 11a of the signal wire 11 is 0.03-0.22 mm2, and the insulating cover 11b of the signal wire 11 is constructed of an insulating material having a dielectric factor of 1.7-2.8, and the property impedance of the signal wire 11 is 75 Ω (±10%).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielded cable used for electrically connecting electric components of a vehicle such as an automobile.

[0002]

2. Description of the Related Art In vehicles such as automobiles, shielded cables are used for electrical connection to various electric components and the like. 2. Description of the Related Art As a conventional shielded cable, there is known a structure in which a plurality of twisted signal lines and drain lines are covered with a shield layer, and the periphery is further covered with an insulating sheath. The signal line is composed of a conductor and an insulating coating covering the conductor.

In such a configuration, external noise is shielded by a shield layer, and the shielded noise is dropped to an external ground through a drain line. Good signals are supplied to various electrical components via signal lines.

[0004] By the way, conventionally, the specifications of a shielded cable generally used in this type are such that a signal wire has a cross-sectional area of 0.3 mm ² and an outer diameter of a signal wire is 1.4 m.
mφ, the material of the insulating coating was polyvinyl chloride (PVC), the material of the shield layer was copper or aluminum, and the material of the insulating sheath was polyvinyl chloride, polyethylene, or the like.

On the other hand, recently, car navigation and DV
With the rapid development of D equipment, monitors, DVD units, and the like have been mounted in automobiles. However, these electric and electronic devices that are newly installed in automobiles have higher resolution and higher quality of images and voices, so that, for example, on a monitor of a car navigation system, a blur occurs in an enlarged image such as a road map. And it is hoped that some measures will be taken.

[0006] Further, the outer diameter of the signal line is 1.3 due to the standard of the connector of electric / electronic equipment newly mounted on the automobile.
mmφ, and the conventional connector standard has a signal line outer diameter of 1.4 to 1.6 mmφ. Therefore, it is incompatible with a connector of a newly mounted device, so that the outer diameter of the signal line has to be reduced.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a shielded cable which can sufficiently cope with the latest electronic and electric equipment newly mounted on vehicles such as automobiles. Is the task.

[0008]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems of the prior art, and as a result, obtained the following knowledge and completed the present invention. The defect in the electronic / electric equipment newly installed in the automobile is largely related to the characteristic impedance of the signal line, and the value of the conventional one is about 50Ω. If a conventional shielded cable is connected to a device such as a DVD unit or a monitor, reflections will occur between the signal supply side and the device side due to impedance mismatching, and the above-mentioned problems will occur. Can be Therefore, the characteristic impedance of the signal line is set to 75Ω (± 10%).
It was confirmed that matching could be achieved if the size was increased to the extent, and that the above-mentioned problems could be solved. On the other hand, the outer diameter of the signal line needs to be 1.3 mmφ from the relation with the standard for a new connector for electronic / electric equipment. In consideration of these facts, it was confirmed that a required characteristic impedance could be obtained by adjusting the size of the cross-sectional area of the conductor of the signal line and the dielectric constant of the insulating coating of the signal line. Incidentally, the dielectric constant of polyvinyl chloride used for the conventional insulation coating of signal lines was about 5.0.

According to the present invention, in order to solve the above problems, a plurality of signal lines with insulation coating and a drain line are included,
A shielded cable in which the periphery thereof is sequentially covered with a shield layer and an insulating sheath, wherein an outer diameter of the signal line is 1.3 mm, and a cross-sectional area of a conductor of the signal line is 0.03 to 0.3 mm.
22 mm ² , and the insulating coating of the signal line has a dielectric constant of 1.7.
The present invention provides a shielded cable which is made of an insulating material of 2.8 and has a characteristic impedance of the signal line of 75Ω (± 10%). Further, according to the present invention, there is provided a shielded cable according to the above configuration, wherein the insulating coating of the signal line is made of foamed polyethylene. Further, according to the present invention, in the above configuration, the drain wire has a cross-sectional area of 0.22 to 0.5 mm.
^2. A shielded cable is provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples. In FIG. 1, reference numeral 10 indicates a shielded cable according to the present invention. The shielded cable 10 includes a plurality of signal lines 11 and a drain line 12, the periphery thereof is covered with a shield layer 13, and the periphery thereof is covered with an insulating sheath 14. The signal line 11 is composed of a conductor 11a and its insulating coating 11b.

The outer diameter of each signal line 11 is 1.3.
mmφ, which may include a nominal error. In the present invention, the characteristic impedance of the signal line 11 is 7
5Ω (± 10%), that is, 67.5 to 82.5Ω. If the characteristic impedance deviates from the above range, unmatching may occur. The cross-sectional area (hereinafter, also referred to as a conductor size) of the conductor 11a of the signal line 11 is 0.03 to 0.22 m ² . If the conductor size is smaller than the above range, good signal transmission cannot be performed, and the strength of the signal line 11 is insufficient. On the other hand, if the conductor size is larger than the above range, it becomes difficult to obtain a required characteristic impedance. As the conductive wire 11a, a soft copper twisted wire (including a compression twisted wire), a soft copper single core wire, a tin-plated soft copper twisted wire, or the like can be used. The insulating coating 11b of the signal line 11 is made of an insulating material having a dielectric constant of 1.7 to 2.8. Examples of such a material include foamed polyethylene and tetrafluoroethylene, and foamed polyethylene is particularly preferable in terms of cost, durability, and the like. Foamed polyethylene can have a dielectric constant in the above range by adjusting the expansion ratio. When the dielectric constant of the insulating coating 11b is less than 1.7, it is extremely difficult to manufacture an electric wire, and when the dielectric constant is too large, it becomes difficult to obtain a required characteristic impedance. The thickness of the insulating coating 11b is set according to the conductor size of the conductive wire 11a (because the outer diameter of the signal wire 11 is determined). The number of included signal lines 11 can be arbitrarily set according to the application.

The drain line 12 is made of a material such as a soft copper wire or a Sn-plated soft copper wire. The conductor size of the drain line 12 is preferably 0.22 to 0.5 mm ² . If the conductor size is smaller than the above range, insufficient strength of the signal line 11 cannot be compensated. If the conductor size is larger than the above range, the terminal dimensions of the connector will be incompatible.

The shield layer 13 is made of a material having a shielding effect, specifically, a Sn-plated copper foil PET tape, a Sn-plated copper foil / PET tape, an aluminum PE
T tape or the like can be used, and its thickness is about 10 to 30 μm.

The insulating sheath 14 has insulating properties, oil resistance,
A material having chemical resistance is used, and specifically, an insulating material such as polyvinyl chloride or a polyolefin resin such as polyethylene can be used, and its thickness is about 0.3 mm.

Here, the shielded cable 10 according to the present invention is used.
An example will be described. Sn-plated soft copper stranded wire (conductor size 0.22 mm ² ) as conductive wire 11a, foamed polyethylene (dielectric constant 1.7, thickness 0.375 m as insulating coating 11b)
m), Sn-plated soft copper stranded wire (conductor size 0.22 mm ² ) as the drain wire 12, Cu as the shield layer 13
A shielded cable 10 having the structure shown in FIG. 1 was manufactured using a PET tape (thickness 21 μm), a halogen-free material (thickness 0.75 mm) as the insulating sheath 14, and five signal lines. It was 71Ω.

[0016]

According to the present invention, since the above-mentioned configuration is employed, the present invention can be applied to devices such as a DVD unit and a monitor mounted on an automobile, and impedance matching with these devices can be achieved. Problems such as image bleeding do not occur. Further, the flat cable of the present invention is lighter than the conventional one.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a shielded cable according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Shielded cable 11 Signal wire 11a Conductive wire 11b Insulation coating 12 Drain wire 13 Shield layer 14 Insulating sheath

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Tanaka 1-7-10 Kikuzumi, Minami-ku, Nagoya City, Aichi Prefecture Inside of Auto Network Engineering Laboratory Co., Ltd. (72) Inventor Shizuya Kawabe 1st Nishi-Suehirocho, Yokkaichi City, Mie Prefecture No. 14 Sumitomo Wiring Systems, Inc. F-term (reference) 5E321 AA21 BB21 GG09 5G319 EA01 EB04 EC04

Claims (3)

[Claims] 1. A shielded cable comprising a plurality of signal wires with insulation coating and a drain wire, and the surroundings thereof are sequentially covered with a shield layer and an insulating sheath, wherein the outer diameter of the signal wire is 1 mm. 0.3 mm, and the cross-sectional area of the conductor of the signal line is 0.3 mm.
03 to 0.22 mm ² , the insulating coating of the signal line is made of an insulating material having a dielectric constant of 1.7 to 2.8, and the characteristic impedance of the signal line is 75Ω (± 10%). Characterized shielded cable. 2. The shielded cable according to claim 1, wherein the insulating coating of the signal line is foamed polyethylene. 3. A drain line having a cross-sectional area of 0.22-0.
The shielded cable according to claim 1, wherein the shielded cable is 5 mm ² .