JPS6140018Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a shielded electric wire. A shield is formed by placing insulating cores coated with an insulator on the conductor, arranging them in single core or two cores in parallel, or by covering them with aluminum foil. Shielded wires are often used as feeder wires from television antennas or as wiring materials in electronic devices. Such shielded wires are often used by bonding aluminum foil with polyester tape, etc., by bonding it with thin paper, or by using aluminum foil alone as a tape, but in either case, there is a grounding wire on the surface of the aluminum foil. A drain wire such as a copper wire is often used as an additional source. In this case, it is unlikely to be a problem when the shielded wire is relatively long, such as a feeder wire from a television antenna or a computer cable, but it is not a problem when the shielded wire is short, such as the wire inside an electronic device. When short lengths such as 50 mm are used, the contact force between the aluminum foil surface and the drain wire (called contact force) must exceed a certain level or the drain wire can easily move, and accordingly the contact between the drain wire and the aluminum foil increases. The resistance increases and a sufficiently good grounding cannot be achieved.
There is a problem that a sufficiently good shielding effect cannot be obtained. The present invention was developed to solve such problems, and is characterized by applying a conductive paint to the side of the aluminum foil that comes into contact with the drain wire. FIG. 1 shows an embodiment of the present invention. In Fig. 1, 1 is the core, which may be a single core by applying a plastic insulator or the like on top of the conductor.
In addition, a core may be formed by twisting two fibers in parallel or by twisting a plurality of fibers together. A drain wire 2 is made of a metal wire such as an annealed copper wire or a copper wire plated with tin, nickel, or the like. 3 is aluminum foil or a bonding tape of aluminum foil and polyester, etc., with the aluminum foil side facing the drain wire side. Reference numeral 4 denotes a conductive paint layer, which is applied to the entire surface of the aluminum foil that comes into contact with the drain wire, or is applied only to the surface of the aluminum foil in the vicinity of the contact with the drain wire. 5 is an outer covering made of plastic such as polyethylene vinyl chloride. The contact surface between the aluminum foil surface and the drain wire is shown in detail in FIG. 2. That is, the aluminum foil surface 3 is coated with a conductive paint 4, and the drain wire 2 is embedded in the conductive paint 4 and is in contact with the aluminum foil surface 3 at the same time, making the drain wire conductive. It is not in contact with the aluminum foil surface through the adhesive paint layer. We actually applied cross-linked polyethylene to a tin-plated annealed copper wire of size AWG24 to have an outer diameter of 1.4 mm, prepared a tape made by pasting 7 micron aluminum foil and 6 micron polyester tape, and used it as a shielding material on the insulating core. A shielded wire with an outer diameter of 2.9 mm was manufactured by extruding a vinyl chloride jacket while rolling a horizontally wound drain wire with a tin-plated annealed copper wire of size AWG24. Two of these shielded wires were manufactured, and one was used with the shielding material as described above, and the other was used after applying carbon-containing conductive paint with a volume resistivity of 10 ^-1 Ω-cm to the aluminum foil surface of the shielding material. . From the shielded wire manufactured in this way, the third
A sample as shown in the figure was prepared. In Figure 3, 8 is the shield wire, 6, 6', 6'', 6 is the drain wire, 7, 7' is the insulated core, L is 50 mm, L' is 10 mm, and the L part is the shield wire as it is. However, part of the outer covering of the L' portion was removed with the shield remaining, and the drain wire was cut into 6' and 6'' sections. 10 such samples were prepared from shielded wires coated with conductive paint, and 10 samples were prepared from shielded wires without coating.
The electrical resistance was measured between the drain wires 6' and 6. Thereafter, vibration of 50 Hz and amplitude of 0.5 mm was applied for 1 minute, and the electrical resistance was measured in the same manner and averaged. The results shown in Table 1 were obtained. Looking at these results, the resistance is high at the initial value before vibration for the one coated with conductive paint, but the resistance value does not deteriorate much after vibration, but for the one without conductive paint, the resistance deteriorates significantly due to vibration. Therefore, the shielded wire of the present invention is useful because it can maintain low contact resistance even in wires that are cut into short lengths and are susceptible to vibrations due to movement or the like, such as wiring inside electronic devices. 【table】

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the shielded wire of the present invention.
The figure shows the contact state between the aluminum foil and the drain wire in the third example.
The figure is a diagram explaining the method of measuring the test sample.
1 is the core, 2 is the drain wire, 3 is the aluminum foil,
4 indicates a conductive paint, and 5 indicates an outer covering.

Claims (1)

[Scope of utility model registration request] In a shielded wire that uses aluminum foil as a shielding material and has a drain wire provided along the aluminum foil between the aluminum foil and a plastic sheath provided outside the aluminum foil, the wire comes into contact with the drain wire of the aluminum foil. 1. A shielded wire, the surface of which is coated with a conductive paint, and the drain wire is arranged so as to be in contact with both the aluminum foil and the conductive paint.