JPH05282921A - Flat cable - Google Patents

Abstract

PURPOSE:To improve signal propagating velocity and to facilitate thermal molding work by using foam polyethylene for an internal layer of an insulator of a cable and by using a PVC compound for the external layer. CONSTITUTION:To manufacture an insulated conductor, foam polyethylene of an internal layer is extrusion molded by a main extruder, while a PVC compound of an external layer is extrusion molded by a sub-extruder. The ratio of thickness of the internal layer to the external layer is adjusted according to a predetermined impedance. A plurality of the insulated conductor are arranged in parallel to each other, while the PVC compound layer 2 of the external layer is thermally fused and is formed into a flat form, and then molded into a round shape. High frequency or thermal roller is used for the thermal fusion of the conductor, and the thermal fusion can be carried out throng the entire length of a cable, or at a certain interval, or only on the terminal parts. When the fusion at a certain interval is carried out, the form of the conductors between the fused parts can be loose or twisted, but when the conductors are twisted, the crosstalk characteristic is improved. A conventional shield 3 and a sheath 4 are provided on the outer periphery of the flat wire core molded into circle, which is thus finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-impedance flat round cable used for an interface between electronic devices.

[0002]

2. Description of the Related Art Conventionally, as an interface cable between electronic devices, first, a vinyl insulation core is heat-sealed by using a heat roll or a high-frequency current to form a flat shape.

Next, the flat cores are twisted together to form a round shape, and a braided shield and a sheath are further applied. This cable is used for signal transmission between electronic devices. ing. There is an advantage in that the devices can be connected using the one-touch pressure welding connector by the flat fusion-bonding portion located in this cable.

[0004]

However, since this flat round cable uses a PVC compound for the insulating core, it has a drawback that the impedance is small, that is, the signal propagation speed is slow.

Further, the insulating core has a low dielectric constant, that is,
When polyethylene or fluorocarbon resin with high impedance is used, when it is molded into a flat shape by heat fusion, when high-frequency current is used, self-heating is insufficient due to the low dielectric constant and the adhesion between the cores becomes incomplete. The problem of being sufficient occurs.

Further, when a hot roll is used, there is a drawback that the melt viscosity becomes high and a predetermined line pitch or shape cannot be obtained.

[0007]

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide a high-impedance flat round cable.

[0008]

The gist of the present invention is to increase the impedance by using polyethylene, foamed polyethylene, or a fluororesin for the inner layer as a cable insulator.
That is, by improving the signal propagation speed and using a PVC compound for the skin (outer layer), the thermoforming process is facilitated as usual.

By using a PVC compound for the outer layer, the fusion force between the cores is strengthened and the resin flow is appropriate, so that a stable pitch between the cores can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A specific embodiment of the present invention is shown in FIG.

Reference numeral 5 is a conductor, 1 is foamed polyethylene used as an inner layer, 2 is a PVC compound used as an outer layer, 3 is a shield braid, and 4 is a sheath.

The insulated core can be manufactured by extruding the foamed polyethylene of the inner layer using a main body extruder and extruding the PVC compound of the outer layer using a sub-extruder.

The wall thickness ratio between the inner layer and the outer layer can be adjusted to any desired impedance.

A plurality of the insulated wire cores are arranged in parallel, and the outer PVC compound layer 2 is heat-sealed to form a flat shape and is formed into a round shape.

As the heat-sealing method, there is used a method of self-heating by using high frequency or a method of heat-sealing by using a heat roll. However, since PVC compound is used, the fusion between the cores is It is strong and a predetermined pitch between lines can be obtained.

The core may be heat-sealed over the entire length of the cable or at predetermined intervals in the lengthwise direction, and further, only at the ends of the cable. However, the point is that the structure can be connected by using the one-touch press-connecting connector at the heat-sealing portion, and the terminal processing work is rationalized.

When the heat-sealing portions are provided at predetermined intervals in the cable length direction, even if the cores between the heat-sealing portions are in a discontinuous state,
The twisted pair may be used, and the twisted pair has an advantage that the crosstalk characteristic is improved.

The shield 3 provided on the outer periphery of the flat core formed into a round shape is not limited to braiding, but may be a shield of a conventionally known type such as tape winding, and the sheath 4 is also conventionally known. It can be used as is.

[0019]

As described above, according to the present invention, in the interface cable for communication between devices, the conventional PVC compound insulation core is used instead of the PVC compound insulating core, which has a slow propagation speed.
By using a VC skin layer, polyethylene, foamed polyethylene, or a fluororesin insulator, an electronic device (eg.
(Computer) can accelerate the calculation speed, and the terminal processing work is easy, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a flat round cable of the present invention.

[Explanation of symbols]

 1 Foamed polyethylene inner layer insulator 2 PVC outer layer insulator 3 Shield braid 4 Sheath 5 Conductor

Claims (3)

[Claims] 1. A conductor, a low-dielectric-constant insulator provided on the outer periphery of the conductor, and a plurality of wire cores made of a PVC insulator skin provided on the outer periphery of the conductor are arranged in parallel, and the insulator skin is heated. A flat cable characterized by being formed into a flat shape by fusing, forming the flat wire core into a round shape, and then providing a protective sheath in the outermost layer. 2. The flat cable according to claim 1, wherein the flat core comprises heat-sealing portions provided at predetermined intervals in the longitudinal direction. 3. The flat cable according to claim 2, wherein the non-fused cores between the heat-fused portions provided at predetermined intervals are twisted in pairs.