JP2021073657A - Two-core parallel cable - Google Patents

Abstract

To provide a two-core parallel cable which can make output quantity (Scd21) of common mode for an input signal of a differential mode small in a transmission of a differential signal.SOLUTION: A two-core parallel cable 1 comprises: a pair of insulated wire 2 having an insulating layer 22 around a conductor 21; a coating resin layer 3 contacting with the pair of insulated wire 2 and collectively coating the insulated wire; and a shield layer 4 arranged by contacting with the coating resin layer outside of the coating resin layer 3 and including a metal layer 4a. The insulated wire 2 contacts each other, is not twisted and is arranged parallel, and the coating resin layer 3 is pushed resin.SELECTED DRAWING: Figure 2

Description

The present invention relates to a two-core parallel cable.

For example, Patent Document 1 discloses a configuration in which a stranded wire of a pair of insulated electric wires is extruded and covered, and a drain wire or a shield tape is wound around the stranded wire. Further, Patent Document 2 includes a multi-core cable in which a metal tape is vertically attached with two insulated wires and drain wires arranged in parallel, and a resin is extruded to the outside of the metal tape to form a coating. It is disclosed.

U.S. Pat. No. 8,981216 Japanese Unexamined Patent Publication No. 2015-72772

In the transmission of Scd21, if the positional relationship between the shield layer and the two insulated wires deviates in the length direction of the cable, the impedance of the cable may change in the length direction. Due to such a change in the impedance of the cable, the output amount (Scd21) in the common mode with respect to the input signal in the differential mode may increase.

An object of the present invention is to provide a two-core parallel cable capable of reducing the output amount (Scd21) of the common mode with respect to the input signal of the differential mode in the transmission of the differential signal.

The two-core parallel cable according to one aspect of the present invention includes a pair of insulated electric wires having an insulating layer around a conductor.
A coated resin layer that is in contact with the pair of insulated wires and collectively covers the insulated wires.
A shield layer that is arranged on the outside of the coating resin layer in contact with the coating resin layer and includes a metal layer,
With
The insulated wires are arranged in parallel without being twisted in contact with each other, and the resin is extruded from the coated resin layer.

According to the present invention, in the transmission of a differential signal, the output amount (Scd21) of the common mode with respect to the input signal of the differential mode can be reduced.

It is a perspective view which shows the structure of the two-core parallel cable which concerns on 1st Embodiment. It is sectional drawing which is orthogonal to the length direction of the two-core parallel cable of FIG. It is a perspective view which shows the structure of the two-core parallel cable which concerns on 2nd Embodiment. It is sectional drawing which is orthogonal to the length direction of the two-core parallel cable of FIG. It is sectional drawing which is orthogonal to the length direction of the two-core parallel cable of the second embodiment. It is sectional drawing which is orthogonal to the length direction of the two-core parallel cable of the comparative example. It is a simulation result (Scd21) of Examples 1 and 2 and a comparative example. It is a simulation result (Sdd21) of Examples 1 and 2 and a comparative example.

[Explanation of Embodiments of the Present Invention]
First, embodiments of the present invention will be listed and described.
The two-core parallel cable according to the embodiment of the present invention
(1) A pair of insulated wires having an insulating layer around the conductor,
A coated resin layer that is in contact with the pair of insulated wires and collectively covers the insulated wires.
A shield layer that is arranged on the outside of the coating resin layer in contact with the coating resin layer and includes a metal layer,
With
The insulated wires are arranged in parallel without being twisted in contact with each other, and the resin is extruded from the coated resin layer.
Since the pair of insulated wires are covered with the coated resin layer, the insulated wires are not easily displaced from each other, and the positional relationship with the shield layer arranged outside the coated resin layer is stable. Therefore, the impedance of the two-core parallel cable is less likely to change in the cable length direction. As a result, the two-core parallel cable having the above configuration can reduce the output amount (Scd21) of the common mode with respect to the input signal of the differential mode in the transmission of the differential signal.

(2) The coated resin layer covers the insulated wire with the insulating layer without any gap.
Since the pair of insulated wires are covered with the coated resin layer without gaps, the insulated wires are less likely to be displaced from each other.

(3) A resin having different characteristics from the first resin constituting the coating resin layer and the second resin constituting the insulating layer of the insulated electric wire.
The first resin has higher mechanical strength than the second resin.
The second resin has a smaller dielectric constant than the first resin.
Since the resin of the coating resin layer has high mechanical strength, it is possible to easily protect the insulating electric wire inside. Further, since the insulating layer of the insulated wire is a resin having a small dielectric constant, it is possible to easily adjust the electrical characteristics between the conductors of the insulated wire to a desired value. Further, the insulating layer between the conductors of the insulated electric wire can be thinned.

(4) It has a drain wire arranged so as to be in electrical contact with the metal layer of the shield layer.
By connecting the drain wire to the external ground terminal, the shield layer of the two-core parallel cable can be easily grounded.

(5) The drain wire is on the outside of the shield layer.
The shield layer can adhere to the resin coating layer, and the impedance is stable.

(6) It has an insulating jacket layer provided outside the shield layer and the drain wire.
By providing an insulating jacket layer on the outside of the shield layer and the drain wire, the shield layer can be insulated, the mechanical strength of the cable can be increased, and the cable can be made water resistant.

[Details of Embodiments of the present invention]
Specific examples of the two-core parallel cable according to the embodiment of the present invention will be described below with reference to the drawings.
It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

(First Embodiment)
As shown in FIGS. 1 and 2, the two-core parallel cable 1 includes a pair of insulated wires 2 that are in contact with each other and are arranged in parallel without being twisted, and a coated resin layer that covers the pair of insulated wires 2. It is equipped with 3. The coating resin layer 3 is in contact with the insulating electric wire 2.
Further, the two-core parallel cable 1 includes a shield layer 4 outside the coating resin layer 3, a drain wire 5 arranged outside the shield layer 4, and a jacket provided around the shield layer 4 and the drain wire 5. It has a layer 6.

The insulated wire 2 is composed of a signal conductor (conductor) 21 provided at the center and an insulating layer 22 that covers the periphery of the signal conductor 21. The signal conductor 21 is, for example, a single wire or a stranded wire formed of a conductor such as copper or aluminum, a conductor plated with tin or silver, or the like. The insulating layer 22 is made of, for example, LDPE (low density polyethylene) resin or the like.
The dimensions of the conductor used for the signal conductor 21 are, for example, AWG38 to AWG22 in the AWG (American Wire Gauge) standard. The insulating layer 22 is made of, for example, polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), fluororesin, or the like. The outer diameter of the insulated wire 2 is, for example, about 0.3 mm to 3.0 mm, and for example, when the signal conductor 21 of the AWG 30 is used, it is about 0.9 mm.

The coating resin layer 3 is formed so as to integrally cover a pair of insulated electric wires 2 by, for example, full extrusion molding. In this full extrusion molding, for example, the insulating layer 22 of the insulated wire 2 and the molten HDPE (high density polyethylene) resin to be the coating resin layer 3 are pressed in a mold (not shown). Molding is performed by bringing them into contact with each other and extruding them from the mold. By performing full extrusion molding, as shown in FIG. 2, the pair of insulated wires 2 are brought into close contact with the coated resin layer 3 in a state of being in close contact with each other without any gaps.

The resin constituting the coating resin layer 3 (hereinafter, also referred to as a second resin) can be a resin of a different type from the resin constituting the insulating layer 22 (hereinafter, also referred to as a first resin). For example, the above-mentioned second resin can be a resin having different electrical characteristics, mechanical strength, and the like from the first resin.

For example, the first resin may have a higher mechanical strength than the second resin, and the second resin may have a smaller dielectric constant than the first resin. For example, the first resin is a low-density polyethylene (LDPE) resin having excellent electrical characteristics, and the second resin is a high-density polyethylene (HDPE) resin having excellent mechanical strength. In this case, since the second resin (resin of the coating resin layer 3) has high mechanical strength, it is possible to easily protect the internally insulated electric wire 2. Further, since the first resin (resin of the insulating layer 22) is a resin having a small dielectric constant, it is possible to easily adjust the electrical characteristics between the signal conductors 21 of the pair of insulated wires 2 to a desired value.

As the first resin and the second resin, resins other than those described above may be used, and by appropriately adjusting the materials of the first resin and the second resin, the electrical characteristics of the two-core parallel cable 1 and the machine The specific characteristics, outer diameter, etc. can be adjusted to the desired ones.

The first resin and the second resin may be the same type of resin. In this case, since it is sufficient to prepare a single resin, the cost can be lower than that of preparing each of a plurality of types of resins.

The shield layer 4 is formed of a resin tape with a metal layer in which a metal layer 4a such as copper or aluminum is adhered or vapor-deposited on a resin tape such as PET.
The thickness of the shield layer 4 is, for example, about 10 μm to 50 μm, and the thickness of the metal layer 4a is, for example, about 0.1 μm to 20 μm. As the shield layer 4, for example, a metal tape having metal on both sides or a resin tape with a metal layer having metal tapes attached or vapor-deposited on both sides of the resin tape may be used.
The shield layer 4 is wound vertically on the outside of the coating resin layer 3, for example. It is preferable that the vertically attached shield layer 4 has an adhesive attached to the overlapping portion. The overlapping part is fixed with an adhesive to maintain the rolled shape. Further, the shield layer 4 is wound so that the metal layer 4a is arranged on the outside.

For example, in the examples shown in FIGS. 1 and 2, the drain wires 5 are vertically attached to the left and right lateral sides in a direction orthogonal to the length direction of the two-core parallel cable 1 (horizontal direction in FIG. 2). The position where the drain wire 5 is vertically attached may be a position other than the horizontal side surface. In the cross-sectional view shown in FIG. 2, it is preferable to arrange the two drain wires 5 at positions symmetrical with respect to the center of the cable. Further, the number of drain wires 5 may not be two, but may be only one or three or more, as in the examples shown in FIGS. 1 and 2. The drain wire 5 is provided so as to be in electrical contact with the metal layer 4a. In the examples shown in FIGS. 1 and 2, the drain wire 5 is arranged outside the shield layer 4. When the drain wire 5 is arranged inside the shield layer 4, the metal layer 4a is arranged inside the shield layer 4. The outer diameter of the drain wire 5 is, for example, about 0.08 mm to 0.8 mm.

By connecting the drain wire 5 to an external ground terminal or the like of the two-core parallel cable 1, the shield layer of the two-core parallel cable 1 can be easily grounded. When the drain wire is arranged outside the shield layer 4, the shield layer 4 can be brought into close contact with the coating resin layer 3, and the impedance of the two-core parallel cable 1 stabilizes in the length direction of the cable.

The jacket layer 6 is, for example, an insulating layer formed by winding a resin tape such as PET or PVC. The jacket layer 6 may be formed of a plurality of layers. Further, the jacket layer 6 may be formed by extrusion molding a thermoplastic resin such as polyethylene, polyvinyl chloride, or fluororesin.

According to the two-core parallel cable 1 of the first embodiment, since the pair of insulated wires 2 are covered with the coated resin layer 3, the insulated wires 2 are not easily displaced from each other and are arranged outside the coated resin layer 3. The positional relationship with the shield layer 4 is stable. Therefore, the impedance of the two-core parallel cable 1 is less likely to change in the cable length direction. As a result, the two-core parallel cable 1 can reduce the output amount (Scd21) of the common mode with respect to the input signal of the differential mode in the transmission of the differential signal.
Further, by performing full extrusion molding, the pair of insulated wires 2 are in close contact with the coated resin layer 3 in a state of being in close contact with each other, so that the insulated wires are less likely to be displaced from each other.

A coupled cable such as the two-core parallel cable 1 has an impedance Z1 between a pair of signal lines (signal conductor 21) and impedances Z2 and Z3 with respect to the ground (shield layer 4) of each signal line (signal conductor 21). , The characteristic impedance is determined. That is, by adjusting the impedances Z1, Z2, and Z3 described above, the characteristic impedance of the two-core parallel cable 1 can be set to a predetermined value (for example, 100Ω). In this embodiment, since the coating resin layer 3 is provided between the insulating layer 22 and the shield layer 4 of the insulated wire 2, the impedances Z2 and Z3 between the signal conductor 21 and the shield layer 4 are the insulating layer. Even if 22 is made thinner, it can be made larger by compensating (for example, making it thicker) with the coating resin layer 3. If the insulating layer 22 is made thin, the signal conductors 21 can be brought close to each other, so that the electromagnetic field-like coupling (coupling) between the signal conductors 21 can be strengthened and the transmission characteristics can be improved.

Further, the two-core parallel cable 1 has less loss of high-frequency signals and is excellent in high-frequency transmission characteristics as compared with a cable in which a pair of insulated wires are twisted, such as the cable disclosed in Patent Document 1.

Further, when the insulating jacket layer 6 is provided on the outside of the shield layer 4 and the drain wire 5, the shield layer 4 can be insulated, the mechanical strength of the cable is increased, and the cable is water resistant. It can be a two-core parallel cable 1.

(Second Embodiment)
As shown in FIGS. 3 and 4, the two-core parallel cable 11 includes a pair of insulated wires 2 that are in contact with each other and are arranged in parallel without being twisted, and a coated resin layer that covers the pair of insulated wires 2. It is equipped with 13.
Further, the two-core parallel cable 11 includes a shield layer 4 outside the coating resin layer 13, a drain wire 5 arranged outside the shield layer 4, and a jacket provided around the shield layer 4 and the drain wire 5. It has a layer 6.
Since the parts having the same numbers as those in the first embodiment described above have the same configuration, the repeated description will be omitted.

The coating resin layer 13 of the second embodiment is formed so as to integrally cover the pair of insulated electric wires 2 by, for example, pull-down extrusion molding. In this withdrawal extrusion molding, for example, the molten HDPE (high density polyethylene) resin or the like to be the coating resin layer 13 is reduced in diameter after leaving the mold (not shown) to form the insulating layer 22 of the insulated wire 2. Molding is performed so that it comes into contact with the outside of the mold. By performing such pull-down extrusion molding, the pair of insulated wires 2 are in close contact with the coated resin layer, but as shown in FIG. 4, there is a gap in a part between the pair of insulated wires 2 and the coated resin layer 13. Is generated.

Similar to the coating resin layer 3 of the first embodiment, the resin constituting the coating resin layer 13 may be a resin of a different type from the resin constituting the insulating layer 22, and the combination thereof and the like may be the first embodiment. Can be similar to.
Further, as in the first embodiment, the resin constituting the coating resin layer 13 and the resin of the insulating layer 22 may be the same type of resin.

According to the two-core parallel cable 11 of the second embodiment, the same effect as that of the first embodiment described above can be obtained.

The analysis results of Scd21 and Sdd21 in the two-core parallel cable of Examples and Comparative Examples will be described.
Note that Scd 21 is the amount of conversion from the operation mode to the common mode in port 1 (one signal conductor 21) to port 2 (the other signal conductor 21), and is one of the mixed mode S parameters.
Further, Sdd 21 is an output amount when both ends of port 1 (one signal conductor 21) and port 2 (the other signal conductor 21) are in differential mode (when used in normal balanced transmission).

(Example 1)
The configuration of the two-core parallel cable 1 of the first embodiment is the configuration of the first embodiment shown in FIGS. 1 and 2, and is set as follows.
Two insulated wires 2 having a diameter of 0.96 mm and having a signal conductor 21 of AWG28 (conductor cross-sectional area 0.089 mm ^{2) were arranged in parallel.} The thickness of the insulating layer 22 of the insulated wire 2 and the thickness of the coating resin layer 3 were set so that the characteristic impedance of the two-core parallel cable 1 was 100Ω.
The shield layer 4 provided with the copper metal layer 4a was vertically attached around the coating resin layer 3 so that the metal layer 4a was arranged on the outside. The drain wire 5 was vertically attached and arranged outside the shield layer 4. An insulating tape was spirally wound around the shield layer 4 and the drain wire 5 to form a jacket layer 6.
A simulation of transmitting a high frequency signal of 1 GHz to 20 GHz was carried out for the two-core parallel cable 1 having the above configuration, and Scd21 and Sdd21 were obtained.

(Example 2)
The two-core parallel cable 1A of the second embodiment has a configuration in which the distance between the signal conductors is 40% closer than that of the two-core parallel cable 1 of the first embodiment (the form shown in FIG. 5).
The signal conductor 21A of the insulated wire 2A has the same size as that of the first embodiment. The thickness of the insulating layer 22A and the thickness of the coating resin layer 3A were set so that the characteristic impedance of the two-core parallel cable 1A was 100Ω. Other configurations were the same as those in Example 1.
A simulation of transmitting a high frequency signal of 1 GHz to 20 GHz was carried out for the two-core parallel cable 1A having the above configuration, and Scd21 and Sdd21 were obtained.

(Comparison example)
As shown in FIG. 6, the two-core parallel cable 31 of the comparative example has a configuration that does not have a coating resin layer. Therefore, the shield layer 34 is directly wound around the insulating layer 322 of the insulated wire 32 with vertical attachment (Note that 34a is a metal layer). The structure of the drain wire 5 and the jacket layer 6 is the same as that of the first embodiment. The signal conductor 321 of the insulated wire 32 has the same size as that of the first embodiment.
A simulation of transmitting a high frequency signal of 1 GHz to 20 GHz was carried out for the two-core parallel cable 31 having the above configuration, and Scd21 and Sdd21 were obtained.

The results of the frequency characteristics of Scd21 and Sdd21 obtained in the simulations of Examples 1 and 2 and Comparative Examples were compared (see FIGS. 7 and 8).
As shown in FIG. 7, Scd21 obtained better results in Examples 1 and 2 than in Comparative Examples. For Scd21, Examples 1 and 2 are preferable to Comparative Examples.

As described above, the two-core parallel cables 1 and 1A can make Scd21 smaller (improve the transmission characteristics) than the two-core parallel cable having a configuration that does not have a coating resin layer.
Further, when the signal conductors are brought close to each other as in the two-core parallel cable 1A, the electromagnetic field-like coupling (coupling) between the signal conductors becomes stronger, and as shown in FIGS. 7 and 8, more about Scd21 and Sdd21. The transmission characteristics can be improved.

For example, in the case of a two-core parallel cable in which a pair of insulated wires are twisted, such as the cable disclosed in Patent Document 1, the configuration having a coated resin layer may be the same as in Examples 1 and 2. The Scd value of Examples 1 and 2 is better. Further, the value of Sdd is also better in Examples 1 and 2 than in the two-core parallel cable in which the pair of insulated wires are twisted. That is, the two-core parallel cables 1, 1A are superior in high-frequency transmission characteristics to the cable two-core parallel cable in which a pair of insulated wires are twisted.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Further, the number, position, shape and the like of the constituent members described above are not limited to the above-described embodiment, and can be changed to a number, position, shape and the like suitable for carrying out the present invention.

1,11 Two-core parallel cable 2 Insulated wire 3,13 Coated resin layer 4 Shield layer 4a Metal layer 5 Drain wire 6 Jacket layer 21 Signal conductor
22 Insulation layer

Claims (5)

A pair of insulated wires with an insulating layer around the conductor,
A coated resin layer that is in contact with the pair of insulated wires and collectively covers the insulated wires.
A shield layer that is arranged on the outside of the coating resin layer in contact with the coating resin layer and includes a metal layer,
A pair of drain wires that are in electrical contact with the metal layer of the shield layer,
With
The insulated wires are in contact with each other and arranged in parallel.
A gap is provided between the pair of insulated wires and the coated resin layer.
The cross-sectional shape of the outer periphery of the coating resin layer is a shape composed of two arc portions bulging in the outward direction of the coating resin layer and a straight portion connecting between the two arc portions.
The pair of drain wires are provided outside the metal layer without contacting the pair of insulated wires, and come into contact with the metal layer at positions on the outer periphery of each of the two arc portions.
Two-core parallel cable. The shield layer is vertically attached to the outside of the coating resin layer.
The overlapping portion of the shield layer is provided on a straight line perpendicular to the straight line connecting the centers of the pair of insulated wires and passing through the center between the pair of insulated wires in a cross-sectional view.
The two-core parallel cable according to claim 1. The first resin constituting the coating resin layer has higher mechanical strength than the second resin constituting the insulating layer of the insulated wire.
The second resin has a smaller dielectric constant than the first resin.
The two-core parallel cable according to claim 1 or 2. It has an insulating jacket layer provided outside the shield layer and the drain wire.
The two-core parallel cable according to any one of claims 1 to 3. The pair of drain wires are provided at positions symmetrical with respect to the center of the two-core parallel cable in a cross-sectional view.
The two-core parallel cable according to any one of claims 1 to 4.

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