JPH04102511U - multi-pair cable - Google Patents

Abstract

(57) [Summary] [Purpose] A multi-pair cable that does not reduce the characteristic impedance by increasing the distance between adjacent core wires even if the diameter of the twisted pair wires is reduced. [Structure] Two wire cores (core wires) each having a conducting wire 3 covered with an insulator 4 are lined up, and a jacket portion 6 is formed by covering the outside with PVC or polyester tape. , 5 is reduced, and even if the core wires 5, 5 have a small diameter, the distance B between the center points of the conducting wires 3, 3 is kept large.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to improvements in multi-pair cables with shielding layers.

0002

[Conventional technology]

Generally, a multi-pair cable as shown in FIG. 3, which uses a large number of twisted pair wires, is used for interface signal connections between electronic device terminals, particularly between computers. This multi-pair cable 10 has a configuration in which seven pairs of twisted wires 16 are assembled, each consisting of a conducting wire 12 coated with an insulator 14 and wire cores 15, 15 twisted in pairs, and a shielding layer 8 and a sheath layer 9 are sequentially provided thereon. It becomes. This type of multi-pair cable 10 matches the characteristic impedance Z ₀ of each twisted wire pair 16 with the characteristic impedance Z ₁ of each connected device to improve transmission quality, thereby reducing reflections, attenuation, etc. It's supposed to be suppressed.

This characteristic impedance Z ₀ can be calculated by first finding the characteristic impedance Z _A of the two stranded wires using equation (1), assuming that the diameter of the conductor 12 is d and the distance between the conductors 12 is B (see FIG. 4). ,

0004

[Math 1]

Next, the characteristic impedance Z ₀ of the multi-pair cable 10 is determined using equation (2).

Z ₀ = [0.65-0.3exp (-0.22n)] Z _A [Ω] ... (2) where, n: Logarithm (N≧2) Z _A : Two-strand twist without shielding The characteristic impedance of the wire (twisted wire pair 16), that is, the characteristic impedance _Z0 , increases or decreases depending on the distance B between the conductive wires 12, 12 and the dielectric constant _{ε e} of the insulator 14.

[0007]

[Problem that the idea aims to solve]

Generally, the characteristic impedance Z ₁₀ of a transmission path is 75 [Ω], but in recent years, for example, the small computer system (SCSI) interface standard, that is, the high impedance Z _x =100 ± 10 [Ω] has been standardized. Therefore, it is necessary to increase the characteristic impedance Z ₀ of the multi-pair cable 10 to meet this standard. However, in recent years, small-sized connectors (half-pitch connectors) have become mainstream for connections between devices, and in order to realize this, it is necessary to reduce the diameter of the wire core (core wire) 15.

[0008] The SCSI interface standard specifies that conductor diameter d = 28 AWG (0.8 mm ² ) or more, characteristic impedance Z ₀ = 100 ± 10 [Ω] core wire outer diameter = 0.9 mm or less, and twisted wire pairs = 25 pairs. It is being However, even if the diameter d of the conductor 14 in the multi-pair cable 10 is 28 AWG and the diameter of the core wire 15 is 0.9 mm, the characteristic impedance Z ₀ is only 70 to 80 Ω. In other words, when the diameter is made smaller, the characteristic impedance Z ₀ becomes smaller, and to prevent this, reducing the dielectric constant ε _e of the insulator 14 (increasing the degree of foaming) reduces the strength of the core 15 . Therefore, the configuration of the multi-pair cable 10 described above has the disadvantage that it is not possible to provide a multi-pair cable 10 with high impedance such as the SCSI interface standard that satisfies sufficient electrical characteristics (impedance matching) and mechanical strength. .

[0009]

[Purpose of invention]

The present invention improves the disadvantages of the conventional example and provides sufficient electricity with a relatively simple configuration. To provide a high impedance multi-pair cable with good characteristics and mechanical strength. aimed to.

0010

[Means to solve the problem]

Therefore, in this invention, two core wires are twisted together and an insulating layer is provided on the outside of the jacket. The structure consists of a plurality of twisted pair wires and a shielding layer and a sheath layer on the outside. The aim is to achieve the above objectives.

[0011]

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Here, the same reference numerals are given to the same constituent members as in the above conventional example. The multi-pair cable 1 shown in FIG. 1 has a structure in which 19 pairs of twisted wire pairs 7 are assembled, and a shielding layer 8 and a sheath layer 9 are provided thereon. Specifically, this twisted wire pair 7 has a structure in which two wire cores (core wires) in which the conductor wire 3 is covered with an insulator 4 are lined up, and the outer side of the core wire is covered with PVC or polyester tape to form a jacket portion 6. It becomes. That is, each twisted wire pair 7 is a jacketed twisted wire pair each having a jacket portion 6. According to this embodiment, the multi-pair cable conforms to the SCSI interface standard, which requires a high impedance of around 100 [Ω], and is compatible with a half-pitch connector, so the diameter of the core wire 5 must be reduced. However, due to the function of the jacket part 6, when considering the characteristic impedance _Z0 of the twisted wire pair 7 in layer A as shown in FIG. 6, one wire core 15 of the twisted wire pair 7 in each layer is grounded. Even so, compared to FIG. 5, the distance 2a is twice the wall thickness a of the jacket part 6, and the distance from the ground wire of each adjacent layer is set apart to avoid being affected by the ground wire. A decrease in characteristic impedance Z ₀ can be prevented, and as a result, a multi-pair cable 1 with high impedance can be provided.

0012 Note that the number of twisted pairs 7 constituting the multi-pair cable 1 is not particularly limited. These multi-pair twisted wire groups may be twisted together or twisted in each layer.

[0013]

[Effect of the idea]

Since the present invention is configured as described above, it can be said that the configuration is relatively simple. , which has high impedance without reducing electrical properties and mechanical strength. Can provide twin cables.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of a multi-pair cable according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of twisted wire pairs forming a part of FIG. 1;

FIG. 3 is a cross-sectional configuration diagram of a multi-pair cable according to a conventional example.

FIG. 4 is an explanatory diagram of twisted wire pairs forming a part of FIG. 3;

FIG. 5 is an explanatory diagram of a conventional multi-pair cable.

FIG. 6 is an explanatory diagram of the multi-pair cable of the present invention.

[Explanation of symbols]

１……Multi-pair cable ３……Conducting wire 4……Insulator 5... Core wire 6……Jacket part 7......Twisted wire 8......shielding layer 9...Sheath layer

Claims (1)

[Scope of utility model registration request] 1. A multi-pair cable comprising two twisted core wires, a plurality of jacketed twisted wires each having an insulating layer provided on the outside thereof, and a shielding layer and a sheath layer provided on the outside thereof.