JPH04102510U - 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) in which a conductor wire 3 is covered with an insulator 4 are lined up, and an insulating tape 6 is placed on the outside along the longitudinal direction.
are attached vertically so as to have an S-shaped cross section, so that even if the core wires 5, 5 have a small diameter, the distance B between the center points of the conductive wires 3, 3 can be kept apart.

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.

[0003] This characteristic impedance Z ₀ is calculated by first finding the characteristic impedance ZA 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 Figure 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 the 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. There is an urgent need 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. ing. However, even if the diameter d of the conductor 14 of 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 will only be 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, we arrange multiple twisted pair wires made by twisting two core wires in pairs, and In a multi-pair cable in which a shielding layer and a sheath layer are provided, each core wire of each twisted pair is A structure is adopted in which an insulating tape is coated with an S-shaped cross section along the longitudinal direction. This aims 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. , a sheath layer 9 are provided. Specifically, this twisted wire pair 7 is made by covering the conducting wire 3 with an insulator 4 as shown in FIG. Line up two wire cores (core wires) 15 and attach insulating tape to the outside of them along the longitudinal direction. 6 are arranged vertically so as to form an S-shaped cross section. This twisted wire pair 7 is made of PVC or polyester in the process of twisting each core wire 5, 5 as a pair. It can be easily manufactured by covering it in an S-shape with an insulating tape such as L.

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. Even if the insulating tape 6 works, the distance B between the conductors 3, 3 of the core wires 5, 5 can be increased, reducing the strength of the insulator 4 (in order to lower the dielectric constant ε _e) . It is possible to provide a multi-pair cable 1 having a high characteristic impedance Z ₀ without the need to increase the degree of foaming. Note that the number of pairs of twisted wires 7 constituting the multi-pair cable 1 is not particularly limited and may be any number, and these multi-pair twisted wire groups may be twisted in groups or twisted in each layer. Further, according to this embodiment, by changing the thickness of the insulating tape 6, the value of the characteristic impedance _Z0 can be changed using core wires 5 of the same diameter.

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

FIG. 2 is a cross-sectional configuration diagram of a multi-pair cable according to an embodiment of the present invention.

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;

[Explanation of symbols]

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

Claims (1)

[Scope of utility model registration request] Claim 1: A multi-pair cable in which a plurality of twisted wire pairs each having two core wires twisted in pairs are arranged, and a shielding layer and a sheath layer are provided on the outside of the twisted wires, in which each core wire of each twisted wire pair is provided. A multi-pair cable characterized by being coated with an insulating tape having an S-shaped cross section along the longitudinal direction.