JPH04102513U - multi-pair cable - Google Patents

Abstract

(57) [Summary] [Objective] To provide a multi-pair cable that can increase characteristic impedance without making use of the electrical characteristics and mechanical strength of conventional multi-pair cables. [Structure] Wire core (core wire) in which conductor 2 is covered with insulator 3
5, 5 are connected via a contact prevention member (bridge portion) 4 having a function of separating the core wires 5, 5 by a predetermined distance, and three pairs of insulated wires 6 are arranged around the twisted pair insulated wires 6, which are made by twisting the insulated wires 5A. 8 pairs of twisted pair insulated wires 6 are arranged outside the first layer A to form a second layer B, and 14 pairs of twisted pair insulated wires 6 are arranged outside the first layer A.
A press-wound tape (press-wound layer ) 7 is wound, a shielding layer 8 made of a braid is provided thereon, and a sheath layer 9 is provided outside the shielding layer 8.

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, for interface signal connections between electronic equipment terminals, especially between computers. A multi-pair cable as shown in FIG. 5, which uses a large number of twisted pair wires, is used. This multi-pair cable 10 has a wire core (core wire) 1 in which a conducting wire 12 is covered with an insulator 14. The first layer A is formed by arranging three pairs of twisted pair insulated wires 17, which are twisted pairs of wires 5 and 15. Eight pairs of twisted insulated wires 17 are arranged on the outside to form the second layer B, and 14 pairs of twisted wires are arranged on the outside. 25 pairs of twisted insulated wires 17, 17, formed by arranging twisted insulated wires 17 to form the third layer C; ..., 17, a presser winding tape (presser Winding layer) 7 is wound, a shielding layer 8 made of braid is provided on it, and a sheath layer is placed on the outside of the shielding layer 8. The configuration includes 9.

In general, the characteristic impedance Z ₀ of this type of multi-pair cable 10 is given by the characteristic impedance Z A of two stranded wires, assuming that the diameter of the conductor 12 is d and the distance between the conductors 12 is B (see FIG. 4 _). is calculated using equation (1),

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 It can be said that the characteristic impedance of the wire (twisted wire pair 16), that is, the characteristic impedance Z ₀ , increases or decreases depending on the distance B between the conducting wires 12, 12 and the relative dielectric constant ε _{e of} the insulator 14.

[0007] Therefore, the diameter of the conductor wire 12 of this multi-pair cable 10 is set to 28AWG, and the diameter of the conductor wire 12 of this multi-pair cable 10 is If the diameter is 0.58mm, as shown in Table 1,

[0008]

[Table 1]

[0009]The characteristic impedance Z ₀ is 40 to 60Ω.

Specifically, the characteristic impedance Z 0 of the twisted pair insulated wire 17 in the third layer C near the shielding layer 8 is 40 to 50Ω, and the characteristic impedance Z ₀ of the twisted pair insulated wire 17 in the first layer A in the center is ₄₀ to 50Ω. is 45 to 55Ω, and the characteristic impedance Z ₀ of the twisted pair insulated wire 17 of the second layer B is 55 to 60Ω.

[0011]

[Problem that the idea aims to solve]

In recent years, for example, the small computer system (SCSI) interface standard, that is, _the high impedance _Z There is an urgent need to change. 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. The SCSI interface standards are as shown in Table 2.

0012

[Table 2]

[0013] The conductor diameter d is set to be 28 AWG (0.8 mm ² ) or more, the characteristic impedance Z ₀ =100±10 [Ω], the core wire outer diameter = 0.9 mm or less, and the number of twisted wire pairs is 25. However, as shown in Table 1 above, even if the multi-pair cable 10 has a conductor 12 diameter d of 28 AWG and a core wire 15 diameter of 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 in order to prevent this, reducing the dielectric constant ε _e of the insulator 14 (increasing the degree of foaming) reduces the strength of the core wire 15. In addition, the insulator 14 is crushed under the influence of external pressure when the paired core wires 15, 15 are twisted together, and as a result, the distance B between the conductors 12, 12 is reduced. 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, which satisfies sufficient electrical characteristics (impedance matching) and mechanical strength.

[0014]

[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.

[0015]

[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 wrapping layer, a shielding layer and a sheath layer are respectively provided. , the stranded wire pairs are in contact to prevent contact of each core wire between opposing insulating layers of each core wire. The above objective is achieved by adopting a configuration in which the devices are connected via a preventing member. It is intended to be

[0016]

【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. , 5 as shown in the figure, the contact prevention function has the function of separating each core wire 5, 5 by a predetermined distance. The twisted pair insulated wire 6 is made by twisting the insulated wires 5A connected via the member (bridge part) 4. Three sets of twisted wires are arranged in the core to form the first layer A, and eight sets of twisted pair insulated wires 6 are arranged on the outside of the first layer A to form the second layer A. A third layer C is formed by forming layer B, and arranging 14 pairs of twisted pair insulated wires 6 on the outside thereof. The outside of the three-layer twisted pair insulated wire group 11 consisting of 25 pairs of twisted pair insulated wires 6, 6, ..., 6 A pressing tape (pressing wrapping layer) 7 is wound on the side, and a shielding layer 8 made of braid is placed on top of the pressing tape (pressing wrapping layer) 7. is provided, and a sheath layer 9 is provided on the outside thereof.

As shown in FIG. 3, this insulated wire 5A is designed so that the following equation (3) holds, where W is the width in the horizontal direction and d is the outer diameter of the core wire 5. good. 0≦W≦d...(3) This is because if the length of the bridge portion 4 is made relatively short, the distance B between the conductors 2, 2 in the length direction can be kept at a constant value when twisted in pairs. As a result, the value of characteristic impedance Z ₀ becomes uniform and high characteristic impedance can be achieved, and the pitch between the core wires 5, 5 can be maintained at a constant interval in the length direction during terminal processing. This is because the connector pressure welding work becomes easier.

If the width in the horizontal direction is W and the outer diameter of the core wire 5 is d, W>d (4), then when the wires are twisted in pairs as shown in FIG. 4, the bridge portion 4 will bend, The distance B between the conducting wires 2, 2 in the length direction cannot be maintained at a constant value, and as a result, the value of the characteristic impedance Z ₀ varies, resulting in a situation where high characteristic impedance cannot be achieved.

[0019]

[Effect of the idea]

Since the present invention is configured as described above, it can be said that the configuration is relatively simple. A multi-pair cable with high impedance and sufficient electrical properties and mechanical strength. can provide the following information.

[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 the configuration of FIG. 1;

FIG. 3 is an explanatory diagram of the insulated wire shown in FIG. 1.

FIG. 4 is an explanatory diagram of the insulated wire shown in FIG. 1.

FIG. 5 is a cross-sectional configuration diagram of a multi-pair cable according to a conventional example.

FIG. 6 is an explanatory diagram of the twisted pair insulated wire in FIG. 5;

[Explanation of symbols]

１……Multi-pair cable 2……Conducting wire 3……Insulator 4……Contact prevention member 5... Core wire 5A...Insulated wire 6......twisted insulated wire 7……Press roll layer 8......shielding layer 9...Sheath layer

Claims (1)

[Scope of utility model registration request] Claim 1: A multi-pair cable comprising a plurality of twisted pair wires each having two core wires twisted in pairs, and a pressure winding layer, a shielding layer, and a sheath layer provided on the outside thereof, wherein the twisted pair wires are A multi-pair cable, characterized in that each core wire is connected between opposing insulating layers via a contact prevention member that prevents each core wire from coming into contact with each other.