JPH0644831A - Computer interface cable - Google Patents

Abstract

(57) [Summary] [Purpose] To provide this type of interface cable for computers that is the thinnest and has the best handleability while predetermining the allocation of paired signals of high-speed response signals and other signals to ensure performance. Is what you are trying to do. [Structure] In a computer interface cable configured by arranging a large number of pair wires 11, 12, 13 in layers and sequentially applying a shield layer, a sheath, etc., the interface cable for a computer is assigned to transmit a signal requiring high-speed response. A high-foaming insulator (low-foaming polyolefin) having a low dielectric constant is used for the insulating coating of the paired wires 11, and a solid or low-foaming insulating material is used for the insulating coating of the paired wires allocated for signal transmission that does not require high-speed response. Using. A pair line allocated to the transmission of a signal requiring a high-speed response is arranged on the center layer side, and a pair line allocated to the transmission of a signal not requiring a high-speed response is provided outside with or without such a center layer. Arranged in layers.

Description

Detailed Description of the Invention

[0001]

This invention relates to SCSI (Small Compu
ter System Interface) A computer interface cable that conforms to the standard.

[0002]

Prior Art / Problems to be Solved by the Invention FIG.
It is an example of a computer interface cable having 25 pairs of pair wires provided as compliant with the SCSI standard. In FIG. 4, 1 is an insulating coating 3 on the conductor 2.
A pair wire in which the insulated cores obtained by applying the above are twisted in pairs, 4 is a press-wrap tape, 5 is an inner jacket or tape, 6 is a shield layer by braiding, and 7 is a sheath. Some cables that comply with the SCSI standard have 19 pairs of wire pairs.

In order to increase the reliability of the signal transmitted to each pair of wires, the characteristic impedance (Z ₀ ) of the cable may be increased, and most of them are 90 ohms or more, and preferably 1 or more.
It is sufficient if it is 00 ohms or more, but in order to obtain such a large impedance, the insulation coating should be thicker,
It is necessary to form the insulating coating with an insulator having a low dielectric constant (a material having a low dielectric constant, for example, polyolefin whose foaming degree is increased).

The inner jacket 5 separates the outermost pair of wires from the shield 6 to reduce the capacitance (Z ₀
It becomes large).

By the way, the following Table 1 shows SCSI.
The signal types and connections according to the standard are shown.

[0006]

[Table 1]

In Table 1, 19 kinds of signals are shown, but the characteristics required for these signals are not all equal. By the way, "AC
“K” and “REQ” (“ATN” is also better as soon as possible), “DB0” to “DB7” and “DBP” as signals requiring uniformity, and other signals.
A "G" in both the left and right columns indicates that the current standard does not carry a signal.

In the conventional cable of this type, the insulating coating on all the pair wires is designed to obtain a large impedance so that any pair wire can be assigned to high-speed response signal transmission. Was formed in.

However, thickening the insulation coating as in the above makes the outer diameter of the cable thicker and increases the weight, and when the insulation coating is made of a high foam insulation material having a low dielectric constant like As the core, the mechanical strength is unavoidably deteriorated, and in any case, the handleability of the cable is deteriorated.

In order to solve the above-mentioned problems of the prior art, the present invention determines the allocation of the high-speed response signal and the other signal to the paired wire in advance and secures the performance, and can be the thinnest and the handleability is good. This kind of computer interface cable is intended to be provided.

[0011]

A computer interface cable provided by the present invention has a low dielectric constant and a high dielectric constant in an insulating coating of a pair of wires which are assigned to the transmission of a signal requiring a high-speed response among a large number of pair wires. It is characterized in that a foamed insulator is used, and a solid or low-foamed insulator is used for the insulation coating of the pair wires allocated to the transmission of signals that do not require high-speed response.

A specific example of the paired wire insulator that transmits a signal requiring high-speed response is a high-foaming polyolefin, and a specific example of the paired wire insulator that transmits a signal that does not require a high-speed response is: Solid or low-foaming polyolefin or polyvinyl chloride. However, any insulating material comparable to them does not prevent its application.

A pair wire using a high-foam insulating material having a low dielectric constant is arranged on the center layer side as a portion allocated to the transmission of a signal requiring a high-speed response, and is allocated to the transmission of a signal not requiring a high-speed response. As a pair of wires made of solid or low-foamed insulation is placed in the outer layer with or without such a central layer, a decrease in mechanical strength cannot be avoided by using a high-foamed insulation. It is also a feature of the present invention that the paired wire is surrounded by a paired wire of solid or low-foamed insulation having higher mechanical strength.

When the SCSI standard consists of 25 pairs of wires, 2 or 3 pairs of wires assigned to the transmission of signals requiring high-speed response are arranged as a central layer, and the high-speed response is provided around them. It is practical that the 23 pairs of pair lines assigned to the transmission of the signal not required are arranged in layers as the middle layer and the outermost layer.

In the case of 19 pairs of pair wires in the same standard, two pairs of diagonal wires out of 6 pairs of wires arranged as a first layer around one pair of wires as a central axis. Allocate pair wires to the transmission of signals that require high-speed response,
It is practical to allocate the remaining 4 pairs of wires and 12 pairs of wires arranged as a second layer around the first layer for the transmission of signals that do not require high speed response.

[0016]

FIG. 1 is a first embodiment of a computer interface cable embodied by the present invention. In this embodiment, two pairs of pair wires 11 are arranged in the central layer, nine pairs of pair wires 12 are arranged in the middle layer, and 14 pairs of pair wires 13 are arranged in the outermost layer, and a total of 25 pairs of wires are held. It was made. In addition, 1 is a pair wire in which an insulating core formed by applying an insulating coating 3 on a conductor 2 is twisted, 4 is a holding tape, 5
Is an inner jacket or tape, 6 is a braided shield layer, and 7 is a sheath.

A signal requiring a high-speed response for the two pairs of the center-layer pair wires 11: "AC in Table 1"
K "(connector pin numbers 38, 37) and" REQ "
(Connector pin numbers 48, 47) shall be assigned.

Signals that do not require a high-speed response are assigned to 9 pairs of the paired wires 12 of the intermediate layer and 14 pairs of the paired wires 13 of the outermost layer. Signals required to be transmitted: "DB0" to "DB7" and "DBP" in Table 1 are assigned, and other signals are assigned to 14 pairs of the outermost layer pair lines 13.

The paired wires 11 in the center layer are made of high-foaming polyolefin, which is a high-foaming insulator having a low dielectric constant, as an insulating coating, and the characteristic impedance Z ₀ is 90 Ω or more, preferably 100 Ω or more. To do. Further, the pair wire 12 of the intermediate layer uses solid polyolefin or low-foaming polyolefin that is the same insulator material as the insulating coating, and the pair wire 13 of the outermost layer has solid polyolefin or low-foaming polyolefin as the insulating coating. Alternatively, polyvinyl chloride is used, and since their characteristic impedance is a low-speed signal, it is 90 or less, especially 8 or less.
It is less than 5 ohms.

FIG. 2 shows a second embodiment of a computer interface cable embodied by the present invention. In this embodiment, three pairs of pair wires 11 are provided in the center layer,
9 pairs of pair wires 12 in the middle layer and 13 pairs of wire pairs 13 in the outermost layer
They are arranged in pairs to hold a total of 25 pairs of wire pairs.

A signal requiring a high-speed response to the three pairs of the paired wires 11 in the central layer: "ACK" in Table 1.
(Connector pin numbers 38 and 37) and "REQ" (connector pin numbers 48 and 47) and signals for which higher speed transmission is desirable: "ATN" in Table 1 is assigned. Signals similar to those in the above-described embodiment are assigned to the nine pairs of the paired wires 12 in the intermediate layer. Other signals are assigned to the 13 pairs of the outermost pair of wires 13.

For the insulation coating on the pair wire 11 of the central layer, the insulation coating on the pair wire 12 of the intermediate layer, and the edge coating on the pair wire of the outermost layer, the same insulators as those in the above-mentioned embodiments are used. .

In each of the above embodiments, the signals requiring uniformity: "DB0" to "DB7" and "DBP" in Table 1 may be assigned to the outermost pair wire 13.

FIG. 3 shows a third embodiment of a computer interface cable embodied by the present invention. In the present embodiment, with the pair of pair wires 14 as the central axis, 6 pairs of the pair wires 15 are arranged around the center axis to form the first layer, and 12 pairs of the pair wires 16 are arranged around the pair wire 15 to form the second layer. It is formed and has a total of 19 pairs of wires.

For power supply to the central axis pair wire 145: "TERMMPWR" in Table 1 is assigned, and two pairs on the diagonal line out of the six pairs of the pair wires 15 of the first layer are required to have a high-speed response. Signal to be assigned: “ACK” and “REQ” in Table 1 are assigned. Remaining 3 pairs of 1st layer and 12 of 2nd layer
A signal to which a fast response is not required is assigned to the pair, and in particular, a signal that requires uniformity among 9 pairs out of 12 pairs of the second layer pair wires 16: "DB0" to "DB7" in Table 1.
And "DBP", and other signals are appropriately allocated to the remaining three pairs in the first layer and the other three pairs in the second layer.

In the paired wires 16 forming the first layer, the paired wires assigned for high-speed response signal transmission are made of high-foamed polyolefin, which is a high-foamed insulator having a low dielectric constant, and has a characteristic impedance Z. ₀ should be 90 ohms or more, preferably 100 ohms or more.
For the other pair wires, solid polyolefin, low-foamed polyolefin or polyvinyl chloride is used as an insulating coating, and their characteristic impedance is 90 or less, especially 85 ohm or less because of low-speed signals. Note that among the paired wires 17 of the second layer, 9 pairs allocated for transmitting signals requiring uniformity, it is preferable to use solid polyolefin or low-foamed polyolefin that is the same insulator material.

Since "TERMWR" is for power supply and the ground is not specified, it does not necessarily have to be a pair of wires, but may be a single wire core.

In any of the above examples, the "polyolefin" includes a cross-linking type, a flame-retardant type, and a cross-linking flame-retardant type. Further, “high foaming” includes a foaming degree of up to 70% and a foaming degree close to that. Furthermore, “low foaming” means a foaming degree of 40% or less (up to 20% at the minimum).

[0029]

According to the computer interface cable of the present invention as described above, the high-dielectric insulator having a low dielectric constant is used only for the pair wires assigned to the transmission of signals requiring high-speed response, The pair wires assigned to the transmission of signals that do not require high-speed response use solid or low-foaming insulators, and the insulation coating is graded according to the signal transmission speed. It is possible to provide a cable having a smaller outer diameter with the same performance as that of a conventional cable of this type using a high foam insulation having a low dielectric constant. By the way, in the case of the cable with shield braid of 25 × AWG, the finished outer diameter of the conventional cable is 11.3 cm, whereas the finished outer diameter of the cable of the present invention is 10.0 cm.
It was possible to reduce the outer diameter by 15%.

According to another characteristic of the present invention,
A pair of wires made of high-foam insulation is placed on the side of the center layer, and the wire is surrounded by a pair of wires made of solid or low-foam insulation, so the mechanical strength is relatively weak. The paired wires of the body are surely protected, and in combination with the above-mentioned outer diameter reduction, the handleability of the cable is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a computer interface cable according to a first embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view of a computer interface cable according to a second embodiment of the present invention.

FIG. 3 is an explanatory cross-sectional view of a computer interface cable according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional explanatory view of a conventional computer interface cable.

[Explanation of symbols]

 1 paired wire 2 conductor 3 insulating coating 4 presser wound tape 5 inner jacket or tape 6 shield by braid 7 sheath 11 paired wire forming the central layer 12 paired wire forming the middle layer 13 paired wire forming the outermost layer 14 central axis Paired wire 15 that forms the first layer 16 paired wire that forms the second layer 16

Claims (5)

[Claims] 1. An interface cable for a computer, which comprises a number of paired wires arranged in layers and a shield layer, a sheath, etc., successively applied, and a paired wire assigned for signal transmission requiring high-speed response. For computers characterized by using a low-dielectric-constant, high-foaming insulator for the insulation coating of the pair of wires, and using a solid or low-foaming insulation for the insulation coating of the pair wires allocated for signal transmission that does not require high-speed response Interface cable. 2. An insulator of a pair wire that transmits a signal requiring a high-speed response is made of a highly expanded polyolefin, and an insulator of a pair wire that transmits a signal that does not require a high-speed response is solid or low-foamed polyolefin or poly. The computer interface cable according to claim 1, which is made of vinyl chloride. 3. An interface cable for a computer, which is constructed by arranging a large number of paired wires in layers and sequentially providing a shield layer, a sheath, etc., which is low as a signal assigned for high-speed response. A pair wire using a high-foam insulator with a high dielectric constant is placed on the center layer side, and a pair wire using a solid or low-foam insulator is assigned as the one allocated for signal transmission that does not require high-speed response. An interface cable for a computer, which is arranged in the outer layer with or without it. 4. A signal which is composed of 25 pairs of wires and which has two or three pairs of wires allocated for transmission of a signal requiring a high speed response as a center layer and around which a high speed response is not required. 23. The computer interface cable according to claim 3, wherein 23 pairs of pair wires assigned to the transmission of the data are arranged in layers as an intermediate layer and an outermost layer. 5. A pair of diagonal pairs of two pairs of pairs consisting of 19 pairs of pairs and arranged around the pair of pairs as a central axis to form a first layer. Is assigned to the transmission of signals requiring high-speed response, and the remaining 4 pairs of pair lines and 12 pairs of pair lines arranged around the first layer to form the second layer are transmitted for signals not requiring high-speed response. The interface cable for a computer according to claim 3, which is assigned to the computer.